Enhanced beta power emerges from simulated parkinsonian primary motor cortex

Area of Science:

• Neuroscience
• Computational Neuroscience
• Systems Neuroscience

Background:

• Reduced excitability of layer 5B pyramidal tract neurons (PT5B) in the primary motor cortex (M1) is observed in dopamine-depleted parkinsonism models.
• This neuronal hyperexcitability may underlie motor control deficits in Parkinson's disease (PD).

Purpose of the Study:

• To investigate how decreased PT5B neuron excitability impacts M1 neural firing patterns and oscillations in a computational model.
• To elucidate the potential contribution of these changes to motor deficits in PD.

Main Methods:

• Utilized a validated computational model of the mouse primary motor cortex (M1).
• Incorporated experimentally derived decreases in PT5B neuron excitability to simulate parkinsonism.
• Analyzed simulated rest-state and movement-state firing rates and local field potential (LFP) oscillations.

Main Results:

• Simulated parkinsonism led to a paradoxical increase in rest-state PT5B firing rate and elevated beta-band power in LFP.
• During simulated movement, PT5B firing and LFP exhibited reduced beta and increased high-beta/low-gamma (20-35 Hz) activity.
• These oscillatory changes were specific to the simulated parkinsonian condition.

Conclusions:

• Decreased PT5B excitability in M1, characteristic of parkinsonism, can paradoxically increase neural firing and beta oscillations.
• The emergence of beta-band oscillations in M1 disrupts normal motor output, potentially contributing to motor impairments in Parkinson's disease (PD).