Brain Damage Exam 2
stroop test
a standard measure of effortful control over responses, patients given words in different inks, told to read words and ignore ink color, harder when word doesn't match color
Coprolalia
involuntary utterance of obscenities or inappropriate remarks
Neocerebellum
involved in movement planning
What is the experimental evidence that shows the prefrontal cortex is important to multi-tasking?
involves coordination and maximizing efficiency of current goals balanced with future goals. Six elements test: six open-ended tasks to perform in 15 minutes, patients have difficulty coordinating performance across tasks, despite being able to perform each task well in isolation. Multiple errand test requires task switching and maintenance of future goals while dealing with current goals, patients break task rules as well as social conventions
Tower of Hanoi test
is a mathematical game or puzzle. It consists of three rods and a number of disks of different sizes, which can slide onto any rod. The puzzle starts with the disks in a neat stack in ascending order of size on one rod, the smallest at the top, thus making a conical shape. The objective of the puzzle is to move the entire stack to another rod, obeying the following simple rules: Only one disk can be moved at a time, Each move consists of taking the upper disk from one of the stacks and placing it on top of another stack or on an empty rod, No larger disk may be placed on top of a smaller disk.
Akinesia
lack of spontaneous movement
Ideomotor apraxia
loss of ability to plan and execute the complex sequences of motor actions involved in the use of tools or interactions of objects in life
saliency map
A "map" of a visual display that takes into account characteristics of the display such as color, contrast, and orientation that are associated with capturing attention, depicts the visually alluring locations of an image
Anosognosia
A patient's inability to realize that he or she is ill, which is caused by the illness itself, patient will deny that extremities belong to them, deny sensory loss, deny disorders (unawareness of deficits)
homunculus problem
A problem in scientific explanation that arises if an organism's capacity for consciousness is explained by proposing that a structure in its mind or brain is conscious. The problem is the failure to explain how consciousness arises in the mind or brain structure, the problem of explaining volitional acts without assuming a cognitive process that is itself volitional ("a man within a man")
illusory conjunctions
A situation in which features from different objects are inappropriately combined (failures of feature binding), can demonstrate experimentally by presenting two items with different colors and different shapes, patient will more likely bind those features wrong if you overtax the attentional resource system
Wisconsin card sorting task
A test of cognition in which subjects must learn rules for sorting cards based on shape, color, or number. The rules change periodically, and the subjects must learn the new rules by experience, based solely on feedback about whether each response is correct or incorrect
forward model
A theoretical construct referring to the idea that the brain generates predictions of expected events. In motor control, a forward model refers to the prediction of the expected sensory consequences of a movement
Obsessive-compulsive disorder
An anxiety disorder characterized by unwanted repetitive thoughts (obsession) and/ or actions (compulsions).
Characterize the voluntary eye movement behavior observed in patients with Balint's syndrome. How does this behavior impact the patient's ability to perceive the visual scene?
Because of ocular apraxia, the patient has an inability to move eyes voluntarily to points in visual field. Reflexive movements may be spared. There is a failure to disengage from the object of fixation, called "sticky fixation." The patient has difficulty looking at objects in periphery and fails to maintain fixation on an object (non-target elicited wandering eye movements). So, the patient can't make sense of the image cohesively.
What is the distinction between open-loop and closed-loop control systems? How do these systems relate to motor engrams and motor programs in the context of skill learning?
Closed-loop control: early stage skill acquisition, lag time > reaction time, feedback is critical for early-stage skill acquisition. Open-loop control: late stage skill acquisition, lag time < reaction time Closed-loop control = motor engram (organize sequence in advance of execution, not dependent on feedback from prior movement), automated Motor program and motor engram are different. Motor program: Memory representation that generates skilled movements, inaccessible to consciousness, non-verbalizable. Motor engram: memory representation that is used in early stages of skill acquisition and that is used to evaluate sensory feedback, consciously accessible, verbalizable
Schenk argues that Patient DF's ability to effectively "act" on objects that she cannot recognize is driven by a dissociation of allocentric and egocentric spatial processing. Milner and Goodale counter that their results really reflects a task vs. process distinction. Explain these opposing views of Patient DF's performance on Schenk's experimental tasks.
D.F. did poorly on an allocentric perceptual task in which she was asked to report verbally which of two targets was closer to a visual fixation point. She did as well as normal subjects on an egocentric action task in which she was asked to point to a target. Schenk showed that D.F.'s performance improved when her finger was placed on the fixation point. He argued that this was because the task was now an egocentric one in which she was being asked to judge which of two targets was closer to her finger, rather than which was closer to an external reference point. Schenk argues that there is no such thing as two separate streams. If Patient DF put their finger on fixation point and then asked which dot was closest to fixation point, patient DF could do the task. Milner offered another explanation for this behavior from DF: the patient is imagining moving their finger from one place to the other, improved performance could be due to compensatory operation, so you have to be careful about whether the task you are using is tapping into the processes that you think it is. Asking D.F. or any other patient with neurological damage to perform a perceptual task does not guarantee that she will use perception to solve it.
Why is Patient DF's ability to effectively act on objects significantly different under immediate and memory-guided action conditions? How would Schenk and others critics of the two visual stream hypothesis explain these data, as well as the data of optic ataxia patients who show the opposite pattern of performance?
DF's ability to act on objects differently under immediate and memory-guided action conditions was tested in an experiment was a stimulus was flashed. In condition 1, the patient would have to immediately point to it. In condition 2, the patient would point to the flash after a delay. For patient DF there is low error when the identification is immediate and higher error when forced to identify after delay. This is because DF does not have the ventral stream available to them. The optic ataxia patient AT under the same conditions, there is a huge error when stimulus is present, which is reduced after the delay. The improvement for AT is mediated by utilization of the ventral stream. Criticism: The separation of the two tasks is overemphasized, and in fact the two streams work together in large part.
Supplementary motor area (medial premotor cortex)
Deals with spontaneous well-learned actions that don't place strong demands on the environment (in contrast to lateral premotor cortex), Stimulation of primary motor area: subject reported difficulty in executing key presses
Describe the direct and indirect pathways in the basal ganglia and how they serve as the accelerator & the brake, respectively.
