Semester 2 Neuro, Quiz 2 - Cerebellum

The patient's ataxia, characterized by marked swaying back and forth, suggests dysfunction in the cerebellum. The cerebellum plays a crucial role in coordinating movements and maintaining balance. The fact that the swaying persists even when the patient opens his eyes indicates that the problem lies within the cerebellum rather than the sensory input from the eyes. The other structures listed, such as the dorsal columns, cerebral peduncles, posterior limb of the internal capsule, and ventral horns of the spinal cord, are not typically associated with these specific symptoms.

Dysdiadokokinesia refers to the inability to perform rapid alternating movements with the hands. This condition is commonly observed in neurological disorders such as cerebellar dysfunction or lesions. It is characterized by a lack of coordination and smoothness in movements, making it difficult for individuals to perform tasks that require rapid and alternating movements, such as playing a musical instrument or clapping hands.

The researcher would wish to lesion the Fastigial nucleus if they are focusing mainly on the flocculo-nodular lobe circuitry of the cerebellum. This is because the Fastigial nucleus is primarily involved in the control of eye movements and balance, which are key functions of the flocculo-nodular lobe. Lesioning the Fastigial nucleus would allow the researcher to study the specific effects on these functions and understand the circuitry of the cerebellum involved in them.

The patient's symptoms of slurred speech and dysmetria on the left side indicate a lesion in the left cerebellar hemisphere. The cerebellum is responsible for coordinating voluntary movements, including speech and fine motor skills. Lesions in the cerebellar hemisphere can lead to deficits on the opposite side of the body. In this case, the left cerebellar hemisphere is affected, causing symptoms on the left side such as slurred speech and dysmetria. The other options, such as the cerebellar vermis, right cerebellar hemisphere, fastigial nucleus, and vestibular nuclei, are not consistent with the patient's symptoms.

Purkinje cells are known to be the major output neurons of the cerebellar cortex. They receive inputs from various sources within the cerebellum and send their axons to the deep cerebellar nuclei, which then project to other parts of the brain. Purkinje cells play a crucial role in coordinating motor movements and are involved in the regulation of balance, posture, and coordination. Their distinctive morphology and connectivity make them well-suited for integrating and modulating signals within the cerebellum.

The patient's unsteady and "drunk like" gait, as well as swaying while entering the examination room, suggest dysfunction in the vestibulocerebellum, which is responsible for balance and coordination. The vestibulocerebellum is located in the flocculonodular lobe of the cerebellum. Therefore, the most likely region affected by the cerebellar hemorrhage in this case is the flocculonodular lobe.

Granule cell parallel fibers and mossy fibers both provide excitatory input. The granule cell parallel fibers are axons of granule cells in the cerebellar cortex that run parallel to each other. Mossy fibers, on the other hand, are axons that originate from various brain regions and carry sensory information to the cerebellum. Both of these fiber types release excitatory neurotransmitters onto their target cells, which leads to the activation and excitation of these cells. Therefore, the correct answer is Granule cell parallel fibers & Mossy fibers.

Efferent axons from the dentate nucleus terminate in the Ventral lateral nucleus of the thalamus (VL) and travel through the superior cerebellar peduncle.

The correct answer is the anterior spinocerebellar tract. This ascending pathway enters the cerebellum through the peduncle marked in the picture. The other options listed are not associated with this specific peduncle.