Abstract
We simultaneously recorded local field potentials (LFPs) in the primary motor cortex and sensorimotor striatum in awake, freely behaving, 6-OHDA lesioned hemi-parkinsonian rats in order to study the features directly related to pathological states such as parkinsonian state and levodopa-induced dyskinesia. We analyzed the spectral characteristics of the obtained signals and observed that during dyskinesia the most prominent feature was a relative power increase in the high gamma frequency range at around 80 Hz, while for the parkinsonian state it was in the beta frequency range. Here we show that during both pathological states effective connectivity in terms of Granger causality is bidirectional with an accent on the striatal influence on the cortex. In the case of dyskinesia, we also found a high increase in effective connectivity at 80 Hz. In order to further understand the 80-Hz phenomenon, we performed cross-frequency analysis and observed characteristic patterns in the case of dyskinesia but not in the case of the parkinsonian state or the control state. We noted a large decrease in the modulation of the amplitude at 80 Hz by the phase of low frequency oscillations (up to ~10 Hz) across both structures in the case of dyskinesia. This may suggest a lack of coupling between the low frequency activity of the recorded network and the group of neurons active at ~80 Hz.
Highlights
The basal ganglia (BG) represent subcortical structures thought to be involved in action selection and decision making (Redgrave et al, 1999; Grillner et al, 2005)
Dopamine replacement therapy with L-DOPA is the most effective treatment for Parkinson’s disease (PD), within 5 years of starting the treatment, up to 80% of patients will experience severe side effects and develop L-DOPA-induced dyskinesia characterized by abnormal involuntary movements (Bezard et al, 2001; Fabbrini et al, 2007; Thanvi et al, 2007; Pisani and Shen, 2009)
The cortico-striatal network is central to the control of motor functions, as is apparent from the broad range of movement disorders that are caused by dysfunctions of the circuitry
Summary
The basal ganglia (BG) represent subcortical structures thought to be involved in action selection and decision making (Redgrave et al, 1999; Grillner et al, 2005). Understanding the complex nature of cortico-striatal interactions is of crucial importance for clarifying the overall functions and dysfunctions of the BG. Dopamine replacement therapy with L-DOPA is the most effective treatment for PD, within 5 years of starting the treatment, up to 80% of patients will experience severe side effects and develop L-DOPA-induced dyskinesia characterized by abnormal involuntary movements (Bezard et al, 2001; Fabbrini et al, 2007; Thanvi et al, 2007; Pisani and Shen, 2009). Animal models are crucial to study LDOPA-induced dyskinesia and develop potential new therapies (Cenci et al, 2002; Nadjar et al, 2009)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