Direct: accelerator, selectively facilitates certain motor programs, indirect: brake, inhibits the execution of competing motor programs The normal functioning of the basal ganglia apparently involves a proper balance between the activity of these two pathways. Parkinson's: decreased direct, increased indirect (hypokinetic) Huntington's: normal direct, decreased indirect (hyperkinetic)
What is meant by "early" vs. "late" selection of attention? Describe evidence for both processes. What factors can influence the type of attentional selection that occurs (e.g., suggestions by Lavie, Duncan & Humphrey).
Early selection: model of attention that explains selective attention by early filtering out of the unattended message. The feature integration theory is that perceptual features are encoded in parallel and prior to attention. Late selection: a model of selective attention that proposes that selection of stimuli for final processing does not occur until after the information in the message has been analyzed for meaning. Evidence for late selection of attention: neglect patients, Flanker task (you are not a perfect filter of irrelevant items in your environment) If your system is overloaded, attention selection will happen quite early. If you have sufficient attentional resources, you may see evidence of late selection of attention. Complex stimuli involve more effort, leading to early selection. Easy stimuli involve less effort, leading to late selection
early vs. late selection
Early: filter based on simple features, e.g. stimulus location. Late: filter after great deal of processing, e.g. stimulus relevance Attention happens at multiple levels up to semantic representation
Demonstrations that pictorial illusions, such as the Ebbinghaus and Ponzo, can impact both perceptual and object-directed actions in healthy adults have been used to refute the two visual streams hypothesis. Describe these findings and how they weaken the two visual stream hypothesis. What are two counter arguments that Milner and Goodale suggest to explain away these findings?
Ebbinghaus illusion of the dots relative size Ponzo illusion of whether the lines are the same length Vision for action versus vision for perception. Experiments show that perception can influence action, because the crowding influences the grasp aperture. Therefore, this weakens the two streams hypothesis because it shows that action and perception are connected. Counter arguments from Milner and Goodale: Stimuli may influence the movements for purely non-perceptual reasons: visuomotor system appears to treat these flanking stimuli as potential obstacles to the grasping movement The simple fact that actions such as grasping are sometimes sensitive to illusory displays does not refute the idea of two visual systems. One should not be surprised that perception can affect our motor behaviour. Faulty experiments: impurity of measures, may not really be showing effect of perceptual illusions on action.
Egocentric vs. allocentric space
Egocentric space: where are the objects relative to you Allocentric space: where are the objects relative to each other
Define exogenous and endogenous orienting of attention. How can these processes be differentially elicited within the same spatial orienting task (i.e., Posner's task)? How are these different orienting mechanisms affected in neglect patients?
Exogenous orienting: attention is externally driven by the stimulus Endogenous orienting: attention is guided by the goals of the perceiver (such as when searching for a person in a crowd) Posner's task: tested covert orienting of attention. Valid orienting had the patient engage and move attention to cued location and respond to the target at the cued location. Invalid orienting had the patient engage and move attention to cued location, then disengage and move attention to target location, and respond to the target. Posner found automatic, exogenous orientation at short SOAs between cue and target and deliberate, endogenous orienting at longer SOAs between cue and target. Neglect patients appear to have a specific deficit in the automatic/exogenous component of attentional orienting.
Exogenous vs. endogenous orienting
Exogenous orienting: attention is externally driven by the stimulus, endogenous orienting: attention is guided by the goals of the perceiver (such as when searching for a person in a crowd)
Facilitation vs. inhibition of return
Facilitation refers to increased responsiveness to further stimulation object is detected after the object is attended. Inhibition of return refers to a slowing of reaction time associated with going back to a previously attended location.
Frontal apraxia
Failure in tasks of routine activity that involve setting up and maintaining different subgoals, but with no basic deficits in object recognition or gesturing the use of isolated objects (also called action disorganization syndrome)
Covert vs. overt orienting
For example, in the burning house experiment, the overt task is "Are the houses same or different?" and the covert task is "Which house do you prefer/like more?"
Mirror neurons
Frontal lobe neurons that respond to observed as well as self-enacted actions. The brain's mirroring of another's action may enable imitation, language learning, and empathy
dichotic listening task
Hear one stream of auditory information in left, another stream in right, told to repeat what you hear in left ear and ignore right, probe what types of information you are aware of that was presented in the ignored ear, suggests that while you are excluding information in the ignored ear, the information is not completely suppressed
What is the sensory-motor transformation process and why is it necessary for appropriate actions toward objects?
How we interact with our world requires sensory motor transformation. We don't want our brain to have to compute certain types of actions each time we do them. Some actions are automatically accessed through the dorsal stream and become associated with familiar objects. Neurons can respond selectively to 3D shapes of certain sizes and orientation. Other neurons respond to the position of objects relative to someone's hand, irrespective of where the hand happens to be in space.
How do observations of motor performance skills in Huntington's and Parkinson's disease patients fit within the framework of Norman and Shallice's model?
Huntington's: overactive contention scheduling, trouble acquiring new motor programming Parkinson's: underactive SAS, impaired activation of motor programing but still intact motor programming Movement behavior includes excessive movement, dance-like flailing limbs (chorea), and contorted postures. Huntington's patients also show an inability to acquire skill/motor programming, so the slip is in the (a) formation of the intention. Parkinson's: Motor programming is intact per se in that there is normal tracking performance and normal pre-programming of movement sequence, but there is impaired activation of these intact motor programs, so the slip is in the (b) faulty activation of schemas.
simultagnosia
Impaired awareness of multiple visual objects or whole scene
utilization behavior
Impulsive action on irrelevant objects in the environment, in situations where you do not have a routinized set of action, "The patient was found early in the morning wearing someone else's shoes, not apparently talking or responding to simple commands, but putting coins into his mouth and grabbing imaginary objects. He went around the house, moving furniture, opening cupboards and turning light switches on and off"
Inattentional blindness vs. change blindness
Inattentional blindness is the failure to see a stimulus, such as an object that is present in a visual field. Change blindness is directly related to memory, individuals who experience the effects of change blindness fail to notice something different about a visual display from one moment to the next.
