1. Executive Function III
Ref: Theories: Gazzaniga pp

2. Prefrontal Cortex: 3 Major Regions
Dorsolateral Prefrontal Cortex
Key role in executive function
Anterior Cingulate
Evaluating own behaviour
Orbitomedial Prefrontal Cortex
Social/emotional mediation of behaviour

3. Today Review of dorsolateral PFC, anterior cingluate
Discussion of orbitomedial PFC
Theories of executive function

4. Dorsolateral PFC Key role in Working Memory Other Functions:
Initiation, cessation of action
Dynamic filtering (e.g. Stroop task)
Task switching (e.g. Trail making test)
Flexibility - response inhibition, cognitive flexibility (e.g. alternate uses test)

5. Prefrontal Cortex: 3 Major Regions
Dorsolateral Prefrontal Cortex
Anterior Cingulate
Orbitomedial Prefrontal Cortex

6. Anterior Cingulate
Strongly activated in highly demanding tasks e.g divided attention
Also especially active when errors occur
Generally, participates in situations requiring close monitoring, where there is response conflict
Acts in tandem with dorsolateral PFC to ensure that the necessary attentional resources are effectively deployed

7. Prefrontal Cortex: 3 Major Regions
Dorsolateral Prefrontal Cortex
Anterior Cingulate
Orbitomedial Prefrontal Cortex

8. Orbitomedial PFC Social and Emotional Mediation of Behaviour
Phineas Gage: Before the accident he had been their most capable and efficient foreman, one with a well-balanced mind, and who was looked on as a shrewd smart business man. He was now fitful, irreverent, and grossly profane, showing little deference for his fellows. He was also impatient and obstinate, yet capricious and vacillating, unable to settle on any of the plans he devised for future action. His friends said he was "No longer Gage."

9. Orbitomedial PFC: Features
Two key features of damage to orbitomedial PFC:
No initiative, flattened affect: (“pseudodepression”)
Elliott: After removal of a brain tumour that bilaterally invaded the brain's orbital surface, Elliott performed well on standard IQ tests and even outperformed most age-matched control subjects on the WCST. Nonetheless, he had great difficulties coping with the real world. He lost his job, and eventually went bankrupt. As striking as Elliott's lost sense of social norms was his personal detachment from his problems. He had no difficulty recounting the minutest details of his many failings, but spoke of them as if he were a dispassionate observer.

10. Lack of social restraint (“pseudopsychopathy’)
Orbitomedial PFC: Features
Lack of social restraint (“pseudopsychopathy’)
Patient Y: A high velocity missile had entered the patient's left temple and emerged through the right orbit. Prior to injury, Patient Y had been quiet, intelligent, proper, and hard-working. Subsequent to this injury, he was outspoken, facetious, brash and disrespectful. There was no evidence of self-pity, although he frequently made rather morbid jokes about his condition. When asked about how his injury had affected him, he showed some awareness of some aspects of his problems (e.g. no sense of taste), but little concern, often commenting "To tell you the truth, it's a blessing this way".

11. Orbitomedial PFC: What does it do?
Somatic Marker Hypothesis (Damasio):
Orbitomedial PFC binds memories to their emotional and neurophysiological associations
normals: an “emotional” picture (e.g. accident victim) evokes a learned emotional response. This is measurable.
P’s with Orbitomedial PFC lesions: can describe picture in detail, but no strong emotional response
Explains: flattened affect, lack of concern for social conventions

12. Theories of Executive Function
Problems with describing role of PFC in executive function: Many "Frontal" tasks are complex and can be described in >1 way
Problem of circularity
Also terms such as “control” too vague to be tested
How can we describe what the frontal lobes do in a way that is directly testable?
Answer: we must develop a proper theory

13. Contention Scheduling Theory
Shallice and Norman (1989)
Schemas
Two Major Components
Supervisory Attentional System
Schemas:
well-practised routines or action plans e.g. stop at red light
are developed with practice
are "activated" by external stimuli OR internal cues e.g. stop at red light schema -> red light
remain active until "switched off"

14. Contention Scheduling Theory
Supervisory Attentional System (SAS):
overrides normal activation levels of schemas
turns on, switches off schemas when no other cues
creates program of action when no schema avail., or when task has special demands
Schemas are stored in posterior cortical regions
The SAS is in prefrontal cortex

15. Contention Scheduling Theory
Explains:
Inability to initiate or cease an action (psychological inertia, perseveration)
Difficulties dynamic filtering
Poor task switching
Inability to inhibit habitual responses
Lack of cognitive flexibility
Inability to formulate goals

16. Contention Scheduling - Problems
Theory is highly cognitive. It proposes one central system - BUT PFC shows regional specialisation
Very powerful - predicts just about anything, so is difficult to test
Doesn’t deal with working memory

17. Alternatives Miller & Cohen (2001):
PFC maintains patterns of activity that represent goals
These patterns modulate processing in posterior cortex e.g. resolve competition, inhibit inappropriate responses
Similar to Contention Scheduling, but more anatomically- based, allows for the possibility of regional specialisation
Also, gives a primary role to working memory
BUT still a problem with power??

18. Conclusion
The executive functions of prefrontal cortex still poorly understood
Research is in its infancy
The next decade (even the next few years) is likely to change this significantly
Advances will depend as much on cognitive theories, as they do on research technology