Cognitive Neuroscience Lecture 19: Cognitive Control

''L19: Cognitive Control''

Cognitive control, goal-oriented behavior, and prefrontal cortex

Cognitive control: mental abilities that involve planning, controlling, and regulating flow of info processing

'''Goal oriented behavior''': interacting with the world in a purposeful manner

Prefrontal needed for both.

All areas in front of primary and secondary motor areas = PFC

'''John Fulton: lobotomy in chimpsàcalm'''

'''Egas Moniz: lobotomy in humansà worked but not in all cases '''

'''Walter Freeman: ice pic lobotomy '''

Made patients listless

Evidence from nonhuman primates

-         Monkeys with LPFC lesions failed at delayed response task (working memory) 

-         Location of food reward varies randomly from trial to trial

-         Able to do associative memory trial, but unable to do working memory task (no cue)

-         Cells in prefrontal responds when cue turned off until response

PFC and recency/source memory: humans & aging

-         Recency depends on ability to segregate and organize infoà affected by PFC damage

-         Tested in patients with parts of pfc removed for epilepsy

'''Frontal lobe damage did worst on recency test'''

Recency defecits observed only in patients with lesions to DLPFC—right DLPFC for object stim and left DLPFC for word stim

Central exec of Baddeley Hitch = DLPFC

Source memory:Where info was learned

DLPFC damage ruins source info

-         Glisky et al: neuropsych: high/low frontal lobe, high/low medial temporal lobe

-         Low frontal lobe functionàpoor source memory

-         Low temporal lobe functionàpoor item memory

Testing Frontal activity during retrieval of source memory

-         Encode individual words: pleasant/unpleasant, concrete or abstract

-         Test: one of pair

o '''Source test: pleasant/unpleasant? à Left lateral prefrontal activation>'''

o '''Recency: which was most recent? à right lateral prefrontal activation>'''

Componential approaches to PFC

'''Content-based accounts''': focus on the relation of verbal vs. spatial information to particular prefrontal regions, typically in working memory paradigms

-         Instruction cue indicates task required for trial

-         '''Bilateral superior prefrontal & parietal, right inferior frontal: spatial '''

-         '''Left inferior/lateral prefrontal, temporal: verbal '''

-         '''Anterior PFC, near frontal pole, similar for both tasks'''

-         '''DLPFC more active when stim remembered in backward order for any content'''

'''Process-based accounts''': focus on processing differences in specific prefrontal regions, especially role of task complexity in driving prefrontal activity, such as N-back task effects & task manipulations related to hierarchical organization

'''Hierarchical task manipulation: '''

-         Simple stimulus-response rules: press x when y

-         Add task contingencies: press x when specific instance of y

-         '''More complex contingencies: change rules between blocks'''

-         '''Prefrontal activation got more and more anterior suggesting hierarchical organization '''

Cognitive control of goal directed behavior

-         Many processes: need PFC

-         Identify goals, filter goals, switch tasks

-         '''Lateral prefrontal lesions have trouble with goal directed behavior '''

o Do not go in a logical order when given a list

-         Tasks that pinpoint lateral prefrontal damage: Wisconsin card sorting

o Normal people will guess and check after rule stops working

o Lateral PFC damage are prone to perseverate

-         '''Prefrontal cortex also contributes to selecting task-relevant information (filtering)'''

o '''Dynamic filtering: left inferior frontal cortex, left temporal'''

o This is the part damaged in people who do bad for high filter

-         '''Task switching: '''

o Task goal switched every 2 trials: color/color or num/letter

o Prefrontal cortex patients have greater RT “switch cost” only for color cue

§ Color cue involves more complex mapping than num/letteràmore WM demands

-         Anterior Cingulate Cortex: monitoring conflict

o Error related negativity

o “incompatible”