Motor Thalamic Physiology
Tracing from the deep cerebellar nuclei (DCN, blue) and substantia nigra, pars reticulata (SNr, red) into motor thalamus.
“Standard” models of basal ganglia circuits suggest that GABAergic output tonically suppresses activity in the motor thalamus. When an action is to be performed, basal ganglia output pauses, releasing the “motor” thalamus to activate motor cortex. In fact, these circuits are much more complex (including connections from the cerebellum), but a satisfactory replacement for the “standard” model remains elusive. These experiments are focused on understanding the relationships between basal ganglia and cerebellar output, thalamic firing patterns, and network-level activity.
Our recent work (Gaidica et al, J Neurosci, 2018) showed that motor thalamic neurons tend to fire early and transiently during a ballistic movement, with distinct populations of neurons encoding specific aspects of the subsequent movement. Ongoing experiments are aimed at understanding the physiologic and anatomic basis for these coding properties using behavioral, electrophysiological, and optical techniques. Understanding how motor thalamus integrates basal ganglia, cerebellar, and cortical information will be a significant step towards understanding the pathophysiology of Parkinson Disease and related disorders, and likely to improve current treatments (for example, deep brain stimulation).
Magnusson JL, Leventhal DK. Revisiting the "Paradox of Stereotaxic Surgery": Insights Into Basal Ganglia-Thalamic Interactions. Front Syst Neurosci. 2021 Aug 27;15:725876. doi: 10.3389/fnsys.2021.725876. PMID: 34512279; PMCID: PMC8429495.
Gaidica M, Hurst A, Cyr C, Leventhal DK. Interactions Between Motor Thalamic Field Potentials and Single-Unit Spiking Are Correlated With Behavior in Rats. Front Neural Circuits. 2020; 14 52. doi:10.3389/fncir.2020.00052. PubMed PMID: 32922268. PMCID: PMC7457120.
Gaidica M, Hurst A, Cyr C, Leventhal DK. Distinct Populations of Motor Thalamic Neurons Encode Action Initiation, Action Selection, and Movement Vigor. J Neurosci. 2018; 38(29) 6563-6573. doi:10.1523/JNEUROSCI.0463-18.2018. PMCID: PMC6052244.
Ellens DJ, Leventhal DK. Review: electrophysiology of basal ganglia and cortex in models of Parkinson disease. J Parkinsons Dis. 2013; 3 241-254. doi:10.3233/JPD-130204. PubMed PMID: 23948994. PMCID: PMC3991010.
Schmidt R, Leventhal DK, Mallet N, Chen F, Berke JD. Canceling actions involves a race between basal ganglia pathways. Nat Neurosci. 2013; 16 1118-1124. doi:10.1038/nn.3456. PMCID: PMC3733500.
Leventhal DK, Gage GJ, Schmidt R, Pettibone JR, Case AC, Berke JD. Basal Ganglia Beta oscillations accompany cue utilization. Neuron. 2012; 73 523-536. doi:10.1016/j.neuron.2011.11.032. PMCID: PMC3463873.