Neurobiology and Genetics of Mental Disorders — MCQs

Neurobiology and Genetics of Mental Disorders Indian Medical PG Practice Questions and MCQs

Question 31: The site of lesion in Korsakoff's psychosis is

A. Frontal lobe
B. Mammillary body (Correct Answer)
C. Cingulate gyrus
D. Corpus striatum

Explanation: ***Mammillary body*** - **Korsakoff's psychosis** is a neurocognitive disorder characterized by severe **memory impairment**, confabulation, and apathy, primarily due to **thiamine deficiency**. - The disease involves damage to several brain areas, most notably the **mammillary bodies** and the dorsal medial nucleus of the thalamus, which are critical for memory formation. *Frontal lobe* - While frontal lobe dysfunction can lead to cognitive deficits, the **primary lesion** in Korsakoff's psychosis is not typically located here. - Damage to the frontal lobe is more commonly associated with executive dysfunction, personality changes, and disinhibition, rather than the profound amnesia seen in Korsakoff's. *Cingulate gyrus* - The cingulate gyrus plays a role in emotion, learning, and memory, but it is **not considered the primary site of lesion** in Korsakoff's psychosis. - Although it can be affected, lesions in the mammillary bodies are more directly linked to the characteristic memory deficits. *Corpus striatum* - The corpus striatum is involved in motor control and habit formation, and its damage is associated with movement disorders like **Parkinson's or Huntington's disease**. - This area is **not the primary site of pathology** in Korsakoff's psychosis, which is fundamentally a memory disorder.

Question 32: Inability to recognize faces is known as:

A. Inability to read
B. Inability to write
C. Inability to speak
D. Inability to recognize faces (Correct Answer)

Explanation: ***Prosopagnosia (Inability to recognize faces)*** - The inability to recognize faces is medically termed **prosopagnosia**, a neurological disorder. - It often results from damage to the **fusiform gyrus** in the temporal lobe, a region critical for facial recognition. - Patients can see faces clearly but cannot identify familiar individuals, including family members. *Alexia (Inability to read)* - This symptom describes **alexia** or **dyslexia**, which are disorders characterized by difficulty with reading, not face recognition. - Alexia can result from brain injury, while dyslexia is a developmental learning disorder. *Agraphia (Inability to write)* - This condition is known as **agraphia** or **dysgraphia**, referring to impaired writing ability. - Agraphia can occur after brain injury, whereas dysgraphia is often a developmental condition. *Aphasia (Inability to speak)* - Difficulty or inability to speak is called **aphasia** or **dysarthria**, depending on the underlying cause. - **Aphasia** involves language processing issues, while **dysarthria** relates to motor control of speech.

Question 33: What is the most likely neurochemical change associated with schizophrenia?

A. Increased GABA activity
B. Increased dopaminergic activity (Correct Answer)
C. Decreased dopaminergic activity
D. Decreased norepinephrine activity

Explanation: ***Increased dopaminergic activity*** - The **dopamine hypothesis** of schizophrenia posits that the positive symptoms (hallucinations, delusions) are mainly due to **hyperactivity of dopamine D2 receptors** in the mesolimbic pathway. - Most **antipsychotic medications** work by blocking these D2 receptors, reducing dopaminergic transmission and alleviating symptoms. *Increased GABA activity* - **GABA (gamma-aminobutyric acid)** is the primary inhibitory neurotransmitter in the brain; *decreased* GABAergic activity has been implicated in schizophrenia, not increased. - A reduction in GABAergic interneurons can lead to **disinhibition** and contribute to cognitive deficits and positive symptoms. *Decreased dopaminergic activity* - While *decreased* dopamine activity in the **mesocortical pathway** (leading to the prefrontal cortex) is associated with the negative symptoms (e.g., avolition, anhedonia) and cognitive deficits of schizophrenia, the *primary* neurochemical change linked to the characteristic psychotic symptoms is an *increase* in mesolimbic dopamine. - Therefore, considering the overall presentation, **increased dopamine** is the most likely and direct answer. *Decreased norepinephrine activity* - Although **norepinephrine dysregulation** has been observed in schizophrenia, it is not considered the primary neurochemical change. - Changes in norepinephrine are often secondary or contribute to specific symptom clusters like **attention deficits** or mood disturbances rather than the core psychotic features.

Question 34: Which neurological condition is commonly associated with Alice in Wonderland Syndrome?

