Basal Ganglia — MCQs
Loss of striatal fibres in caudate nucleus is associated with?
Areas of brain involved in OCD include:
Lesions within the basal ganglia produce the following signs except:
Substantia nigra is connected to which part of the basal ganglia?
A 60-year-old man has resting tremor, pill-rolling movements, rigidity, and bradykinesia. Which of the following is most likely to be decreased in this man?
A patient is brought to the OPD by his wife, complaining about difficulty expressing emotions and lack of participation in daily activities. On examination, resting tremors and rigidity are noted. Given the possible diagnosis, which part of the brain is affected in this patient?
Which of the following acts as the major neurotransmitter in the substantia nigra?
Which thalamic nuclei can produce basal ganglia symptoms?
Which among the following is implicated in causing Parkinson's disease
Lesion of globus pallidus causes-
Basal Ganglia Indian Medical PG Practice Questions and MCQs
Question 1: Loss of striatal fibres in caudate nucleus is associated with?
- A. Hemiballismus
- B. Huntington's disease (Correct Answer)
- C. Charcot-Marie-Tooth disease
- D. Parkinson's disease
Explanation: ***Huntington's disease*** - This neurodegenerative disorder is pathologically characterized by **atrophy of the striatum**, particularly the **caudate nucleus** [1]. - The loss of striatal neurons, especially medium spiny neurons, leads to the characteristic **chorea** and cognitive decline [1]. *Hemiballismus* - Characterized by **unilateral, violent, flinging movements** of the limbs. - It is typically caused by a lesion in the **subthalamic nucleus**, not the caudate nucleus. *Charcot-Marie-Tooth disease* - A group of inherited disorders that affect the **peripheral nerves**, leading to muscle weakness and sensory loss. - This condition does not involve the degeneration of the striatal fibers in the caudate nucleus. *Parkinson's disease* - Primarily caused by the degeneration of **dopaminergic neurons** in the **substantia nigra pars compacta**. - While it affects the basal ganglia circuitry, its primary pathology is not the loss of striatal fibers in the caudate nucleus but rather a **dopamine deficiency**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Central Nervous System, pp. 1299-1300.
Question 2: Areas of brain involved in OCD include:
- A. Basal ganglia (Correct Answer)
- B. Temporal lobe
- C. All of the options
- D. Cerebellum
Explanation: ***Basal ganglia*** - The **basal ganglia**, particularly the **caudate nucleus**, are a core component of the **cortico-striato-thalamo-cortical (CSTC) circuit**, which is the primary neurobiological model for OCD. - The CSTC circuit involves: **Orbitofrontal cortex → Caudate nucleus → Thalamus → back to cortex**. - Hyperactivity in the **caudate nucleus** is consistently found in OCD patients and correlates with symptom severity. - The basal ganglia's role in **habit formation, motor planning, and behavioral inhibition** directly relates to the compulsive behaviors and ritualistic patterns in OCD. - **Functional neuroimaging** (PET, fMRI) consistently shows increased metabolic activity in the caudate nucleus in OCD patients, which normalizes with successful treatment. *Temporal lobe* - The temporal lobe is **not a primary region** in the classical neurobiology of OCD. - While some studies show volumetric changes, it is not part of the core CSTC circuit. - The primary cortical areas in OCD are the **orbitofrontal cortex and anterior cingulate cortex**, not the temporal lobe. *Cerebellum* - The cerebellum has emerging evidence for involvement in cognitive and affective processing. - However, it is **not a core component** of the established CSTC circuit model for OCD. - Its role appears to be supplementary rather than primary in OCD pathophysiology. *All of the options* - This is incorrect because **temporal lobe is not a primary area** involved in OCD. - The core circuit is the **CSTC loop** involving orbitofrontal cortex, anterior cingulate cortex, basal ganglia (caudate), and thalamus.
