The short-term plasticity of synaptic transmission from rat lateral posterior thalamic nucleus to primary visual cortex

The synaptic connection from rat lateral posterior thalamic nucleus to primary visual cortex is an important part of extrageniculate visual pathway. The short-term plasticity of this synaptic transmission is investigated in vivo by using field potential recording and iontophoresis methods. The field potentials were depressed rigorously by either paired-pulse stimulation or repetitive stimulation at different frequency (10, 20, 50 Hz). lontophoresis of bicucultine and 2-hydroxy-saclofen decreased the depression degree, white iontophoresis of Ca2+ increased the depression degree. Therefore, the short-term plasticity of synaptic transmission in this pathway is affected by many factors, such as: changing the transmitter release level at pre-synaptic terminal and activity of GABAergic receptors. However, when applying APV, the selective antagonist of NMDA receptors, no any obvious change in short-term synaptic plasticity was obtained. The rigorous short-term plasticity in this visual pathway may play a role in the visual attention function, which is related to the lateral posterior thalamic nucleus.