From affective blindsight to emotional consciousness

Abstract

a b s t r a c tFollowing destruction or denervation of the primary visual cortex (V1) cortical blindness ensues. Affective blindsight refers to the uncanny ability of such patients to respond correctly, or above chance level, to visual emotional expressions presented to their blind fields. Fifteen years after its original discovery, affective blindsight still fascinates neuroscientists and philosophers alike, as it offers a unique window on the vestigial properties of our visual system that, though present in the intact brain, tend to be unnoticed or even actively inhibited by conscious processes. Here we review available studies on affective blindsight with the intent to clarify its functional properties, neural bases and theoretical implications. Evidence converges on the role of subcortical structures of old evolutionary origin such as the superior colliculus, the pulvinar and the amygdala in mediating affective blindsight and nonconscious perception of emotions. We conclude that approaching consciousness, and its absence, from the vantage point of emotion processing may uncover important relations between the two phenomena, as consciousness may have evolved as an evolutionary specialization to interact with others and become aware of their social and emotional expressions.

Reconciling cognitive and affective neuroscience perspectives on the brain basis of emotional experience

“…We take this as evidence that affective qualia can be experienced, even though the precipitating cognitive stimuli are totally out of awareness (for a review of the affective blindsight literature, see Celeghin et al, 2015). As a corollary to this, it remains possible that the primary-process brain mechanisms for valenced affective feelings can still operate when cognitive "awareness" consciousness is gone (helping explain the various lines of evidence of learning under anesthesia which RS and RDL highlight).…”

“…This could be examined, for example, by adapting existing paradigms for subliminal instrumental conditioning (e.g.,Pessiglione et al, 2008). Such paradigms have shown that learning can occur without conscious experience of external stimuli (e.g., visual stimuli), but this leaves open the possibility that these subliminal stimuli still trigger conscious affective feelings (i.e., with positive/negative valence, as in:Celeghin et al, 2015;Shevrin et al, 2012). We suggest that this possibility could be further tested by adding continuous self-report measures of emotional state to such paradigms (e.g., a dial indicating changes in pleasantness, while recognizing that such actions may partially diminish/modify experienced affect).…”

The Brainstem in Emotion: A Review

“…The upper brainstem, where the parabrachial complex lies, is therefore the most caudal structure where a topographically complete map of the body can be assembled that includes all manner of interoceptive information (Damasio and Carvalho, 2013). There is also ongoing investigation of the role played by the superior colliculus, a structure in the dorsal aspect of the upper brainstem, in sensory and emotional processing in humans, but the available evidence is sparse (Celeghin et al, 2015). …”

Amygdala Response to Emotional Stimuli without Awareness: Facts and Interpretations

“…Therefore, the study of Amg response to emotional stimuli in these patients can add insights into the mechanisms governing attentional unawareness. On the other end, patients with cortical blindness ensuing from damage to, or denervation of, the primary visual cortex (V1) offer a case study to investigate the differences between conscious and non-conscious emotion processing due to sensory, as opposed to attentional, causes and the role of Amg therein (Celeghin et al, 2015b). In fact, the V1 lesion in such patients determines permanent blindness to stimuli projected within the scotoma (the visual field region affected by the cortical lesion), also if the stimuli are supra threshold and long-lasting (Celeghin et al, 2015a,c; Weiskrantz, 2009).…”