# Electromyographic Characteristics of Postactivation Effect in Dopamine-Dependent Spectrum Models Observed in Parkinson’s Disease and Schizophrenia

## TL;DR

This study explores how dopamine levels affect muscle activity patterns in Parkinson’s disease and schizophrenia using electromyography.

## Contribution

It introduces a novel approach to assess dopaminergic dysfunction through postactivation electromyographic characteristics in neurological and psychiatric conditions.

## Key findings

- PAE triggering was inhibited in hypodopaminergic models compared to controls.
- EMG characteristics during PAE differed significantly between hyperdopaminergic and hypodopaminergic states.
- Healthy controls showed the highest PAE triggering rate and distinct sEMG features.

## Abstract

This study aimed to test the hypothesis that the postactivation effect (PAE, involuntary normal muscle tone) is modified by dopaminergic mechanisms. The PAE was tested with surface electromyography (sEMG) in the “off medication” phase in participants with Parkinson’s disease (PDoff) and in the “on medication” state in participants with schizophrenia (SZon), which modeled hypodopaminegic conditions, and in participants with PD “on medication” (PDon) and in participants with SZ “off medication” (SZoff) state which modeled the hyperdopaminergic conditions. Healthy age-matched participants constituted the control group (HC, n = 11). In hyperdopaminergic models, PAE was triggered in 71.3% of participants in SZoff and in 35.7% in PDon conditions. In the hypodopaminergic models, PAE was triggered in 12% in SZon and in 21.4% in PDoff conditions. In the HC group, PAE was present in 91% of participants. In the HC and PD groups, the mean frequency and correlation dimension of sEMG at PAE was higher than that during voluntary isometric contraction. In conclusion, in hypodopaminergic models, PAE triggering was inhibited. The manifestations and EMG characteristics of PAE in people with PD or SZ may indicate dopaminergic dysfunction.