Emotional expressions modulate low α and β oscillations in a cortically blind patient

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

“…We therefore hypothesise that the increase in the theta band and in frontal sites following stimuli leading to incorrect responses in TN may reflect a top-down cognitive control process. These results may seem contradictory with the results Del Zotto et al (2013) found in the same patient, where increases in alpha and beta bands were observed following the presentation of emotional faces. This discrepancy is certainly due to the type of stimuli used.…”

“…An event-related desynchronisation in the theta band in anterior regions was interpreted by the authors as reflecting the emotional significance of faces. In another investigation, modulations of low alpha and faster beta oscillations in right and left frontal sites were observed for emotional expressions in the same patient examined in our current study (TN) (Del Zotto et al, 2013).…”

“…The aim of our study was to examine the oscillatory brain responses of a cortically blind person (TN) using human faces opposed to (scrambled) non-faces, and to compare his patterns of activation to those of a group of control participants, building on previous observations showing modulations in alpha and beta frequency bands over frontal regions by facial emotional expressions in this patient (Del Zotto et al, 2013). Three main findings were evidenced: oscillatory rhythms were modulated by visual stimuli in TN, differences in oscillatory responses were observed between TN and control participants, and differences in oscillatory responses were found across stimulus categories and accuracy in TN.…”

“…The frequency content of electro-or magneto-encephalography measures provides key information about oscillations and has been divided in low (delta range, < 3 Hz; theta range, 4 -7 Hz), mid (alpha range,(8)(9)(10)(11)(12)beta range,(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) and high (gamma range, 30 -120 Hz) frequencies (Tallon-Baudry, 2009). In patient TN, mentioned above and who suffered from bilateral cortical blindness, alpha and beta oscillations in frontal regions were observed for fearful and happy face processing between 100 and 400 ms post-stimulus (Del Zotto et al, 2013). Another hemianopic patient (GY) showed induced-gamma band oscillations linked to stimulus awareness (Schurger et al, 2006).…”

“…Since it has been shown that blindsight patients may process visual stimuli in the absence of a functional visual cortex, we questioned the electrophysiological correlates of these residual visual capacities. Our aim was to extend the results observed by Del Zotto et al (2013) in frontal regions to the processing of faces, independently of (facial) emotional expressions.…”