Modifying Brain Oscillations to Drive Perception

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An important question in cognitive neuroscience is whether brain oscillations are causally related to cognitive activities or whether they represent epiphenomena. In this context, we will test hypotheses on the relationship between oscillations (in the theta, alpha and beta bands) and visual attentional selection and perception. We will test whether: - alpha-band oscillations over occipito-parietal areas regulate visual detection across the left and right visual fields for selecting visual information on the basis of its spatial location. - beta- and theta-band oscillations over occipito-parietal areas regulate the extraction of local versus global features within objects/scenes. This will be addressed by frequency-specific, rhythmic stimulation of human brain areas and by assessing its electrophysiological and perceptual consequences. Several innovative developments have emerged from brain mapping, such as mind reading. When an individual is asked to relax (wakeful rest), there is substantial fluctuation of brain activity. This occurs in organized patterns along specific neuronal networks--i.e. not randomly--and is thus likely to reflect the waxing and waning of distinct mental activities. In addition, spontaneous fluctuations in oscillatory patterns of activity seem to impact behaviour, because they are shown to co-vary with forthcoming task performance. Thus, momentary brain state can be inferred from brain mapping, and this can be used to predict imminent behaviour. We study to what extent specific patterns of brain activity can be induced by direct cortical stimulation (bypassing sensory input) to alter task performance. Our approach is based on findings in our laboratories that specific signatures of oscillatory activity predict forthcoming perception. We will use up-to-date techniques for direct (transcranial) brain stimulation at these specific frequencies to modify attention and perception. One component of the research is to identify the most effective experimental protocols to optimize our approach of driving attention and perception by direct oscillatory stimulation. This will involve specific parametric modifications of stimulation frequencies and stimulation regions as a function of ongoing brain rhythms. Another important component is to test models of attention and perception. Linking rhythmic neuronal stimulation to perception will advance theories on the functionality of brain oscillations and probe new ideas of how to bias brain function in desired direction (e.g for neurorehabilitation).