Abstract
Repetitive transcranial magnetic stimulation (rTMS) of the posterior parietal cortex (PPC) at frequencies lower than 5 Hz transiently inhibits the stimulated area. In healthy participants, such a protocol can induce a transient attentional bias to the visual hemifield ipsilateral to the stimulated hemisphere. This bias might be due to a relatively less active stimulated hemisphere and a relatively more active unstimulated hemisphere. In a previous study, Jin and Hilgetag (2008) tried to switch the attention bias from the hemifield ipsilateral to the hemifield contralateral to the stimulated hemisphere by applying high frequency rTMS. High frequency rTMS has been shown to excite, rather than inhibit, the stimulated brain area. However, the bias to the ipsilateral hemifield was still present. The participants’ performance decreased when stimuli were presented in the hemifield contralateral to the stimulation site. In the present study we tested if this unexpected result was related to the fact that participants were passively resting during stimulation rather than performing a task. Using a fully crossed factorial design, we compared the effects of high frequency rTMS applied during a visual detection task and high frequency rTMS during passive rest on the subsequent offline performance in the same detection task. Our results were mixed. After sham stimulation, performance was better after rest than after task. After active 10 Hz rTMS, participants’ performance was overall better after task than after rest. However, this effect did not reach statistical significance. The comparison of performance after rTMS with task and performance after sham stimulation with task showed that 10 Hz stimulation significantly improved performance in the whole visual field. Thus, although we found a trend to better performance after rTMS with task than after rTMS during rest, we could not reject the hypothesis that high frequency rTMS with task and high frequency rTMS during rest equally affect performance.
Highlights
Visual attention is controlled by a fronto-parietal attention network in the human brain [2,3,4,5]
We present the analyses of the corrected data in the subsection ‘Corrected conditional response accuracy (CRA) (CORR)’
We found several indications that visual detection might be better after repetitive transcranial magnetic stimulation (rTMS) with task than after rTMS during passive rest, most of the direct comparisons just missed statistical significance
Summary
Visual attention is controlled by a fronto-parietal attention network in the human brain [2,3,4,5]. Theoret and Pascual-Leone, for example, applied rTMS for 10 minutes at a frequency of 1 Hz to the right PPC of a group of healthy participants between two successive blocks of a visual detection task [14]. They found that, after rTMS, their participants were impaired in detecting the left stimulus of a bilateral stimulus pair and showed an additional enhanced detection of stimuli presented in the right half of the visual field, an attentional imbalance similar to the one exhibited by extinction patients [14]
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