Transcript The amygdala also projects to the frontal lobes

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.
Other effects of Frontal Lobe Damage
• Confabulation
– fabricate quick, impulsive answers to questions. Some responses may be quite
fanciful and imaginative. The patient cannot inhibit a response in order to
check its validity. This tendency to fabricate an answer is called
confabulation.
further evidence;Other Frontal Lobe
Syndromes
Frontal lobe epileptic seizures
• likely to involve brief episodes of screaming,
bicycling movements, or even movements
suggestive of sexual activity…perhaps reflecting loss of regulatory
functions…like pseudopsychopathy
FL epilepsy inter-ictal characteristics
• hebephrenic characteristics (i.e. emotional
withdrawal and blunted affect)… activity…perhaps
reflecting depletion or fatigue of PFC generated M&E effects..like
pseudodepression
Pseudodepression suggests that
the frontal Lobes may also
produce emotional responses
The frontal lobes project to the amygdala
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
Anterior Cingulate CtxNeuroimaging studies (Caution,
interpret with reservation)
• motivational valence assignment (12),
• motor response selection (13–15),
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•
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error detection/performance monitoring (16, 17),
competition monitoring (18),
anticipation (19),
working memory (20),
novelty detection (21),
• reward assessment (22),
• emotional responses to pain.
– ( the amygdala is also involved )
Even More Specificity!
ACC neuroimaging studies
• Dorsal ACC- cognitive and motor control, but the mechanisms of these
functions remain unclear. (Posner and DiGirolamo, 1998 ).
Ventral medial ACC - involvement in depression
(like
pseudodepression?), also transient mood changes (Mayberg et al., 1999 ), and
anxiety disorders (Mayberg et al., 2000 ; Brody et al., 2001 ) and the perception of pain
(Rainville et al., 1997 ).
•
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decreased dorsal ACC activation and increased ventromedial ACC activation in induced sadness and
depression (Mayberg et al., 1999 ).
Ventromedial ACC
ACC and Self-reflection
•
Can cognitive and affective components of self-reflection can be dissociated
using functional magnetic resonance imaging.
•
Test procedure-subjects judged the personal relevance of personality
characteristics that were either favorable (e.g., "honest") or unfavorable (e.g.,
"lazy")
–
distinct neural circuits in adjacent regions of the prefrontal
cortex subserved the cognitive and emotional aspects of selfreflection.
The medial prefrontal cortex responded only to material that was self-descriptive, and
this did not differ as a function of the valence of the trait…cognition
•
When material was judged to be self-relevant, the
valence of the
material was associated with changes in activity in the
ventral ACC.
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
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trust, empathy, and the discrimination
of the mental states of others
•
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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.
The Frontal Poles (FPC)
and goal directed behaviors
the most anterior part of the frontal lobes
Neuroimaging studies suggest critical involvement
in Prioritization of Goals ( this logically would require the
suppression of lower priority impulses…so the pseudopsychopathy like symptoms
associated with damage here is logically consistent )
Very Active when there is competition between two concurrent
behavioral plans or mental tasks (that may vary in respective reward
expectations)
capacity appears highly limited, which suggests that the FPC may be especially
important for protecting long-term high priority goals/plans from
immediate environmental demands or temptations.
The Ventral tegmental Area
(VTA) Dopaminergic pathways
• dopamine neurons in the VTA project to wide areas of the neocortex,
esp the frontal lobes ( the Mesocortical DA pathway)
• The amygdala and to the nucleus accumbens ( the Mesolimbic DA
pathways)
•
The Mesocortical pathways are believed to play a role in selective
attention which is a critical component of
cognitive Bias.
VTA-Cortical Dopaminergic
pathways
The VTA projects to the amygdala,
the nucleus accumbens and to the frontal cortex