The Effects of Transcranial Electric Stimulation (tES) on the Correlation between Thalamic and Motor Cortical Neuronal Activity in a Rat Model
Location
Suwanee, GA
Start Date
7-5-2024 1:00 PM
End Date
7-5-2024 4:00 PM
Description
In the past, studies have shown the positive effects in using transcranial electric stimulation (tES) therapy in the management of cerebellar ataxia. However, the precise mechanism of how tES affects the cerebello-thalamo-cerebral pathway of the brain is poorly understood. The Ventral Lateral (VL) and Ventral Medial (VM) nuclei of the thalamus likely play a role in relaying motor messages to the motor cortex, where movement signals are generated. Our previous research focused solely on thalamic changes with cerebellar tES. This study is to test the hypothesis that stimulation of the cerebellar cortex causes a correlated increase of activity in both the motor nuclei of the thalamus and the motor cortex. To better our understanding of tES effects on the cerebello-thalamo-cerebral pathway the motor cortical activity must be monitored. Recordings of neuronal electrical activity were taken simultaneously from the motor nuclei of the thalamus (Ventral Lateral and Ventral Medial nuclei) and motor cortex of anesthetized rats. To examine the correlation between the thalamic cerebral activities during tES, four holes were prepared for the recording. Two for the thalamic sites (1.5 mm lateral, 3.0 mm posterior to the bregma) and two for the motor cortical sites (3.0 mm laterally and 1.6 mm anteriorly to the bregma). Recordings from the thalamic nuclei were taken at various depths of 5.5 mm to 7.5 mm from the cortical surface to reach either the ventral medial (VL) or ventral lateral (VL) nuclei while another recording from the motor cortex 0.5 mm from the cortical surface were taken. Each recording session included 5 minutes of pre-stimulation, 20 minutes of 200 μA stimulation, and 5 minutes of post-stimulation from the thalamus and motor cortex regions. Twelve simultaneous recordings were taken from nine rats. Matlab
software was used for data analysis. Cross-correlation and coherence between the thalamic and cortical activities were studied in addition to previous firing rate and power spectrum analysis. There was no significant difference between the pre-stim and stimulation correlation (p-value = 0.125) or coherence (p-value = 0.191 (low frequency range) and p-value = 0.252 (high frequency range)) with all the cells (n = 12). The cells with a decrease in firing rate by tES (n = 6) showed a significant difference between the pre-stimulation and stimulation firing rates (p-value = 0.031) and the stimulation and the post-stimulation thalamic power spectrum showed a significant decrease under the high frequency range (p-value = 0.034). Neuronal activity under the high frequency condition decreased which may indicate post-stimulation effect in the inhibitory cells. There was no correlation or coherence change between the thalamus and motor cortical activities after cerebellar tES. More recordings will be collected from VM and VL and separately analyzed to see if there is a change in coherence or correlation for the future studies.
Embargo Period
5-23-2024
The Effects of Transcranial Electric Stimulation (tES) on the Correlation between Thalamic and Motor Cortical Neuronal Activity in a Rat Model
Suwanee, GA
In the past, studies have shown the positive effects in using transcranial electric stimulation (tES) therapy in the management of cerebellar ataxia. However, the precise mechanism of how tES affects the cerebello-thalamo-cerebral pathway of the brain is poorly understood. The Ventral Lateral (VL) and Ventral Medial (VM) nuclei of the thalamus likely play a role in relaying motor messages to the motor cortex, where movement signals are generated. Our previous research focused solely on thalamic changes with cerebellar tES. This study is to test the hypothesis that stimulation of the cerebellar cortex causes a correlated increase of activity in both the motor nuclei of the thalamus and the motor cortex. To better our understanding of tES effects on the cerebello-thalamo-cerebral pathway the motor cortical activity must be monitored. Recordings of neuronal electrical activity were taken simultaneously from the motor nuclei of the thalamus (Ventral Lateral and Ventral Medial nuclei) and motor cortex of anesthetized rats. To examine the correlation between the thalamic cerebral activities during tES, four holes were prepared for the recording. Two for the thalamic sites (1.5 mm lateral, 3.0 mm posterior to the bregma) and two for the motor cortical sites (3.0 mm laterally and 1.6 mm anteriorly to the bregma). Recordings from the thalamic nuclei were taken at various depths of 5.5 mm to 7.5 mm from the cortical surface to reach either the ventral medial (VL) or ventral lateral (VL) nuclei while another recording from the motor cortex 0.5 mm from the cortical surface were taken. Each recording session included 5 minutes of pre-stimulation, 20 minutes of 200 μA stimulation, and 5 minutes of post-stimulation from the thalamus and motor cortex regions. Twelve simultaneous recordings were taken from nine rats. Matlab
software was used for data analysis. Cross-correlation and coherence between the thalamic and cortical activities were studied in addition to previous firing rate and power spectrum analysis. There was no significant difference between the pre-stim and stimulation correlation (p-value = 0.125) or coherence (p-value = 0.191 (low frequency range) and p-value = 0.252 (high frequency range)) with all the cells (n = 12). The cells with a decrease in firing rate by tES (n = 6) showed a significant difference between the pre-stimulation and stimulation firing rates (p-value = 0.031) and the stimulation and the post-stimulation thalamic power spectrum showed a significant decrease under the high frequency range (p-value = 0.034). Neuronal activity under the high frequency condition decreased which may indicate post-stimulation effect in the inhibitory cells. There was no correlation or coherence change between the thalamus and motor cortical activities after cerebellar tES. More recordings will be collected from VM and VL and separately analyzed to see if there is a change in coherence or correlation for the future studies.