Neurophysiology Practice Questions

Q: EEG waves prominent in occipital lobe are

Alpha. ***Alpha*** - **Alpha waves** are typically most prominent in the **occipital and parietal lobes** when an individual is awake but in a relaxed state with their eyes closed. - They are associated with a state of **relaxed awareness** and tend to disappear when the eyes open or during mental activity or sleep. *Gamma* - **Gamma waves** are the fastest brain waves and are associated with **higher-level cognitive functions**, such as learning, memory, and information processing across different brain regions. - While present throughout the brain, they are not specifically prominent in the occipital lobe in isolation during baseline resting states. *Beta* - **Beta waves** are characteristic of an **alert, awake state** and are often recorded over the frontal and central regions of the brain. - They are associated with active thinking, problem-solving, and concentration, and tend to be suppressed in the occipital region during rest. *Theta* - **Theta waves** are typically associated with **sleep stages 1 and 2**, as well as deep meditation and certain emotional states. - While they can be observed in various brain regions during specific activities or sleep, they are not primarily prominent in the occipital lobe during awake, relaxed states.

Q: The EEG recorded shown below is normally recordable during which stage of sleep?

Stage II. ***Stage II*** - The provided image is characteristic of **Stage II sleep**, which is defined by the presence of **sleep spindles** and **K-complexes** on the EEG. - Sleep spindles are bursts of rhythmic waves (12-14 Hz in the sigma frequency range), and K-complexes are high-amplitude, biphasic waves, both of which are visible in the tracing and are unique to this stage. *Stage IV* - Stage IV sleep (now often combined with Stage III into N3 sleep) is characterized by a high proportion of **delta waves** (slow-wave sleep), which are high-amplitude, low-frequency (0.5-2 Hz) waves, distinctly different from the activity shown. - This stage represents the deepest sleep, with minimal muscle activity and reduced responsiveness to external stimuli. *Stage III* - Stage III sleep (now often combined with Stage IV into N3 sleep) is characterized by the presence of **20-50% delta waves**, which are slow, high-amplitude waves. - While it is also considered deep sleep, the predominant features in the given EEG, such as sleep spindles and K-complexes, are more indicative of Stage II. *Stage I* - Stage I sleep is the lightest stage of non-REM sleep, characterized by a transition from awake alpha waves to **theta waves** (3-7 Hz). - It lacks the distinct features of sleep spindles and K-complexes that are central to the provided EEG pattern.

Q: All of the following are known functions of hypothalamus except

Increase in heart rate with exercise. ***Increase in heart rate with exercise*** - The **hypothalamus** has an indirect role in cardiovascular responses during exercise, primarily through its influence on the **autonomic nervous system** to maintain homeostasis. - However, the primary control of increased heart rate during exercise originates from the **medulla oblongata** and the **motor cortex**, which directly modulates the sympathetic nervous system to increase cardiac output. *Temperature regulation* - The **hypothalamus** contains thermoregulatory centers that monitor and adjust body temperature through mechanisms such as **sweating** and **shivering**. - This function is a fundamental aspect of maintaining **homeostasis**. *Hypophyseal control* - The **hypothalamus** directly controls the **pituitary gland** (hypophysis) by producing releasing and inhibiting hormones that regulate the secretion of pituitary hormones. - This neuroendocrine function is crucial for controlling various **endocrine axes**. *Food intake* - The **hypothalamus** plays a key role in regulating appetite and satiety, with specific nuclei like the **arcuate nucleus** integrating signals related to hunger and fullness. - This control is essential for maintaining **energy balance**.

Q: Ablation of the somatosensory area I of the cerebral cortex leads to

Loss of tactile localization and two point discrimination. ***Loss of tactile localization and two point discrimination*** - The **somatosensory area I (S1)** is crucial for processing higher-order somatic sensations, including the **discriminative aspects of touch**. - Its ablation leads to deficits in distinguishing distinct points of touch (**two-point discrimination**) and precisely identifying where touch occurred (**tactile localization**). *Loss of tactile localization but not of two point discrimination* - This option incorrectly suggests that **two-point discrimination** would be preserved, which is not the case as S1 is essential for both functions. - While other cortical areas contribute to sensation, S1 is paramount for fine tactile distinctions. *Total loss of pain sensation* - **Pain sensation** is processed across multiple brain regions, including the **thalamus**, **insula**, and **anterior cingulate cortex**, not solely S1. - S1 primarily processes discriminatory aspects of somatosensation, not the affective component of pain. *Total loss of touch sensation* - A total loss of touch sensation implies a complete unawareness of touch, which would require more extensive damage than just S1 ablation, potentially affecting **thalamic pathways** or other cortical regions. - S1 ablation primarily affects the *quality* and *interpretation* of touch, rather than its complete absence.

