Can theories of visual representation help to explain asymmetries in amygdala function?
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Can theories of visual representation help to explain asymmetries in amygdala function? Brenton W. McMenamin & Chad J. Marsolek
Published online: 14 December 2012 # Psychonomic Society, Inc. 2012
Abstract Emotional processing differs between the left and right hemispheres of the brain, and functional differences have been reported more specifically between the left and right amygdalae, subcortical structures heavily implicated in emotional processing. However, the empirical pattern of amygdalar asymmetries is inconsistent with extant theories of emotional asymmetries. Here we review this discrepancy, and we hypothesize that hemispheric differences in visual object processing help to explain the previously reported functional differences between the left and right amygdalae. The implication that perceptual factors play a large role in determining amygdalar asymmetries may help to explain amygdalar dysfunction in the development and maintenance of posttraumatic stress disorder.
(Table 1). We propose that bottom-up perceptual processes heavily influence the amygdalae, and that hemispheric asymmetries in visual object processing can help to provide a parsimonious explanation of amygdalar asymmetries. This review is organized into five sections: In the first section, we review differences in emotional processing between the two cerebral hemispheres (including the amygdala). The second section reviews functional asymmetries specific to the amygdalae, and the third reviews hemispheric asymmetries in visual object processing. In the fourth section, we describe ways in which visual object processing asymmetries may help to explain the amygdalar asymmetries, and the final section provides an example of how a consideration of perceptual factors can provide insight regarding amygdalar dysfunction in posttraumatic stress disorder (PTSD).
Keywords Amygdala . Visual cortex . Emotion . Hemisphere . Laterality
Theories of emotion asymmetry
The cerebral hemispheres differ in their processing of emotional information, and modern neuroimaging techniques have begun to explore precisely which neural structures are involved in these hemispheric asymmetries. The amygdalae are subcortical structures located bilaterally in the temporal lobes that play roles in diverse emotional processes (Zald, 2003). Recently, several meta-analyses of amygdalar activation have confirmed that the left and right amygdalae function differently, but these findings were not consistent with previous theories for emotional asymmetries in general, or with previous theories of amygdalar asymmetries in particular B. W. McMenamin (*) : C. J. Marsolek Department of Psychology and the Center for Cognitive Sciences University of Minnesota, 75 E River Road, Minneapolis, MN 55455, USA e-mail: [email protected]
Emotional asymmetries in humans For a century, researchers have hypothesized that the left and right hemispheres of the brain process emotion differently (Mills, 1912, cited in Murphy, Nimmo-Smith, & Lawrence, 2003). Three major theories have been proposed to c
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