Patients with Balint's syndrome have difficulty perceiving more than one object at a time (simultagnosia). Describe the factors that can mitigate this difficulty at perceiving multiple objects and what this suggests about pre-attentive feature binding and top-down influences. (See lecture and & Montoro et al., 2011)
Mitigate: Gestalt grouping, which helps draw attention to objects especially if the grouping is strong (proximity, similarity, continuity, closure, connectedness). One example is that a Star of David would be reported when the two triangles were the same color but only one triangle would be reported if they were different colors. Simultanagnosic patients can also have difficulties in disengaging attention, once stimuli are selected. Pre-attentive feature binding is integrating different aspects of conscious perception, such as "yellow" and "moon" combined to show that there is a yellow moon. Feature binding is compromised in Balint's syndrome, such as in the example of the cookie theft scene. Patients are unable to grasp the scene of multiple components despite retained ability to identify individual details and unable to report all items and relations in relation. Top-down factors are how familiarity and semantic knowledge influences object perception. There is a study on how semantic knowledge can influence visual awareness of an object: words were written in different colors (which took a Stroop effect), the words had semantic color meaning such as "pea" which is usually associated with green, and this semantic association would affect their answer. Top-down factors do affect object perception.
Describe some of the experimental manipulations that have been done to illustrate that emotionally salient/relevant stimuli can reduce visual extinction deficits in neglect patients. What do these data suggest about the perceptual processing of neglected information?
Neglect patients are often able to detect objects on the left if cued there. Objects in neglected space activate the appropriate visual regions in occipital lobes, which suggests that there is full processing of the objects. Neglect affects auditory and tactile judgements as well as vision. If it were perceptual deficit, it would be limited to a specific sensory modality. Phenomenon of visual extinction suggests that different perceptual representations are competing for attention (and visual awareness). If the sounds were anger, happy or fear, there was a reduction in the items missed in the contralesional side compared to the neutral. Neglected information is still being processed, just not attended to Study tested face that is either happy, neutral, or sad, The number of reports of the contralesional faces was better when there was an emotional expression on it. Neutral face had less of a priority (preservation of emotion priority) Neglect can be reduced by connecting two objects into one
What is neglect syndrome? What are the common clinical symptoms of neglect that result from unilateral right parietal lobe damage? How is the lack of awareness in neglect different from the lack of awareness in blindsight (See Chapter 8 pp. 158-159)?
Neglect patients have unilateral parietal lobe damage, particularly to right hemisphere (left hemisphere patients exist but do not show the severe neglect systems). Patients can orient to a cue on the left or right, but have trouble shifting attention from a right cue to a subsequent left target, which suggests problem in shifting attention rather than initial perception. In blindsight, patient does not see the surrounding world but can sense motion - not attention based. In neglect, patients can see the other side but do not have attention drawn to it - don't perceive it
Briefly describe the model of motor control developed by Norman and Shallice (1986). Define the horizontal vs. vertical threads. How does contention scheduling work? What is a capture error? What is a slip of action? How does the supervisory attentional system influence the selection of a motor program for action?
Norman-Shallice model: two main processes manage the functioning and control of schemas: contention scheduling and SAS Contention scheduling is a lower-level mechanism that regulates schemata processes for familiar, automatic actions as well as some novel situations. Contention scheduling ensures the proper schema is activated and, through inhibition, prevents multiple competing actions from executing simultaneously. Contention scheduling is fast, automatic, and consistent in activating schema. 2 complementary processes in control of action: Automatic ("horizontal thread"), Attentional ("vertical thread") Automatic—do not require conscious control, triggered in response to familiar, environmental stimuli Attentional—require conscious control, respond to unique situations A slip is the error that occurs when a person does an action that is not intended. The three major categories of slips are: (a) errors in the formation of the intention (b) faulty activation of schemas (c) faulty triggering A capture error occurs when two potential actions share the same or similar initial sequences but one action is relatively unfamiliar and the other is a well-known and well-practiced action. The well-practiced action sequence will "capture" the action Supervisory Attentional System, SAS has control over contention scheduling, monitors conscious, deliberate planning of actions, novel situations that cannot be solved by previously learned schemata and when preventing error or habitual responses. SAS modifies general strategies to solve non-routine problems, a new schema may be created, takes approximately 8-10 seconds.
Compare and contrast the motor symptoms of Parkinson's disease and Huntington's disease. Identify the neural locus of damage in each disease.
Parkinson's Disease: hypokinetic. classic motor triad: resting tremor (when stationary), rigidity, and bradykinesia (slowness of movement). There is Akinesia (lack of spontaneous movement), decay of movement sequences (i.e. walking degenerates to a shuffle), failure to scale muscle activity for movement amplitude. Motor programming is intact per se—normal tracking performance/normal pre-programming, but impaired activation (Kinesia paradoxica, Bradykinesia, increased attention or "will" to active schemas, increased interference between activated schemas). Huntington's Disease: progressive dementia, patients usually die within 12 years of onset. hyperkinetic. excessive movement, dance-like flailing limbs (chorea), and contorted postures. inability to acquire skill/motor programming. Parkinson's: loss of pigmented cells in substantia nigra (pc) and Huntington's: profound loss of cells in striatum (80-90%).
Describe how representational neglect (personal vs. extra-personal) can be assessed clinically in a variety of ways. What is distinguishes topological and non-topological tasks? What are some of the limitations of these clinical tests?
