Investigating cortico-striatal loop and its role in health and disease

by Jovana Belic (CB/CSC/KTH and Bernstein Center, University of Freiburg)

Friday 13 Mar 2015, 10:15 → 11:00 Europe/Stockholm

Fantum (Fantum)

Linkage between behavioral states and neural activity is one of the most important challenges in neuroscience. Therefore, we simultaneously recorded local field potentials (LFPs) in right primary motor cortex (MR) and right sensorimotor striatum (SR) to study features directly related to healthy versus pathological states such as Parkinson disease and levodopa-induced dyskinesia. The striatum, the input stage of the basal ganglia (BG), is an inhibitory network that contains several distinct cell types and receives massive excitatory inputs from the cortex. Cortex sends direct projections to the striatum, while striatum can affect cortex only indirectly through other BG nuclei and thalamus. Firstly we analyzed spectral characteristics of the obtained signals (Belić et al., 2015) and observed that for automatic classification of dyskinesia the most informative was gamma frequency range, while for the PD that was beta frequency range. Secondly our preliminary results have shown that during pathological states effective connectivity is bidirectional with accent on striatal influence on cortex while in the case of healthy state influence looks rather unidirectional. In the case of dyskinesia we have also found high increase in effective connectivity values at 80Hz. Previous study showed that dyskinesia in hemiparkinsonian rats is strongly associated with pronounced 80 Hz local field potential oscillations in MR following levodopa treatment (Halje et al., 2012). In order to further understand that phenomenon we have performed cross-frequency analysis across all states and both structures and we have observed characteristic pattern in the case of dyskinesia in both structures but not in the case of PD and healthy state. We have seen high deep in modulation of the amplitude at 80Hz by the phase of low frequency oscillations (up to ~10Hz). It has been suggested that the activity of local neural populations is modulated according to the global neuronal dynamics in the way that populations oscillate and synchronize at lower frequencies and smaller ensembles are active at higher frequencies, so we interpret our results as a lack of synchronization between population activities and a certain smaller group of neurons active at 80Hz. Belić, J., Halje, P., Richter, U., Petersson, P., Hellgren Kotaleski, J. (2015). Behavior Discrimination Using a Discrete Wavelet Based Approach for Feature Extraction on Local Field Potentials in the Cortex and Striatum. IEEE/EMBS Conf Proc. Neural Engineering (NER) 7, Montpellier, France. Halje, P., Tamte, M., Richter, U., Mohammed, M., Cenci, A., Petersson, P. (2012). Levodopa-Induced Dyskinesia Is Strongly Associated with Resonant Cortical Oscillations. J Neurosci. 32, 16541-16551.