Cognitive Neuroscience Midterm

Brain-Machine Interface (BMI)

A device that uses the interpretation of neuronal signals to perform desired operations with a mechanical device outside of the body. For instance, signals recorded from neurons or EEG can be used to move a prosthetic arm.

Balint's Syndrome

A disorder following bilateral occipitoparietal stroke, characterized by difficulty in perceiving visual objects. Patients with the disorder can correctly identify objects but have difficulty relating objects to one another. They tend to focus on attention to one object to the exclusion of others when the objects are presented simultaneously.

Corpus Callosum

A fiber system composed if axons that connect the cortex of the two cerebral hemispheres.

Aphasia

A language deficit following brain damage or disease. Disturbances of language comprehension.

Cerebellum

A large, highly convoluted (infolded) structure located dorsal to the brainstem at the level of the pons. The cerebellum maintains (directly or indirectly) interconnectivity with widespread cortical, subcortical, brainstem, and spinal cord structures, and plays a role in various aspects of coordinating ranging from locomotion to skilled, volitional movement. Also known as "little cerebrum".

Broca

Broca showed that a lesion of the posterior third of the left inferior frontal gyrus causes a motor speech disturbance without affecting understanding of speech. He believed that the "motor images of words" are localized in this part of the brain.

Cortical Pyramidal Cells

Cells in the cortex which lengthen with neocorticalization.

Chimeric Face Experiment

Tasks that can be broken into logical elements in an analytic way are best performed by left hemisphere. *Left hemisphere is best suited to verbal encoding. Tasks that require global processing of whole input are best performed by right hemisphere. *Right hemisphere is best suited to spatial-perceptual analysis.

Adaptive Resonance Theory

The Adaptive Resonance Theory (ART) is a class of computer models that captures some of the cardinal features of active visual perception. Grossberg & Carpenter developed ART beginning in the 1980s. ART models can be trained to perform pattern recognition, i.e. after learning, they recognize a category of input patterns.

Anhedonia

The absence of pleasure from experience that would normally be pleasurable

Action Potential

The active or regenerative electrical signal that is required for synaptic communication. They are propagated along the axon and result in the release of neurotransmitter.

Autonomic Nervous System

The body system that regulates heart rate, breathing, and glandular secretions and may become activated during arousal, initiating "fight or flight" behavioral response to a stimulus. It has two subdivisions, the sympathetic and parasympathetic branches.

Central Nervous System

The brain and spinal cord.

Cognitive Psychology

The branch of psychology hat studies how the mind internally represents the external world and performs the mental computations required for all aspects of thinking. Cognitive psychologists study the vast set of mental operations associated with such things as perception, attention, memory, language, and problem solving.

Degeneracy

The capacity to elicit the same response when their different components are stimulated.

Blood Oxygen Level Dependent (BOLD) Signal

The change in magnetic resonance signal intensity of hydrogen ion concentration in the brain, which results from changes in local tissue oxygenation state, When neurons become more active, this triggers an increase in the amount of oxygenated blood entering local capillaries in the tissue. This alters the ratio of oxygenated to deoxygenated hemoglobin in the tissue. Because deoxygenated hemoglobin is paramagnetic, it disrupts the local magnetic properties of the tissue and the MR signal intensity drops. Conversely, when oxygenated blood increases in response to local neuron activity, the MR signal intensity increases, and this is known as the BOLD response. The BOLD signal is an indirect measure of neural activity, and is delayed with respect to the neural activity that leads to the BOLD signal, taking about 2-3 seconds to begin, and 5-6 seconds after the onset of neural activity to peak.

Connectivity

The cognitive code is a relational code, based on connectivity between discrete neuronal assemblies of the cortex; any neural element of cognition derives its meaning from its contextual relations to others.

Central Sulcus

The deep fold or fissure between the frontal and parietal cortex that separates the primary motor cortex from the primary somatosensory cortex.

Delayed Match-to-Sample Task

The delayed match-to-sample task: a) a sample stimulus is briefly presented, followed by the delay period. b) after the delay, the monkey is presented with 2 or more test stimuli, and is required to respond in a way that indicates which one is a match to the sample. c) the motor act depends, or is contingent, on the stimulus information held in memory. d) the monkey receives a reward for correct performance.

Deep-Brain Stimulation

The electrical stimulation of brain structures via an implanted electrode. Stimulation of the subthalamic nucleus, one of the nuclei of the basal ganglia, is used as a treatment for Parkinson's disease.

Cerebral Cortex

The layered sheet of neurons that overlies the forebrain. The cerebral cortex consists of neuronal subdivisions (areas) interconnected with other cortical areas, subcortical structures, and the cerebellum and spinal cortex.

Anterior Commissure

The nerve bundle connecting the left and right cerebral hemispheres. Located anterior to the corpus callosum.

Beta Rhythm

The normal electrical activity of the brain when conscious and alert, consisting of oscillations ( beta waves ) with a frequency of 18 to 25 hertz.

Axon

The process extending away from a neuron down which action potentials travel. The terminals of axons contact other neurons at synapses.

Brainstem

The region of the nervous system that contains groups of motor and sensory nuclei, nuclei of widespread modulatory neurotransmitter systems, and white matter tracts of ascending sensory information and descending motor signals.

Cognitive Neuroscience

The study of how the brain enables the mind.

Behaviorism

The theory that environment and learning are the primary factors in mental development, and that people should be studied by outside observation.

Brainstem Motor Nuclei

The vestibular nuclei, the nuclei of the reticular formation, and nuclei of the substantia nigra.

Association Cortex

The volume of the neocortex that is not strictly sensory or motor, but receives inputs from multiple sensorimotor modalities.

