Chatper 14: Decision Making
Antonio Damasio is a neuroscientist & professor at the University of Southern Carolina: pioneered a
number of neurobiological theories on Emotion and decision-making (emotions play a critical role in
- Dscartes’ Error: Emotion, Reason, & the Human Brain (Descartes: Mind-Body Problem. Postulated
that the mind and body are separate; body performs like a machine & responds to events, mind
decides what movements the body makes).
Descartes postulated that the mind and body interact via the pineal body (pineal gland).
Damasio argues that emotions are a crucial component to decision-making: body and mind
(emotion) have a role in rational decision-making. Body is a content that is part and parcel with
the working mind. “The mind is embodied, not just embrained”.
We are trained to regard emotions as irrational impulses that lead us astray; describing someone
as emotional is a criticism suggesting they lack good judgment.
- The amygdala is a small structure (group of nuclei) located medially within temporal lobes.
Part of the limbic system (memory, decision-making, emotion)
Main role: assigns emotional meaning to sensory stimuli; stores emotional events and codes
Involved in associative learning
Codes the valence of stimuli (ex: should you approach an object yes if it’s a stick, avoid if it’s a
Orbitofrontal cortex (OFC) is part of the prefrontal cortex region that sites in front of the frontal
lobes of the brain. Situated immediately above the orbits in which our eyes are
located (Broadmann regions: 10,11 47).
Important role in fucntions critial to everyday life: important role in higher-
Ventromedial prefrontal cortex is considered anatomically synonymous
anatomical overlap, but not the same (Broadmann 10, 14, 25). Distinguished by distinct
functions/neural connections, but also involved in decision-
OFC receives inputs from different sensory modalities:
Gustatory (anterior insula), olfactory (piriform cortex),
somatosensory(areas SI and SII), auditory (auditory cortex),
visual (temporal), visceral information (thalamus).
Considered one of the most polymodal regions of the cortex.
Receives inputs from other brain regions in the limbic system: Amygdala connections are
important for emotional decision-making. OFC modulates associative learning & emotion
regulation in the amygdala
Receives inputs from Anterior cingulate cortex, hypothalamus (important role in body
Nearly all connections to the OFC are reciprocal - projects back to the different brain regions
- OFC plays a major role in emotional processing by sensory inputs/outputs to areas important for
emotional processing/expression (limbic system)
- OFC signals and encodes information about the expected outcomes of a situation
- OFC uses associative information to help guide or bias decision-making. Emotions: How do we define emotion?
- James & Lange argued that emotions are not just a response; function of how we perceive the
physiological changes in our body (do not tremble at the sight of the bear because you are afraid,
become afriad because you start to tremble).
- Canon: Cutting PNS does not eliminate emotional responsive; cognitive factors are also essential for
generating emotion. Advancements in neuroscience field have increased knowledge of brain regions
for emotion (primate neurophysiology, human neuroimaging).
The Case of Phineas Gage: Incurred a TBI (rod through head); normal physical & cognitive capacities.
Effect of personality change.
- Capacity for emotional processing changed (profanity, impatience, lack of restraint, ignoring advice
that conflicts with desires, difficulty planning).
- Confirmed theories on localization of function & role of frontal lobes on social cognition, emotion, &
The Case of Elliot: “modern day phineas gage”
- Severe disturbance of higher cognitive after bilateral frontal lobe ablation: Tumour surgery damaged
the OFC bilaterally
- Intact cognitive functioning, but lost time management skills, prioritization, meeting goals, ability to
make financial decisions, etc. Unable to make simple, rapid decisions: stuck making endless cost-
benefit analyses and contrasts… often making either no decision or a random one.
- Blunted emotional processing - lacked sympathetically mediated skin conductance response for
stimuli requiring an evaluation of emotoinal content.
SCRs: skin momentarily becomes a better conductor of electricity when a person is exposed to
external/internal stimuli that are physicall arousing; essentially indicator of anxiety.
Somatic marker hypothesis proposes that emotional signals from the body (somatic markers) play a
critical role in guiding/biasing our behaviours, especially in the context of decision-making.
- Feelings in the body associated with emotion (rapid heart-rate, nausea, from “internal milieu” -
- Damasio: emotions are changes in the body & brain states that occur in response to a stimulus
(muscle tone, heart-rate, endocrine activity, facial expressions).
The body’s expressions of emotion are relayed back to the brain & help to inform the individual
about what kind of stimulus this is (good or bad).
Over time, we develop learned associations between body changes (somatic markers) and
particular outcomes (positive vs negative); when we go make a decision in the future, the somatic
marker associated with past outcomes is activated (helps influence decision-making). Somatic
markers MARK respons options to real or simulated decisions.
- Activation of somatic markers can occur through:
1) The body loop: emotions are caused by changes in the body in
response to a stimulus that are projected back to the brain
2) The “as if” body loop: Cognitive representations of the emotion (thinking as if you were in that
situation) are activated without peripheral feedback from the body.
- Activation of the somatic markers occurs by:
1) Overt: somatic signal as an “alarm” or incentive signal (gut feeling)
2) Covert: somatic signal as a biasing signal (neurotransmitters)
- With OFC Patients:
Decision-making deficits due to inability to activate somatic markers Deficits guiding future behaviours based on past experiences; rely instead on cost-benefits
Unable now to learn from past mistakes
OFC patients don’t have somatic markers - stuck using only cognitive analysis
Iowa Gambling Task: created to simulate a real-life situation of decision-making that can tap at the
deficits observed in OFC patients.
- 4 virtual card decks; 2 decks have higher gain but overall lower
net value (bad), the other two have a lower gain but overall
higher net value (good).
- Control subjects tend to make more selections from th