A. Subacute sclerosing panencephalitis (SSPE)
B. Epileptic seizures (Correct Answer)
C. Cerebral hemorrhage
D. Multiple sclerosis

Explanation: ***Epileptic seizures*** - **Alice in Wonderland Syndrome (AIWS)**, characterized by distortions of visual perception, body image, and sense of time, is often reported as an **aura or part of focal epileptic seizures**, particularly those originating in the temporal or parietal lobes. - The **transient and episodic nature** of AIWS symptoms aligns well with the paroxysmal electrical activity seen in epilepsy. *Subacute sclerosing panencephalitis (SSPE)* - **SSPE** is a rare, fatal brain disorder caused by a persistent **measles virus infection**, primarily affecting children and young adults. - While it causes progressive neurological deterioration, including cognitive decline, motor dysfunction, and seizures, **Alice in Wonderland Syndrome** is not a characteristic or commonly associated symptom. *Cerebral hemorrhage* - A **cerebral hemorrhage** involves bleeding within the brain tissue, leading to acute neurological deficits depending on the location and size of the bleed. - Although it can cause a variety of symptoms, such as headache, weakness, and altered consciousness, **Alice in Wonderland Syndrome** is not a typical manifestation of acute hemorrhage. *Multiple sclerosis* - **Multiple sclerosis (MS)** is a chronic autoimmune disease affecting the central nervous system, leading to demyelination and neurological symptoms. - Common symptoms involve motor, sensory, visual, and cognitive deficits, but **Alice in Wonderland Syndrome** is not a recognized or common neurological manifestation of MS.

Question 35: Which of the following is not associated with subcortical dementia?

A. Wilson's disease
B. Alzheimer's disease (Correct Answer)
C. Huntington's chorea
D. Parkinsonism

Explanation: ***Alzheimer's disease*** - Alzheimer's disease is primarily a **cortical dementia**, characterized by global cognitive decline, specifically affecting memory, language, and executive functions. - It involves the accumulation of **amyloid plaques** and **neurofibrillary tangles** predominantly in the cerebral cortex. *Parkinsonism* - Parkinsonism, particularly Parkinson's disease dementia, is a common cause of **subcortical dementia**. - It presents with prominent **motor symptoms** (bradykinesia, rigidity, tremor) along with cognitive impairment affecting executive function and attention. *Wilson's disease* - Wilson's disease is a genetic disorder leading to **copper accumulation**, which can cause significant damage to the basal ganglia and other subcortical structures. - This often results in a **subcortical dementia** characterized by motor symptoms, psychiatric disturbances, and cognitive decline. *Huntington's chorea* - Huntington's chorea is a neurodegenerative genetic disorder primarily affecting the **basal ganglia**, a key subcortical structure. - It is a classic example of **subcortical dementia**, presenting with characteristic choreiform movements, psychiatric disturbances, and cognitive impairment.

Question 36: Which of the following speech patterns is most indicative of Wernicke's aphasia?

A. Normal speech with comprehension
B. Non-fluent speech with intact comprehension
C. Fluent but nonsensical speech (Correct Answer)
D. Speech with meaningful content

Explanation: ***Fluent but nonsensical speech*** - Wernicke's aphasia is characterized by **fluent**, often grammatically correct, speech that is **devoid of meaning** and often includes **paraphasias** (word substitutions) and **neologisms** (made-up words). - Patients have significant **comprehension deficits**, making meaningful conversation difficult despite preserved speech fluency. - This is also known as **receptive aphasia** or **sensory aphasia**, caused by damage to Wernicke's area in the superior temporal gyrus. *Normal speech with comprehension* - This describes **healthy speech patterns**, where both production and understanding of language are intact. - It directly contradicts the definition of **aphasia**, which involves impairment in language abilities. *Non-fluent speech with intact comprehension* - This describes **Broca's aphasia** (expressive aphasia), where speech production is effortful and halting. - Unlike Wernicke's aphasia, patients with Broca's aphasia have **preserved comprehension** but struggle with speech output. - The key differentiator is that Wernicke's has **fluent speech with poor comprehension**, while Broca's has **non-fluent speech with good comprehension**. *Speech with meaningful content* - This indicates that the speaker can convey understandable and relevant information, which is precisely what is lacking in **Wernicke's aphasia**. - In Wernicke's aphasia, the content is typically **empty** or **circumlocutory**, making it difficult to extract any coherent meaning.

Question 37: In the context of seizure disorders, gustatory hallucinations are most commonly associated with which of the following?