Personal: Three clinical tests of personal neglect are the modified comb and razor test, the fluff test, and the vest test. In the comb and razor test, patients are asked to simulate combing their hair for 30 seconds. Experimenters check how many times they stroke each side of their head (laterality index). In the fluff test, circles made of cardboard are attached on the patient's clothes (only on frontal body surface). The patient is blindfolded and required to remove all the targets by using contralesional hand. If less than 13 are removed, this indicates a representational deficit. In the vest test, the patients wear a vest with 24 pockets, each containing 1 of 24 everyday objects. The patient has 5 minutes to search using ipsilesional hand. If they detect less than 9 on the left, this is indicative of a representational deficit. Extra-personal: Topological tests of extra-personal neglect test mental representation of stimuli in which it is possible to navigate. This is the familiar square description (patient asked to imagine themself in a particular vantage point in an image of a square, more identification of items in last vantage point), familiar room description (imagine themself in a familiar room such as in their room and list all the objects they can remember), and geographic map description (name all the cities on a map, how many named on right v. left side of state). In non-topological tests, patients mentally represent stimuli such as objects. Tests include the o'clock test (imagine a clock with two different times, which clock hands create a bigger angle), complex scene description (describe image, see if patient neglects one side of space), and drawing from memory (patients draws flower or clock, neglects contralesional side of image). This is not defined by your position in that space. Topological tests: mental representation of stimuli in which it is possible to navigate, non-topological tests: mental representations of stimuli such as objects Limitations of these tests are that performance can depend on prior knowledge. For example, for the map test, if the patient does not know the map of Texas, they would not be able to perform well on it. Or if they do not have good recall of objects in general they would perform poorly on the familiar room description.
Degrees-of-freedom problem
Potentially infinite number of motor solutions to whatever goal the person has (for example, in terms of joint positions and trajectories), makes action computationally difficult
Characterize the clinical/behavioral symptoms of a patient with bilateral lesions to the parietal lobe (e.g., Private M). Are the deficits limited to vision? How do these symptoms relate to the idea of two visual streams?
Private M had two strokes that led to bilateral lesions to the parietal lobes. He had disturbances in visual attention and awareness and seemed to able to only see one or a small subset of available objects at any particular time and would localize them incorrectly in space. He had normal visual perception, meaning he had intact acuity in central vision and could detect presence of objects in periphery as well as motion. He had no physical weakness, could see and recognize objects (which is a double dissociation with object agnosia), but could not determine location of objects or accurately reach out to grasp object, which led him to develop a groping strategy. This suggests damage to the dorsal stream but not ventral.
Briefly describe the differential contributions of cerebral cortex to movement and action. Be able to specify the differential contributions of the various structures within the frontal lobe described in the book.
Roles in action: Occipital lobes (Visual analysis of scene), temporal lobes (Object recognition, object knowledge), Parietal lobes (Locating objects in space, sensory-motor transformation), Frontal lobes (Planning actions, maintaining goals, executing actions), Parieto-frontal circuits (Link action with current environment), Subcortex (Basal ganglia: modulate force and likelihood of action, Cerebellum: monitor action online) Frontal lobes lie in front of premotor regions: planning and higher aspects of control of action, mediating the selection of what action you're going to do and the maintenance of a goal. important in novel/new situations, complicated situations. The prefrontal cortex is involved in coordination of cognition generally and selection and maintenance of goals and responses. Damage to this region does not impair physical movement but actions become disorganized and/or inappropriate for current goal (frontal apraxia) and produces actions that are automatically driven by habits and objects in the environment, rather than by controlled goal-driven behavior (perseveration).
allesthesia
Sensation experienced at a site remote from point of stimulation, If you touch the patient on the side opposite the lesion, they might report that they were touched on their ipsilesional limb
Define skill learning. What are the 3 characteristic stages of skill acquisition? What is the critical component needed to reach the final stage of skill acquisition? How does the Frith & Lang (1978) study illustrate the need for this component?
Skilled performance involves the refinement through practice of the sequencing and timing of the movements underlying a task and is reflected in more coordinated and rapid performance, as well as in economy of effort and muscle groups used to perform the task. The three stages of skill acquisition are the cognitive phase (controlled, attentional), associative phase (controlled, attentional), and autonomous phase (automatic). The key to automaticity is predictability. The Frith & Lang study has two conditions. Condition 1: target moves in random x and y directions, Condition 2: target moves in random y direction, but in a predictable sinusoidal x directional. Subjects had to track the moving target. Predictability in information provided in the x-direction. In condition 1, the time on target never decreased because there was no predictability and patients couldn't learn. In condition 2, patients get much better as time goes on in terms of the x-direction because of predictability. After a 10-minute break their performance in the y-direction improves as well because attentional resources are freed up to focus on the unpredictability of the y-direction.
Action schema
Stored motor programs for specific objects (such as lifting a cup) and schemas for familiar situations (such as making tea), each behavior is represented as a schema, contention scheduling selects the most active schema
Neglect is both an attentional and representational disorder, rather than a low-level perceptual disorder. Describe some experimental evidence for perceptual encoding of information in the neglected contralesional space and for impaired disengagement and biased competition attentional mechanism in neglect patients.
The Dichotic listening task suggests that while you are excluding information in the ignored ear, the information is not completely suppressed. The experiment is that patients hear one stream of auditory information in left and another stream in right and are told to repeat what they hear in left ear and ignore the right. The intent is to probe what types of information the patient is aware of that was presented in the ignored ear. Experimental evidence for perceptual encoding of information in the neglected contralesional space is the Burning House Experiment. Patients were presented with two images: a house and then the same house with a fire on the neglected side of space. The patients said the images were the same but would pick the one not on fire at above chance levels when asked which one they would like to live in. Impaired disengagement is that when patients have been cued to the ipsilesional side of space, there is a significant slowing to detect something on the contralesional side of space. Posner's experiment shows this. The biased competition theory is supported by the burning house experiment.
What do the Piazza experiment and cloud study illustrate about representational neglect? What might be the roles of the hippocampus and parietal lobes in representing spatial maps?
The Piazza experiment demonstrates that changing viewpoint changes the knowledge recalled. Standing on one side of the street, describe whats in front of you. Could only describe one side but when on other side of the street, they noticed the other half which they did not see before (now ignoring the previous side) In the cloud study, patients were directed to look at stimuli for two seconds, then at a black screen, then other stimulus for two seconds. They were asked if they were the same cloud or different. The experimenters manipulated whether or not the difference in the cloud was on the contralesional or ipsilesional side. There was also a dynamic condition where the object moves behind a slit either to the left or right. There were more errors when the difference was on the contralesional side of the object regardless of whether object moved left or right. The parietal lobes are primarily concerned with linking sensory and egocentric maps of space to create representations of observable environment. The hippocampus stores long-term representations of space that need not be presently observed of even viewpoint specific. In the Piazza del Duomo study, the hippocampus may store the map of the square and may superimpose a viewpoint on this map.
