Cognitive Psych Exam 1
Sarah Scotts case tells us, Broca's area:
-high-level speech planning is separate from ability to move and co-ordinate vocal musculature -speech output is separate from speech comprehension -Speech output is localized to one particular brain region: left, inferior, frontal cortex. -She didn't have an issue with pronuncing words couldn't figure out what words to use -Brocas area- issues with speech output
Brain
The brain is composed of the networks , which are organized according to their cognitive functions -This is known as localization of function
Winkielmann Pen Experiment
The participants had to bite pen down in mouth and then shown different emotions. Biting down affected the participants recognition of happy face, but no other emotion - they concluded that people need to simulat similing in order to percieve happiness -mimicry reflects internal simulation of perceived emotion in order to facilitate its understanding
Cognitive Psychology
The scientific study of mental processes and their role in thinking, feeling, and behaving
Controlling brain regions
This is an ERP fMRI study showing memory failure as a problem of encoding -What if the whole brain lights up more for remembered than forgotten? Need control brain regions. -Activity over the left visual cortex and right motor cortex is identical following words that subsequently are either remembered or forgotten. These results demonstrate that the memory effect is specific to the frontal and hippocampal regions. -no differences between remembered and forgotten
Single Cell Recordings: in a neuron
Tip of electrode in cell. Tip of ref electrode outside cell. Baseline firing rate established. (By the way "spike sorting" methods are apparently something of a black art. The physiologist listens to (or observes) a train of spikes and decides from the pattern that they are all coming from one cell, rather than from two neighboring cells. Often no way of knowing for sure).
Axon
Travels the message(the action potential) to the synaptic terminal
What they discovered from HM and Clive:
Two things: -Like HM, almost total hippocampal damage -Hippocampus (and surrounding cortex) is important for forming new declarative memories -BUT, Hippocampus is not important for all kinds of memory. Procedural learning is ok, Visual perception ok, language, ok. -SO, brain system for declarative memory must be separate from brain systems for other cognitive functions. (To some extent this is still believed to be true, but recent research shows that it is not as simple as that).
Father of Cog. psych
Ulric Neisser(1967) , integrated such topics as memory, perception, attention, and language as a unified field.
Biological Perspective: What in our brains might underlie the representations of representationalism? What in our brains might underlie the cognitive process of, say, learning? (changes in synaptic strength)
What in our brains might underlie the representations of representationalism? - patterns of neural firing ... ons and offs across particular connections What in our brains might underlie the cognitive process of, say, learning? -changes in synaptic strength
In neurons, ...
an electrical signal transmits info inside the neuron, whereas a chemical signal transmits info between neurons
PET has mostly been replaced as a brain imaging technique by the newer method of fMRI. This is because....
it gives better spatial resolution than PET, is non-invasive(no ingesting of radioactive substance) . Better temporal resolution than PET.
When did Cog Psych develop further ?
When the computer was invented. The computer presented an information-processing model as a way of thinking of cog. processes - the brain is thought of a computer that can store large amounts of info and acting to alter the info as learning takes place - cog.processes are the software that processes the information - the brain is the hardware - it gave researchers a new way to look at storage info - this model provided a universal language to allow researchers to discuss the processes of the mind and their connection to the brain
fMRI offers.... than EEG
better spatial resolution (precise location of brain activity) than EEG, but EEG offers better temporal resolution (precise timing) than fMRI Answer is True
Ventral pathway is involved(...)
-Ventral pathway is involved in object recognition
Neurons
-Basic cells of the brain -Activity is both chemical and electrical -Use neurotransmitters and action potentials Dendrites, axon, synapse
Clive WearinG: Case Study
Clive wearing- memory can be less than 7 seconds - had viral encephalitis And it destroys his hippocampus He seemed normal, but memory was not good -He lost ability to make new long-term declarative memories **Different brain regions have different contributions to functions.
Wernicke's aphasia
Damage to the left temporal lobe close to the front of the occipital lobe \, aka Wernicke's area - A deficit in language comprehension and meaningful language production - They can speak, but speech is meaningless "word salad"- fluent but incomprehensible
Different brain regions have ...
Different brain regions have different contributions to functions.
How is information processed in the brain?
Each neuron is connected to other neurons in an organized network that allows the pattern of firing in the network to translate into specific thoughts or behaviors. This is how information is processed and stored in the brain: through the pattern of firing across multiple neurons within the network (i.e., specific neurons being active or not active or firing at different rates) and types of connections (excitatory or inhibitory) across the neurons connected in each network.
What type of neural activity is recorded in single-cell, EEG and MEG recordings?
Electrical activity
Tan: case study
Tan was a pt studied by Broca - he was unable to speak for many years, only word was "Tan" - His brain was examined and there was damage to the left frontal lobe , near the front of the temporal lobe (aka Broca's area) - Broca's aphasia: a disorder where a person has difficulty producing speech
What is the earlier dip in TMS graph?
