Cerebral Cortex Advance Access originally published online on August 14, 2006
Cerebral Cortex 2007 17(6):1376-1385; doi:10.1093/cercor/bhl048
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Changes in Visual Responses in the Feline dLGN: Selective Thalamic Suppression Induced by Transcranial Magnetic Stimulation of V1
1 Neuroscience and Motor Control Group, Department of Medicine, Universidad de A Coruña, Campus de Oza, 15006 A Coruña, Spain, 2 Faculty of Life Sciences, The University of Manchester, M60 1QD, UK
Address correspondence to email: jcud{at}udc.es.
Transcranial magnetic stimulation (TMS) of the cortex can modify activity noninvasively and produce either excitatory or inhibitory effects, depending on stimulus parameters. Here we demonstrate controlled inhibitory effects on the large corticogeniculate feedback pathway from primary visual cortex to cells of the dorsal lateral geniculate nucleus (dLGN) that are focal and reversibleinduced by either single pulses or trains of pulses of TMS. These effects selectively suppress the sustained component of responses to flashed spots or moving grating stimuli and are the result of loss of spikes fired in tonic mode, whereas the number of spikes fired in bursts remain the same. We conclude that acute inactivation of the corticogeniculate downflow selectively affects the tonic mode. We found no evidence to suggest that cortical inactivation increased burst frequency.
Key Words: burst corticothalamic TMS