Brain Advance Access originally published online on September 18, 2009
Brain 2009 132(11):3021-3031; doi:10.1093/brain/awp212
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When seeing outweighs feeling: a role for prefrontal cortex in passive control of negative affect in blindsight
1 Institute of Medical Psychology and Behavioural Neurobiology, University of Tübingen, Germany 2 Neuroimage Nord and Department of Neurology, University of Lübeck, Germany 3 Department of Psychology, Stockholm University, Sweden 4 University Medical Center Hamburg-Eppendorf, Germany 5 Functional Imaging Unit, Center for Diagnostic Radiology and Neuroradiology, University of Greifswald, Germany 6 Department of Psychiatry, University of Tübingen, Germany
Correspondence to: Silke Anders, Neuroimage Nord and Department of Neurology, University of Lübeck, Ratzeburger Alle 160, 23538 Lübeck, Germany E-mail: silkeanders{at}neuro.uni-luebeck.de
Affective neuroscience has been strongly influenced by the view that a ‘feeling’ is the perception of somatic changes and has consequently often neglected the neural mechanisms that underlie the integration of somatic and other information in affective experience. Here, we investigate affective processing by means of functional magnetic resonance imaging in nine cortically blind patients. In these patients, unilateral postgeniculate lesions prevent primary cortical visual processing in part of the visual field which, as a result, becomes subjectively blind. Residual subcortical processing of visual information, however, is assumed to occur in the entire visual field. As we have reported earlier, these patients show significant startle reflex potentiation when a threat-related visual stimulus is shown in their blind visual field. Critically, this was associated with an increase of brain activity in somatosensory-related areas, and an increase in experienced negative affect. Here, we investigated the patients’ response when the visual stimulus was shown in the sighted visual field, that is, when it was visible and cortically processed. Despite the fact that startle reflex potentiation was similar in the blind and sighted visual field, patients reported significantly less negative affect during stimulation of the sighted visual field. In other words, when the visual stimulus was visible and received full cortical processing, the patients’ phenomenal experience of affect did not closely reflect somatic changes. This decoupling of phenomenal affective experience and somatic changes was associated with an increase of activity in the left ventrolateral prefrontal cortex and a decrease of affect-related somatosensory activity. Moreover, patients who showed stronger left ventrolateral prefrontal cortex activity tended to show a stronger decrease of affect-related somatosensory activity. Our findings show that similar affective somatic changes can be associated with different phenomenal experiences of affect, depending on the depth of cortical processing. They are in line with a model in which the left ventrolateral prefrontal cortex is a relay station that integrates information about subcortically triggered somatic responses and information resulting from in-depth cortical stimulus processing. Tentatively, we suggest that the observed decoupling of somatic responses and experienced affect, and the reduction of negative phenomenal experience, can be explained by a left ventrolateral prefrontal cortex-mediated inhibition of affect-related somatosensory activity.
Key Words: emotion; phenomenal experience; affective feeling; startle reflex potentiation; ventrolateral prefrontal cortex
Abbreviations: BVF, blind visual field; fMRI, functional magnetic resonance imaging; SCR, skin conductance response; SVF, sighted visual field; VLPFC, ventrolateral prefrontal cortex
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Received December 2, 2008. Revised June 26, 2009. Accepted June 29, 2009.
*These authors contributed equally to this work.