PFC Flashcards
PFC and personality
Link bw personality and PFC – esp. personality expression, moderating social behaviour.
Damage causes deficits in concentration, abstracting, judgement and problem solving.
Destruction of FL = inappropriate social behaviour
How did we come to know the PFC plays a role in personality?
- Phineas Gage.
- But PFC damage doesn’t always cause personality changes.
- E.g. Welt’s case of man who fell out of window. Experienced big personality changes, which went back to normal after about a month.
So Welt said personality change is more often absent than seen – examined 9 PFC cases and found significant orbitofrontal damage, and said this = personality change causation.
Why did people initially think the PFC was a silent area, and why did they then change their minds?
They initially thought it was silent bc lesion evidence was contradictory and not conclusive. However, studies of monkey lesions showed marked change in behaviour; PFC lesions caused aggression, impulsivity, sociality.
What does the PFC do?
Coordinates action, long-term planning and decisions, inhibition, determine consequences, social control.
HIGH LEVEL COGNITIVE PROCESSES GOVERNING WAYS OF BEHAVING OPTIMALLY AND APPROPRIATELY.
Does the PFC deal with routine or non-routine functioning?
PFC does not support routine functioning; these are things which are largely autonomic and well-rehearsed.
PFC deals with non-routine function, for instances mental operations which are poorly-rehearsed, or when there has been a behavioural impasse.
What is an example of this?
Reading is a low level process, which PFC has little executive function role in. However in the context of an exam hall, the PFC will inhibit the ‘reading aloud’ response that might otherwise go uninhibited in a more appropriate social context.
What is utilisation behaviour and why does it happen?
Utilization behaviour is the uncontrollable use of objects as they are seen in the environment: e.g. locking every door they come across with a key in it. It is social inappropriate, and makes you a ‘slave to the environment’.
Damage to the PFC causes this, as utilization cannot be inhibited. Normally, the PFC exerts top-down control over the rest of the brain, modulating other systems. (E.g. here, the motor system).
Is the PFC important for novel stimuli? What is the evidence?
Yes. When responding to unexpected novel stimuli, P300 is shown when the target is detected or when unexpected stimuli are.
Controls and PFC patients show no difference in P300 when target detection happens, but PFC patients show no P300 in response to novel stimuli, whereas controls do.
What is some evidence for the PFC’s role in working memory?
Monkeys with PFC lesions show STM deficits; they fail to retrieve food from a cup even if the food was only out of sight for a few seconds: they were unable to hold the information in mind.
This is backed up by other monkey studies, where non-lesioned monkeys showed enhanced PFC neural activity in the delay where the reward couldn’t be seen – suggesting the PFC is actively maintaining the representation of the reward.
Is the PFC involved in prospective memory?
Yes. Prospective memory = remembering to carry out an intention after a delay. PFC patients show deficits in long term planning, suggesting a prospective memory deficit.
However, in an experiment where PPs had to carry out an action after some stimuli but not others, there was bilateral FL activation, but different brain regions showed elevated activation too during specific sub-conditions, suggesting the role of other brain regions in prospective memory too.
Does the PFC have a role to play in delayed gratification?
Yes! PPs had to imagine spending certain amounts of money in a timeframe, OR just what the money could buy. When imagining spending the money in the timeframe, there was more rostral PFC activation when PPs chose to delay monetary gratification, suggesting the PFC was involved in the future planning/delayed gratification responses.
Are there deficits seen in these kind of decision making tasks in PFC patients?
Yep! Damage to the ventromedial PFC results in poor decision making (even when other intellectual functions are unimpaired). E.g. patient EVR – always made bad decisions, but had other normal functions (STM, WCST, IQ).
In tasks where you had to choose cards from low reward/punishment and high reward/punishment decks, healthy controls learned v quickly to go for the former, whereas EVR chose the latter.
Is there any difference in social behaviour depending on PFC damage onset?
Yes. Lesions before 16m result in severely impaired social behaviour, despite otherwise normal functioning.
Young onset PFC patients show more defective social/moral reasoning than adult-onset – psychopathy-like symptoms if onset is early.
Does the PFC have anything to do with humour?
Yep!
Damage to the right FL is associated with disrupted humour appreciation abilities – they react less to humour and have diminished responses to it emotionally.
Suggested that verbal humour is dependent on holding the details in working memory (and being able to pay attention to the details) and this might be why PFC patients show the deficit in humour appreciation.
Also, it is thought that the right FL is responsible for integrating cognitive and affective information, and this is needed to find jokes funny!
But is the PFC a singular system?
No, probably not. There is typically low correlation bw different PFC task performances, factor analysing symptoms shows they don’t load on to one factor. Different symptoms are related to impairments on different clinical PFC tasks.
Some symptoms are independent of all others in most cases (confabulation, e.g.)
NEUROIMAGINING DATA SUGGESTS FRACTIONATION OF THE PFC/EF SYSTEM.