Q: Which of the following acts as the major neurotransmitter in the substantia nigra?

Dopamine. ***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.

Q: True statement about cerebrospinal fluid is

Maximum secreted by choroid plexus. ***Maximum secreted by choroid plexus*** - The **choroid plexus**, located within the ventricles, is the primary site of cerebrospinal fluid (CSF) production, responsible for approximately **70-80%** of its secretion. - Cells of the choroid plexus actively transport ions and solutes, drawing water into the ventricular system to form CSF. *More in ventricle than in subarachnoid space* - The majority of CSF volume, approximately **120-150 mL**, is found in the **subarachnoid space** surrounding the brain and spinal cord, not within the ventricles. - The ventricles, while producing CSF, serve more as a conduit for its circulation. *Flows from lateral ventricles to 3rd ventricle through aqueduct of sylvius* - CSF flows from the lateral ventricles to the third ventricle through the **foramina of Monro (interventricular foramina)**, not the aqueduct of Sylvius. - The **aqueduct of Sylvius (cerebral aqueduct)** connects the third ventricle to the fourth ventricle. *CSF formation and absorption are equal at 68 mm CSF pressure* - CSF formation and absorption typically achieve equilibrium at a pressure of approximately **130 mm H2O (or about 10 mmHg)** in a recumbent adult, not 68 mm. - Fluctuations outside this range can indicate issues with CSF circulation or absorption.

Q: Mechanical stimulation of the pain-sensitive structures of the brain can cause headache. All of the following are pain-sensitive structures of the brain, EXCEPT?

Choroid plexus. ***Choroid plexus*** - The choroid plexus is primarily involved in the production of **cerebrospinal fluid (CSF)** and does not contain **pain receptors**. - Its stimulation typically does not cause headache, distinguishing it from other structures. *Dural sheath surrounding vascular sinuses* - The dura mater, especially the dural sheath surrounding **venous sinuses** and major arteries, contains numerous **pain-sensitive nerve endings**. - **Distension or traction** on these structures can result in significant pain, contributing to headache. *Falx cerebri* - The **falx cerebri**, a dural fold, is richly innervated and highly **pain-sensitive**. - **Inflammation, traction, or displacement** of the falx can cause severe headache. *Middle meningeal artery* - The **meningeal arteries**, including the middle meningeal artery, are richly supplied with **nociceptive fibers**. - **Vasodilation or inflammation** of these vessels is a common cause of headache, such as in migraines.

Q: A patient came to OPD with a stamping gait. On examination,when he was asked to close his eyes and walk, he fails to walk. Which of the following tracts is most probably affected?

Posterior column tract. ***Posterior column tract*** - A **stamping gait** (high-stepping gait where feet are lifted high and slapped down) combined with inability to walk with eyes closed (positive **Romberg's sign**) indicates loss of **conscious proprioception**. - The **posterior column (dorsal column) tract** carries conscious proprioception, fine touch, and vibration sense from the body to the brain. - Patients compensate for proprioceptive loss using visual input; when eyes are closed, they cannot maintain balance or coordinate movement. *Rubrospinal tract* - Controls **muscle tone** and **fine motor movements**, particularly of distal limb muscles. - Damage causes **flexor posturing** and altered tone, not sensory ataxia or stamping gait. *Vestibulospinal tract* - Maintains **postural stability** and **balance** using vestibular input from the inner ear. - Damage causes imbalance and ataxia, but patients typically have difficulty with balance even with eyes **open**, unlike pure proprioceptive loss where vision compensates. *Spinocerebellar tract* - Carries **unconscious proprioception** to the cerebellum for motor coordination. - Damage causes **cerebellar ataxia** with uncoordinated movements, but Romberg's sign remains **negative** because conscious proprioception (posterior columns) is intact, allowing patients to maintain posture with eyes closed.

