Prefrontal Cortex Flashcards
Are there some different in human PFC and human ancestors?
The prefrontal cortex represents up to 29% of the surface of the human cerebral cortex, while it represents 17% and 11.5% of that in the chimpanzee and the rhesus monkey, respectively
In which processes is the PFC involved?
• representing the emotional and motivational value of stimuli (both primary and secondary reinforcers) and monitoring changes or reversals in the reward value of learned stimuli;
• using feedback signals from the body to guide complex decision-making;
• cognitive control, through action selection, response inhibition, performance monitoring;
• emotion regulation;
• social processing
The activation of the medial orbitofrontal cortex reflects…
the relative (not absolute) reward value of stimuli (context-dependent)
When do dorsolateral and orbitofrontal cortex activate?
Dorsolateral and orbitofrontal cortex activate upon changes in reward contingencies
(affective switching), i.e., when switching to new associations as stimulus-reinforcement
contingencies reverse.
What are the somatic markers?
Somatic markers (SM) are somatic responses (autonomic or muscular) that occur during emotionally relevant situations and thus “mark” the value of the event and, most importantly, the value (“good” or “bad”) of the outcomes of a given course of action. Somatic signals “mark the future” (i.e., the long-term, potentially harmful consequences of a decision, regardless of its predictable immediate reward).
when the information is so complex and the patterns are not so clear, our cognition may keep struggling explicitly to figure which strategy might be best, but our somatic signals are what implicitly or explicitly bias us towards the advantageous strategy. In other words, in situations of uncertainty and ambiguity, logic and conscious deliberation may offer certain choices, but somatic states, in the form of “hunches” or “gut feelings,” help select the most advantageous response option, they help select the solution that feels the best
How do somatic markers develop?
SM develop through experience, as various bodily states become associated with positive and negative events. When one contemplates possible options before making a decision, somatic signals marking options as either positive or negative are re-activated, and thus allow to weigh options and ultimately make a choice.
Who created the “somatic marker hypothesis”?
Damasio
What induces SM?
Somatic states can be induced from
1) primary inducers
2) secondary inducers
What is a primary inducer?
Primary inducers are innate or learned stimuli that induce pleasurable or aversive (somatic) states
automatically and obligatorily
What’s the role of amygdala in SM?
The amygdala is a critical substrate in the neural system necessary for triggering somatic states from primary inducers via effector structures such as the hypothalamus and autonomic brainstem nuclei that produce changes in internal milieu and visceral structures along with other effector structures such as the ventral striatum, periacqueductal gray, and other brainstem nuclei, which produce changes in facial expression and specific approach or withdrawal behavior
What’s a secondary inducer?
After a somatic state has been triggered by a primary inducer and experienced at least once, a pattern for this somatic state is formed. The subsequent presentation of a stimulus that evokes thoughts/memories about a specific primary inducer will then operate as a secondary inducer. Secondary inducers are presumed to re-activate the pattern of somatic state belonging to a specific primary inducer
What’s the role of ventromiedal Prefrontal Cortex in SM?
Triggering somatic states from secondary inducers becomes dependent on cortical circuitry in which the ventromedial Prefrontal Cortex (vmPFC) plays a critical role.
In secondary induction the VmPFC couples recalled or imagined scenarios supported by neural systems important for memory, such as the DlPFC (for working memory) and the hippocampus, to neural systems involved in the representations of somatic states, such as the insula, somatosensory cortices, and posterior cingulate/precuneate region
A key role in the neural system necessary for implementing advantageous decisions is played by the vmPFC
The vmPFC integrates and regulates the neural representations of actual or predicted somatic states associated with options, and uses them to guide decision making based on the value a current event has had in the past
This “emotion-guided decision making” is crucial in conditions of complexity and uncertainty, where detailed analysis of options based on costs and benefits would be overly time-consuming or even impossible
The neural architecture implicated in the “somatic marker hypothesis”
Somatic markers can reflect homeostatic changes/actions of the body proper (body loop) or the central representation (forward model) of the changes expected to take place in the body (“as if” loop)→ more rapid response to external stimuli without waiting for activity to actually emerge in the periphery
Which are the consequences of vmPFC damages?
Adaptive decision making is based on emotion-guided anticipation and planning that involves the ensemble of all enacted responses in the body proper and in the brain associated with an anticipated outcome
vmPFC patients fail to activate a negative marker for the bad decks based on past punishment history, and thus are insensitive to the possibility of further punishment on those decks (myopia for the future)
Davidson’s valence asymmetry hypothes
Two basic emotional/motivational systems:
- approach system facilitates appetitive behavior and generates positive affect (e.g., joy, interest, enthusiasm, pride) that are approach-related (moving toward a desired goal)
- withdrawal system facilitates the withdrawal of an individual from sources of aversive stimulation and generates negative affect (e.g., fear, sadness, disgust) that are withdrawal-related
Left-sided PFC regions are involved in approach-related appetitive goals and positive affect
Right-sided PFC regions are involved in withdrawal-related goals and negative affect
What did lesion studies (PFC) show?
damage to the left PFC is associated with increased likelihood of developing depressive symptoms
What did neuroimaging studies show about PFC?
brain reactivity measured by fMRI is lateralized towards the left hemisphere for positive
pictures and towards the right hemisphere for negative pictures
What did electrophysiological studies on PFC show?
