The Role of Emotion in Decision Making (Naqvi, Shiv, & Bechera, 2006)

A Cognitive Neuroscience Perspective

Does anyone know who this man is?- Antonio Damasio: Neuroscientist who created the “somatic marker hypothesis” which has gained traction recently in the fields of affective and cognitive neuroscience- He also happens to be an author whose books on neuroscience and cognition have won him numerous prizes in the literary community.

Abstract: “Decision making often occurs in the face of uncertainty about whether

one’s choices will lead to benefit or harm. The somatic marker hypothesis is a

neurobiological theory of how decisions are made in the face of uncertain outcomes”

Common examples of decision making in our daily lives include:

- which house to buy- which stock to invest in- which food to eat

However, derangements in the decision-making process leads to some of the more severe psychiatric illnesses such as schizophrenia, mania, OCD, and drug addiction (to name a few)

Methods used to study the role of emotion in decision-making include: Lesion Studies, functional imaging, and other physiological techniques.

- “The combined results show that decision making involves not only the cold-hearted calculation of expected utility based upon explicit knowledge of outcomes, but also more subtle and sometimes covert processes.”

-- The study’s author, Bechera, worked initially with Antonio Damasio in creating the somatic marker hypothesis.

-- So if decisions are not completely based off of logic and reason, what else guides the decision making process?

To answer this question, we have to use insights from patients with focal brain damage.

- Damage to the ventromedial prefrontal cortex (vmPFC) in patients showed them engaging in behaviors that were detrimental to their well-being.

- These led to financial losses, loss of social standing, and so on.-Damasio hypothesized that the primary dysfunction of patients with vmPFC damage was an inability to use emotions to aid in decision making, particularly in three realms:-(1) Personal-(2) Financial-(3)Moral

-- This is the fundamental tenet of the somatic marker hypothesis, that emotions play a role in guiding decisions, especially in situations in which the outcome are uncertain.

- Damasio and colleagues designed the Iowa Gambling Task to determine how vmPFC patients simulated real-life decision-making tasks which required rewards or losses.- The vmPFC patients tended to continue choosing from the disadvantageous decks, seemingly insensitive to the negative consequences of their choices. They demonstrated a pattern of perseveration, unlike the normal control group.-According to the theory, emotions are constituted by changes in the body. These bodily states are elicited during the decision-making process and function to “mark” certain options as advantageous and other ones as disadvantageous.-- Further experimentation with amygdala damaged patients elicited similar results to the vmPFC patients, but differed in one characteristic way: The amygdala patients had impaired skin conductance responses (SCR) compared to the vmPFC patients when performing the Iowa Gambling Task, which indicated the amygdala subjects had an impairment in registering the emotional impact of rewards and punishments.

- The amygdala elicits emotional/bodily states in response to receiving rewards and punishments.- Through a learning process, these states become linked to mental representations of the specific behaviors that brought them about.- During decision making, the patient will deliberate these behaviors as options for the future.- As each option is brought into their mind, the somatic state that was triggered by that past behavior is reenacted by the vmPFC.- There are two ways in which emotional/bodily states are represented in the brain:1) Mapping at the cortical levels (such as within the insular cortex) which give rise to “gut feelings”2) Mapping of bodily states at the subcortical level, which is non-conscious (like in the mesolimbic dopamine [DA] system).

Evidence from physiological studies:- Rolls and colleagues (2004) recorded individual neurons within the vmPFC, and found that vmPFC neurons respond to the reception of various primary reinforcers.- They also found that responses to specific primary reinforcers were reduced by manipulations that diminished their value, such as feeding someone a tasty snack, and they also found that vmPFC neurons respond to conditioned stimuli that predict the delivery of primary reinforcers.

- fMRI studies (Gottfried, O’Doherty, & Dolan, 2003) found that the vmPFC responses to conditioned stimuli reduced by devaluing the specific primary reinforcer they were supposed to predict!

- Suggests that the vmPFC plays a role in predicting the future rewarding consequences of different behaviors by accessing memories from the past.

Role of Insular Cortex- The insular cortex has been shown to be involved in engaging

in certain types of decision making.- - Activity in the insular cortex is higher during high-risk

decisions than it is during low-risk decisions.- - An fMRI study found that the insular cortex is activated when

subjects evaluate the fairness of offers of money from another subject.

- - This study found that the level of activity in the insular cortex predicts the likelihood of rejecting an unfair offer.

- - This suggests the insular cortex plays a role in assessing risk and guiding behavior based on the anticipation of emotional consequences.

- - The Somatic-Marker Hypothesis attributes this function to the mapping of visceral states within the insular cortex, which give rise to “gut feelings”.

Neuroanatomy and Neurotransmitter Systems- The mesolimbic dopamine (DA) system is hypothesized by the

somatic-marker theory to play a role in the unconscious biasing of action.