TMS before visual stimulus- Answer Trials when the TMS pulse caused the participant to blink (and miss the stimulus)
Brain visualization Research
In a series of three experiments, undergraduate students were either asked to read brief articles that made fictitious and unsubstantiated claims such as "watching television increases math skills," or they read a real article describing research showing that brain imaging can be used as a lie detector. When the research participants were asked to rate their agreement with the conclusions reached in the article, ratings were higher when a brain image had accompanied the article, compared to when it did not include a brain image, or included a bar graph representing the data (instead of an image of the brain). This effect occurred regardless of whether the article described a fictitious, implausible finding or realistic research. The papers with the images were much more compelling than the words, even if it was a real picture or fake article Pictures of the brain makes things seem more real
What is cognitive psychology?
It includes: -Perception -Attention -Memory -Language -Decision making -(Brain activity)
Language is..
Language is left-lateralized
Dendrites
Takes in info from the top of the neuron
Cell body
Takes in these chemical signals from dendrites and determines if there is enough of an excitatory signal to allow the neuron to fire.
Parietal Lobe
Processing Sensory input Goal directed movements Sense of touch and smell Manipulation of objects Primary and secondary somatic areas
Neurotransmitters
Providesignals to the cell that are excitatory (more likely to fire) or inhibitory(less likely to fire)
What can we conclude from Tan and Sarah Scoot?
Speech comprehension must have separate neural mechanisms from speech production
Occipital Lobe
Visual receptive area Visual interpretation Color identification
synapse
once the action potential signal is received at the end of the axon, the terminal buttons release neurotransmitter into the synapse to be collected by the post-synaptic neurons
What happened around 1990-1995?
the cognitive psych trend/interest went down
A synapse is ...
the gap between two neurons, where NTs are released and received
Brain visualizations
-EEG -fMRI -MEG Both allow researchers to visualize brain activity; to combine behavior with brain activity
Science Means ...
1. Testing Ideas-An honest interest in whether your ideas are wrong. 2. Method for objectively establishing that ideas are wrong. 3. Better ideas produce more accurate predictions for experiments that interact with the universe.
The Relativity of Wrong
"right" and "wrong" are NOT absolute; ; that everything that isn't perfectly and completely right is totally and equally wrong." -It does not establish objective truth, but can support ideas to such a degree that you'd be crazy to doubt them.
Four parts of a sensory system for the visual sense system *primary visual cortex
(1) sense organ—the eye, (2) receptor cells—the rods and cones in the retina, (3) nerve conduit to the brain—optic nerve, and (4) brain area where the information is being processed— *primary visual cortex (also called V1) in the occipital lobe of the brain (with extensions to other areas to connect with other cognitive processes).
Critical Thinking
-All of these are indirect measurements We assume these are correlated with cognitive processes - But, correlation does not imply causation Always critically evaluate assumed connections between measured behavior and the inferred cognitive processes
Measuring neural activity
-Electroencephalography (EEG) -Magnetoencephalography (MEG) -Functional magnetic resonance imaging (fMRI) -All of these allow us to visualize brain activity Can be combined with accuracy and/or response time
Measures of brain metabolism (blood flow)
-Functional Magnetic Resonance Imaging: refers to the machine for measuring activation -Positron Emission Tomography
-tactile sensory information is processed in... -gustatory sensory information is processed in... -olfactory sensory information is ...
tactile sensory information is processed in the parietal cortex; -gustatory sensory information is processed in the insular cortex at the junction of the frontal, temporal, and parietal lobes; and -olfactory sensory information is processed in the olfactory bulb near the temporal lobe and then sent to several connected areas of the brain.
Cognitive Neuroscience
the study of how cognitive functions are underpinned by neural processes
cerebral cortex
-Cerebral cortex- all the sulci and gyri, all the brain matter excluding cerbellum and brain stem -Cerebral cortex- all higher processing, INCLUDES: -sensory processing (vision, hearing ... ) -motor control -planning -memory -language * In other words, the processing of spelling, grammar, and meaning of words is distributed across several areas of the brain. Thus, there is localization of function for cognitive processes, but for most functions multiple areas are organized into processing systems for different cognitive abilities.
Perception can be(..)
