Inhibiting cholinergic signalling in the cerebellar interpositus nucleus impairs motor behaviour

Area of Science:

• Neuroscience
• Motor Control
• Behavioral Pharmacology

Background:

• The precise role of neuromodulators, particularly the cholinergic system, within the cerebellum remains poorly understood.
• The behavioural significance of cerebellar cholinergic signalling is largely unknown, hindering our comprehension of motor control mechanisms.

Purpose of the Study:

• To investigate the importance of cerebellar cholinergic signalling in behaviour.
• To elucidate the specific roles of muscarinic and nicotinic acetylcholine receptors in cerebellar function and motor behaviour.

Main Methods:

• Bilateral infusion of acetylcholine receptor antagonists (scopolamine and mecamylamine) into the rat cerebellum (interpositus nucleus).
• Assessment of motor effects using a battery of behavioural tests, including open field exploration, horizontal ladder walking, beam walking, and pellet reaching tasks.
• Evaluation of reward-related behaviours through pellet consumption in a free access to food task.

Main Results:

• Combined antagonists reduced spontaneous movement, impaired coordination in walking tasks, decreased reaches, slowed goal-directed reaching, and reduced food consumption.
• Scopolamine alone caused motor deficits and reduced food intake, while mecamylamine alone primarily affected beam walking time.
• Motor learning in specific tasks was not impaired, suggesting a role in motor execution and coordination rather than learning.

Conclusions:

• Acetylcholine in the cerebellar interpositus nucleus is vital for the execution and coordination of voluntary movements.
• Muscarinic receptor signalling plays a predominant role in mediating these effects, particularly in reward-related behaviours.
• These findings highlight the significance of the cerebellar cholinergic system in motor control and motivated behaviours.