Somatosensation
The body senses, including body position, touch, skin temperature, and pain, knowledge of current state of the body
Describe the different qualities that define attention. What is the spotlight metaphor of attention? Why might attention be necessary for us to effectively interact with the world?
The different qualities that define attention are selection, vigilance, and control. The spotlight metaphor of attention is that attention can be directed to different spatial locations in your environment, such as the gorilla video where the viewer is instructed to count the number of balls and misses the gorilla that walks by. Attention is necessary to effectively interact with the world because our neural systems are limited in capacity, so we need to select attention towards what information to process based on relevance to current goals.
What are affordances and how might the dorsal stream compute them to guide object-directed actions? How might the ventral stream influence the way in which objects are acted upon?
The dorsal route may compute affordances, or associations between the structure of objects and potential functions (sharp=cutting, hollow=container). However, affordances are not always enough. An agnosia patient may use scissors bimanually rather than unimanually based on stored knowledge that has been lost In optic ataxia patients where the dorsal stream is damaged, patients have recognition of objects without appropriate action and poor visual guidance of reaching. In visual agnosia where the ventral stream is damaged, there is action on objects without semantic recognition (may not be used for its intended purpose).
Distinguish between what is meant by egocentric, retinocentric and allocentric spatial reference frames. Why might encoding these different representations be important?
The egocentric spatial reference frame is gauging where the object is relative to yourself (self-to-object). Allocentric is gauging the location of the object relative to other objects (object-to-object). Retinocentric space is locating an object based on where the object hits the retina in your two eyes. Encoding these different representations is important because processing depends on what your goal-directed behavior is. For example, the difference in finding a restaurant and picking up a pen shows that different spatial reference frames are necessary for different tasks.
Compare the Feature Integration, Biased Competition, and Premotor theories of attention. What do each theory provide in terms of explanation of different attentional findings?
The feature integration theory is the early selection model that perceptual features are encoded in parallel and prior to attention. If an object has a unique perceptual feature then it may be detected without the need for attention—pop-out effects. The biased competition theory states that competition occurs at multiple stages rather than at some fixed bottleneck—there is neither early nor late selection but something more dynamic. Competition occurs in parallel at most stages with serial processing linked to the motor output stage, and priority is given to ipsilesional side of space. Premotor theories of attention: you can do that pop-out search without any attentional processing, you have automatic feature maps that process different components of our visual world. Attention is not costly in pop-out search because you don't see change in reaction time
contention scheduling
The mechanism that selects one particular schema to be enacted from a host of competing schemas (selects most active schema)
Briefly compare the representational & hemispheric models of spatial attention. How is exogenous and endogenous attention implemented into Corbetta's model? Can any of these models accommodate the effects of emotional stimuli on attention?
The representational model from Heilman suggests that the right hemisphere represents both the left and right space and the left hemisphere represents only the right space, so damage to left hemisphere does not lead to significant contralesional neglect because the intact right hemisphere is capable of allocating attention to both the left and right space. The hemispheric bias from Kinsborne suggests that the left and right hemisphere have naturally biases towards attention that is contralateral but the bias is asymmetrical, the left hemisphere is more biased towards the right hemispace than the right is biased towards the left. Damage to the right parietal lobe would cause a loss of asymmetry towards the left, leading to a much stronger rightward attentional bias. Corbetta & Shulman's model shows different types of neglect: egocentric neglect (patients neglect everything on the contralesional side: cat dog), stimulus-centered neglect (neglect the left side of each word cat dog), and object-centered neglect (even if you turn the orientation of the word they still neglect the left side). Dominguez-Borras did an experiment to see the effect of emotional stimuli on attention. The patients were presented with a face presented in contralesional side of space which was either happy, sad, or neutral. The subject was asked to report what they saw but were not asked to report emotion of the face. The experiment result was that the neutral face had less of a priority, showing a preservation of emotional processing (perceptual processing is preserved in the contralesional side of space).
What are the roles of subcortical structures in movement and action? Describe the two main subcortical loops that are involved in movement generation and what the characteristics of damage to either loop would be.
The two main subcortical loops are the cerebellar loop and the basal ganglia loop. Cerebellar loop: timing, trajectory, coordination of movement (execution), including coordination of movement. Damage produces tremulous movements, patient cannot smoothly terminate particular movements, instead the hand (or whatever it is) oscillates. Vestibulocerebellum- controls balance and coordinates eye movements, spinocerebellum- receives input and regulates actual motor performance, neocerebellum- involved in movement planning Basal ganglia loop: selection, influence probability of movement, initiation and execution of internally generated movements, linking actions. Damage leads to hypokinetic and hyperkinetic disorders, including Parkinson's disease, Huntington's disease, and Tourette's syndrome.
Describe the two vision processing stream model that distinguishes action from perception.
The two visual processing streams that distinguish action from perception are the dorsal stream and the ventral stream. The dorsal ("how"/"where") route goes through the parietal lobe and is specialized for spatial processing. The dorsal stream brings together different types of spatial representation needed for action such as integrating visual space with body space. The dorsal stream mediates visual control of skilled actions, such as reaching or grasping directed at objects in the world in order to register the visual information about that object on a moment to moment basis and transform this information in real time into appropriate coordinates. The dorsal stream functions to find out what size things are in real time, which changes as objects move. The ventral stream ("what" route) is primarily concerned with identifying what an object is. The ventral stream functions to take in an entire scene. It does not compute actual size, but rather relative size.
Which hemisphere is considered to be more specialized for spatial attention in the normal brain and why? Describe the basic findings of the Nicholls et al (1999) study in support of this hemispheric specialization.
