Changes in pallidal activity during cortical activation depend on striatal output in an animal model of Parkinson's disease

ESCANDE MV; ZOLD CL; POMATA PE; RIQUELME LA; MURER MG

Huerta Grande, Cordoba, Argentina

Congreso; XXVI Congreso Anual de la Sociedad Argentina de Investigación en Neurociencia; 2011

Excessive synchronization between basal ganglia and cortex is a hallmark of Parkinsonís disease. The underlying mechanisms remain unclear. The aim of the present study was to determine whether striatal output drives oscillations in the parkinsonian GP during the condition known as ?activated state?. In order to do that, we recorded GP activity before and during the administration of an antangonist of NMDA receptors inside the striatum through reverse microdialysis. Synchronization of pallidal firing to the activated ECoG is increased in 6-OHDA rats across a wide range of frequencies, specially at low and beta frequencies. Importantly, pallidal coupling with cortical rhythms in control rats was negligible, indicating a truly anomalous nature of cortico-pallidal synchronization in the parkinsonian condition. Modulation of pallidal firing by the low frequency components of the activated ECoG was markedly reduced during AP-5 infusion. Striatal NMDA receptor blockade had less marked effects on beta synchronization. It reduced the number of neurons modulated by low but not high cortical beta rhythm. Thus, intrastriatal AP-5 infusion reduced cortico-pallidal synchronization in 6-OHDA rats in a frequency dependent manner.