(...) unconscious -No conscious experience of "seeing", yet able to make rudimentary visual discriminations -V1 damage--> Cortical blindness (full or hemianopia) But a small % of the cortically blind have "blindsight" *V1 cannot be critical for all aspects of vision - Blindsight patients can: move their eyes or point their finger toward moving stimuli distinguish orientation of a straight line -judge an item as moving vs. stationary -basic color judgments -basic perception of form -avoid stationary obstacles NOTES: -Blindsight is more than just in the occipital lobe -Diffusion of V1 causes blind sight -There is a Primary route to conscious vision -Secondary route from retina to superior colliculus to LIP -Dorsal pathway in the brain is involved in where an object is located -Ventral pathway is involved in object recognition
Object Agnosia: Case Study
-Oliver sacks talked about a patient who had damage in the inferior(lower) temporal cortex, and he had object agnosia - the inability to correctly recognize objects, thought fire hydrants were children - his deficit related to language abilities
Other Cog Psych Measures
-RT records time to initiate a response; some measures instead record duration, velocity or direction of a response (a movement) -Recent advances allow for brain visualization -Other research focuses not on the time taken to initiate a response but rather on other characteristics (e.g., duration, velocity, direction of movement) of response (
Phineaus Gage: Case Studies
- Phineas Gage: railroad worker. -In 1848, was using a "tamping iron" (rod) to pack explosive powder into a hole Powder exploded, sending the rod through his cheek, eye and frontal lobe -"The iron passed through the regions of the organs of BENEVOLENCE and VENERATION, which left these organs without influence in his character, hence his profanity and want of respect and kindness." John Harlow, 1851. - We learned that the frontal lobe is important in emotional regulation and decision making - It was a clean lesion, changes that people saw: Personality changed- he became aggressive Became more reckless, vulgar, cant follow through with plans -This is when they thought about using damage brain areas to figure out what the brain did or what parts were affected and how that affected cognition -He died of seizures
Early Representationalism
- early models belived info was stored as symbols that could be operated on like mathematical variable symbols. This allowed researchers to study the operations as processes of cognitions -As knowledge of cognition has advanced, these symbol systems have become more complex in representing the knowledge stored in our minds.
Cog Psych approach: Biological Perspective
- these researchers examine brain activity underlying cognitive processes through networks of neurons -builds 'neural network' models (using computers) -also known as 'connectionist' models -have also been developed to explain how we identify language through individual features of letters and spoken words. -our knowledge of the biological architecture of the brain and the neurological functioning of the brain has guided researchers in their attempts to better understand how different cognitive processes work.
Cog. Approaches: Embodied Cognition
-An approach to study cognitive processes through our visual senses providing information from allowing us to interact with the world and should be studied according to the purpose they serve. - cognition as an interaction between humans and their environment ex. that people will look at the space on an empty screen when recalling information previously presented at that location on the screen So: Cognition involves the way we interact with the world Cognition involves using not just our brains, but our bodies, too Cognition involves simulation
Cog Psych Approaches: Representationalism
-Arose from information-processing models of cognition - in cognition is to consider information from the world as being represented in some form in our minds. -approach is that knowledge about the world is represented in our minds such that cognitive processes can "operate" on the representations. -Ex. the concept of armadillos, we may think of them based on their characteristics , If we read about armadillos or see a documentary about them, we might change or add to this stored information as we learn more about armadillos than we previously knew. - info is stored in computers as 0 and 1 and in humans have neurons that fire on and off -This allows researchers to think of information as being stored in the mind and available for processing as we interpret, analyze, and alter this information in our thinking.
Transcranial magnetic stimulation
-Briefly disrupts cognitive processing -Affects surface cortical areas Summary: -Coil placed over target brain region -Cognitive failures recorded Interrupts functioning of the brain in the region of interest by sending a magnetic pulse to that region -Transcranial magnetic stimulation over the occipital lobe. (a) The center of the coil is positioned over the occipital lobe to disrupt visual processing. The participant attempts to name letters that are briefly presented on the screen. A transcranial magnetic stimulation (TMS) pulse is applied on some trials, either just before or just after the letter. (b) The independent variable is the time between the TMS pulse and letter presentation. Visual perception is markedly disrupted when the pulse occurs 80-120 ms after the letter due to disruption of neural activity in the visual cortex. There is also a drop in performance if the pulse comes before the letter. This is likely an artifact due to the participant blinking in response to the sound of the TMS pulse. The use of TMS for depression is discussed online at http://www.youtube.com/watch?v=3OM_JhFkB-Y NOTES: -X axiS: the pulse (zap) of TMS before and after stimulus -Y-axis: letters said correctly - the TMS stops the visual processing throughout the experiment , so visual processing is delayed by 70-130 ms
Event- Related Potentials (ERPs)
-EEG can reveal little about cognitive processes - too noisy. --The relatively small electrical responses to specific events can be observed only if the EEG traces are averaged over a series of trials. The large background oscillations of the EEG trace make it impossible to detect the evoked response to the sensory stimulus from a single trial. -Averaging across tens or hundreds of trials, however, removes the background EEG, leaving the event-related potential (ERP). Note the difference in scale between the EEG and ERP waveforms. -Electrocortogram (ECoG) is similar to an EEG, except that the electrodes are placed directly on the surface of the brain. -Auditory stimulus: ERPs can tell you about an event *combine EEG to make ERPs
Measures of electrical (neural) activity
-Electrophysiological (single-cell) recordings -Electroencephalography (EEG) and Event-Related Potentials (ERP) -Magnetoencephalography (MEG):refers to the nature of the activation itself
Single Cell Recording : Mirror neurons
-For example, using single-cell recordings from monkeys, Rizzolatti, Fadiga, Gallese, and Fogassi (1996) discovered a new type of neuron they called a mirror neuron. This neuron fired both when the monkeys picked up an object and when the monkeys were watching the researchers or other monkeys perform that action. In other words, these neurons were active when motor actions were performed and when the monkeys were just watching a motor action they knew how to perform. Since this discovery, researchers have suggested that mirror neurons may play a role in many sorts of social cognitions, including understanding others' actions, imitation of others' actions, and facilitation of language through gestures -For example, Quiroga, Reddy, Kreiman, Koch, and Fried (2005) found neurons in the hippocampus (known to be involved in memory functioning) that were selectively responsive to photos of celebrities such as Jennifer Aniston and Halle Berry (in recordings from epilepsy patients undergoing treatment). These results are consistent with the idea that neurons serve as feature detectors. These neurons have been called "grandmother cells" (Gross, 2002), because they suggest that we might even have a neuron (or set of neurons) that selectively responds to the face of our grandmother (assuming we have met her before).
