Project 2: Neural Basis of Emotion-Reason Interactions

We are also probing the relationship between rational and emotional processing. Much neuropsychological data implicates VMPFC in emotional processing (Damasio, 1997; Goel & Dolan, 2001a; Harlow, 1868; Lane, Reiman, Ahern, Schwartz, & Davidson, 1997; Pietrini, Guazzelli, Basso, Jaffe, & Grafman, 2000) and the L/DLPFC in high-level cognitive processing (Drewe, 1974; Goel, Grafman, Tajik, Gana, & Danto, 1997; Goldman-Rakic, 1987; Rowe, Owen, Johnsrude, & Passingham, 2001; Shallice, 1988; Stuss et al., in press), including logical reasoning (Goel et al., 2000; Goel & Dolan, 2001b; Goel & Dolan, in press-a; Goel, Gold et al., 1997; Goel et al., 1998; Houde et al., 2001; Knauff, Mulack, Kassubek, Salih, & Greenlee, in press; Parsons & Osherson, 2001). However, with a few exceptions (Gray, Braver, & Raichle, 2002), the literatures on cognition and emotion are largely independent of each other. It has been observed that some patients with VMPFC lesions, in addition to having significant emotional and social problems, make poor decisions (Anderson, Damasio, Tranel, & Damasio, 2000). This has led to the suggestion that there is a causal connection between emotional deficits and poor decision making (Bechara, Damasio, & Damasio, 2000; Damasio, 1996). One possible basis for this connection is an interaction between L/DLPFC and VMPFC during reasoning. While several neuroimaging and patient studies have shown a dissociation between L/DLPFC and VMPFC in cognitive and affect processing (Goel & Dolan, 2001a; Greene, Sommerville, Nystrom, Darley, & Cohen, 2001; Hariri, Bookheimer, & Mazziotta, 2000; Koechlin, Corrado, Pietrini, & Grafman, 2000; Stuss & Levine, in press), very little is known about the functional interaction between the two regions.

We are currently undertaking a series of fMRI studies in which normal controls are confronted with a conflict between rational and emotional responses within the domain of deductive and inductive reasoning. In one recent study we explored the interaction between belief and reason. We have shown (Goel & Dolan, 2003) that within the context of reasoning involving inhibitory or misleading beliefs, the crucial element in the modulation of reasoning by beliefs is the preferential engagement of VMPFC. Where the VMPFC is preferentially engaged, subjects are more likely to generate responses based upon their belief-biases. This contrasts with correct logical reasoning that requires relatively greater activation of L/DLPRC. The involvement of VMPFC and its strong associations with affective processing indicates that belief-bias effects on reasoning may be a special instance of the modulatory effect of emotion on cognition (Damasio, 1994). The fact that the response of the VMPFC is specific to inhibitory belief trials and is deactivated (with respect to facilitory belief trials) during correct inhibitory belief trials (while L/DLPFC is activated) suggests a reciprocal relationship between VMPFC and L/DLPFC.

To further explore this relationship we (Goel & Dolan, in press-b), scanned normal subjects using event-related fMRI, while they engaged in identical logical reasoning tasks that varied only in emotional saliency (e.g. Some Canadians are not children; All Canadians are people; Some people are not children. vs. Some wars are not unjustified; All wars involve raping of women; Some raping of women is not unjustified). Despite identical logical form and content categories across emotionally salient and neutral reasoning conditions, lateral and ventral medial prefrontal cortex showed reciprocal response patterns as a function of content saliency. Neutral reasoning trials resulted in enhanced activity in L/DLPFC and suppression of activity in VMPFC. By contrast, salient reasoning trials resulted in enhanced activation in VMPFC and suppression of activation in L/DLPFC. This reciprocal engagement of L/DLPFC and VMPFC provides evidence for a dynamic neural system for reasoning, the configuration of which is strongly influenced by emotional saliency and leads us to the following hypothesis:

H2. The interaction between rational and emotional processing is underwritten by reciprocal neural activation in L/DLPFC and VMPFC,

We are now expanding the scope of this project. In particular, we are interested in the fact that emotions can be introduced into the decision-making process in at least 3 ways: (i) in the content/substance of the reasoning task (as in the above study); (ii) in the presentation of the content of the reasoning task (i.e. context); and (iii) in the preexisting mood of the subject. Given this, we want to focus on two questions: (a) Do these three manipulations engage the same neural systems? (b) How does content/substance of reasoning interact with context (e.g. voice intonation) and subject mood.

Basic operating funds for this study are covered by my NSERC grants (Title of Project: Neurology of Belief & Logic) and Premier’s Research Excellence Award (Title of Project: Neurobiology of Rationality).

Nov. 10, 2003