Visual experience regulates the development of long-term synaptic modifications induced by low-frequency stimulation in mouse visual cortex

Publication date: Available online 8 March 2017
Source:Neuroscience Research
Author(s): Taketoshi Sugimura, Mariko Yamamoto, Kazumasa Yamada, Yukio Komatsu, Yumiko Yoshimura
Manipulation of visual experience can considerably modify visual responses of visual cortical neurons even in adulthood in the mouse, although the modification is less profound than that observed during the critical period. Our previous studies demonstrated that low-frequency (2Hz) stimulation for 15minutes applied to layer 4 induces T-type Ca²⁺ channel-dependent long-term potentiation (LTP) at excitatory synapses in layer 2/3 neurons of visual cortex during the critical period. In this study, we investigated whether low-frequency stimulation could induce synaptic plasticity in adult mice. We found that 2Hz stimulation induced LTP of extracellular field potentials evoked by stimulation of layer 4 in layer 2/3 in adulthood as during the critical period. LTP in adulthood was blocked by L-type, but not T-type, Ca²⁺ channel antagonists, whereas LTP during the critical period was blocked by T-type, but not L-type, Ca²⁺ channel antagonists. This developmental change in LTP was prevented by dark rearing. Under pharmacological blockade of GABAA receptors, T-type Ca²⁺ channel-dependent LTP occurred, whereas L-type Ca²⁺ channel-dependent LTP did not occur. These results suggest that different forms of synaptic plasticity can contribute separately to experience-dependent modification of visual responses during the critical period and in adulthood.



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