Patient HM: Case study
-He had intractable epilepsy (anti-convulsant drugs not sufficient to control seizures) - To stop the seizures, surgeons took out the bilateral removal of medial temporal lobes (hippocampus) -eplielptic geneic focus: is in the medial temporal lobe, often in the hippocampus - this removal led to profound amnesia - they could not acquire new long-term declarative memories *All inputs come through: hippocampus, dentate gyrus, subiculum entorhinal cortex amygdala perirhinal cortex and parahippocampal cortex -From H. M.'s case, researchers learned about the importance of the role of the hippocampus in memory abilities, but they also learned that the hippocampus is not the only brain structure involved in forming and retrieving all types of memories. H. M. showed the ability to improve on tasks requiring motor skills, indicating that he could still retain new information and retrieve implicitly (i.e., without intention). Thus, H. M.'s case taught us that the hippocampus is not necessary for all types of memory formation and retrieval but is important for intentional retrieval of memories. -Medial- close to midline -Temporal- temporal side of head *showing that portions of H.M.'s posterior hippocampus were not removed during surgery.
Can all mental processes be explained in terms of brain activity?
-Libet (1985) describes studies of EEG brain activity showing that about half a second before someone is aware that he or she will perform an intentional action (e.g., pressing a button in an experiment), the brain signals that it is preparing to perform that action. -Libet argued this evidence suggests that our choices (at least simple ones like button presses) are determined unconsciously by the brain before we are consciously aware of making such choices. More recently, Schurger, Sitt, and Dehaene (2012) have argued that the activity seen in the brain before these choices are consciously made indicates readiness to make a choice rather than the actual choice itself. The debate on this question continues, but conscious choices are one area where researchers -An alternate idea is that the mind and body (i.e., the brain) are separate and distinct entities. In other words, the mind exists and functions separately from the functioning of the brain. This idea has been debated by philosophers for over a century and is called the mind-body problem. Dualists believe that the mind exists separately from the brain—that the mind is our conscious self and is not reducible to brain function. In contrast is the view presented earlier—that the mind is defined by brain function and cannot be separated from brain activity. T
Magnetoencephalography (MEG)
-MEG involves placing the head in or near an electrical scanner that can detect electrical activity with better location accuracy than EEG. - As with EEG recordings, MEG recordings can occur during a task such that changes in activity can be detected that correspond to the presentation of cognitive stimuli. - However, as with EEG, MEG is limited to recordings on the outer cortex and cannot provide a good measure of activity occurring below the cortex. -Synchronous activity in aligned dendrites creates a dipole (as in EEG). -Dipole generates a magnetic field. -BUT need magnetic shielding expensive! -And only get good signal from cortical folds
MEG
-MEG: similar to EEG, except that it involves detecting magnetic fields (rather than electrical potentials) emanating from the head. -These magnetic fields are generated by the electrical current that is associated with synaptic activity (magn fields are perpendicular to the current). -Good temporal resolution (like EEG) and also better spatial resolution than EEG. But more expensive. -electric current in the brain creates a magnetic field around it An electric dipole generates a magnetic field -But need magnetic shielding In the folds the dendrites align in one direction, so by physics only generates well here **MEG signal is best in fold of cortical sheet -Advantage: EEG has bad spatial resolution, MEG has better spatial resolution
PET (positron emission tomography) Disadvantages
-Measures blood flow -More active brain regions get increased blood flow (can infer which regions are active) -Subject ingests radioactive substance (binds to O2) -poor spatial resolution (~1cm) but good in its day! -poor temporal resolution (>1min) *PET: subject drinks a liquid containing radioactive substance. This is absorbed by blood (bound to O2). More blood flows to more active brain regions. Blood (containing O-15) is constantly emitting photons. More photon emissions from areas with more blood. So by measuring emitted photons we can detect which parts of the brain are most active.
