Visual stimuli modulate frontal oscillatory rhythms in a cortically blind patient: evidence for top-down visual processing

Tipura, Eda, Pegna, Alan J., de Gelder, Beatrice and Renaud, Olivier (2017) Visual stimuli modulate frontal oscillatory rhythms in a cortically blind patient: evidence for top-down visual processing. Clinical Neurophysiology, 128 5: 770-779. doi:10.1016/j.clinph.2017.02.009

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Author Tipura, Eda
Pegna, Alan J.
de Gelder, Beatrice
Renaud, Olivier
Title Visual stimuli modulate frontal oscillatory rhythms in a cortically blind patient: evidence for top-down visual processing
Journal name Clinical Neurophysiology   Check publisher's open access policy
ISSN 1872-8952
1388-2457
Publication date 2017-05-01
Sub-type Article (original research)
DOI 10.1016/j.clinph.2017.02.009
Open Access Status File (Author Post-print)
Volume 128
Issue 5
Start page 770
End page 779
Total pages 10
Place of publication E Park, Shannon, Clare Ireland
Publisher Elsevier Ireland
Language eng
Subject 2809 Sensory Systems
2808 Neurology
2728 Clinical Neurology
2737 Physiology (medical)
Abstract Objective We investigated neuronal correlates of faces versus non-faces processing in a cortically blind patient (TN) and a group of healthy age-matched controls in order to test electrophysiological correlates of the processing of pertinent stimuli in this patient. Methods An EEG paradigm was used, in which intact and scrambled faces were displayed on a screen. First, time-frequency transforms were conducted on the patients’ data alone. These oscillations were then compared to the frontal activity of six control participants. Results Post stimulus oscillatory modulations (synchronisation in theta and alpha frequency bands) of both intact and scrambled faces at frontal scalp sites were observed in TN. These modulations were different for correct and incorrect responses. A more important increase in the theta band for incorrect responses was observed. The oscillatory rhythms highlighted in blindsight and in frontal regions differ from the ones observed in control participants. Conclusion Despite the destruction of the visual cortex, oscillatory rhythms are not cancelled out but are shifted to anterior regions, revealing the activity of an alternate pathway for residual visual function. Significance The results provide evidence for a top-down cognitive control process in blindsight.
Formatted abstract
Objective: We investigated neuronal correlates of faces versus non-faces processing in a cortically blind patient (TN) and a group of healthy age-matched controls in order to test electrophysiological correlates of the processing of pertinent stimuli in this patient.

Methods: An EEG paradigm was used, in which intact and scrambled faces were displayed on a screen. First, time-frequency transforms were conducted on the patients’ data alone. These oscillations were then compared to the frontal activity of six control participants.

Results: Post stimulus oscillatory modulations (synchronisation in theta and alpha frequency bands) of both intact and scrambled faces at frontal scalp sites were observed in TN. These modulations were different for correct and incorrect responses. A more important increase in the theta band for incorrect responses was observed. The oscillatory rhythms highlighted in blindsight and in frontal regions differ from the ones observed in control participants.

Conclusion: Despite the destruction of the visual cortex, oscillatory rhythms are not cancelled out but are shifted to anterior regions, revealing the activity of an alternate pathway for residual visual function.

Significance: The results provide evidence for a top-down cognitive control process in blindsight.
Keyword Blindsight
EEG
Event-related spectral perturbation
Frontal cortex
Frontal midline theta rhythm
Vision
Q-Index Code C1
Q-Index Status Provisional Code
Grant ID 320030-144187
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: HERDC Pre-Audit
School of Psychology Publications
 
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