Executive Function and the Frontal Lobes

Psy391h - Class 21

(This page last updated 24 April 2006.)

Baddeley proposes working memory system with three components
- central executive
- phonological loop
- visuospatial sketchpad

In monkeys, damage impairs performance in delayed matching task.
- Also, single cells active during delay, apparently maintaining info.
- Specialization: Some cells active when shape must be remembered, while others active for location.
- Monkey can still form simple associations after prefrontal damage.
In humans, performance at Wisconsin Card Sort Task impaired with prefrontal damage.
- Must figure out mapping.
- Must remember mapping.
- Must adjust when mapping changes.
In humans, frontal damage impairs recency memory, but ot recognition.
Right prefrontal more active in spatial memory; left in nonspatial memory.
Tasks requiring only maintenance of info activate more ventral region; tasks including manipulation of info activate more dorsal region.
Frontal areas work to filter out unwanted info.
Frontal areas active in task switching.

At top of hierarchy of attentional system
- Stimuli with changes in color, motion, shape.
- Selective attention conditions
  - Attend to motion
  - Attend to color
  - Attend to shape
  - In each case, a different region of cortex is activated.
- Divided attention condition
  - Monitor changes in all three dimensions simultaneously
  - Activates anterior cingulate
Responds more to novel situations
- Task: See noun, generate verb.
  - At first anterior cingulate is active.
  - As the nouns are repeated, it becomes less active.
  - If a new list of nouns is introduced, anterior cingulate activation returns to hight level.
May have role in resolving response conflicts
- Error-Related Negativity
  - ERP more negative on trials with error response
- More active during Stroop interference
  - Interference makes task more difficult, but few errors made.