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What hypothesis proposes that emotion-based biasing signals from the body regulate decision-making, especially in complex situations?

The Somatic Marker Hypothesis (SMH)

According to the SMH, where are emotion-based biasing signals primarily integrated in the brain?

Higher brain regions, in particular the ventromedial prefrontal cortex (VMPFC)

What experimental task is the empirical support for the SMH largely based upon?

The Iowa Gambling Task (IGT)

What psychophysiological measure is linked to successful performance on the IGT in healthy participants, according to support for the SMH?

Anticipatory skin conductance responses (SCRs)

In early studies supporting the SMH, what pattern of anticipatory SCRs was observed in healthy controls on the IGT?

Larger anticipatory SCRs for selections from the ‘risky’ decks than the ‘safe’ decks, differentiating advantageous from disadvantageous decks over time

What finding regarding patients with VMPFC lesions on the IGT was used to support the SMH?

These patients showed absent anticipatory SCRs and poorer IGT performance. They continued to prefer the disadvantageous decks

What deficit was described in VMPFC patients, suggesting their decisions were driven by immediate reward rather than delayed punishment on the IGT?

‘Myopia for the future’

Describe the general reward/punishment structure of the four decks (A, B, C, D) in the standard IGT.

Decks A & B offer high immediate rewards but higher total long-term punishment (net loss). Decks C & D offer lower immediate rewards but lower total long-term punishment (net gain). Successful performance means selecting more from C and D

Why was the reward/punishment schedule of the IGT argued to be 'opaque'?

So that participants would be unlikely to perform an exact calculation of net gains and losses and instead rely on intuitive, emotion-based processes

Learning via emotion-based biasing signals is believed to precede explicit insight on the IGT

Learning via emotion-based biasing signals is believed to precede explicit insight on the IGT

What criticism has been raised regarding the "cognitive impenetrability" of the IGT reward/punishment schedule?

Recent data suggests the schedule is more cognitively penetrable than previously thought20. Participants can develop reasonably accurate conscious knowledge about deck outcomes sufficient to guide behaviour

How might the finding that participants gain conscious knowledge of the IGT schedule early undermine the SMH?

Conscious knowledge could mean anticipatory SCRs are a consequence of explicit knowledge rather than a causal signal for decision-making

What did Maia and McClelland (2004) argue regarding participants' knowledge on the IGT, based on using more detailed questions?

Advantageous performance was nearly always accompanied by verbal reports of reasonably accurate quantitative and qualitative knowledge about the deck outcomes

What alternative explanation did Maia and McClelland (2005) offer for why participants with partial explicit knowledge might still make seemingly non-optimal choices on the IGT?

Exploratory behaviour to further gather information about the task

According to the SMH, what are the two main types of somatic markers?

Signals reflecting actions of the body proper (the 'body' loop) and signals reflecting the brain's representation of expected bodily action (the 'as-if' loop)

What is the purpose of the 'as-if' loop in the SMH?

Allows the brain to construct a forward model of expected bodily changes, enabling faster response without waiting for actual peripheral activity

What core brain structure is believed to be crucial for integrating body-state representations with potential response options in the SMH network?

The ventromedial prefrontal cortex (VMPFC)

Besides VMPFC, name one other brain area mentioned as part of the proposed somatic marker network involved in representing and regulating body-state.

Amygdala, insula, somatosensory cortex, cingulate, basal ganglia, brainstem nuclei

What distinction does the SMH draw between 'primary inducers' and 'secondary inducers'?

Primary inducers are innate or learned stimuli generating pleasurable/aversive states. Secondary inducers are thoughts/memories recalling or imagining an emotional event

The VMPFC is believed to encode an association between which two elements, according to the SMH neural substrate?

Between secondary inducers and the bioregulatory state linked with that situation in past experience (including bodily aspects of emotion)

What critique exists regarding the interpretation of anticipatory SCRs on the IGT beyond simply indicating "good" or "bad" decks?

SCRs might represent responses to feedback, indicators of risk magnitude, markers of post-decision emotion state, or reflect shifting attentional focus across decks

Studies have examined the necessity of intact body-state feedback for IGT performance. What was found in a preliminary study of patients with peripheral neuropathy?

They were mildly impaired on the IGT compared to controls, although this was only reported as a conference abstract

What evidence from studies involving patients with Pure Autonomic Failure (PAF) is mentioned regarding the SMH?

Some studies show impaired IGT performance in PAF patients, although critics note that PAF patients often have changes in brain morphology and retain other sources of peripheral feedback

How might working memory capacity affect performance on the IGT?

Studies suggest that working memory processes contribute to IGT acquisition and the development of anticipatory somatic markers. Interference with working memory impairs performance

How is impaired working memory reconciled with the finding that VMPFC patients with normal working memory show IGT deficits, according to a perspective related to the SMH?

Central executive resources (related to working memory) are necessary but not sufficient for the development of somatic markers. Somatic markers may help allocate working memory/attentional resources to better options

What is 'reversal learning', and how is it suggested as an alternative explanation for IGT performance deficits in VMPFC patients?

The ability to learn from negative feedback and inhibit previous responses. VMPFC patients might be unable to inhibit switching away from advantageous decks after occasional losses, or inhibit selecting disadvantageous decks for immediate wins

What is another proposed alternative mechanism potentially underlying IGT performance deficits besides somatic markers or reversal learning?

Altered risk-taking behaviour

What is 'apathy', and how is it suggested as a potential explanation for impaired IGT performance in VMPFC patients?

Apathy might produce both the behavioural deficit and the failure to generate anticipatory SCRs seen in VMPFC patients. Low engagement levels could contribute

What brain area, in addition to VMPFC, is sometimes damaged in patients with IGT deficits, leading critics to question if VMPFC is the sole critical area?

Other portions of the frontal lobes, particularly dorsolateral PFC (DLPFC) or larger combined lesions

What finding from fMRI studies on the IGT provides some support for the neural substrate proposed by the SMH?

Risk anticipation on the IGT exclusively activated the medial frontal gyrus55, part of the broader VMPFC region.

How is the role of neurotransmitters like dopamine and serotonin related to the SMH and IGT?

It is proposed that these neurotransmitters mediate the biasing action of somatic states on response selection and could boost cognitive resources for advantageous options. Studies show these systems are related to IGT performance

The review suggests that while the SMH is an intriguing idea, it needs what to remain tenable?

Additional empirical support and a clearer conceptualisation/specification

What is one way suggested in the review to improve empirical testing of the SMH in the future?

Develop experimental designs where alternative mechanisms make competing predictions; More detailed specification of the SMH; Making the IGT less consciously comprehensible (e.g., using artificial grammar learning); Pursuing causal tests in populations with altered peripheral feedback (e.g., peripheral neuropathy, facial paralysis); Pharmacological challenge studies; Looking at individual differences in interoceptive ability; Simultaneously recording a wider range of peripheral and central variables

The review concludes that despite its limitations, what valuable contribution has the SMH and IGT made to the literature?

They have helped reintroduce the idea that emotion can be a benefit (not just a hindrance) in decision-making to the neuroscience community. They outlined a plausible neural substrate

According to the review, what is one conceptual reservation about the SMH besides the issues with the IGT evidence?

Concerns about its novelty compared to earlier theories; its specification of the somatic marker mechanism; and its parsimony (whether it's the simplest explanation)