EEG and ERPs
-Researchers can use EEG recordings to examine an event-related potential (ERP), which is a change in activity related to a specific event like the presentation of a stimulus. In that way, they can determine if there is an effect of that stimulus presentation on neuron activity and in what general area of the brain the effect occurs. -ERPs are obtained by averaging over the EEG signal from many occasions, all aligned in time to a specific event (e.g. presentation of a stimulus) -Therefore provide some idea of WHEN processes in the brain occur (e.g. that attention can influence neural events as early as 150ms after stimulus presentation).
Resurrection of Cog Psych : The digression
-Skinner proposed that language learning occurs through conditioning processes (Skinner, 1957). In other words, language development occurred through the imitation of speakers around a child and the feedback (reinforced or punished) the child's speech elicited. -Noam Chomsky; proposed that children produce language that has never been produced around them before, like grammatical errors, he believed children have an innate capacity to learn rules of language. -psychologists began to realize that the study of cognitive processes is an important part of understanding behavior—that understanding the processes behind the overt behaviors would advance our understanding of the mind and behavior in important ways -Experimentation is still the focus, but cognitive psychologists examine the behaviors resulting from the mental processes being studied. -behaviorism did influence the way we study cognitive processes today. Its focus on the experimental examination of behavior shaped the way researchers approach the study of mental processes.
Dependent Variable Independent Variable -Research begins with(...) - Which make (...)
-The behavior of interest(response) ;Measured by us -The variable we have control over and can manipulate; Causes changes in the dependent variable (stimulus) -(..) with hypotheses or theories -(..)predictions about the relationship between these variables
-The primary job of the sensory system then is to.. -distal stimulus
-The primary job of the sensory system then is to receive stimulus energy from the environmental stimulus and to recode that stimulus, called the distal stimulus, into something the brain can interpret and process. -stimulus in the environment
ERP components
-When we average EEG trials, we find some typical "components" that are related to cognitive events -e.g. P100 : P for 'positive' deflection in waveform, occurs 100ms after stimulus -P100 happens with 'selective attention' Cannot localize these components to structures In the brain. Cortical events are too spread out across lots of areas within cortex. -the bumps are typical components related to cognitive events after a stimulus -up is positive in this picture - P100 only happens from selective attention, like if you have 2 tasks, this only happens to the attention you give to one task
Electrical Measures: Single ell REcordings
-a tiny recording needle is inserted into a neuron in an area of the brain the researcher is interested in (see Figure 2.8). However, this technique requires surgical insertion of the needle and bonding to the head to keep the needle steady (see Figure 2.9). Thus, this technique is typically used only in research with laboratory animals. *records electrical signals *Animals Extensively used in a variety of visual and auditory tasks *Humans Occasionally used in treating epilepsy of the medial temporal lobe (MTL) -In humans, doctors, they wait for a seziure to happen and map out which parts of the brain causes a problem and only take out those parts -While the activity of a single cell is monitored, the monkey is required to maintain fixation, and stimuli are presented at various positions in its field of view. The cell fires vigorously when the stimulus is presented in the upper right quadrant, thus defining the upper right as the receptive field for this cell.
Research Methods: Coorelational Studies
-allows one to systematically observe groups, recording the frequency and/or intensity of many variables at once. These observations may include indirect measures such as self-report -Minimal impact on the measured behavior, observe natural behavior -Advantages: Allows observation of many variables in natural contexts -Disadvantages: Does not imply causal inference, or make generalizations
EEG: Advantages Disadvantages Eplipesy EEG is used in.. Epliepsy has wave forms that....
