Neurophysiology Practice Questions

Q: Tremors are observed during movements in which of the following conditions?

Cerebellum injury. ### Explanation The correct answer is **D. Cerebellum injury**. **1. Why Cerebellum Injury is Correct:** The cerebellum is responsible for the coordination, precision, and timing of voluntary movements. It acts as a "comparator," constantly adjusting motor output by comparing intended movement with actual performance. Damage to the **neocerebellum** (posterior lobe) results in **Intention Tremors** (also known as kinetic tremors). These tremors are absent at rest but appear during active, purposeful movement and typically worsen as the limb approaches its target. This occurs due to the loss of the cerebellum's damping effect, leading to "overshooting" and "undershooting" (dysmetria). **2. Why Other Options are Incorrect:** * **Spinal Cord Injury:** Typically results in motor paralysis (upper or lower motor neuron lesions) and sensory loss below the level of the lesion. It may cause spasticity or clonus, but not intention tremors. * **Thalamus Injury:** Usually presents with sensory deficits (Dejerine-Roussy syndrome) or contralateral hemiparesis. While the thalamus is a relay station, isolated injury does not characteristically produce movement-induced tremors. * **Internal Capsule Injury:** This is a common site for strokes, leading to contralateral hemiplegia or hemiparesis due to damage to the corticospinal tract. It results in spasticity, not tremors. **3. NEET-PG High-Yield Pearls:** * **Resting Tremors:** Characteristically seen in **Parkinson’s Disease** (Basal Ganglia/Substantia Nigra lesion). Described as "pill-rolling" tremors. * **Cerebellar Signs (DANISH):** **D**ysdiadochokinesia, **A**taxia, **N**ystagmus, **I**ntention tremor, **S**lurred speech (Scanning speech), **H**ypotonia. * **The Rule of Thumb:** Basal Ganglia lesions = Tremors at **Rest**; Cerebellar lesions = Tremors during **Activity**.

Q: The mu rhythm on EEG arises from which area?

Primary sensorimotor area. **Explanation:** The **Mu rhythm** (also known as the wicket rhythm) is a specific EEG pattern characterized by frequencies between **8–13 Hz**. While it shares a similar frequency range with the Alpha rhythm, it is distinguished by its location and reactivity. 1. **Why the Correct Answer is Right:** The Mu rhythm originates from the **Primary Sensorimotor Area** (around the central sulcus). Its key physiological characteristic is that it is **suppressed by motor activity** or the intention to move (motor imagery). For example, moving the contralateral hand or even thinking about moving it will cause the Mu rhythm to disappear (desynchronization). 2. **Why the Other Options are Wrong:** * **Primary Visual Area (Option A):** This area (occipital lobe) is the site of the **Alpha rhythm**. Alpha waves are prominent during wakeful relaxation with eyes closed and are suppressed by eye-opening or mental concentration. * **Primary Auditory Area (Option B):** EEG rhythms specific to the auditory cortex (temporal lobe) are not typically classified under the standard Greek-letter rhythms like Mu or Alpha in routine clinical EEG. * **Primary Olfactory Area (Option D):** This area is located on the inferior surface of the frontal lobe and uncus; it does not produce a surface-recordable rhythm like the Mu rhythm. **High-Yield Clinical Pearls for NEET-PG:** * **Alpha Rhythm:** 8–13 Hz; Occipital location; suppressed by **eye-opening**. * **Mu Rhythm:** 8–13 Hz; Central/Parietal location; suppressed by **motor activity**. * **Beta Rhythm:** 13–30 Hz; Frontal location; associated with active thinking and anxiety. * **Theta Rhythm:** 4–7 Hz; Normal in children and during sleep; abnormal in awake adults (suggests encephalopathy). * **Delta Rhythm:** <4 Hz; Normal in deep sleep (Stage N3); highest amplitude waves.

Q: Which of the following is an inhibitory neurotransmitter in the spinal cord?

