Transcranial magnetic stimulation of the human frontal eye field facilitates visual awareness

Abstract

Abstract& When looking at one object, human subjects can shift their attention to another object in their visual field without moving the eyes. Such shifts of attention activate the same brain regions as those involved in the execution of eye movements. Here we investigate the role of one of the main cortical oculomotor area, namely, the frontal eye field (FEF), in shifts of attention. We used transcranial magnetic stimulation (TMS), a technique known to disrupt transiently eyemovements preparation. We hypothesized that if the FEF is a necessary element in the network involved in shifting attention without moving the eyes, then TMS should also disrupt visuospatial attention.For each volunteer, we positioned the TMS coil over the probabilistic anatomical location of the FEF, and we verified that single pulses delayed eye movements. We then applied TMS during a visuospatial attention task. In this task, a central arrow directed shifts of attention and the subject responded by a keypress to a subsequent visual peripheral target without moving the eyes from the central fixation point. In a few trials, the cue was invalid or uninformative, yielding slower responses than when the cue was valid. We delivered single pulses either 53 msec before or 70 msec after target onset.Contrary to our prediction, the main effect of the stimulation was a decrease in reaction time when it was applied 53 msec before target onset. TMS over the left hemisphere facilitated responses to targets in the right hemifield only and for all cueing conditions, whereas TMS over the right hemisphere had a bilateral effect for valid and neutral but not invalid cueing. Thus, TMS interfered with shift of attention only in the case of right hemisphere stimulation: it increased the cost of invalid cueing.Our results suggest that TMS over the FEF facilitates visual detection, and thereby reduces reaction time. This finding provides new insights into the role of the human FEF in processing visual information. The functional asymmetry observed for both facilitation of visual detection and interference with shifts of attention provides further evidence for the dominance of the right hemisphere for those processes. Our results also underline that the disruptive or facilitative effect of TMS over a given region depends upon the behavioral context. &

Event-Related Repetitive Transcranial Magnetic Stimulation of Posterior Superior Temporal Sulcus Improves the Detection of Threatening Postural Changes in Human Bodies

“…A variety of functional and behavioral studies support the notion that the amygdalae may strengthen the visual processing of emotional stimuli, which is thought to be carried out in extrastriate areas (Morris et al, 1998;Vuilleumier et al, 2004;Chouchourelou et al, 2006). Although in the present experiment it is difficult to attribute the rTMS effect to perceptual or memory processes, the reported modulation is in line with previous findings (Töpper et al, 1998;Grosbras and Paus, 2003;Hayward et al, 2004;Pulvermüller et al, 2005;D'Ausilio et al, 2009). In particular, our results may expand the state-dependent TMS literature on primary and higher-order (MT/V5) visual cortices (Silvanto et al, 2007(Silvanto et al, , 2008aSilvanto and Muggleton, 2008;Cattaneo et al, 2008;Silvanto and Cattaneo, 2010), demonstrating that the magnetic pulse activates cells that are less active in the instant of stimulation and may thus induce both facilitatory and inhibitory perceptual effects depending on the baseline activation of the stimulated population of cells (Matthews, 1999;Siebner et al, 2009).…”

Rapid enhancement of visual cortical response discriminability by microstimulation of the frontal eye field

“…In addition, reversible inactivation of the SC produces deficits in target selection that cannot be attributed to a purely visual or motor impairment (37). Consistent with neurophysiological studies in monkeys, transcranial magnetic stimulation experiments provide causal evidence that the attentional role of the FEF is conserved in humans (38)(39)(40)(41)(42)(43). Finally, studies in the barn owl have found that microstimulation of gaze-control circuits homologous with primate FEF produces space-specific modulation of auditory responses (44).…”

Working memory improvement with non-invasive brain stimulation of the dorsolateral prefrontal cortex: A systematic review and meta-analysis

“…Importantly, our review focused on the off-line rTMS effects on WMexperiments that, in fact, evaluate the after-effects of brain stimulation on WM. Online rTMS paradigms usually show worsening of cognitive performance due to disruption of cortical activity (Sandrini et al, 2011); although several exemptions exist, for instance, accordingly to state-dependent activity (as exemplified above in (Silvanto, Cattaneo, et al, 2008)), or when TMS is delivered early in the time course of the trial, before the brain region was supposed to be activated (Grosbras & Paus, 2003).…”