Neurophysiology Practice Questions

Q: Intracranial pressure is not raised during

Hyperventilation. ***Hyperventilation*** - **Hyperventilation** reduces **PaCO2**, leading to cerebral vasoconstriction and decreased cerebral blood flow, thereby lowering **intracranial pressure (ICP)**. - This is a common maneuver used to temporarily reduce acutely elevated ICP in emergency settings. *Status epilepticus* - **Status epilepticus** significantly increases **cerebral metabolic demand**, leading to increased cerebral blood flow and volume, which can raise **ICP**. - Prolonged seizures can also cause **cerebral edema** due to metabolic disturbances, further contributing to elevated ICP. *Head injury* - **Head injury** frequently causes **brain swelling** (cerebral edema), hematoma formation (extradural, subdural, intraparenchymal), or hydrocephalus, all of which expand intracranial contents and increase **ICP**. - The direct trauma can disrupt the **blood-brain barrier**, leading to vasogenic edema and increased brain volume. *Subdural hematoma* - A **subdural hematoma** is a collection of blood between the dura mater and the arachnoid mater, which acts as a mass lesion within the rigid cranial vault. - This added volume directly increases **intracranial pressure** by occupying space and compressing brain tissue.

Q: What is the maximum duration of time spent in the NREM sleep stage N2?

20-40 minutes. ***20-40 minutes*** - **NREM stage N2** can last up to 20-40 minutes in a single sleep cycle, particularly in the later cycles of the night when N2 episodes become more prolonged. - This stage is characterized by **sleep spindles** and **K-complexes** on EEG, representing consolidated sleep that is deeper than N1 but lighter than N3. - While N2 comprises 45-55% of total sleep time across the entire night, the question asks about maximum duration in a single episode, not cumulative time. *45-60 minutes* - This duration would encompass most of an entire sleep cycle (90-110 minutes), leaving insufficient time for N3 and REM stages. - This likely confuses the **percentage of total sleep time** (45-55%) with the **duration per cycle**. - No single NREM stage typically lasts 45-60 minutes continuously in a normal sleep cycle. *5-10 minutes* - This duration is typical for **NREM stage N1**, the lightest stage of sleep and the transition from wakefulness to sleep. - N1 accounts for only about 5% of total sleep time and is characterized by theta wave activity on EEG. *1-5 minutes* - This represents the **initial entry into sleep (NREM stage N1)** or very brief arousals during the night. - This is far too short to represent the maximum duration of N2, which is a more substantial and prolonged sleep stage.

Q: Which of the following is the primary excitatory neurotransmitter in the central nervous system?

Glutamate. ***Glutamate*** - **Glutamate** is the primary **excitatory neurotransmitter** in the central nervous system - It acts on ionotropic receptors (AMPA, NMDA, kainate) and metabotropic receptors to **depolarize** the postsynaptic membrane - Increases the likelihood of postsynaptic neuron firing by opening ligand-gated ion channels - Plays a crucial role in **synaptic plasticity**, learning, and memory *GABA* - **GABA (gamma-aminobutyric acid)** is the primary **inhibitory neurotransmitter** in the CNS - Hyperpolarizes the postsynaptic membrane by opening chloride channels - Reduces neuronal excitability throughout the brain *Glycine* - **Glycine** is the primary **inhibitory neurotransmitter** in the spinal cord and brainstem - Acts via glycine receptors (chloride channels) leading to hyperpolarization - Important for motor and sensory processing in the spinal cord *Aspartate* - **Aspartate** is also an **excitatory neurotransmitter** acting on NMDA receptors - However, it is **much less abundant** and less important than glutamate - Glutamate is considered the main excitatory neurotransmitter due to its widespread distribution and predominant role

Q: Which of the following is a primary function of the cerebellum?

Coordination of voluntary movements. ***Coordination of voluntary movements*** - The cerebellum plays a crucial role in **coordinating voluntary movements**, ensuring they are smooth, precise, and fluid. - It receives sensory input from the body and motor commands from the cortex, integrating this information to **adjust ongoing movements** for accuracy. - This is considered the **most prominent and primary function** of the cerebellum in clinical and physiological contexts. *Regulation of muscle tone* - The cerebellum **does regulate muscle tone** and is part of the classical triad of cerebellar functions (coordination, equilibrium, and muscle tone). - However, when compared to coordination of voluntary movements, this is considered a **secondary or supporting function**. - Cerebellar lesions typically cause **hypotonia** (reduced muscle tone), demonstrating its role in tone regulation. - In the context of "primary function," coordination takes precedence over tone regulation. *Planning and initiation of movement* - **Planning and initiation of movement** are primarily functions of the **cerebral cortex**, particularly the supplementary motor area and premotor cortex, along with the basal ganglia. - The cerebellum contributes to motor planning but does not initiate the movement itself. *None of the options* - This option is incorrect because the cerebellum has a clear and primary function as described in the correct option.

