Loss of one type of sensory input can cause improved functionality of other sensory systems. This form of plasticity, cross-modal plasticity, is well established (Bavelier and Neville, 2002; Goel et al., 2006). We have previously shown that visual deprivation (VD) induces trafficking of the AMPA-type glutamate receptors into layer 4 to layer 2/3 synapses (Jitsuki et al., 2011). VD leads to sharpening of the functional whisker-barrel map at layer 2/3. However, the mechanism maintaining sharpened functional whisker barrel map is still unclear.
In this study, we found that VD increases evoked miniature inhibitory postsynaptic current (evoked mIPSC) and IPSC/excitatory postsynaptic current (EPSC) ratio in the layer 2/3 to 2/3 synapses (lateral pathway), but not in the layer 4 to 2/3 (vertical pathway). Moreover, VD sharpened functional whisker-barrel map in layer 2/3 of the barrel cortex. These results indicate that VD enhances lateral inhibition and that maintains sharpened neural circuits in the barrel cortex.