Electrophysiological measures of regional activation in healthy individuals exposed to stimuli
that elicit emotion: increased left anterior activation during positive affect and increased
right anterior activation during negative affect
Duchenne smiles effect on PFC activation?
Voluntary production of Duchenne smiles produces similar asymmetry pattern as during spontaneous enjoyment.
Which are the doubts about anterior asymmetry?
Research on functional frontal EEG asymmetry typically confounds emotional valence and
motivational direction, so what anterior asymmetry indeed reflects is unclear
Solution: examine frontal brain activity underlying negative emotions with approach motivational tendencies
The strange case of anger
Anger is a negative emotion that mobilizes energy for action and prepares the organism for an approach response (aggression, but also competitiveness, assertiveness). Would a right (valence=negative) or a left (motivational direction=approach) frontal lateralization be expected in
association with anger?
Trait anger relates to relatively greater left frontal cortical activity when measured at rest:
By demonstrating that dispositional anger, an approach-related motivational tendency with negative affective valence, is related positively to the anterior asymmetry in alpha activity, the results support the idea that the anterior asymmetry in alpha activity reflects motivational direction rather than affective valence
State and trait anger are associated with increased left frontal cortical activity in response to anger-eliciting stimuli
Participants in the insult condition report more anger and show greater relative left-frontal activity
relative to participants in the no-insult condition
Individuals who are chronically high in anger show increased relative left-frontal activity in
response to anger-evoking picture stimuli
What’s the implication of motivational direction model?
Supporting the motivational direction model, emotions with negative valence and approach motivational tendencies appear to be related to relatively greater left frontal activity
However approach motivation is not always associated with positive affect (anger, greed,
lust, and mania are examples of approach motivations that may have negative consequences)
Which are the levels of the hierarchical networks active in approach and avoidance goal pursuit?
System level: the goal to pursue
Strategic level: the means or process of attaining a potential desirable outcome or preventing a
potential undesirable outcome
Tactical level: how a strategy could be implemented in a particular context
Emotional laterality
the right hemisphere should subsume only the basic ‘schematic’ level of emotions, characterized by an automatic and unconscious processing, whereas the more propositional and conscious ‘conceptual” level could be less lateralized or subsumed by the left hemisphere.
Right Hemisphere: associations between innate and universal sensorimotor programs and events of the individual experience; unconscious/automatic
Left Hemisphere: Abstract notions about emotions (concepts about emotions, about the situations that provoke them, and the manners that can be used to deal appropriately with them, according to the social “display rules”); conscious/controlled
What’s the emotional regulation?
Emotion regulation entails the modification of ongoing - or the initiation of new – emotional responses through the active engagement of regulatory processes
Can be guided by regulatory goals that are implicit, automatic or outside awareness or explicit, effortful (voluntary and deliberate), and accessible to awareness
Which are the emotion regulation strategies?
The effects of different emotion regulation strategies descending from the cognitive control processes, can be understood in terms of the stages of the emotion generation sequence that they influence:
- Stimuli in the context, internal (thoughts, sensations, ecc…) or external (people, action, events…): influenced by Situation Selection and Situation Modification strategies.
- Attention (to a stimulus or its attribute): influenced by Attentional Deployment strategy (Selective attention, Distraction)
- Appraisal (Aversive or Appetitive): influenced by Cognitive Change strategy (language, memory, attention)
- Response (experience behavior physiology): influenced by Response modulation strategy
What’s the Reappraisal?
Reappraisal involves reinterpreting the meaning of a stimulus, including one’s personal connection to it, to change one’s emotional response
The majority of studies to date have focused on reappraisal because it can be studied easily in an
imaging environment and because it is the strategy referenced by countless aphorisms (“look on the bright side”, “when life gives you lemons, make lemonade”, “every dark cloud has a silver lining”,…)
The emotion-modulatory effects of reappraisal stem from interactions between cognitive control processes implemented in prefrontal and cingulate regions and emotional appraisal processes implemented in multiple emotion-related structures, including the amygdala
Which are the neural systems involved in using cognitive strategies such as reappraisal, to regulate emotion?
- dmPFC (attributing mental states)
- dACC (conflict monitoring)
- posterior PFC, dlPFC, inferior parietal PFC (selective attention, working memory)
- vlPFC (selection/inhibition)
Which are the systems involved in generating the responses derived from cognitive strategies?
- Ventral striatum (encode reward value of stimulus)
- Amygdala (arousal/threat value of stimulus)
- Insula (represent body states associated with emotion)
Which are the systems with an undefined or intermediary role in reappraisal?
- TP, TPJ, STG/MTG (representing perceptual and semantic features)
- vmPFC/mOFC (value of stimulus in current context)
Whats the role of mediation pathways involved in the downregulation of negative emotion whereby ventrolateral or dorsomedial prefrontal regions?
diminishing amygdala responses via their impact on ventromedial prefrontal cortex
What’s the role of mediation pathways involved in the downregulation of negative or positive emotion whereby ventrolateral or dorsolateral prefrontal regions ?
diminishing self-reports of negative affect or craving via their impact on the amygdala or ventral striatum, respectively
