Properties of the corticostriatal long term depression induced by cortical high frequency stimulation in vivo

BRAZ BY; GALIÑANES GL; BELFORTE J; MURER MG

buenos aires

Congreso; 2nd FALAN Congress; 2016

Goal directed behavior and habit formation depend oncorticostriatal circuit operation and it is assumed that longlasting changes in corticostriatal synaptic efficacy take placeduring these processes. However little is known about the invivo long-lasting synaptic plasticity properties in this system.Our aim was to study the mechanisms of corticostriatallong term depression (LTD) induced by high frequencystimulation (HFS) in vivo. We performed in vivo recordingsof local field potential responses evoked by corticalstimulation before and after HFS stimulation of the samecortical afferents in the presence of NMDA, CB1, D1 andD2 receptor antagonists. We also performed experimentsin CB1 receptor knockout mice, in animals with chronicdopamine neuron lesions (6-hidroxydopamine injectionat PD2) or cholinergic interneuron lesions. In contrast withwhat is known from ex vivo experiments, we found thatHFS-LTD in vivo is independent of CB1 receptor, dopaminereceptor and cholinergic interneuron activity. We also foundthat HFS-LTD in vivo is NMDA dependent. Thus, HFS-LTDin vivo does not abide to the same rules that in brain sliceslikely as consequence of higher levels of neuronal activityand neuromodulators available in the intact circuit.