brain areas main functions

Question 1

Prefrontal Cortex

Answer 1

Responsible for top down control (excitatory bias) and encoding task rules, and it is an internal source of action control. It has a unique, but overlapping, pattern of connectivity with all sensory neocortical, motor systems and a wide range of subcortical structures. Individuals with damage can seem strikingly normal upon superficial examination. Behavior can be described as stimulus-bound – they are unable to override impulses and display increased distractibility. For example, during the Wisconsin Card Sorting Task, individuals with prefrontal damage can usually learn the first rule but are unable to escape it: they make a great deal of errors because they lapse back to the earlier rule. PFC also plays a role in socially interactive decision making. Frontal Polar Cortex involved in encoding task rules and goals/rewards and involved in rule representation.

Question 2

Lateral Prefrontal Cortex

Answer 2

Extends to inferior frontal junction and is interconnected with higher order sensory and motor cortex and indirectly (through VMPFC) linked to limbic structures. Responsible for integration of stimuli and outcome, reward learning, working memory, and representation of options and cues (state representation). Most neurons are task-dependent (44%) and cells fire differentially during the delay according to the specific rule in operation. Activity here is related to working memory – sensory evidence accumulates. Important for task switching (lesions impair this)

Question 3

Dorsolateral Prefrontal Cortex / BA46

Answer 3

Involved in the retrieval of information (working memory task), executive function, and transformation of perceptual input into motor output. Area is active during n-back task - represents and maintains contextual information. Neurons here exhibit rule sensitivity.

Question 4

Ventrolateral Prefrontal Cortex

Answer 4

Involved in retrieval and maintenance of information (left-lateralized, working memory task), learning, maintaining, and implementing simple rules. Lesions result in disruption of acquisition and expression of a match-to-sample rule (impair ability to learn and maintain). Interacts with temporal cortices to retrieve the rule associated with a particular cue.

Question 5

Posterior Prefrontal Cortex / Frontal Eye Fields / BA8

Answer 5

Responsible for specifying eye-movements and maintenance of items. Neural signal gradually accumulates prior to eye movement onset. Area also shows delay activity during response delay periods. Principal sulcus bridges BA8 and BA46.

Question 6

Medial Prefrontal Cortex

Answer 6

Codes for possible actions to obtain rewards, endogenous control over action, emotions and motivation. High levels of activity are seen when people are not engaged in a particular task. Level of activity here predicts which items will be remembered (activates differently for self vs other words).

Question 7

Dorsomedial Prefrontal Cortex

Answer 7

involved in action selection

Question 8

Ventromedial Prefrontal Cortex

Answer 8

comprises the affective part of the Default Mode Network (involved in rest and self-referencing; affective node responsible for inhibition of emotional responses; control) and is involved in goal-oriented decision making and value expectation.

Question 9

Anterior Cingulate Cortex

Answer 9

Anterior cingulate cortex (affective) and medial cingulate cortex (motor) are involved in error detection, self-initiated movement, reward anticipation, attention positive self-information, and action-value comparison/association (action value task). It is involved in updating, weighing and evaluation of action-outcome associations. Lesions impair ability to make optimum decision and result in less interest in gathering information from social stimuli such as faces. Responsible for choosing appropriate action when environment is uncertain or dynamic (updates decision making and detects whether an outcome should lead to an error). Region for negative feedback as well as self-detected errors elicit a negative event related brain potential (ERN). Involved in metacognition and lesions result in less interest in gathering information from social stimuli

Question 10

Anterior Cingulate Sulcus

Answer 10

encodes value of goals in terms of probability, payoff, and costs.

Question 11

Ventral Anterior Cingulate Cortex

Answer 11

is responsible for focusing attention on positive information about the self (biases self- perception).

Question 12

Posterior Cingulate Cortex

Answer 12

Posterior Cingulate Cortex is comprised of the memory portion of the Default Mode Network (memory related node), while the paracingulate cortex (BA32) is involve in monitoring of outcomes (high activity during errors)

Question 13

Orbitofrontal Cortex

Answer 13

Association between stimulus (object) and value/reward (stimulus value task), decision making, reward expectancy (value assignment/comparison), sensory specific satiety (OFC activity decreases). Also involved in emotion and motivation. Activity is determined by expected outcome (value representation). Also involve in providing insight into own behaviour (accurate self-perception counteracting positively biased view made by ACC). Lesions impair ability to adjust decision strategies and result in loss of social dominance with increased aversion and reduced aggression in threatening situations. Helps people have accurate insight into their behaviour.

Question 14

Lateral Orbitofrontal Cortex

Answer 14

is involved in learning and updating of stimulus-reward associations (activated for new reward cues and value changes of reward cues). Lesions disrupt the assignment of precise values to stimuli; area is concerned with updating value representations.

Question 15

Superior Frontal Gyrus

Answer 15

Not necessary when a single action is selected, but necessary when the set of action selections rules changed or when they are first selected. Lesions here impair task switching when changes have to be made to the way that responses are selected. It is less important when switch simply entails a change in the way sensory stimuli are processed

Question 16

Anterior Superior Frontal Gyrus

Answer 16

involved in anticipatory preparation and selection of task set

Question 17

Inferior Frontal Junction

Answer 17

Engaged flexibly in attentional selection of different objects appearing at the same spatial location as well as attention-biased perception through neural synchrony with posterior regions where the actual sensory signals are contained. Involved in spatial attention and responsible for flexible coding of rules.