There is a bias for spatial attention in the left side of space. The Nicholls study showed patients images of a gradient that was copied, but the second image was flipped. He asked the patient which was lighter/darker, which was larger, which had more stars, etc., and concluded that there is a bias towards the left side of space. Left side of space=right hemisphere of the brain
cancellation task
This measure of spatial neglect asks the client to mark each occurrence of a target item on a piece of paper, a variant of the visual search paradigm in which the patient must search for targets in an array, normally striking them through as they are found
frontal eye fields
Voluntary movement of eyes, damage leads to impairments in endogenous orienting of attention
mimicry vs. imitation
While social psychologists assess mimicry by means of action observation, cognitive psychologists assess automatic imitation with reaction time based measures on a trial-by-trial basis. In the present research we assessed both phenomena and did not find a meaningful correlation.
Attentional blink
a brief period after perceiving a stimulus, during which it is difficult to attend to another stimulus/the phenomenon that the second of two targets cannot be detected or identified when it appears close in time to the first
Tourette's syndrome
a common neurodevelopmental disorder with onset in childhood, characterized by multiple motor tics and at least one vocal (phonic) tic.
anarchic/alien hand syndrome
a rare neurological disorder that causes hand movement without the person being aware of what is happening or having control over the action. This usually occurs after a person has had the two hemispheres of the brain surgically separated, as in split-brain surgery.
Population vector
a statistical procedure to represent the activity across a group of neurons
resting tremor
a tremor that is apparent when the client is at rest and diminishes with activity
Phenomenal consciousness vs. access consciousness
access consciousness: representational and has direct control of thought and action, the functional aspect of mind, phenomenal consciousness is the experiential aspect
Flanker task
an experimental procedure in which participants respond to the direction of the central arrow in an array, regardless of the direction the other arrows are pointing, an experiment in which participants may be influenced by an irrelevant stimulus beside the target (congruent or incongruent objects, incongruent causes slowing of response)
Lateral premotor cortex
anterior to the primary motor cortex, involved in planning and coordinating actions based on external cues or stimuli
balint's syndrome
bilateral parietal lobe damage, leads to simultagnosia, optic ataxia, optic apraxia
Top-down vs. bottom-up attention
bottom-up attention: attentional guidance purely by externally driven factors to stimuli that are salient because of their inherent properties relative to the background, top-down attention: internal guidance of attention based on prior knowledge, willful plans, and current goals
Palilalia
continuous repetition of sounds and words
line bisection
examinee is asked to bisect lines on a page placed at midline, experiment where patients points to near space using pen and paper, far space using projected image and laser pointer. "Near" is defined as within reach and is dynamic. If patient is given long stick rather than laser pointer then the near deficit extends into far space, causes remapping of space
Optic apraxia
fixation of gaze without primary motor deficit, impaired ability to voluntarily shift gaze toward visual stimuli
remapping
functions of areas of the cerebral cortex can shift in response to (lack of) input/activity, cortical map is affected by a stimulus, is changed and then creates a 'new' cortical map
hemispatial neglect vs. extinction
hemispatial neglect: patients neglect the hemispace that is contralateral to their lesion, extinction: shown in frog vs. sun experiment is that patient fixates on cross in the middle, see frog in contralesional side of space by itself, see sun by itself in ipsalesional side of space, when both are presented at once patient only sees object in ipsalesional side of space
Hypokinetic vs. hyperkinetic
hypo: less action, hyper: more action
Kinesia paradoxica
in Parkinson's, individuals who typically experience severe difficulties with the simple movements may perform complex movements easily
pseudo-neglect
in a non-lesioned brain there is over attention to the left side of space, bias representation of left side of space due to right hemisphere dominance in spatial representation and attention
sensorimotor transformation
linking together of perceptual knowledge of objects in space and knowledge of the position of one's body to enable objects to be acted on, actions that are automatically accessed through the dorsal stream become associated with familiar objects, explains why particular neurons are responsive to certain types of behaviors
What is ideomotor apraxia and the characteristics of its movement impairment?
loss of ability to plan and execute the complex sequences of motor actions involved in the use of tools or interactions of objects in life Ideomotor apraxia is a disorder traditionally characterized by deficits in properly performing tool-use pantomimes (e.g., pretending to use a hammer) and communicative gestures (e.g., waving goodbye). These deficits are typically identified with movements made to verbal command or imitation. Impaired performance in unusual context, but normal performance in proper context (such as pantomiming versus doing actual action). Memory representations associated with apraxia are accessible to consciousness. Impaired performance on early (i.e. closed-loop) stage of skill learning in tracking task.
Motor extinction vs. motor impersistence
motor extinction: Patients will fail to use their left limb especially when they are also using their right limb to do something, if you draw attention to the left limb they can use it and not have motor deficits, motor impersistence: patients will often have difficulty sustaining movements or postures, will only follow command for a few seconds
Hemiakinesia
motor neglect (motor extinction and motor impersistence)
Near vs. far vs. body space neglect
near: visual search of external objects in environment, "near" is defined as within reach and is dynamic, double dissociation between near and far space body space: failure to groom left side of body or notice position of limbs
Space-based vs. object-based neglect
object-based: attention appears to select an entire object, rather than a specific region of space (attend to objects on the left side of space but fail to attend to one half of the object itself), double dissociation with space-based neglect
ventriloquist effect
occurs when a visual cue that is presented simultaneously with an auditory stimulus biases the localization of that auditory stimulus toward the location of the visual cue
hemiplegia
paralysis of one side of the body
Posner's spatial cueing task
participants make reaction time responses to indicate whether a target item appeared to the left or to the right of fixation. The key manipulation across each trial involves a cue that is "valid" or "invalid": Automatic, exogenous orientation at short SOAs between cue and target, deliberate, endogenous orienting at longer SOAs between cue and target
phantom limb
perceived sensation, following amputation of a limb, that the limb still exists
Provide neuropsychological evidence in support of (and/or against) this model (dorsal/ventral). (See Milner & Goodale, 2008).
perceptual: ventral stream, action: dorsal M.H.: optic ataxia in which only pointing with his right arm to targets in the right visual field is impaired. highly selective deficit, only ignoring potential obstacles on his right, and only doing that when he is reaching with his right hand. This identical pattern of deficits in pointing and obstacle avoidance suggests that the two may both be mediated by the same dorsal-stream subsystem. M.H. shows quite normal obstacle avoidance behaviour with respect to the right-side object when tested in a delayed version of the reaching task. As in delayed pointing or grasping, the ventral stream is recruited to code the spatial array in readiness for making the delayed reach, enabling M.H. to perform normally.
