Event-related power modulations of brain activity preceding visually guided saccades

Abstract

To analyze the characteristics of the event-related desynchronization (ERD) and synchronization (ERS) of cortical rhythms during the preparation and execution of a lateralized eye movement, EEG was recorded in normal subjects during a visually guided task. Alpha and beta bands were investigated in three temporal intervals: a sensory period, a delay period and a saccade preparation period time locked with saccade onset. Modulations of ERD/ERS power, coupled with the task, reached the largest amplitudes over the frontal and parieto-occipital regions. Differences of oscillatory activity in the alpha bands revealed an intriguing pattern of asymmetry in parieto-occipital areas. Rightward saccades induced a larger desynchronization with respect to the leftward saccades in the left hemisphere, but not in the right. If representative, these findings are congruent to the established righthemisphere dominance of the brain areas that direct attention. Moreover differences between the two alpha types emerged in the frontal areas before and during the saccade preparation periods, indicative of differential engagement of these areas depending on the task demands. In conclusion, the present approach shows that planning eye movements is linked with covert orienting of spatial attention and may supply a useful method for studying eye movements and selective attention-related processes. IntroductionSaccades are short duration ballistic eye movements performed in order to foveate an image on the retina. They are generated in the brain stem, but there is extensive evidence from electrophysiological studies in monkeys (Bruce and Goldberg, 1985;Funahashi et al., 1989;Funahashi et al., 1990;Lynch et al., 1977;Schlag and Schlag-Rey, 1987) as well as from neuroimaging (Anderson et al., 1994;Fox et al., 1985;Law et al., 1997;Luna et al., 1998;Sweeney et al., 1996) and lesion studies in humans (Pierrot-Deseilligny et al., 2003a;Pierrot-Deseilligny et al., 1991b) that the cerebral cortex is involved in their control and preparation. Three main cortical areas are involved in the generation of saccades: the frontal eye field (FEF), located mostly at the intersection between the precentral sulcus and the superior frontal sulcus (Paus, 1996), the supplementary eye field (SEF), located on the medial surface of the superior frontal gyrus (Grosbras et al., 1999) and the parietal eye field (PEF), located in the intraparietal sulcus (Medendorp et al., 2003). These areas contribute to the triggering of saccades with, apparently, different roles depending on the type of saccade to be performed. Actually, saccades may be reflexive, externally

Early event‐related cortical activity originating in the frontal eye fields and inferior parietal lobe predicts the occurrence of correct and error saccades

“…A tentative hypothesis is that the bilateral representation of spatial attention for the right hemisphere cancelled out the tiny differences between electrophysiological activity preceding voluntary and reflexive saccades. Interestingly, a recent fMRI study [Petit et al, 2009] and studies examining power modulations in EEG alpha-band activity have observed similar asymmetries suggesting dominance of the right hemisphere in spatial processing [Brignani et al, 2007;Thut et al, 2006]. Since EEG-power modulations may serve as an index of attentional orienting to the left or right hemifield, examining the occurrence of such modulations prior to target onset might clarify the role of spontaneous attentional fluctuations in the control of voluntary and reflexive saccades.…”

Response-Modality-Specific Encoding of Human Choices in Upper Beta Band Oscillations during Vibrotactile Comparisons

“…In preparation for and during voluntary hand movements like button presses, the same pattern of beta band decrease followed by a rebound over contralateral motor areas is also reliably observed (e.g., Jasper and Penfield, 1949; Pfurtscheller, 1981). Likewise, several studies suggest that a decrease in beta band amplitude over contralateral posterior parietal areas accompanies the execution of saccades (e.g., Pesaran et al, 2002; Brignani et al, 2007; Carl et al, 2016). Moreover, Jo et al (2016) recently reported a negative correlation between the level of beta band amplitude over motor areas before initiating voluntary button presses and according RTs.…”

Analysis of slow- and fast-alpha band asymmetry during performance of a saccadic eye movement task: Dissociation between memory- and attention-driven systems

“…In line with this, spectral features of the qEEG in the alpha (8)(9)(10)(11)(12) band are sensitive to variations in perception, cognition or motor action [10,11]. The study of the alpha sub-bands, i.e., alpha 1 or slow-alpha (8-10 Hz) and alpha 2 or fast-alpha (10-12 Hz), has been shown to represent qualitative differences.…”

“…Several investigations have demonstrated that during tasks involving voluntary attention, the right hemisphere plays a role in the saccadic movements programming of both frontal eye fields [1], while the left hemisphere plays a role in the movement control of the contralateral side of our body [8,9]. In line with this, spectral features of the qEEG in the alpha (8)(9)(10)(11)(12) band are sensitive to variations in perception, cognition or motor action [10,11].…”