- - Recent research has shown that the activity of single neurons within the mesolimbic DA system is increased by primary reinforcers but only when these are delivered in an unpredictable fashion.

- - Researchers have shown that activity within the mesolimbic DA system signals an error between actual and predicted reward and that such a signal can bias behavior in the direction of behaviors that are likely to lead to rewards in the future (consistent with the role of the mesolimbic DA system in the somatic-marker hypothesis.

Applications of the Somatic-Marker Theory- Recent research has used fMRI to examine the neural systems that

enable moral decisions. Structures included in this moral circuitry include the vmPFC.

- - vmPFC activation is greater when the moral decision involves negative consequences for another person, compared to when it involves no negative consequences for another person.

- - This suggests that moral decision-making engage emotions, especially when one has to take into account the well-being of others.

- - The somatic-marker framework has been applied to understanding drug addiction as well. Substance abusers show real-life decision-making impairments that are similar to those of patients with vmPFC damage.

- - In fact, drug addicts and vmPFC patients perform uniformly on the Iowa Gambling Task, suggesting that addiction may be partially caused by dysfunction in the vmPFC.

Future Directions

- Research still needs to be conducted to parse the mesolimbic DA system and the insular cortex, and how they influence both conscious gut feelings and non-conscious biasing of behavior.

- - Further research is being conducted on the role of the mesolimbic DA system in decision making (see Robbins, 2000).

- - Studies have shown how drug therapies can be used to treat the decision-making impairments associated with certain mental illnesses. Panksepp extensively talks about DA levels, and how excessive DA levels lead to schizophrenia.

- - The somatic-marker hypothesis provides a basis for understanding how the capacity to make decisions in the moral, social, and financial realms, are related to basic motivational and homeostatic processes shared by all mammals. This theory serves as a launching point for understanding not only decision making, but also a variety of goal directed processes in which affect and motivation are integrated with the planning of complex action.

Naqvi et al. (2006) vs. Panksepp (1991)

- Panksepp’s SEEKING system is essentially a DA system very similar to the system Antonio Damasio describes.

- - For Panksepp, the extended lateral hypothalamus (LH) is the system he describes as reacting to homeostatic imbalances, although Naqvi and Damasio describe more.

- - Both articles focus primarily on the role of the DA systems: Panksepp describes the DA pathway as coursing through the ventrolateral regions of the diencephalon (areas of the brain called the medial forebrain bundle of the lateral hypothalamus [LH]) which contain many neurochemically specific tracts. One major set of pathways, the ascending DA circuits, outlines the sites from which this psychobehavioral state can be most easily evoked with localized brain stimulation.

Naqvi et al. (2006) vs. Panksepp (1991)

- Panksepp describes his own version of Damasio’s somatic marker hypothesis as: “the transient external cues associated with life sustaining events may be the ones that gradually develop conditioned neural routes back to the appetitive system. In other words, the SEEKING system is initially activated by the unconditional distal incentive cues of rewards, such as smells and sights; eventually, through learning, neutral cues can come to arouse and channel activity in this system through a reinforcement process that is linked to the inhibition of approach in some presently unknown manner.”

- - The SEEKING system and the somatic-marker hypothesis share most of the same neural circuits, including the: mesolimbic DA system (consisting of many smaller structure), mesocortical from the ventral tegmental area (VTA), and nucleus accumbens.

Naqvi et al. (2006) vs. Panksepp (1991)

- However, Panksepp detailed other systems that may play a role such as: DA antagonists which have no role in blocking ESB rat-sniffing, which is beyond DA control.

- - This means that other neurotransmitters or chemicals must be involved, and it is believed that the glutamatergic circuits that provide regulatory control over neuronal bursting activity within the DA system may be responsible.

- It has been proven that DA is released from the ventral striatum (i.e., nucleus accumbens), but comparable DA release is not evident in the dorsal striatum (caudate nucleus) which receives DA projections mainly from the more lateral nigrostriatal system from the A9 DA neurons (neurons and pathway responsible for voluntary movement).

Naqvi et al. (2006) vs. Panksepp (1991)

- For Panksepp, the homeostatic detectors were located in the medial strata of the hypothalamus, whereas Naqvi and Damasio add the vmPFC as the emotional homeostatic control mechanism.

- - Panksepp calls the homeostatic neurons “interoreceptive neurons” and claims they are the vital resources in promoting the arousability of the SEEKING system.

- - Both agree that DA from the VTA are responsive to “incentive stimuli” and are anticipatory in nature.

- - Naqvi et al. (2006) indirectly describes how Damasio created his theory based off the earlier research of Olds & Milner (1954), who recorded action potentials from neurons during anticipatory situations.

Pioneers in Affective Neuroscience

ANTONIO DAMASIO JAAK PANKSEPP