Pop out search vs. conjunction search
pop-out: visual stimulus that is comprised of differing components has mostly similar looking objects but one differing object that 'pops-out' or stands out very noticeably from the other objects in the visual field, conjunction: visual search process that focuses on identifying a previously requested target surrounded by distractors possessing one or more common visual features with the target itself
Parkinson's disease
poverty of self-initiated movement. Parkinson's has the classic motor triad: resting tremor (positive symptom when stationary), rigidity (positive), and bradykinesia (slowness of movement, negative)
Primary motor cortex
region of posterior frontal lobe: input from all cortical areas implicated in motor control, output contains largest signal in cortical tract, Somatotopically organized and crossed: Left primary motor cortex represents right side of body and vice versa, Executes all voluntary movements of the body, Stimulation results in movement and lesions results in paralysis
Perseveration
repeating an action that has already been performed and is no longer relevant
Echolia
senseless repetition of a word or phrase spoken by another
Bradykinesia
slowness of movement
Optic ataxia
spatial disorientation in which the patient is unable to accurately reach for objects using visual guidance
Motor programs
stored routines of actions and action sequences that minimize the problem, may be abstract (handwriting patterns used for blackboard writing, regular writing, etc.)
Chorea
sudden, rapid, jerky, purposeless movement
negative priming effect
target stimuli is processed slower if preceded by a word related to target's alternate meaning, depends on the amount of distractors, effectiveness of the cognitive control mechanism and the availability of the cognitive control resources
rubber hand illusion
the feeling that an extraneous object, usually a rubber hand, is actually part of one's own body—Subjects with normal brain function were positioned with their left hand hidden out of sight. They saw a lifelike hand in front of them. The experimenters stroked both the subjects hidden left hand and the visible hand with a paintbrush. The experiment showed that if the two hands were stroked synchronously and in the same direction, the subjects began to experience the rubber hand as their own.
affordances
the possibilities for action offered by objects and situations (between structure of object and potential actions, such as sharp=cutting, hollow=container)
Somatic marker hypothesis
idea that the bodily (somatic), emotional component of thought is a necessary part of problem solving and decision making.
Describe the evidence for functional specialization for: (1) affective vs. cognitive control; (2) task setting vs. task monitoring; (3) error detection vs. error correction; and (4) a hierarchical organization of simple sensory-motor to more complex schematic control processes.
(1) affective vs. cognitive control: reversal learning conditions=affective, dimensional set shifting=cognitive, OFC lesion affects affective, lateral PFC affects cognitive, Dorsal region more involved in cognitive division, Ventral more involved in affective division (2) task setting vs. task monitoring: damage to left lateral PFC causes task setting deficit in WCST, slower to switch. Damage to right lateral PFC causes task monitoring deficit, more likely to revert to previous rule (3) error detection vs. error correction: anterior cingulate detects but doesn't correct for errors (4) a hierarchical organization of simple sensory-motor to more complex schematic control processes: As you get farther along in interior part of PFC, more involved in multiple tasks simultaneously
Temporal lobes
Object recognition, object knowledge
Proprioception
position of limbs in space
Go/No-Go test
A test of response inhibition in which participants must respond to a frequent stimulus (go trials) but withhold a response to another stimulus (no-go trials)
Iowa Gambling Task
An experimental paradigm that tests subjects' sensitivity to risk and reward; the test reveals that patients with damage to the inferior prefrontal cortex tend to make risk-seeking choices.
Subcortex (Basal ganglia, Cerebellum)
Basal ganglia: modulate force and likelihood of action, Cerebellum: monitor action online
What are the arguments for and against the unitary vs. multiple processes account of executive function? How does the multiple-demand network theory characterize executive function?
Duncan's multiple demand network: tests of executive function and fluid intelligence (e.g. Raven's matrices) activate the same brain regions (multiple demand network). So executive function is not modular Multiple processes: Decision making, error correction, novel strategies, difficult/dangerous, overcoming habituation are separate processes Unitary: processes are all interrelated. Tasks are not distinct, similar performance of patients in the different tasks. Ability to form and maintain a task plan is the unitary process that is damaged by lesions to the prefrontal cortex (goal neglect)
What did the findings of Ferrier's electrical stimulation studies suggest about the cognitive function of the frontal lobe?
Experimented with electrical stimulation of the surface of the brain, concluded that frontal lobe's job was to inhibit other brain areas
What is the difference between crystallized and fluid intelligence? Which type of intelligence seems to be particularly impaired in patients with frontal lobe damage?
Fluid intelligence refers to the ability to reason and think flexibly. Crystallized intelligence refers to the accumulation of knowledge, facts, and skills that are acquired throughout life. Fluid intelligence is impaired in patients with frontal lobe damage.
Describe the opposing views of frontal lobe function and the arguments/evidence in support of these two views (Hebb vs. Goldstein/Luria).
Hebb: frontal lobe has few if any intellectual functions. Observed that patients with frontal lobe damage showed no appreciable change in IQ scores, lobotomies happened because they thought it did not damage brain function because there was no change in IQ score Goldstein: frontal lobe supports highest level of intellectual activity. Argued that IQ tests don't tap the highest functioning abilities of human being, frontal lobe (i.e. goal directed behavior, organizing behaviors), Luria: There were 18 books on 2 shelves and there were twice as many on one than on the other. How many books were on each shelf? Patient response: 18/2=9 and 18x2=36; The son is 15 years old, his father is 25 years older, and his mother is 5 years younger than the father. What is their combined ages? Patient response: 15+20+5=40. Running a routine procedure without any thought.
cognitive estimate test
How many camels are in holland, requires problem solving based on known semantic information, PFC patients produce bizarre responses
Utilization behavior
Impulsive action on irrelevant objects in the environment, in situations where you do not have a routinized set of action "The patient was found early in the morning wearing someone else's shoes, not apparently talking or responding to simple commands, but putting coins into his mouth and grabbing imaginary objects. He went around the house, moving furniture, opening cupboards and turning light switches on and off" (Shallice et al., 1989)
What is the experimental evidence that shows the prefrontal cortex is important to overcoming potent or habitual responses?