Cytocarchitectonics

The way in which cells differ between brain regions.

Bottom-Up Processing

Thought to originate at the lowest levels of sensory processing and to be determined by properties of sensory stimuli, such as saliency and novelty. That is, stimuli that are salient or novel will be processed with greater bottom-up attention. The classical example of bottom-up attentional processing based on saliency in vision is figure-ground separation, or pop-out.

Critical Period

Time windows before or after birth during which a set of enabling factors act to guide normal development.

Computational Mind

Treats the mind as an information-bearing and information-processing system.

Computational Theory of Mind

Treats the mind as an information-bearing and information-processing system.

Backward Error Propagation

A common method of training artificial neural networks used in conjunction with an optimization method such as gradient descent. (1) Randomize the weights (2) Present an input pattern (3) Compare the output with the desired output (i.e. compute the error) (4) Slightly adjust the weights to reduce the error (5) Repeat (2) - (4)

Depolarization

A change in the membrane potential in which the electrical current inside the cell becomes less negative. With respect to the resting potential, a depolarized membrane potential is closer to the firing threshold.

Basal Ganglia

A collection of five subcortical nuclei: the caudate, putamen, globus pallidus, subthalamic nucleus, and substantia nigra. The basal ganglia are involved in motor control and learning. Reciprocal neuronal loops project from cortical areas to the basal ganglia and back to the cortex. Two prominent basal ganglia disorders are Parkinson's disease and Huntington's disease. Input comes to the striatum. Output is from the globus pallidus and part of the substantia nigra. The other parts of the basal ganglia modulate internal b.g. activity. Axons from the globus pallidus terminate in the thalamic nuclei, which project to frontal neocortex.

Diffusion Tensor Imaging (DTI)

A neuroimaging technique employed using an MRI scanner that allows white matter pathways in the brain to be imaged.

Axon Hillock

A part of the cell body of a neuron where the membrane potentials are summated before being transmitted down the axon.

Blood-Brain Barrier

A physical barrier formed by the end feet of astrocytes between the blood vessels in the brain and the tissues of the brain. The BBB limits which materials in the blood can gain access to neurons in the nervous system.

Cerebral Vascular Accident (Stroke)

A rapid loss of brain function due to a compromise in the blood supply to the brain secondary to arterial occlusion or hemorrhage.

Artificial Neural Network

A term for PDP models because they are thought to work like brain regions.

Brain Graph

A visual model of the connections within some part of the nervous system.

Angiography

An imaging method used to evaluate the circulatory system in the brain.

Anterior Cingulate Cortex (ACC)

Anterior portion of the cingulate cortex, located below the frontal lobe along the medial surface. This region is characterized by a primitive cytoarchitecture (three-layered cortex) and is part of the interface between the frontal lobe and the limbic system. The ACC is implicated in various executive functions, such as response monitoring, error detection, and attention.

Axon Collateral

Branches off an axon that can transmit signals to more than one cell.

Disexecutive Syndrome

Damage to lateral prefrontal cortex leads to a set of symptoms that have been characterized as the disexecutive syndrome (Baddeley 1986). This syndrome consists of the inability to formulate, initiate, and execute plans of action.

Apraxia

Difficulty pronouncing words. Impaired ability to carry out purposeful movement.

Degenerative Disorder

Disorders or diseases, either genetic or environmental, in which the function or structure of the affected tissues will continue to deteriorate over time.

Attentional Bottleneck

Filter model of Attention.

Delta Rhythm

Frequency of oscillation between 0-4 hertz. Deep Sleep.

Alpha Rhythm

Frequency range of 7.5-12.5 Hz. During wakeful relaxation with closed eyes.

Amygdala

Known to be involved in the assignment of emotional significance to external events. Groups of neurons anterior to the hippocampus in the medial temporal lobe that are involved in emotional processing. Lesions of the amygdala also cause memory deficits.

Dendrite

Large tree-like processes of neurons that receive inputs from other neurons at locations called synapses.

Cortical Achromatopsia

Loss of ability to detect color.

Anopsia

Loss of focal vision.

Connectionism

Mental phenomena can be described by interconnected networks of simple and often uniform units.

Color-Attentive Neurons

Neurons which respond significantly more to their preferred color. Evidence for Top-Down Processing of Attention

Cognitive Hierarchy

Perceptual categories are organized in cognitive hierarchies of progressive generality and abstraction.

Brainstem Neurotransmitter System

Plays a role in the formation of neocortical networks.

Delay-Period Prefrontal Neuron Activation

Properties of delay-period prefrontal neuron activation: 1) it is strictly dependent on the task requirement to perform a motor act contingent on some information kept in working memory 2) it is not induced by expectancy of the reward 3) it is correlated with the monkey's ability to remember the information 4) it can be obliterated by distraction

Damasio

Proposed Convergence Zones

Broca's Area

Region in the frontal lobe of the dominant hemisphere (usually the left) with functions linked to speech production.

Associative Memory

Relating patterns from the input space to corresponding patterns in the output space.

Brain Lesion

Structural damage to the white or gray matter of the brain. Lesions result from many causes, including tumor, stroke, and degenerative disorders such as Alzheimer's disease.

Cortical Modularity

Structure of the cortex.

Convergence Zone

Symbolic networks may consist of nodes of convergence. Damasio proposed that convergence zones (nodes) are high-level networks in association cortex that represent association patterns, i.e. they code for specific patterns of sensory activities. A symbol is a pattern of association of sensory activities. When the symbolic network is activated, it may re-activate the lower-level sensory networks from which it was formed.

Cholinergic System

System which is important for memory consolidation in neocortex.