Focal Stimulation of the Thalamic Reticular Nucleus Induces Focal Gamma Waves in Cortex

Kurt D. Macdonald , Eva Fifkova , Michael S. Jones , and Daniel S. Barth Department of Psychology, University of Colorado at Boulder, Boulder, Colorado 80309-0345 MacDonald, Kurt D., Eva Fifkova, Michael S. Jones, and Daniel S. Barth. Focal stimulation of the thalamic reticular nucleus induces focal gamma waves in cortex. J. Neurophysiol. 79: 474-477, 1998. Electrical stimulation of the thalamic reticular nucleus (TRN; 0.5-s trains of 500-Hz 0.5-ms pulses at 5-10 µA) evokes focal oscillations of cortical electrical potentials in the gamma frequency band (~35-55 Hz). These evoked oscillations are specific to either the somatosensory or auditory cortex and to subregions of the cortical receptotopic map, depending on what part of the TRN is stimulated. Focal stimulation of the internal capsule, however, evokes focal slow potentials, without gamma activity. Our results suggest that the TRN's role extends beyond that of general cortical arousal to include specific modality and submodality activation of the forebrain.