Transcript Prefrontal cortex - People Server at UNCW

MOTIVATION/EMOTION and
the FRONTAL LOBES
left frontal lobe
may be most
involved in
processing
positive emotions
Remember that the thalamus projects to both
the amygdala
right frontal lobe
….and to sensory cortex areas.. Where it isinvolved
eventually
with processed
by the frontal lobes
negative emotions
The amygdala also projects to the frontal lobes
mainly to the “Prefrontal cortex” …the frontal
cortical areas found anterior to the 2nd and primary
motor areas
The Amygdala also projects to the Anterior
Cingulate cortex (ACC) of the frontal
lobes…(sometimes referred to as the “limbic lobe” )
The frontal lobes, esp.the medial
prefrontal cortex (mPFC.. further specificity considered
in later slides) also project to amygdala
Frontal lobes and the Amygdala
• What role does the
pathway from the
prefrontal cortex
to the amygdala
play in emotion
and motivation??
1. Cortex Dampens Subcortical
Affect…..SHAM RAGE
• sham rage—occurs following removal of the cerebral
cortex from experimental animals..
• In Cats:
– lashing of the tail, vigorous arching of the back, clawing and attempts to
– bite, and autonomic responses. It is called sham rage because unlike
– genuine rage ( or predatory aggression)
the rage occurs spontaneously or can be triggered by
mild tactile or other non-noxious stimuli.
Evidence that the frontal lobes
Regulate Subcortical Affective
impulses
• Phineas Gage• Emotional lability
emotional outbursts
• irrationality
(Deficits in emotional
Impusle control)
Prefrontal lobotomy
The effects of this
procedure varied
considerably
Perhaps due to differences in procedure- two
general syndromes associated with frontal
lobotomy (as well as naturally incurred frontal lobe damage)
-Pseudopsychopathy- (indicates loss of regulatory functions)
• Immature impulsive behavior, aggressive outbursts,
Inappropriate jocular affect , Poor judgment and
insight , coarse language, promiscuity, general loss
of social skills, euphoria, Emotional lability,
Distractibility (see orbito-frontal cortex)
Pseudodepression – (loss of M&E influences of PFC)
– Apathy, indifference, loss of initiative, loss of
libido (see ventromedial ACC)
Other effects of Frontal Lobe Damage
relating to affect and motivation
-difficulty formulating common rules and goals.
if a rule or goal is given to the patient there is great difficulty in using it to
guide behavior. ..perhaps related to social motivations
•
Actions are motivated by immediate
impulses…
gratification of simple
Relates to circumstantiality
• dissociation between the discriminative and affective
aspects of pain. When stuck with a pin, such a patient reports that it hurts, but
it doesn't bother him.
The Anterior Cingulate Cortex
may be critical in frontal
generation of emotion
lesion of the ACC
• - patients described as apathetic and
unconcerned when significant events
occur, such as making mistakes (Eslinger
and Damasio, 1985 ; Rylander, 1947 )…like
pseudodepression
VON ECONOMO NEURONS and
the ACC
When we interact with another person we create a mental model of how that persons thinks and
feels. We are likely to have initial, quick intuitions about the person, which are then followed by
slower, more reasoned judgments.
Both intuition and deliberation are influenced by emotional value judgments.
Von Economo neurons (VENs) are a recently evolved cell type which may be involved in the fast
intuitive assessment of complex situations.
VENs emerge mainly after birth and increase in number until age 4 yrs.
•
The Social Function
of
VENs?
Social bonding
?
– More active when subjects view an image of a loved one compared with that of an
acquaintance
• Certainty
– active when subjects make decisions under a high degree of uncertainty.
• Pain?
– Active when subjective experience of pain … which is powerfully magnified by uncertainty.
•
also active when subjects experience guilt, embarrassment and engage in deception
•
ACC also active in
•
•
trust, empathy, and the discrimination
of the mental states of others
•
•
All of these social emotions are influenced by the degree of uncertainty involved.
humor (Watson and Allman,
Orbito-frontal cortex and Frontal
Poles
ORIBITO-FRONTAL CORTEX- counterfactual
processing/ Regret?
Counterfactual processing -The consequence of a decision/behavior can lead
to feelings such as: satisfaction, relief, or regret… evaluation of the potential
outcomes of alternative decisions.
Testing the role of the orbito-frontal cortex in counterfactual reactionsa simple gambling task was used- subject’s choices were categorized in terms
of their anticipated and actual emotional impact.
Normal subjects reported emotional responses consistent with counterfactual thinking;
they chose to minimize future regret and learned from their emotional experience. (also
associated with increased activity in the orbito-frontal regions)
Patients with orbitofrontal
cortical lesions, however, did not
report regret or anticipate negative consequences of their choices.
Damage to the orbito-frontal cortex?
May partially account for the pseudopsychopathic syndrome
• lack of originality and creativity
• impairment of attention
• difficulty initiating behavior; when they do engage in activity, they
may continue the activity without stopping.
• They may only start activity when prompted by others
(“circumstantiality?”).
• “Like pseudopsychopathy”-Emotional disturbance most often results
from lesion of the orbital frontal areas.
• superficial emotional expression like laughing, crying etc in situations
inappropriate to the emotion. The patient usually has no awareness that
their emotional response is incorrect or extreme.