Q: The EEG pattern in REM sleep is:

Low amplitude, rapid waves. ***Low amplitude, rapid waves*** - REM sleep is characterized by an **EEG pattern** that is very similar to wakefulness, featuring **desynchronized, low amplitude, high frequency (rapid) waves**. - This pattern reflects high brain activity despite the body being in a state of muscle paralysis (**atonia**), and is often referred to as **paradoxical sleep**. *High amplitude, slow waves* - This EEG pattern, indicative of **delta waves**, is characteristic of **deep non-REM (NREM) sleep** stages 3 and 4 (or N3 in newer classifications). - It signifies a highly synchronized brain state where neuronal firing is slow and highly rhythmic, unlike the active brain state of REM sleep. *Low amplitude, slow waves* - While low amplitude waves can be seen in wakefulness or some lighter NREM stages, the presence of **slow waves** does not align with the highly active and desynchronized nature of REM sleep. - Slow waves are more typical of deeper sleep stages or general drowsiness. *High amplitude, rapid waves* - Although REM sleep involves **rapid waves (high frequency)**, they are typically of **low amplitude**. High amplitude waves suggest synchronization, whereas REM is characterized by desynchronization. - **High amplitude rapid waves** are not a typical EEG characteristic of any sleep stage; rapid waves usually imply lower amplitude due to desynchronization.

Question 1

EEG waves prominent in occipital lobe are

Accepted Answer

Alpha

Answer

Gamma

Answer

Beta

Answer

Theta

Question 2

The EEG recorded shown below is normally recordable during which stage of sleep?

Accepted Answer

Stage II

Answer

Stage IV

Answer

Stage III

Answer

Stage I

Question 3

All of the following are known functions of hypothalamus except

Accepted Answer

Increase in heart rate with exercise

Answer

Temperature regulation

Answer

Hypophyseal control

Answer

Food intake

Question 4

Ablation of the somatosensory area I of the cerebral cortex leads to

Accepted Answer

Loss of tactile localization and two point discrimination

Answer

Loss of tactile localization but not of two point discrimination

Answer

Total loss of pain sensation

Answer

Total loss of touch sensation

Question 5

Which of the following acts as the major neurotransmitter in the substantia nigra?

Accepted Answer

Dopamine

Answer

Serotonin

Answer

Acetylcholine

Answer

Noradrenaline

Question 6

True statement about cerebrospinal fluid is

Accepted Answer

Maximum secreted by choroid plexus

Answer

More in ventricle than in subarachnoid space

Answer

Flows from lateral ventricles to 3rd ventricle through aqueduct of sylvius

Answer

CSF formation and absorption are equal at 68 mm CSF pressure

Question 7

The rigidity seen in Parkinson's disease is due to

Accepted Answer

Loss of dopaminergic inhibition from substantia nigra.

Answer

Excessive stimulation of alpha motor neurons of all the muscles.

Answer

Basal ganglia dysfunction affecting muscle tone regulation.

Answer

Increased sensitivity of stretch reflex.

Question 8

Mechanical stimulation of the pain-sensitive structures of the brain can cause headache. All of the following are pain-sensitive structures of the brain, EXCEPT?

Accepted Answer

Choroid plexus

Answer

Dural sheath surrounding vascular sinuses

Answer

Falx cerebri

Answer

Middle meningeal artery

Question 9

A patient came to OPD with a stamping gait. On examination,when he was asked to close his eyes and walk, he fails to walk. Which of the following tracts is most probably affected?

Accepted Answer

Posterior column tract

Answer

Rubrospinal tract

Answer

Vestibulospinal tract

Answer

Spinocerebellar tract

Question 10

The EEG pattern in REM sleep is:

Accepted Answer

Low amplitude, rapid waves

Answer

High amplitude, slow waves

Answer

Low amplitude, slow waves

Answer

High amplitude, rapid waves

Neurophysiology — MCQs

Neurophysiology — MCQs

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