M and the Frontal Lobes UNCW Faculty and Staff

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M and the Frontal Lobes UNCW Faculty and Staff Powered By Docstoc
					 MOTIVATION/EMOTION and
   the FRONTAL LOBES



                                           left frontal lobe
                                           may be most
                                           involved in
                                           processing
                                           positive
Remember that the thalamus projects to both the emotions
                                                    amygdala
                                           right frontal lobe
….and to sensory cortex areas.. Where it isinvolved with processed
                                             eventually
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           gratification of simple
    impulses…       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 Ctx-
    Neuroimaging studies (Caution,
      interpret with reservation)
• motivational valence assignment (12),
• motor response selection (13–15),
•   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 ).



•   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 self-
         reflection.
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
•                                      valence of the
    When material was judged to be self-relevant, 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
•   Social bonding
                     of VENs?
                         ?
     – 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   humor (Watson and Allman,
•   trust, empathy, and the discrimination
•   of the mental states of others

•   All of these social emotions are influenced by the degree of uncertainty involved.
•
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 reactions-
         a 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

				
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