-excellent temporal resolution (ms by ms) -very poor spatial resolution -Epilepsy - an electrical storm. Neurons fire in large quantities at once (bursts of activity) at random times. Increases in amplitude of firing over ALL electrodes shown here. Can be reduced by anti-convulsant drugs. -EEG used in sleep research - Epliiptic seizure has wave forms that cant even be measured
fMRI (functional magnetic resonance imaging)
-fMRI is a technique that records brain activity with a scan of the magnetic properties of the blood flowing through the brain. -Similar to PET, fMRI shows blood flow activity to specific areas of the brain with more active areas shown in brighter colors on the scan. -fMRI relies on a subtraction method, where activity recorded before the task (called the baseline recording, which is a control condition in this type of study) is subtracted from the activity recorded during the task. - fMRI requires that the participant be placed in a magnetic scanner during the task. Typically, a mirror is positioned in the scanner for the participant to view the stimuli presented. fMRI is often preferred by researchers conducting brain scans because they are able to view brain activity during a task (unlike MRI) and there is no potentially harmful radioactive substance that needs to be ingested by the participant
Research Methods: CAse Study
-focuses on intensive analyses of a single individual or more broadly on a single observation unit (e.g., the unit of analysis for the research could be on a couple or on a single institution). Often, the focus of case studies is on unique individuals who display characteristics outside of what is considered the norm. - Ex. HM, to relieve epileptic seizures , he had surgery in his medial temporal lobe . After surgery, he couldnt form new long-term declarative memories -But Case studies CANNOT be generalized casue its only one person Advantages Researchers can gather a large number of observations of a broad range of behaviors Disadvantages unique exemplar isn't always generalizable - researcher can speculate to demonstrate behaviors are related, need lots of subjects and show that they are related in this way in all subjects (or on average, across subjects)
Research Methods: Experimental Studies
-is designed to simplify the contexts surrounding the behavior of interest, allowing for focused investigation of the impact of a relatively small set of variables. -manipulate the variables - can do quasi-independent variables; natural groups; As a result, when interpreting any of the results that involve natural groups, one needs to be appropriately conservative about making causal claims. -Uses independent and dependent variables -Can have more than one of each -ADVANTAGE: By virtue of experimental control and the explicit manipulation of independent variables, Provides more confidence closer to being able to infer cause and effect - DISADVANTAGE : cant generalize to othe context (external validity); one must be careful in generalizing the conclusions drawn from experiments to the more complex, naturally occurring contexts in which the behavior normally occurs. Ex: Suppose that you want to know whether people prefer the taste of cane sugar or a sugar substitute that you developed. You design an experiment in which you ask two groups of people to taste one of the types of sweetener and then rate how much they like the taste. Then you compare the ratings of the two groups (see Figure 1.1). In this example, the behavior of interest (our dependent variable) is taste, as measured by the tasters' ratings. The independent variable is which sweetener is presented to each group. However, how something tastes is complex, with many different variables influencing it (e.g., whether in food or drink, what smells are present, how the food looks). To keep your observations focused on the sweetener, you may also manipulate these other variables by keeping them constant for everybody in both groups (e.g., use lemon cookies baked using the same recipe with the only difference being the kind of sweetener used). The logic of doing this is to try to ensure that the only difference between the two groups is the independent variable
fMRI (functional magnetic resonance imaging)
-measures hemodynamic response (i.e., blood flow being delivered to neurons) -response is delayed relative to neural activity (6-8sec) -Good spatial resolution (~2mm) temporal resolution not great (2-4 sec) -HRF starts about 2 secs after stimulus presentation, peaks 6-8 seconds later and falls to zero after 16 sec. -This technique measures regional changes in blood flow. -As blood flow increases (to an active brain region), so does the oxygen concentration in the blood. -Although the active neurons gobble up some of the oxygen, they cannot absorb all the extra oxygen that arrives, so there is a greater concentration of oxygenated hemoglobin in active brain regions. -Oxygenated hemoglobin increases the MRI signal relative to deoxy-Hb. -Therefore can detect regions with increased blood flow. These are the active regions. ADVANTAGE: Excellent spatial resolution (2-3 mm) DISADVANTAGE: Poor temporal resolution (on the order of seconds) NOTES: Measures bloodlike PET but different Measures BOLD signal Temporal resolution not great, how fine a window we can put around the pic, cant finely hone in to the data;
MRI (magnetic resonance imaging)
-often used medically to gain clear images of interior structures of the body. - In an MRI scan, a magnetic field is generated to create an image using recordings of the signal coming from the positive hydrogen atoms within the cells of the body. - An MRI of the brain can create a clear image of the different structures of the brain that allows comparison across individuals and identification of damage or the presence of tumors
EEG -Electroencephalography
-records electrical signals in the brain - When recording an EEG, a set of electrodes is placed on the head (see Photo 2.1) to record the electrical signals from groups of neurons in different areas of the brain. Because the electrodes are recording from outside the skull, it is the activity of the neurons closest to the skull (primarily neurons in the outer cortex) that is being recorded. The activity is recorded over time to detect changes (positive or negative) in the electrical signals -electrical potential at electrode = summed electrical activity of large populations of synchronously active neurons - signal comes from dendrites - dendrites have to be aligned - and perpendicular to the scalp EEGs do not pick up electrical firing from individual parts of the brain. -Dendrites are aligned in the gyrus, we are able to read the electrical potential *It gives you more temporal resolution
PET (positron emission tomography)
-researchers can measure the blood flow to different areas of the brain. - Blood flows in greater volume to more active areas of the brain; thus, the measure of the blood flow will indicate the areas of the brain most active during a cognitive task. -Blood flow is detected through the ingestion of a small amount of a radioactive substance. - The radioactive substance is then absorbed into the blood and flows to the brain as blood is needed in active areas. - The radioactivity in the blood is then measured in a PET scan to determine which areas of the brain are more active than others during a task. - The recording of the radioactivity is then overlaid onto a map of the brain to examine which areas are the most and least active. In a PET scan, color indicates the level of activity occurring in different areas
transcranial magnetic stimulation (TMS)
-researchers use a magnetic field to excite or inhibit neuron activity to investigate functioning in specific areas or processing systems of the brain. Like EEG and MEG, this technique is noninvasive, as it involves tracing a magnetic coil over the area of the brain the researcher wishes to study -The electrical activity (an increase or decrease) can then be recorded using one of the brain imaging techniques discussed in the next section (e.g., magnetic resonance imaging). -Studies using TMS have shown that some cognitive tasks (e.g., making spatial judgments for visual stimuli) use a broader range of brain areas (e.g., frontal lobe) than what was previously thought using other brain recording techniques.
