%0 Journal Article
%T A transition from unimodal to multimodal activations in four sensory modalities in humans: an electrophysiological study
%A Emi Tanaka
%A Koji Inui
%A Tetsuo Kida
%A Takahiro Miyazaki
%A Yasuyuki Takeshima
%A Ryusuke Kakigi
%J BMC Neuroscience
%D 2008
%I BioMed Central
%R 10.1186/1471-2202-9-116
%X Results of source modeling showed multimodal activations in the anterior part of the cingulate cortex (ACC) and hippocampal region (Hip). The activity in the ACC was biphasic. In all sensory modalities, the first component of ACC activity peaked 30¨C56 ms later than the peak of the major modality-specific activity, the second component of ACC activity peaked 117¨C145 ms later than the peak of the first component, and the activity in Hip peaked 43¨C77 ms later than the second component of ACC activity.The temporal sequence of activations through modality-specific and multimodal pathways was similar among all sensory modalities.In previous studies using magnetoencephalograms (MEGs) to monitor tactile [1], auditory [2], visual [3,4] and pain [5,6] systems, we found very similar mechanisms of sensory processing among these sensory modalities. In brief, several 'early' activities appear serially with a time delay of about 4 ms at each step followed by one or two 'late' activities. In general, the 'early' activity reverses polarity twice with an interval of 10 ms, which results in a characteristic triphasic waveform, while the 'late' activity is long-lasting without a polarity reversal at such a short interval [7]. For example, following tactile stimulation, 'early' activations are elicited in area 3b, area 1 and the posterior parietal cortex in this order with a delay of 3¨C4 ms between each step, and then a long-lasting 'late' activity is evoked in the secondary somatosensory area. We postulate that a basic role of the 'early' activity is to receive inputs from the thalamus or convergent inputs from the thalamus and/or adjacent cortical areas and to send this information to the next point quickly, while the long-lasting 'late' activity is involved in recognition of the stimuli [2].In the present study, we sought to compare mechanisms of sensory processing at latencies later than the 'late' activity among these sensory modalities (vision, audition, touch and pain). At first,
%U http://www.biomedcentral.com/1471-2202/9/116