In the stroop test, fMRI and lesion studies implicate the involvement of the anterior cingulate cortex. The Hayling test asks patients to fill in the blank with a nonsense word, i.e. The captain wanted to stay with the sinking _____. PFC patients are impaired on this task and will have trouble not saying ship, in this instance.
Describe the anatomical and functional divisions of the prefrontal cortex.
Lateral prefrontal : executive function, short-term retention, inhibition of prepotent responses, behavioral planning, selective attention for action, selecting an intended action, enactment of behavioral rules, setting multiple behavioral goals (action hierarchy), strategic behavioral planning, planning of event-action sequences. Medial frontal cortex: has anterior cingulate involvement, reward anticipation, rational cognitive functions, heart rate, empathy, and emotion (detection of errors and detection of response conflict). Orbitofrontal cortex (OFC): decision making and functions in emotion and reward, memory retrieval, hierarchical representation of action goals. most anterior region of the frontal pole is subject to imaging artifacts.
Parieto-frontal circuits
Link action with current environment
Parietal lobes
Locating objects in space, sensory-motor transformation
Who is Phineas Gage and what were his cognitive deficits after his accident? How did the diverging views of brain function at the time of his accident influence the perceived severity of his deficits?
Phineas Gage had a iron pole go through his head (orbitofrontal cortex) and remained conscious. The diverging views of brain function were holism v. localism of function. Both sides held Gage up as poster child supporting both views. Since people said his brain function was normal except for damage to his one eye, this supported Floren's view that there is not functional specialization. However, he did have damaged that showed itself later, including inability to stick to plans, profanity and lack of concern for others.
Frontal lobes
Planning actions, maintaining goals, executing actions
Motor tics
Repetitive, jerking movements of a particular muscle group in the body.
What module in Norman & Shallice's model is hypothesized to be damaged in frontal lobe patients? Damage to this module should result in 2 characteristic types of behavior under different environmental contexts. Describe those behaviors and the contexts under which frontal lobe patients would exhibit them.
SAS when responses are not well-learned or contain novel sequences of actions, situations where one must overcome strong habitual response or temptation, error correction or trouble shooting, and dangerous or technically difficult tasks. Frontal lobe damage does not impair movement/execution, but actions become disorganized, and/or inappropriate for goals. Actions are automatically driven by habits & objects in the environment, rather than controlled behavior driven by current goals. Two types of behavior: perseveration/behavioral rigidity (repeating an action that has already been performed and is no longer relevant)-gambling, utilization behavior/distractibility (impulsive actions on irrelevant objects in the environment)-easily sidetracked
What is the experimental evidence that shows the prefrontal cortex is important to task switching?
Simpler tasks developed that isolate different aspects of a switch, Used more often in healthy participants than patients, difference in response between switch trials (higher) and non-switch trials (lower)
Describe the four domains in which executive function is needed. For each domain, describe the experimental evidence that the prefrontal cortex is important to implement that behavior.
The four domains where executive function is needed are task setting and problem solving, overcoming potent or habitual responses, task switching, and multitasking.
Reversal learning
The ability to stop responding to a previously rewarded stimulus that is no longer rewarded
hayling test
The captain wanted to stay with the sinking _____, complete the sentence with a sensible and then nonsense word, PFC patients are impaired on this task
Delay discounting
The tendency to undervalue, or downright ignore, future consequences and rewards in favor of more immediate gratification.
N-back test
a procedure where participants are given a sequence of items and must report whenever the current item is identical to the one "n" items before
Occipital lobes
Visual analysis of scene
Switch cost
a slowing of response time due to discarding a previous schema and setting up a new one
FAS test
a test of verbal fluency in which participants must generate words beginning with a letter in a limited amount of time, generate as many non-proper words beginning with "f" in a minute, involves generating novel strategies, selecting between alternatives and avoiding repeats, patients with lateral PFC lesions are often impaired
Error-related negativity
an electrical potential ("error potential") that can be detected at the scalp when an error is made
Vestibulocerebellum
controls balance and coordinates eye movements
Egas Moniz
developed the practice of lobotomies and won a Nobel prize for his work
Task switching
discarding a previous schema and establishing a new one
Multi-tasking
fitting tasks together to make the best use of time; doing two tasks at the same time
Executive functions
higher order thinking processes that include planning, organizing, inhibition, and decision-making
What is the experimental evidence that shows the prefrontal cortex is important to task setting and problem solving?
patients with either unilateral or bilateral frontal lobe damage (n=50) or posterior lesions (n=25) are given a metal cup with hole in the bottom, bottom of metal cup, metal hook, cork inside glass vial, glass container of water, and a small open bottle of gasoline with the objective to get cork outside of the cylinder and cap the gasoline bottle. Frontal lobe patients are impaired on this task. The cognitive estimates test asks odd questions such as how many camels are in holland which require problem solving based on known semantic information and the plausibility of the answer is tested. PFC patients produce bizarre responses.
Spinocerebellum
receives input and regulates actual motor performance
Prefrontal lobotomy
surgical procedure that severs fibers connecting the frontal lobes of the brain from the underlying thalamus
Impulsivity
tendency to act quickly without careful thought
sustained attention
the ability to maintain attention to a selected stimulus for a prolonged period of time
Monitoring
the act of observing something (and sometimes keeping a record of it), feedback on the progress and outcome of an action
Six Element Test
the patient is given six open-ended tasks to perform within a 15-minute period. Patients are instructed to attempt each task. However they will be unable to switch tasks, they spend too much time planning but never execute plans
tower of london test
two boards with pegs and several beads with different colors. The examiner uses the beads and the boards to present the examinee with problem-solving tasks, Frontal 33%, posterior 76%