Glycine. **Explanation:** The correct answer is **Glycine**. In the central nervous system, neurotransmitters are classified based on their effect on the postsynaptic membrane. **1. Why Glycine is correct:** Glycine is the **primary inhibitory neurotransmitter in the spinal cord** and brainstem. It acts by binding to ionotropic receptors that open **chloride (Cl⁻) channels**. The influx of negatively charged chloride ions causes hyperpolarization of the postsynaptic neuron, resulting in an Inhibitory Postsynaptic Potential (IPSP), which makes the neuron less likely to fire an action potential. **2. Analysis of Incorrect Options:** * **Glutamic acid (Glutamate):** This is the major **excitatory** neurotransmitter in the entire CNS. It works by opening cation channels (Na⁺/Ca²⁺). * **Histidine:** This is an amino acid precursor to histamine, not a primary neurotransmitter itself. Histamine acts mainly as an excitatory neuromodulator in the hypothalamus. * **GABA (Gamma-Aminobutyric Acid):** While GABA is the major inhibitory neurotransmitter in the **brain** (supraspinal levels), Glycine takes precedence in the spinal cord. **3. High-Yield Clinical Pearls for NEET-PG:** * **Renshaw Cells:** These are inhibitory interneurons in the spinal cord that utilize **Glycine** to mediate recurrent inhibition of alpha motor neurons. * **Strychnine Poisoning:** Strychnine is a potent **Glycine receptor antagonist**. By blocking glycine, it removes spinal inhibition, leading to severe, unchecked muscle convulsions (opisthotonus). * **Tetanus Toxin:** Produced by *Clostridium tetani*, this toxin prevents the **release** of Glycine and GABA from inhibitory interneurons, leading to spastic paralysis and "lockjaw." * **Co-localization:** In many spinal cord synapses, GABA and Glycine are co-released to fine-tune motor control.

Q: Which of the following functions is primarily controlled by the left lobe of the brain?

Processing of written and spoken language. In neurophysiology, the concept of **Cerebral Lateralization** (or Hemispheric Specialization) dictates that while the two hemispheres are anatomically similar, they are functionally distinct. ### Why Option D is Correct In approximately 95% of right-handed individuals and 70% of left-handed individuals, the **left hemisphere** is the **categorical hemisphere**. It is specialized for sequential, analytical, and symbolic processing. Its primary functions include: * **Language:** Both Broca’s area (speech production) and Wernicke’s area (comprehension) are typically located here. * **Mathematical calculations** and logical reasoning. * **Processing of written and spoken language.** ### Why Other Options are Incorrect Options A, B, and C are primarily functions of the **right hemisphere** (the **representational hemisphere**), which deals with holistic, visuospatial, and creative patterns: * **A. Appreciation of music:** The right hemisphere processes melody, pitch, and the emotional intonation of speech (prosody). * **B. Spatial orientation:** Navigating 3D space and recognizing faces/geometric patterns are right-brain dominant. * **C. Processing of visual stimuli:** While both occipital lobes process vision, the *interpretation* of complex visual patterns and three-dimensional relationships is a right-hemisphere specialty. ### High-Yield Clinical Pearls for NEET-PG * **Wada Test:** Used clinically to determine which hemisphere is dominant for speech before neurosurgery (involves injecting sodium amobarbital into the carotid artery). * **Lesion Correlation:** A left-sided stroke typically results in **Aphasia** (language deficit), whereas a right-sided stroke often leads to **Agnosia** (inability to recognize objects) or **Neglect syndrome**. * **Astereognosis:** The inability to identify an object by touch; usually associated with a lesion in the parietal lobe of the non-dominant (right) hemisphere.

Q: A patient is unable to speak but can communicate by writing. Which of the following brain areas is most likely affected?

Broca's area. ### Explanation **Correct Option: A. Broca’s Area** The patient is presenting with **Broca’s Aphasia** (also known as motor, expressive, or non-fluent aphasia). Broca’s area (Brodmann areas 44 and 45) is located in the posterior part of the inferior frontal gyrus of the dominant hemisphere. It is responsible for the motor programming of speech. * **Key Concept:** In Broca’s aphasia, the patient understands language and can often communicate through writing (as the motor pathways for manual dexterity are distinct) or gestures, but they struggle with the mechanical production of spoken words. Speech is typically "telegraphic" and effortful. **Incorrect Options:** * **B. Wernicke’s Area:** Located in the superior temporal gyrus (Brodmann area 22), damage here causes **Sensory Aphasia**. Patients speak fluently but the content is nonsensical ("word salad"), and they have impaired comprehension of both spoken and written language. * **C. Paracentral Lobule:** This area on the medial surface of the hemisphere controls motor and sensory functions of the contralateral lower limb and the urinary bladder. It is not involved in language production. * **D. Insula:** While the insula plays a role in diverse functions like perception and self-awareness, it is not the primary center for speech production. **High-Yield Clinical Pearls for NEET-PG:** * **Blood Supply:** Broca’s area is supplied by the **Superior division** of the Middle Cerebral Artery (MCA), while Wernicke’s is supplied by the **Inferior division**. * **Arcuate Fasciculus:** The white matter tract connecting Broca’s and Wernicke’s areas. Damage leads to **Conduction Aphasia** (characterized by an inability to repeat phrases). * **Exner’s Area:** Located just above Broca’s area; damage specifically causes **isolated agraphia** (inability to write).

