Inhibition of Neuronal Activity and Its Detection Using Electrophysiology in a Rat

Begin with an anesthetized rat secured in a stereotaxic frame with its skull exposed.

Using the anatomical landmarks, the bregma and the lambda, locate the superior colliculus, a deep brain structure responsible for processing visual information.

Drill to create a bone flap, remove it, and apply a buffer to keep the exposed brain hydrated.

Position an injectrode assembly consisting of a micropipette with an electrode attached to a microsyringe.

The micropipette contains an inhibitory neurotransmitter solution to suppress neuronal excitability while the electrode simultaneously records neuronal activity.

Lower the injectrode into the superior colliculus and cover the exposed surface with molten agar to prevent dehydration.

Present light flashes to the eye to stimulate neurons and evoke synchronized action potentials.

Inject the neurotransmitter, which binds to its receptors and triggers chloride ion influx.

This influx hyperpolarizes the membrane potential, thereby suppressing action potentials.

As the neurotransmitter concentration declines over time, neuronal activity recovers.

To prepare the recording injection pipettes, first, pull a 7-centimeter capillary with a 1 millimeter outer diame