Isolation and Recording of Thalamic Neuronal Activity from Ventral Medial and Ventral Lateral Thalamic Nuclei in Rat

The cerebellum, known for its role in coordination and motor adaptation, is hypothesized to travel through the thalamus in its signaling to and from the cerebral cortex, specifically through the ventral medial (VM) and ventral lateral (VL) thalamic nuclei. The thalamus is located within the diencephalon between the midbrain and cerebral cortex. It is an important relay center between the cerebellum and the motor cortex.

Isolation and recording of electrical activity from neurons in the ventral medial and ventral lateral thalamic nuclei in rats is the first step to study the thalamic response to electrical cerebellar stimulation in future experiments.

In this experiment, a male Sprague-Dawley rat was used following administration of an anesthetic cocktail containing ketamine, xylazine, and acepromazine after the use of isoflurane for initial anesthetization. A stereotaxic apparatus was used for the surgery. Two holes were prepared in the skull (1.5 mm lateral, 3.0 mm posterior to the bregma). A recording electrode was inserted to a depth of 5.5 mm from the cortical surface. Recordings were established at various sites from a depth of 5.5 mm to 7.5 mm from the cortical surface to cover the entire depth of the VM and VL nuclei (Clampex 9). Coordinates were determined via (Paxinos, 2007). Graphical representation and data analysis were performed using Matlab software.

A total of four recordings were obtained from cortical depths of 5.6 mm, 5.7 mm, 6.0 mm, and 6.8 mm. The frequency ranges of each recording were found to be 0-13 Hz, 0-8 Hz, 0-7.5 Hz, and 0-8.5 Hz respectively.

Being able to successfully record neuronal activity within the thalamus indicates that the methodology provides an accurate way to measure neuronal firing. This acts as a foundation to later explore the cerebello-thalamo-cerebral pathway.