Question 3: Lesions within the basal ganglia produce the following signs except:
- A. Hypotonia (Correct Answer)
- B. Hemiballismus
- C. Athetosis
- D. Tremor
Explanation: ***Hypotonia*** - **Hypotonia** is characterized by decreased muscle tone and is typically associated with lesions of the **cerebellum**, lower motor neurons, or sensory pathways, not primarily the basal ganglia. [1] - Basal ganglia disorders usually manifest with either **hypertonia** (rigidity) or dystonia, rather than hypotonia. [1] *Hemiballismus* - **Hemiballismus** is a rapid, involuntary, and flailing movement of a limb on one side of the body, often caused by a lesion in the **subthalamic nucleus**, which is part of the basal ganglia circuit. [2] - This symptom is a classic example of **hyperkinetic movement disorder** resulting from basal ganglia dysfunction. [2] *Athetosis* - **Athetosis** involves slow, writhing, involuntary movements, especially in the distal parts of the limbs, and is commonly seen in lesions affecting the **globus pallidus** and striatum, components of the basal ganglia. [2] - It is classified as an **extrapyramidal symptom** indicative of basal ganglia pathology. *Tremor* - **Tremor**, particularly at rest (e.g., in Parkinson's disease) or postural tremor, is a common sign of **basal ganglia dysfunction**, specifically involving the dopaminergic pathways. [1], [2] - Lesions affecting the **substantia nigra** or other basal ganglia structures can disrupt motor control and lead to various types of tremors.
Question 4: Substantia nigra is connected to which part of the basal ganglia?
- A. Thalamus
- B. Pallidum
- C. Striatum (Correct Answer)
- D. Subthalamic nucleus
Explanation: ***Striatum*** - The **substantia nigra pars compacta (SNc)** provides **dopaminergic input** to the striatum via the **nigrostriatal pathway**, which is crucial for motor control [1]. - This connection establishes the direct and indirect pathways of the basal ganglia, modulating **movement initiation** and **inhibition** [1]. *Thalamus* - The thalamus acts as a **relay station** for information leaving the basal ganglia, but it is not directly connected to the substantia nigra as a primary input or output structure within the basal ganglia circuitry [1]. - The basal ganglia influence the thalamus, which then projects to the **motor cortex**, but the direct connection from substantia nigra is to the striatum. *Pallidum* - The **pallidum (globus pallidus)** receives input from the striatum and projects to the thalamus, but it is not directly connected to the substantia nigra as the **primary recipient** of nigral efferents [1]. - While it's part of the basal ganglia, the substantia nigra's main direct projection is to the **striatum**. *Subthalamic nucleus* - The **subthalamic nucleus (STN)** is an excitatory component of the basal ganglia that receives input from the cortex and projects to the globus pallidus. - While there are some indirect connections, the STN is not the primary target of the **nigrostriatal dopaminergic projections** from the substantia nigra [1].
Question 5: A 60-year-old man has resting tremor, pill-rolling movements, rigidity, and bradykinesia. Which of the following is most likely to be decreased in this man?
- A. GABA neurons in the caudate nucleus and putamen
- B. Serotonin neurons in the raphe nuclei
- C. Acetylcholine neurons in the forebrain
- D. Dopamine neurons in the substantia nigra (Correct Answer)
Explanation: ***Dopamine neurons in the substantia nigra*** - The symptoms described—**resting tremor**, **pill-rolling movements**, **rigidity**, and **bradykinesia**—are classic signs of **Parkinson's disease** [5]. - Parkinson's disease is pathologically characterized by the degeneration of **dopamine-producing (dopaminergic) neurons** in the **substantia nigra pars compacta**, leading to decreased dopamine levels in the **striatum** [1]. *GABA neurons in the caudate nucleus and putamen* - **GABAergic neurons** in the **caudate nucleus and putamen** are primarily affected in conditions like **Huntington's disease**, where their degeneration leads to increased involuntary movements (chorea) [4]. - While there can be secondary changes in these neurons in Parkinson's, the primary deficit is not in GABA but in dopamine. *Serotonin neurons in the raphe nuclei* - **Serotonin neurons** in the **raphe nuclei** are involved in mood regulation, sleep, and appetite, and their dysfunction is primarily linked to conditions like **depression**, anxiety, and certain sleep disorders [3]. - While some serotonergic involvement can occur in Parkinson's, it is not the primary neurological deficit explaining the motor symptoms. *Acetylcholine neurons in the forebrain* - **Acetylcholine neurons** in the **nucleus basalis of Meynert** (part of the forebrain) are primarily implicated in **Alzheimer's disease**, where their degeneration contributes to cognitive decline [2]. - While some cholinergic deficits may be present in advanced Parkinson's, they are not the hallmark pathology or the initial cause of the characteristic motor symptoms.
