Parkinson's Disease Research Today is a free monthly online journal that collates and summarizes the latest research about Parkinson's Disease, including details on symptoms, treatment, genetics, medication. | ||||||||
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Elevations in local gamma activity are accompanied by changes in the firing rate and information coding capacity of neurons in the region of the subthalamic nucleus in Parkinson's disease.Pogosyan A, Kühn AA, Trottenberg T, Schneider GH, Kupsch A, Brown P Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, Queen Square, London, WCIN 3BG, UK. Local field potential (LFP) gamma (55-95 Hz) activity has been recorded in the vicinity of the subthalamic nucleus with both microelectrodes and macroelectrodes in patients with Parkinson's disease undergoing functional neurosurgery. Although this activity increases with movement its functional significance remains unknown. We hypothesised that elevations in local gamma activity might be associated with an increase in the capacity of individual spike trains to code information. Changes in the median firing frequency, entropy and baud were determined during spontaneous variations in the level of simultaneously recorded LFP gamma activity in a sample of 31 neurons. The latter were recorded from the zona incerta (n = 5) and subthalamic nucleus (n = 26) in 10 parkinsonian patients. Although 19% of neurons showed a decrease in firing rate, overall there was a net increase in spike frequency and baud of 18.0+/-5.5% and 16.9+/-5.3%, when periods of high gamma were compared to periods of low gamma LFP activity. In contrast, entropy dropped by only 0.8+/-0.2% across the sampled neuronal population during periods of high gamma. All net changes were significant. We conclude that overall there was a net elevation in firing rate and potential information coding capacity, assessed in terms of baud, amongst neurons during periods of elevated gamma LFP activity in the subthalamic region. Published 13 November 2006 in Exp Neurol, 202(2): 271-9.
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