Affective blindsight relies on low spatial frequencies. (May 2019)

• Record Type: Journal Article
• Authors: Burra, Nicolas; Hervais-Adelman, Alexis; Celeghin, Alessia; de Gelder, Beatrice; Pegna, Alan J.
• Is Part Of: Neuropsychologia. Volume 128(2019)
• Page Start: 44
• Page End: 49
• Publication Date: 2019-05
• Subjects: Affective blindsight -- Amygdala -- Facial expressions -- Fear emotion -- Spatial frequency -- Hemianopia; Neuropsychology -- Periodicals; Neurology -- Periodicals; Psychophysiology -- Periodicals; Neuropsychologie -- Périodiques; Neuropsychology; Periodicals; Electronic journals; 616.8
• DOI: 10.1016/j.neuropsychologia.2017.10.009
• Languages: English
• ISSNs: 0028-3932

Abstract

Abstract: The human brain can process facial expressions of emotions rapidly and without awareness. Several studies in patients with damage to their primary visual cortices have shown that they may be able to guess the emotional expression on a face despite their cortical blindness. This non-conscious processing, called affective blindsight, may arise through an intact subcortical visual route that leads from the superior colliculus to the pulvinar, and thence to the amygdala. This pathway is thought to process the crude visual information conveyed by the low spatial frequencies of the stimuli. In order to investigate whether this is the case, we studied a patient (TN) with bilateral cortical blindness and affective blindsight. An fMRI paradigm was performed in which fearful and neutral expressions were presented using faces that were either unfiltered, or filtered to remove high or low spatial frequencies. Unfiltered fearful faces produced right amygdala activation although the patient was unaware of the presence of the stimuli. More importantly, the low spatial frequency components of fearful faces continued to produce right amygdala activity while the high spatial frequency components did not. Our findings thus confirm that the visual information present in the low spatial frequencies is sufficient to produce affective blindsight, further suggesting that its existence could rely on the subcortical colliculo-pulvino-amygdalar pathway. Highlights: An individual with cortical blindness was investigated using brain imaging (fMRI). Unseen fearful faces were found to activate the right amygdala. Activation was maintained for low spatial frequency components of fearful faces. Affective blindsight thus seems to rely on information from low spatial frequencies.