Q: Which of the following statements about 'Sham Rage' is not true?

Abolished by decortication. **Explanation:** **Sham Rage** is a state of violent, undirected aggression observed in experimental animals when the inhibitory control of the cerebral cortex over the lower brain centers is removed. **Why Option B is the Correct Answer (The False Statement):** Sham rage is **not abolished** by decortication; rather, it is **caused** by decortication (removal of the cerebral cortex). In a normal physiological state, the cortex exerts an inhibitory influence on the hypothalamus. When the cortex is removed or disconnected from the hypothalamus, this inhibition is lost, leading to an exaggerated, unprovoked rage response. **Analysis of Other Options:** * **Option A (Hypothalamic stimulation):** This is true. The hypothalamus (specifically the lateral and dorsomedial nuclei) is the primary center for the expression of rage. Sham rage occurs only if the hypothalamus remains intact and connected to the brainstem. * **Option C (Pathological rage reaction):** This is true. It is termed "Sham" because it lacks a situational trigger and is not directed toward a specific object. It is a purely physiological, pathological outburst. * **Option D (Association with sympathetic stimulation):** This is true. Sham rage is characterized by massive sympathetic discharge, resulting in tachycardia, pupillary dilation (mydriasis), piloerection, and increased blood pressure. **High-Yield Clinical Pearls for NEET-PG:** * **Key Structure:** The **Hypothalamus** is the "effector" of sham rage. * **The "Downstream" Rule:** If the transection is **above** the hypothalamus (decortication), sham rage occurs. If the transection is **below** the hypothalamus (decerebration), sham rage disappears. * **Placid Reaction:** Conversely, the removal of the **Amygdala** (as seen in Klüver-Bucy Syndrome) leads to extreme docility or a "placid" state, which is the functional opposite of sham rage.

Q: Which of the following is NOT a feature of a pyramidal tract lesion?

Involuntary movement. The pyramidal tract (Corticospinal tract) is the primary pathway for voluntary motor control. A lesion here results in **Upper Motor Neuron (UMN)** syndrome [1]. ### Why "Involuntary Movement" is the Correct Answer Involuntary movements (such as tremors, chorea, athetosis, or ballismus) are characteristic features of **Extrapyramidal system** lesions (e.g., Basal Ganglia disorders like Parkinson’s or Huntington’s disease) [1]. Pyramidal lesions cause a loss of movement (paralysis/paresis) rather than the addition of abnormal movements [1]. ### Explanation of Incorrect Options (Features of UMN Lesions) * **Positive Babinski’s Sign:** This is the hallmark of a pyramidal tract lesion. The loss of descending inhibition leads to an upgoing hallux (extensor plantar response), which is pathological in adults [2]. * **Spasticity:** UMN lesions cause "clasp-knife" spasticity [1]. This is a velocity-dependent increase in muscle tone resulting from the loss of inhibitory control over the stretch reflex [2]. * **Increased Deep Tendon Reflexes (DTRs):** Hyperreflexia occurs because the lower motor neuron (LMN) is freed from the inhibitory influence of the pyramidal tract, leading to an exaggerated response to muscle stretch [2]. ### NEET-PG High-Yield Pearls * **Pyramidal Signs (UMN):** Spasticity, Hyperreflexia, Positive Babinski, Pronator drift, and loss of superficial reflexes (e.g., abdominal reflex). * **Extrapyramidal Signs:** Rigidity (Lead-pipe/Cogwheel), Bradykinesia, Tremors, and Dystonia. * **LMN Signs:** Fasciculations, Fibrillations, Atrophy, and Hyporeflexia. * **Note:** In the **acute** stage of a pyramidal lesion (Spinal Shock), reflexes may be temporarily absent before hyperreflexia develops.

