Reversible changes of presumable synaptic connections between primary somatosensory cortex and ventral posterior lateral thalamus of rats during temporary deafferentation

Abstract

Many single neurons were simultaneously recorded from forepaw areas of both primary somatosensory cortex and the ventral posterior lateral thalamus of anesthetized rats to characterize the changes of presumable excitatory synaptic connections between two nuclei following temporary deafferentation (TD). Thalamic and cortical interactions were examined by analyzing spike-triggered cross-correlation histograms (STCCHs, n=426). Before TD, 46.48% of STCCHs exhibited thalamocortical (TC) excitation and 7.51% of STCCHs showed corticothalamic (CT) connectivity. After TD, these connections were less frequently observed (after 20 min of TD, TC: 13.38% of STCCHs, CT: 5.40% of STCCHs). Fifty-seven TC and nine CT connections were reversibly suppressed during TD. However, 23 CT connections were reversibly augmented following TD. These results imply that temporary blocking of afferent information may induce system-wide plasticity involving corticofugal modulation.