The role of emotion in decision-making: Evidence from neurological patients with orbitofrontal damage

Abstract

Most theories of choice assume that decisions derive from an assessment of the future outcomes of various options and alternatives through some type of cost-benefit analyses. The influence of emotions on decision-making is largely ignored. The studies of decision-making in neurological patients who can no longer process emotional information normally suggest that people make judgments not only by evaluating the consequences and their probability of occurring, but also and even sometimes primarily at a gut or emotional level. Lesions of the ventromedial (which includes the orbitofrontal) sector of the prefrontal cortex interfere with the normal processing of “somatic” or emotional signals, while sparing most basic cognitive functions. Such damage leads to impairments in the decision-making process, which seriously compromise the quality of decisions in daily life. The aim of this paper is to review evidence in support of “The Somatic Marker Hypothesis,” which provides a systems-level neuroanatomical and cognitive framework for decision-making and suggests that the process of decision-making depends in many important ways on neural substrates that regulate homeostasis, emotion, and feeling. The implications of this theoretical framework for the normal and abnormal development of the orbitofrontal cortex are also discussed.

Introduction

The orbitofrontal region of the prefrontal cortex includes the rectus gyrus and orbital gyri, which constitute the inferior surface of the frontal lobes lying immediately above the orbital plates. Lesions of this region are not usually restricted to the orbitofrontal cortex, but they extend into neighboring cortex and involve different size sectors of the ventromedial prefrontal (VM) region. The VM region includes the medial and varying sectors of the lateral orbitofrontal cortex, thus encompassing Brodmann’s areas (BA) 25, lower 24, 32, and medial aspect of 11, 12, and 10, and the white matter subjacent to all of these areas. Patients with bilateral lesions of the VM cortex (Fig. 1) develop severe impairments in personal and social decision-making, in spite of otherwise largely preserved intellectual abilities. Before their brain damage, they have normal intelligence and creativity. After the damage, they develop difficulties in planning their workday and future; difficulties in choosing friends, partners, and activities (Bechara, Damasio et al., 2000; Bechara, Tranel, & Damasio, 2002).

The “Somatic Marker Hypothesis” was proposed in order to provide a neural explanation of the real-life decision-making defect of these patients. The main point of this hypothesis is that decision-making is a process guided by emotions. There is a link between the abnormalities in emotion and feeling of these patients and their severe impairment in judgment and decision-making in real-life (Bechara, Damasio et al., 2000, Bechara et al., 2002).

We tested the somatic marker hypothesis using the gambling task (GT) paradigm for measuring decision-making (Bechara, Tranel, & Damasio, 2000). However, there are other paradigms, namely the “betting task” (also referred to as the Cambridge Gamble Task) developed by Rogers and colleagues (Rogers, Everitt et al., 1999), and tasks of delayed discounting (Bickel, Degrandpre, & Higgins, 1995). It has been shown that there is a significant correlation between performance on the GT, the “betting task,” and tasks of delayed discounting (Monterosso, Ehrman, Napier, O’Brien, & Childress, 2001), thus supporting the notion that these three sets of tasks may engage a common mechanism of decision-making, tied to the VM region.