Q: Knee jerk is an example of what type of reflex?

Monosynaptic reflex. ### Explanation **Correct Option: A. Monosynaptic reflex** The knee jerk (patellar reflex) is the classic example of a **stretch reflex (myotatic reflex)**. When the patellar tendon is tapped, it stretches the quadriceps muscle, stimulating the **Muscle Spindles** (primary sensory receptors). The afferent impulse is carried via **Type Ia nerve fibers** directly to the spinal cord (L2-L4 levels), where it synapses **directly** onto the alpha-motor neuron. Because there is only **one synapse** between the sensory afferent and the motor efferent within the central nervous system, it is classified as a monosynaptic reflex. **Why other options are incorrect:** * **B. Polysynaptic reflex:** These reflexes involve one or more **interneurons** between the sensory and motor neurons. Most reflexes in the body (like the crude touch or autonomic reflexes) are polysynaptic. * **C. Withdrawal reflex:** This is a protective reflex (e.g., pulling a hand away from a hot stove). It is a **polysynaptic reflex** involving nociceptors, multiple interneurons, and "crossed extensor" components to maintain balance. **High-Yield Clinical Pearls for NEET-PG:** * **Components of the Reflex Arc:** Receptor (Muscle spindle) → Afferent (Ia fiber) → Center (Spinal cord) → Efferent (Alpha motor neuron) → Effector (Extensor muscle). * **Reciprocal Inhibition:** While the knee jerk is monosynaptic, the simultaneous relaxation of the antagonist (hamstrings) is **polysynaptic**, mediated by inhibitory interneurons. * **Root Value:** The patellar reflex tests the **L2, L3, and L4** spinal segments. * **Jendrassik Maneuver:** A clinical maneuver (clinching teeth/interlocking fingers) used to distract the patient and exaggerate a sluggish patellar reflex by decreasing descending inhibition.

Question 1

Tremors are observed during movements in which of the following conditions?

Accepted Answer

Cerebellum injury

Answer

Spinal cord injury

Answer

Thalamus injury

Answer

Internal capsule injury

Question 2

The mu rhythm on EEG arises from which area?

Accepted Answer

Primary sensorimotor area

Answer

Primary visual area

Answer

Primary auditory area

Answer

Primary olfactory area

Question 3

Which of the following is an inhibitory neurotransmitter in the spinal cord?

Accepted Answer

Glycine

Answer

Glutamic acid

Answer

Histidine

Answer

GABA

Question 4

Which of the following functions is primarily controlled by the left lobe of the brain?

Accepted Answer

Processing of written and spoken language

Answer

Appreciation of music

Answer

Spatial orientation

Answer

Processing of visual stimuli

Question 5

A patient is unable to speak but can communicate by writing. Which of the following brain areas is most likely affected?

Accepted Answer

Broca's area

Answer

Wernicke's area

Answer

Paracentral lobule

Answer

Insula

Question 6

Which of the following statements about 'Sham Rage' is not true?

Accepted Answer

Abolished by decortication

Answer

Caused by hypothalamic stimulation

Answer

Pathological rage reaction

Answer

Association with sympathetic stimulation

Question 7

Learning by exposure to repeated stimulus is known as:

Accepted Answer

Habituation

Answer

Sensitisation

Answer

Potentiation

Answer

None of the above

Question 8

Which of the following is NOT a feature of a pyramidal tract lesion?

Accepted Answer

Involuntary movement

Answer

Positive Babinski's sign

Answer

Spasticity

Answer

Increased deep tendon reflexes

Question 9

Knee jerk is an example of what type of reflex?

Accepted Answer

Monosynaptic reflex

Answer

Polysynaptic reflex

Answer

Withdrawal reflex

Answer

None of the above

Question 10

Which of the following neural mechanisms is not involved in synaptic plasticity and learning?

Accepted Answer

Desensitization

Answer

Post-tetanic potentiation

Answer

Habituation

Answer

Long-term depression

Neurophysiology — MCQs

Neurophysiology — MCQs

On this page

Practice by Chapter

Want unlimited practice?