Question 6: A patient is brought to the OPD by his wife, complaining about difficulty expressing emotions and lack of participation in daily activities. On examination, resting tremors and rigidity are noted. Given the possible diagnosis, which part of the brain is affected in this patient?
- A. Basal ganglia (Correct Answer)
- B. Hippocampus
- C. Cerebellum
- D. Premotor cortex
Explanation: **Basal ganglia (Correct)** - The symptoms described—**resting tremors**, **rigidity**, difficulty expressing emotions, and lack of participation—are classic features of **Parkinson's disease**, which is characterized by the degeneration of dopaminergic neurons in the **substantia nigra**, a component of the basal ganglia [1]. - The basal ganglia play a crucial role in motor control, learning, and emotion, and their dysfunction leads to the characteristic motor and non-motor symptoms observed [2]. *Hippocampus (Incorrect)* - The hippocampus is primarily involved in **memory formation** and spatial navigation. - Damage to the hippocampus typically results in **amnesia** or difficulties with new learning, not motor symptoms like tremors or rigidity [3]. *Cerebellum (Incorrect)* - The cerebellum is responsible for **coordination**, balance, and fine motor control [2]. - **Cerebellar dysfunction** typically manifests as **ataxia**, dysmetria, and intention tremors, which differ from the resting tremors and rigidity seen in this patient. *Premotor cortex (Incorrect)* - The premotor cortex is involved in the planning and preparation of movements, as well as the control of trunk and proximal limb muscles. - While it contributes to motor control, its primary dysfunction does not typically cause the combination of **resting tremors** and **rigidity** characteristic of Parkinson's disease.
Question 7: Which of the following acts as the major neurotransmitter in the substantia nigra?
- A. Serotonin
- B. Dopamine (Correct Answer)
- C. Acetylcholine
- D. Noradrenaline
Explanation: ***Dopamine*** - The **substantia nigra** is a critical midbrain structure, and its pars compacta (SNc) is the primary site for **dopaminergic neurons** that project to the striatum (nigrostriatal pathway). - The degeneration of these **dopamine-producing neurons** is the hallmark pathology of **Parkinson's disease**. *Serotonin* - While serotonin (5-HT) neurons are found throughout the brain, their primary concentrations are in the **raphe nuclei**, not the substantia nigra. - Serotonin is involved in mood, sleep, appetite, and other functions, but it is not the major neurotransmitter of the substantia nigra. *Acetylcholine* - **Acetylcholine (ACh)** is crucial for muscle contraction, learning, memory, and is prominent in the **basal forebrain** and **brainstem cholinergic nuclei**. - Although it plays a role in basal ganglia function, particularly in the striatum, it is not the major neurotransmitter in the substantia nigra itself. *Noradrenaline* - **Noradrenaline (norepinephrine)** is primarily produced in the **locus coeruleus** in the brainstem and projects widely to the cerebral cortex. - It is involved in arousal, attention, and the stress response, but it is not the dominant neurotransmitter within the substantia nigra.
Question 8: Which thalamic nuclei can produce basal ganglia symptoms?