Q: CSF pressure is increased in all except -

Forced inspiration. ***Forced inspiration*** - During forced inspiration, the **intrathoracic pressure** decreases, which can lead to a slight **reduction** in CSF pressure rather than an increase, by increasing venous return from the head. - This creates a negative pressure gradient that facilitates blood flow from the cranial venous sinuses into the thoracic cavity. *Coughing* - Coughing significantly increases **intrathoracic pressure** and **intra-abdominal pressure**, which in turn impede venous return from the head and increase **intracranial venous pressure**, thereby raising CSF pressure. - This pressure transmission causes a transient but marked surge in CSF pressure. *Valsalva manoeuvre* - The **Valsalva manoeuvre** involves forced expiration against a closed glottis, leading to a significant increase in **intrathoracic** and **intra-abdominal pressures**. - This impedes **venous return** to the heart, causing a rise in **central venous pressure** and subsequently **intracranial venous pressure**, which increases CSF pressure. *Crying* - Crying, particularly vigorous crying, involves sustained **muscle contractions** in the face, neck, and chest, leading to an increase in **intrathoracic pressure** and **venous congestion**. - This rise in venous pressure within the head can cause a temporary increase in **CSF pressure**.

Q: What is the total volume of cerebrospinal fluid (CSF) in an adult human?

150 ml. ***150 ml*** - The total volume of **cerebrospinal fluid (CSF)** in an adult human is approximately 150 ml, distributed within the brain's ventricles, subarachnoid space, and spinal canal. - This volume is constantly replenished; about 500 ml of CSF are produced daily, meaning the entire volume is replaced several times a day. *500 ml* - While 500 ml is the approximate **daily production rate** of CSF, it is not the total static volume present in the central nervous system at any given time. - The CSF is continually produced and reabsorbed, maintaining a circulating volume of about 150 ml. *50 ml* - 50 ml is significantly **lower** than the actual total volume of CSF found in an adult human. - Such a low volume would likely be insufficient to provide adequate **cushioning** and metabolic support for the brain and spinal cord. *800 ml* - 800 ml is an **excessively large** volume for the total CSF in an adult human and would indicate a severe condition of **hydrocephalus**. - This volume is far beyond the normal physiological capacity for circulating CSF.

Q: 'C' fibers carry sensations through which pathway?

Lateral spinothalamic tract. ***Lateral spinothalamic tract*** - **C fibers** are unmyelinated nerve fibers that transmit **slow, dull, burning, or aching pain**, as well as **temperature** sensations. - The **lateral spinothalamic tract** is the primary ascending pathway responsible for conveying these **pain and temperature** sensations from the spinal cord to the brain. *Posterior column* - The **posterior column-medial lemniscus pathway** is primarily responsible for transmitting **fine touch, vibration, conscious proprioception, and two-point discrimination**. - It consists of thickly myelinated A-beta fibers, which are distinct from the unmyelinated C fibers involved in pain transmission. *Anterior spinothalamic tract* - The **anterior spinothalamic tract** mainly carries crude touch and pressure sensations. - While it is a part of the anterolateral system, it does not primarily transmit the pain and temperature signals carried by C fibers. *All of the options* - This option is incorrect because C fibers specifically transmit sensations through the **lateral spinothalamic tract**, not all the listed pathways. - Each pathway has distinct roles in sensory transmission, and C fibers are not associated with the posterior column or exclusively with the anterior spinothalamic tract for their primary functions.

Q: At what gestational age does the swallowing-breathing reflex first appear in the fetus?

16 weeks. ***16 weeks*** - The **swallowing-breathing reflex** is a crucial protective mechanism that ensures coordination between swallowing and breathing to prevent aspiration. - This reflex is considered to fully develop and become consistently observable in the fetus around **16 weeks of gestation**. *14 weeks* - While some rudimentary swallowing movements may be observed earlier, the integrated and mature **swallowing-breathing reflex** is not fully established at 14 weeks. - The coordination required for this reflex is still developing during this period. *12 weeks* - At 12 weeks, the fetal swallowing mechanism is even less mature, and the **swallowing-breathing reflex** is not yet present. - Fetal development at this stage is primarily focused on organogenesis and basic motor functions. *Appear in all above period* - This statement is incorrect because the **swallowing-breathing reflex** has a specific developmental timeline and is not consistently functional at all gestational ages mentioned. - Its full emergence is a hallmark of more mature neuromuscular coordination.