Perception Sensation Consciousness
-the cognitive processes by which we interpret the sensory stimuli in the world around us -the registration of incoming sensory stimulation by a sense organ - the state of being aware (of something)
Phrenology Brain Imaging
-the detailed study of the shape and size of the cranium as a supposed indication of character and mental abilities. -Brain imaging = a more principled version of phrenology? (Using empirical studies of brain activation to map out the areas corresponding to each 'function'). - They use brain imaging to map out the brain Problems? 1. First - it's an oversimplification - "more activation" doesn't always mean that region makes a critical contribution. 2. Second - what does this tell us about *how* the brain achieves these cognitive feats? At best, finding a blob of activation during a given task gives us a 'map' of cognitive architecture in the brain, not a deep understanding of how cognitive operations are computed by neurons.
Metabolic measures of brain activation are in general: ..than electrical measures
...More sluggish( slower) than electrical measures - metabolic measure are blood flow measures
The Scientific method : 4 principles
1. Empiricism-the principle that the key to understanding new things is through systematic; much of cognitive psychological theory is based on clever indirect measurements of these processes. observation. 2. Determinism-the principle that behaviors have underlying causes and that "understanding" involves identification of what these causes are and how they are related to the behavior of interest. - These sets of cause-and-effect relationships between variables (the "causes" and the "behaviors" that they influence) are what make up theories of behavior. 3. Testability-the principle that theories must be stated in ways that allow them to be evaluated through observation. -Theories must make testable predictions and must be evaluated through observation in experiments to test those predictions; 4. Parsimony-the principle to prefer the simple explanations over more complex ones. If there are two or more theories left standing (accounting for the same amount of data), then adopting the least complex one is preferred (at least until further data are collected that refute the simpler theory). ex. Parsimony: Occam's razor - Use this in your life. Car won't start - Friend 1: probably the battery; Friend 2: could be that your unknown identical twin runs a drug cartel. The FBI mistook you for your brother, installed a tracking device in your car (and weren't bothered that a drug kingpin apparently drives a 2006 Toyota Corolla) and didn't properly reinstall your alternator afterwards. Conspiracy theories.
Cog Psych History: 1.Artistotle- 2. Wilheim Wundt- 3. Hermann Ebbinghaus
1.asked about the nature of cognition. Memory as a wax tablet - events are stored like molds in hot wax, with durability that varies depending on the memory or the wax, or subsequent events like heating. 2. Studied conscious expierence, INTROSPECTION; not really precise measurement, e.g. reaction times or accuracy, but for the first time emphasized observation and control. Treating the study of the mind as an empirical science. Had the idea of making psych a science 3. studied his own memory. Recorded his responses, calculated accuracy or percent recalled and mapped out a forgetting curve.(EXPERIMENTS); did experiments like we do now; forgetting ccurve:huge difference between 5 mins and 1 day , but not 6 months to 7 months
Single cell electrode in animals Advantages Disadvantages
A microelectrode is inserted into brain tissue and recordings of action potentials can be made from nearby neurons, ideally a single neuron. The animal can then be presented with various sensory stimuli, or trained to perform some task, and the effects on neural activity can be monitored. -Tip of electrode in cell. Tip of ref electrode outside cell. Baseline firing rate established. (By the way "spike sorting" methods are apparently something of a black art. The physiologist listens to (or observes) a train of spikes and decides from the pattern that they are all coming from one cell, rather than from two neighboring cells. Often no way of knowing for sure). Advantages: great spatial and temporal resolution Pros: Excellent spatial and temporal resolution Disadvantages: samples only a very small fraction of a functional neural system Cons: invasive, and cannot measure "population code" -Cannot measure population code- can only see on neuron, not many neurons and those patterns may be important -Example of a key discovery: cells in prefrontal cortex keep information in memory during a short delay
Common measures in Psych
Accuracy: Involves right or wrong responses Could involve the number and kinds of errors, e.g. false memories Response Time: How long it takes to respond to a stimulus -Donders's methodology assumes that components of mental processes are strictly discrete and serial. That is, each stage operates separately and in sequence. With these assumptions, one may subtract the reaction times of the first task from the reaction times of the second task, leaving a measurement of the time required to perform discrimination and choice. Ex. eye movement studies - Priming: Priming - might be the word nurse and target is doctor, which leads to test: word or non-word Idea is that seeing nurse primes on to see doctor and then faster to choose which is the word, but if you see bread and then doctor takes longer to pull that concept from head so it takes you longer to choose the word
We saw two brain regions that showed a rembered> forgotten difference. Why do we still need to find a region that shows no difference?