A. Temporal lobe epilepsy (Correct Answer)
B. Generalized tonic-clonic seizures
C. Panic disorder
D. Substance use disorder

Explanation: ***Temporal lobe epilepsy*** - Gustatory hallucinations, often described as **metallic or bitter tastes**, are a characteristic type of **sensory aura** in temporal lobe seizures - Seizures originating in the **temporal lobe**, particularly involving the **insula and opercular regions**, can affect areas involved in taste perception - These hallucinations are highly localizing signs suggesting **temporal lobe origin** of seizures - Note: In psychiatric contexts, gustatory hallucinations are more commonly associated with **schizophrenia and psychotic disorders** *Generalized tonic-clonic seizures* - These seizures involve **widespread bilateral electrical activity** in the brain - Typically present with loss of consciousness, body stiffening (tonic phase), and rhythmic jerking (clonic phase) - While an aura may precede them if they evolve from a focal seizure, **isolated gustatory hallucinations are not characteristic** of primary generalized seizures *Panic disorder* - Panic disorder involves sudden episodes of intense fear with physical symptoms like **palpitations, dyspnea, chest pain, and dizziness** - Does not primarily involve **sensory hallucinations** as a core diagnostic feature - Patients may report altered perceptions during panic attacks but not true gustatory hallucinations *Substance use disorder* - Certain substances can induce hallucinations, but these are more commonly **visual or auditory** - Hallucinogens may cause complex sensory distortions, but **gustatory hallucinations are not the predominant feature** - Withdrawal states typically produce visual hallucinations (e.g., alcohol withdrawal) rather than gustatory ones

Question 38: Which of the following statements best describes the phenomenon of synesthesia?

A. Perception in one sensory modality caused by stimulus in the same sensory modality
B. A stage of altered consciousness caused by drugs like cannabis
C. Perception in one sensory modality caused by stimulus in another sensory modality (Correct Answer)
D. Experiencing sensations in one part of the body when another part is stimulated.

Explanation: ***Perception in one sensory modality caused by stimulus in another sensory modality*** - Synesthesia is a neurological phenomenon where **stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway**. - A classic example is **seeing colors when hearing sounds** (e.g., specific musical notes or words), or **tasting shapes**. *Perception in one sensory modality caused by stimulus in the same sensory modality* - This statement describes **normal sensory perception**, where a stimulus in one sense (e.g., light waves for vision) produces a perception in that same sense (e.g., seeing an image). - It does not involve the **cross-modal sensory experiences** that characterize synesthesia. *A stage of altered consciousness caused by drugs like cannabis* - This describes drug-induced altered states, which can include **hallucinations or distorted perceptions**, but these are distinct from the inherent and involuntary cross-modal experiences of synesthesia. - Synesthesia is a **neurological condition**, not a drug-induced state. *Experiencing sensations in one part of the body when another part is stimulated.* - This phenomenon is known as **referred sensation** or, in some contexts, a type of phantom limb sensation, and does not involve cross-modal sensory experiences. - It is distinct from synesthesia, which involves the **interplay between different sensory systems** like sight and sound.

Question 39: Fluent aphasia with preserved comprehension and impaired repetition is characteristic of which type of aphasia?

A. Broca's Aphasia
B. Wernicke's Aphasia
C. Anomic Aphasia
D. Conduction Aphasia (Correct Answer)

Explanation: ***Conduction Aphasia*** - Patients with **conduction aphasia** exhibit fluent speech and good comprehension but have a striking inability to **repeat** words or sentences. - This is often caused by damage to the **arcuate fasciculus**, which connects Wernicke's and Broca's areas. *Broca's Aphasia* - Characterized by **non-fluent** speech, **impaired repetition**, and relatively preserved comprehension. - Patients struggle to form words and sentences, often using **telegraphic speech**. *Wernicke's Aphasia* - Involves **fluent** but often meaningless speech, **poor comprehension**, and **impaired repetition**. - Patients may produce **neologisms** and have difficulty understanding spoken language. *Anomic Aphasia* - The primary deficit is **word-finding difficulty**, leading to frequent pauses and circumlocutions. - However, **fluency**, **comprehension**, and **repetition** are typically well-preserved.

Question 40: Which of the following neuroanatomical areas is/are considered to be involved in the etiology of depression?

A. Striatum
B. Amygdala
C. Hippocampus
D. All of the options (Correct Answer)

Explanation: ***All of the options*** - The **amygdala**, **hippocampus**, and **striatum** are all part of complex neural circuits that have been implicated in the pathophysiology of depression. - Dysregulation in these areas can lead to emotional processing deficits, memory impairments, and anhedonia, which are core symptoms of depression. *Amygdala* - The **amygdala** is primarily involved in processing emotions, particularly fear and anxiety, and shows increased activity in depressed individuals, contributing to negative mood. - While significant, it is just one component of a broader network involved in depression. *Hippocampus* - The **hippocampus** plays a crucial role in memory and mood regulation, and studies often show reduced volume and function in depressed patients, affecting learning and emotional context. - Although it is significantly affected, depression involves multiple brain regions, not solely the hippocampus. *Striatum* - The **striatum**, particularly the **ventral striatum**, is vital for reward processing, motivation, and motor control, and its dysfunction can contribute to anhedonia and lack of motivation in depression. - While critical for reward pathways, the striatum is part of a larger interconnected system implicated in this condition.

Practice by Chapter

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Psychoneuroimmunology

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Circadian Rhythms and Psychiatry

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