Working Memory Brain Substrates

prefrontal cortex

critical for working memory and executive control

absence of an executive control system

impulsive behavior driven by reflexive stimulus-response behaviors

Dysexecutive Syndrome

Frontal lobe damage

deficits in working memory and executive control

WM and executive control tasks

• Updating memory in the N-back task

• Self-ordered tasks that require updating and monitoring previous items

• Also STM deficits: digit span, STM for colors, shapes and object locations

loss of ability to plan and organize task

Tower of Hanoi

task switching procedure

monitoring streams of letters on the left and digits on the right

Wisconsin Card Sorting Test in frontal lobe damage patients

perseveration errors - when the rules change, they stick to the old one

delay

activity in frontal neurons

DLPFC lesions

deficits in manipulation (temporal ordering) but not in maintenance of info

maintenance of info

Ventrolateral PFC and posterior brain

central executive (in brain)

Dorsolateral PFC

Phonological loop (in brain)

L Ventrolateral PFC

Visuo-spatial sketchpad (in brain)

R Ventrolateral PFC

left DLPFC specification

verbal working memory

anterior posterior gradient

goal abstraction

DLPFC’s role in LTM

candidate for retrieval and manipulation of specific episodic memories

Intentional encoding

more associated with ventro-lateral PFC activity (active rehearsal)

Semantic processing and rehearsal

Ventro-lateral PFC anterior

Phonological processing and rehearsal

Ventro-lateral PFC posterior

Schizophrenia patients

DLPFC deficit - WM problems with large delays and manipulation

ADHD

• smaller right prefrontal cortex - WM deficits