- A. Lateral dorsal
- B. Pulvinar
- C. Ventral anterior (Correct Answer)
- D. Intralaminar
Explanation: ***Ventral anterior*** - The **ventral anterior (VA)** and **ventral lateral (VL)** nuclei of the thalamus receive significant input from the **basal ganglia** and project to the motor cortex [1]. - Dysfunction in these nuclei can disrupt the basal ganglia's influence on motor control, leading to symptoms like **dyskinesia** or **rigidity** [1]. *Lateral dorsal* - The **lateral dorsal nucleus** is primarily involved in **limbic system** functions and episodic memory. - It does not have direct nor significant connections with the basal ganglia motor circuits that would produce typical basal ganglia symptoms. *Pulvinar* - The **pulvinar** is the largest thalamic nucleus, primarily involved in **visual processing**, attention, and eye movements. - While it has extensive cortical connections, it is not directly involved in the motor circuits of the basal ganglia. *Intralaminar* - The **intralaminar nuclei** (e.g., centromedian and parafascicular) receive input from the basal ganglia but primarily project diffusely to the cerebral cortex and are involved in **arousal** and consciousness [2]. - While they modulate cortical activity, their dysfunction typically wouldn't produce the classic motor symptoms associated with basal ganglia disorders.
Question 9: Which among the following is implicated in causing Parkinson's disease
- A. Ethanol
- B. Manganese (Correct Answer)
- C. Carbon dioxide
- D. Zinc
Explanation: ***Manganese*** - Chronic exposure to **high levels of manganese** can lead to **manganism**, a neurological disorder with symptoms highly similar to **Parkinson's disease**, including **tremors**, **rigidity**, and **bradykinesia**. - Manganese neurotoxicity primarily affects the **basal ganglia**, specifically the **globus pallidus**, leading to neuronal damage that mimics the dopaminergic dysfunction seen in Parkinson's. *Ethanol* - While chronic **alcohol abuse** can cause various neurological problems, including cerebellar degeneration and peripheral neuropathy, it is **not generally recognized as a direct cause or strong risk factor for Parkinson's disease**. - Some studies suggest a potential inverse relationship or no significant association between moderate alcohol consumption and Parkinson's risk. *Carbon dioxide* - Exposure to **elevated levels of carbon dioxide** can cause symptoms like **headache**, **dizziness**, and **confusion**, and in very high concentrations, can be fatal due to **asphyxiation**. - There is **no evidence** linking carbon dioxide exposure to the development of Parkinson's disease or the specific degeneration of dopaminergic neurons in the substantia nigra. *Zinc* - **Zinc** is an essential trace element vital for numerous physiological processes, and both **deficiency and excess** can lead to health problems. However, it is **not implicated in the causation of Parkinson's disease**. - While zinc dysregulation has been studied in neurodegenerative diseases, its role in Parkinson's is complex and not a direct causative factor like manganese.
Question 10: Lesion of globus pallidus causes-
- A. Hemibalismus
- B. Chorea
- C. Athetosis (Correct Answer)
- D. Flexion dystonia
Explanation: ***Athetosis*** - A lesion in the **globus pallidus**, particularly the *internal segment*, or its connections can lead to **athetosis**, characterized by slow, writhing, involuntary movements. - The **globus pallidus** plays a crucial role in regulating movement patterns by modulating the activity of the thalamus and cortex. *Hemibalismus* - **Hemiballismus** is typically caused by a lesion in the **subthalamic nucleus**, often due to stroke. - It involves violent, flinging, involuntary movements on one side of the body. *Chorea* - **Chorea** is characterized by brief, irregular, unpredictable, and rapid involuntary movements, often associated with lesions in the **caudate nucleus** or **putamen** (e.g., in Huntingdon's disease). - The globus pallidus is involved in the overall basal ganglia circuit but isn't the primary site for chorea. *Flexion dystonia* - **Dystonia**, including flexion dystonia, involves sustained or repetitive muscle contractions resulting in twisting and repetitive movements or abnormal fixed postures. - While basal ganglia dysfunction is implicated, lesions primarily causing flexion dystonia are more diverse and not exclusively localized to the globus pallidus.
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