Question 18

Supplementary Eye Fields

Answer 18

self-generation, control, and inhibition of eye movements (NCE), voluntary control of action, lesions cause deficits in voluntary eye movement control.

Question 19

Pre- Supplementary Motor Area

Answer 19

self-generated behaviour, uncertainty and response conflict (control). Lesions in the pre-SMA and SMA result in monkeys show deficits in movements when they are self-initiated but not when guided by sensory cues, as well as inability to learn new movements.

Question 20

Supplementary Motor Area

Answer 20

self-generated voluntary movements (internal), self-reflection, suppression of involuntary movements, control of movement sequences, SMA damage can cause “alien hand”. Activation for established condition- action associations may cause automatic subconscious motor activation (priming).

Question 21

Pre-Motor Cortex

Answer 21

contributes to motor planning. The dorsal part (PMd) is involved in movement specification/motor commands, reaching, posture, and stimulus-movement learning. The ventral part (PMv) involved in abstract motor goals, sensory guidance of movement, damage causes limb apraxia (impairments in cognitive aspects of skilled object/tool use).

Question 22

PMd

Answer 22

is involved in movement specification/motor commands, reaching, posture, and stimulus-movement learning

Question 23

PMv

Answer 23

involved in abstract motor goals, sensory guidance of movement, damage causes limb apraxia (impairments in cognitive aspects of skilled object/tool use).

Question 24

Primary Motor Cortex / M1

Answer 24

Execution of movement, complex goal-directed movement, selection of appropriate action. Medial Motor Cortex is involved in action selection, selection and initiation of voluntary behaviour. Neural activity in motor cortex prior to movement correlates with movement direction and extent, speed, curvature

Question 25

Parietal Cortex

Answer 25

Specification of accurate action trajectory, representing response contingencies. Damage to left parietal lobe causes ideomotor apraxia (difficult producing complex movements by imitation or verbal command, while damage to Parietal Occipital Sulcus causes optic ataxia (mis-reaching to objects). Superior Parietal Lobe involved in attention switching. Lateral Intra-Parietal Area contains a salience map for visual attention (value-guided choice).

Question 26

Inferior Parietal Lobe

Answer 26

Sensitive to cue type (visual verbal) during cue presentation and to rule type (compound simple) during cue and delay periods and makes inferences about the function of an object from its structure (use action representation). Damage causes limb apraxia (impairments in cognitive aspects of skilled object/tool use).

Question 27

Superior Colliculus

Answer 27

Neural signal gradually accumulates prior to movement onset

Question 28

Striatum

Answer 28

receives input from cerebral cortex, brain stem, and thalamus. Internal capsule separates this into caudate nucleus and putamen. Transiently inhibits globus pallidus internal and external.

Question 29

Ventral Striatum

Answer 29

made up of nucleus accumbens and medial and ventral portions of the caudate and putamen. Also has striatal cells of the olfactory tubercle and anterior perforated substance. Receives input from limbic areas (associated with emotion). Activates during reward processing and positive feedback

Question 30

Dorsal Striatum

Answer 30

is made up of caudate nucleus (associated with cognition) and putamen (associated with sensorimotor function). These components are separated by the internal capsule (no clear structural or functional boundary. Receives input from sensorimotor areas.

Question 31

Globus Pallidus

Answer 31

GABAergic and part of putamen, Internal Segment (major output; tonically inhibiting VA/VL complex of thalamus) and the External Segment (part of their intrinsic circuitry that inhibits subthalamic nucleus)

Question 32

Substantia Nigra

Answer 32

GABAergic and contains two nuclei; Pars Compacta, containing dopaminergic cells that project heavily to the striatum and to the other nuclei of the basal ganglia (dopaminergic D1 and D2) and the Pars Reticulate (major output).

Question 33

Subthalamic Nucleus

Answer 33

small nucleus situated between thalamus and substantia nigra; transiently excites internal segment of GP. Receives projections from the external segment of the globus pallidus, cerebral cortex, thalamus, and brain stem. Sends output to both segments of the globus pallidus and substantia nigra pars reticulate (glutamatergic).

Question 34

Posterior Temporal Cortex:

Answer 34

important for generating action words in response to objects and retrieving knowledge about tools and is thus thought to represent functional information about objects. Activation profile consistent with a role in rule retrieval but not maintenance.

Question 35

Left Middle Temporal Cortex

Answer 35

exhibits rule sensitivity during the cue but not delay period.

Question 36

Amygdala

Answer 36

It is essential for linking objects with the current value of food rewards. The amygdala contributes to stimulus- reward association, to the extent that an affective tag from the amygdala provides the value signal (positive and negative affect). critical role of the amygdala in establishing expected reward representations in PFC that may be used to guide behavioral choice. Also contributes to emotional responses (reactions to fake snake or sight of food). Has no role in the reward processing that underlies the tasks (object-reversal learning), only processing emotional aspects of reward, including its valence and its relative value

Question 37

Inferior Temporal and Perirhinal Cortex:

Answer 37

Interaction with the frontal cortex is important for implementation of visually guided rules. IT/PRh-OFC route processes visual information (including foods and rewards). Object reversal learning does not require an intact amygdala, both does depend on both the OFC and the IT/PRh cortex.