Answer—> AS a control to show that it isn't the whole brain that lights up more for remembered than forgotten
Temporal lobe
Auditory reception Expressed behavior Receptive speech Categorization of objects Memory Acquisition
ACtion Potential
Before the neuron fires, the inside of the axon contains a resting state negative charge due to the division of ions in the fluid inside and outside the cell (see Figure 2.4). The action potential redistributes these ions through channels in the axon's membrane that control the flow of potassium (K+), sodium (Na+), and chlorine (Cl-) ions in and out of the cell. When the excitatory signal comes down the axon from the cell body, the axon opens specific channels in the axon membrane to allow sodium to flow into the axon, producing a positive charge inside the cell. The channels open quickly in sequence from the top of the axon (at the axon hillock) near the cell body down to the end near the terminals that contain the neurotransmitter (see Figure 2.5). Once the action potential is complete, other channels open in the axon membrane to allow potassium (K+) to flow out of the cell and the sodium channels close. This redistributes the ions back to the resting negative state inside the axon. The excitatory message then reaches the terminals and a neurotransmitter is released into the synapse
Temporary fall of Cog Psych
Behaviorism : only public events (behaviors) can be objectively observed, and so private events (thoughts, emotions, mental calculations) should be ignored. -People began to reject observing mental processes because they argued you just cant say things that happen in between, so behaviorist began to do stimulus -->watch response
frontal lobe function
executive function Concentration Attention Elaboration of thought Judgement Decision Making Inhibition Personality Controls emotional response Memory for habitual behavior
Cog neuroscience methods include:
finding a subject population, study brain damage or brain areas, and a measure of behavior.
Each of these sense organs contains (...)
receptor cells of different sorts that convert the stimulus energy (e.g., air waves and pressure, chemicals in the air and food, temperature and pressure from stimuli) received by the sense organ into neural signals to be sent to the brain for processing.
sensory system for auditory stimuli:
sensory system for auditory stimuli: (1) the ear, (2) hair cells in the ear, (3) the auditory nerve, and (4) **the primary auditory cortex (also called A1) receiving area in the temporal lobe.
Transcranial direct current stimulation (tDCS)
tDCS delivers a small electric current to the brain through electrodes attached to the scalp. Thus, it is also a noninvasive technique. tDCS is cheaper and easier to use than TMS but produces a weaker effect on neuron activity than TMS.
fMRI : event-related
Event-related fMRI study showing memory failure as a problem of encoding. the left inferior frontal gyrus (LIFG) in the left hemisphere exhibits greater activity during encoding for words that are subsequently remembered compared to those that are forgotten. -Posterior LIFG had a bigger activation when you rembered and less when forgotten -figure shows brain activation AT TIME OF ENCODING sorted by whether the word was later remembered or forgotten -the parahippocampal region in the left hemisphere exhibits greater activity during encoding for words that are subsequently remembered compared to those that are forgotten. (A = parahippocampal region; B = fusiform gyrus.)
fMRI graph
Figure 3.32: Functional MRI signal observed from visual cortex in the cat with a 4.7-tesla scanner. - The black bar indicates the duration of a visual stimulus. Initially, there is a dip in the blood oxygen level-dependent (BOLD) signal, reflecting the depletion of oxygen from the activated cells. -Over time, the BOLD signal increases, reflecting the increased hemodynamic response to the activated area (i.e. the flood of oxygenated blood into the area). -BOLD signal is highest, when therre is extra blood around - The dip is a theory that the brain sucks up so much blood that it it takes time for the blood to regenerate a surplus to send more to the vascular system -detects differences between two states (more oxygenated blood in one state) -e.g., detecting regions involved in memory: compare activation when studying words that were later remembered with activation when studying words that were later forgotten -You measure two states, baseline state and what you are trying to observe (condition of interst)
What is cognitive neuroscience? Methods:
The study of how cognitive functions are underpinned by neural processes -Case Studies (brain damage) -Techniques for measuring neural activity -Techniques for perturbing neural activity -Also need to measure cognitive function!
Broca's aphasia:
a disorder where a person has difficulty producing speech Language is left-lateralized Brocas area- they still have comprehension, they know what they want to say , but they cant form sentences -problem with speech output -no motoric problems with - -vocal musculature (therefore must be linguistic) -no obvious problems with language comprehension -telegram-like speech ("need help, send money") with conjunctions / prepositions missing
Our sense organs—ears, eyes, nose, tongue, and skin—all (..)
begin the process of perception for us, sometimes unintentionally. Often, we are simply sensing the world without intending to hear, see, or feel, but our sense organs work automatically to bring in the sensations from our environment.
