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This Article Full Text Full Text (PDF) All Versions of this Article: 574/3/929    most recent jphysiol.2006.110379v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Magill, P. J. Articles by Brown, P. Search for Related Content PubMed PubMed Citation Articles by Magill, P. J. Articles by Brown, P. Related Collections Integrative

¹ Medical Research Council Anatomical Neuropharmacology Unit, University of Oxford, Oxford, UK
² Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, London, UK

Oscillations may play a role in the functional organization of cortico-basal ganglia-thalamocortical circuits, and it is important to understand their underlying mechanisms. The cortex often drives basal ganglia (BG) activity, and particularly, oscillatory activity in the subthalamic nucleus (STN). However, the STN may also indirectly influence cortex. The aim of this study was to characterize the delayed (>200 ms) responses of STN neurons to synchronized cortical inputs, focusing on their relationship with oscillatory cortical activity. We recorded the short-latency and delayed responses of STN units and frontal electrocorticogram (ECoG) to cortical stimulation in anaesthetized rats. Similar to previous studies, stimulation of ipsilateral frontal cortex, but not temporal cortex, evoked a short-latency triphasic response, followed by a sustained reduction or pause in firing, in rostral STN units. Caudal STN units did not show the short-latency triphasic response but often displayed a prolonged firing reduction. Oscillations in STN unit activity and ECoG were common after this sustained firing reduction, particularly between 200 and 600 ms after frontal cortical stimulation. These delayed oscillations were significantly coherent in a broad frequency band of 5–30 Hz. Coherence with ECoG at 5–15 Hz was observed throughout STN, though coherence at 15–30 Hz was largely restricted to rostral STN. Furthermore, oscillatory responses at 5–30 Hz in rostral STN predominantly led those in cortex (mean latency of 29 ms) after frontal cortical stimulation. These findings suggest that STN neurons responding to corticosubthalamic inputs may provide a delayed input to cortex, via BG output nuclei, and thence, thalamocortical pathways.

(Received 29 March 2006; accepted after revision 12 May 2006; first published online 18 May 2006)
Corresponding author P. J. Magill: Medical Research Council Anatomical Neuropharmacology Unit, University of Oxford, Mansfield Road, Oxford OX1 3TH, UK. Email: peter.magill{at}pharm.ox.ac.uk