Q: Which of the following is not a sign of upper motor neuron paralysis

Denervation potential in EMG. Denervation potential in EMG - **Denervation potentials** (e.g., fibrillation potentials, positive sharp waves) on electromyography (EMG) are indicative of **lower motor neuron (LMN) damage** and muscle fiber denervation [1]. - This finding suggests that muscle fibers have lost their direct innervation from the spinal cord or motor nerves, which is characteristic of LMN lesions, not UMN lesions [1], [3]. *Babinski sign* - The **Babinski sign** (extensor plantar response) is a classic indicator of **upper motor neuron (UMN) lesion** in adults. - It involves dorsiflexion of the great toe and fanning of the other toes upon stimulation of the sole, reflecting impairment of descending inhibitory pathways. *Spastic paralysis* - **Spastic paralysis** is a hallmark feature of **upper motor neuron (UMN) lesions**, characterized by increased muscle tone, hyperreflexia, and weakness [2], [3]. - This results from the loss of inhibitory control from descending UMN pathways on spinal reflexes [3]. *Exaggeration of tendon reflexes* - **Exaggerated (hyperactive) tendon reflexes** are a common sign of **upper motor neuron (UMN) lesions** [2]. - This occurs due to the release of spinal reflex arcs from the inhibitory modulation normally exerted by descending UMN pathways [2].

Q: While walking or standing, posture is maintained by?

Cerebellum. ***Cerebellum*** - The **cerebellum** plays a crucial role in maintaining **balance and posture** by coordinating muscular activity, regulating muscle tone, and integrating sensory input. - It receives information about planned movements from the motor cortex and current body position from sensory receptors, allowing it to make real-time adjustments for stable locomotion and standing. *Basal ganglia* - The **basal ganglia** are primarily involved in the **initiation and control of voluntary movements**, motor learning, and routine behaviors. - While they influence movement, their direct role in the instantaneous maintenance of posture is less prominent than that of the cerebellum. *Hypothalamus* - The **hypothalamus** is a key brain region for regulating **autonomic functions**, hormone release, and maintaining homeostasis (e.g., body temperature, hunger, thirst). - It does not have a direct or primary role in the control of conscious posture or balance during walking or standing. *Amygdala* - The **amygdala** is a central component of the **limbic system**, primarily involved in processing emotions, particularly fear, and emotional memory. - It has no direct involvement in the motor control mechanisms required for maintaining posture during locomotion.

Question 1

Intracranial pressure is not raised during

Accepted Answer

Hyperventilation

Answer

Status epilepticus

Answer

Head injury

Answer

Subdural hematoma

Question 2

What is the maximum duration of time spent in the NREM sleep stage N2?

Accepted Answer

20-40 minutes

Answer

5-10 minutes

Answer

45-60 minutes

Answer

1-5 minutes

Question 3

Which of the following is the primary excitatory neurotransmitter in the central nervous system?

Accepted Answer

Glutamate

Answer

GABA

Answer

Glycine

Answer

Aspartate

Question 4

Which of the following is a primary function of the cerebellum?

Accepted Answer

Coordination of voluntary movements

Answer

None of the options

Answer

Regulation of muscle tone

Answer

Planning and initiation of movement

Question 5

CSF pressure is increased in all except -

Accepted Answer

Forced inspiration

Answer

Valsalva manoeuvre

Answer

Crying

Answer

Coughing

Question 6

What is the total volume of cerebrospinal fluid (CSF) in an adult human?

Accepted Answer

150 ml

Answer

500 ml

Answer

50 ml

Answer

800 ml

Question 7

'C' fibers carry sensations through which pathway?

Accepted Answer

Lateral spinothalamic tract

Answer

Posterior column

Answer

Anterior spinothalamic tract

Answer

All of the options

Question 8

At what gestational age does the swallowing-breathing reflex first appear in the fetus?

Accepted Answer

16 weeks

Answer

14 weeks

Answer

12 weeks

Answer

Appear in all above period

Question 9

Which of the following is not a sign of upper motor neuron paralysis

Accepted Answer

Denervation potential in EMG

Answer

Babinski sign

Answer

Exaggeration of tendon reflexes

Answer

Spastic paralysis

Question 10

While walking or standing, posture is maintained by?

Accepted Answer

Cerebellum

Answer

Basal ganglia

Answer

Hypothalamus

Answer

Amygdala

Neurophysiology — MCQs

Neurophysiology — MCQs

On this page

Practice by Chapter

Want unlimited practice?