When seeing outweighs feeling : a role for prefrontal cortex in passive control of negative affect in blindsight

• Affective neuroscience has been strongly influenced by the viewthat a ‘feeling’ is the perception of somatic changesand has consequently often neglected the neural mechanisms thatunderlie the integration of somatic and other information inaffective experience. Here, we investigate affective processingby means of functional magnetic resonance imaging in nine corticallyblind patients. In these patients, unilateral postgeniculatelesions prevent primary cortical visual processing in part ofthe 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 reportedearlier, these patients show significant startle reflex potentiationwhen a threat-related visual stimulus is shown in their blindvisual field. Critically, this was associated with an increaseof brain activity in somatosensory-related areas, and an increasein experienced negative affect. Here, we investigated the patients’response when the visual stimulus was shown in the sighted visualfield, that is, when it was visible and cortically processed.Despite the fact that startle reflex potentiation was similarin the blind and sighted visual field, patients reported significantlyless negative affect during stimulation of the sighted visualfield. In other words, when the visual stimulus was visibleand received full cortical processing, the patients’ phenomenalexperience of affect did not closely reflect somatic changes.This decoupling of phenomenal affective experience and somaticchanges was associated with an increase of activity in the leftventrolateral prefrontal cortex and a decrease of affect-relatedsomatosensory activity. Moreover, patients who showed strongerleft ventrolateral prefrontal cortex activity tended to showa stronger decrease of affect-related somatosensory activity.Our findings show that similar affective somatic changes canbe associated with different phenomenal experiences of affect,depending on the depth of cortical processing. They are in linewith a model in which the left ventrolateral prefrontal cortexis a relay station that integrates information about subcorticallytriggered somatic responses and information resulting from in-depthcortical stimulus processing. Tentatively, we suggest that theobserved decoupling of somatic responses and experienced affect,and the reduction of negative phenomenal experience, can beexplained by a left ventrolateral prefrontal cortex-mediatedinhibition of affect-related somatosensory activity.

Ämnesord

SAMHÄLLSVETENSKAP  -- Psykologi (hsv//swe)

SOCIAL SCIENCES  -- Psychology (hsv//eng)

Nyckelord

blindsight

emotion

affect

Psychology

Psykologi

Psychology

psykologi

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)