Neurophysiology Practice Questions

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: 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: Which receptor is primarily associated with Brain-Derived Neurotrophic Factor (BDNF)?

TrkB receptor (Tropomyosin receptor kinase B). ***TrkB receptor (Tropomyosin receptor kinase B)*** - The **TrkB receptor** is the primary high-affinity receptor for **Brain-Derived Neurotrophic Factor (BDNF)**. - Activation of TrkB by BDNF plays a crucial role in neuronal survival, differentiation, and synaptic plasticity. *TrkC receptor (Tropomyosin receptor kinase C)* - The **TrkC receptor** primarily binds to **Neurotrophin-3 (NT-3)**, not BDNF. - It is involved in the development and function of proprioceptive neurons. *TrkA receptor (Tropomyosin receptor kinase A)* - The **TrkA receptor** is the main high-affinity receptor for **Nerve Growth Factor (NGF)**. - It is essential for the survival and differentiation of sympathetic and sensory neurons. *p75NTR receptor (Low-affinity neurotrophin receptor)* - The **p75NTR receptor** binds to all neurotrophins, including BDNF, but with **low affinity**. - It often functions as a co-receptor with Trk receptors, modulating their signaling, or can initiate independent signaling pathways, sometimes leading to apoptosis.

Q: Which is not an extrapyramidal tract?

Corticospinal tract. ***Corticospinal tract*** - The **corticospinal tract** is the primary component of the **pyramidal system**, directly mediating voluntary, skilled movements. - It originates in the cerebral cortex and descends through the medullary pyramids, distinguishing it from extrapyramidal tracts which primarily modulate movement indirectly. *Reticulospinal tract* - The reticulospinal tract is a major **extrapyramidal tract** involved in controlling **posture, balance**, and **muscle tone**. - It originates in the brainstem reticular formation, mediating movements below the level of conscious control. *Rubrospinal tract* - The rubrospinal tract is an **extrapyramidal tract** that originates in the **red nucleus** and contributes to the control of **flexor muscle tone** and fine motor movements. - It plays a role in coordinating upper limb movements, particularly in the distal musculature. *Tectospinal tract* - The tectospinal tract is an **extrapyramidal tract** originating in the **superior colliculus** of the midbrain. - It is primarily involved in mediating **reflexive head and neck movements** in response to visual and auditory stimuli.

Q: Feed forward inhibition synapse is seen in:

Cerebellum. ***Cerebellum*** - The **cerebellum** is well-known for its role in motor control and learning, utilizing intricate neural circuits, including **feedforward inhibition**. - **Granule cells** excite **Purkinje cells** (the output neurons of the cerebellar cortex) and also excite **Golgi cells**, which then inhibit granule cells, creating a feedforward inhibitory loop to regulate granule cell activity. *Medulla* - The **medulla oblongata** is primarily involved in vital autonomic functions like respiration, heart rate, and blood pressure, and typically features different types of neural circuits. - While inhibition is crucial in medullary circuits, the prominent **feedforward inhibitory synapse** structure described in motor control is not its defining characteristic. *Basal ganglia* - The **basal ganglia** are involved in voluntary motor control, procedural learning, and habit formation, characterized by direct and indirect pathways that are largely modulatory. - While it has complex inhibitory and excitatory loops, the specific architecture of a **feedforward inhibitory synapse** that modulates the same input neuron, as seen in the cerebellum, is not its primary organizational principle. *Hypothalamus* - The **hypothalamus** is a key control center for endocrine and autonomic functions, regulating things like hunger, thirst, and body temperature. - Its neural circuitry is focused on hormonal regulation and homeostatic control, rather than elaborate motor coordination networks that prominently feature **feedforward inhibition** for precise timing.

Q: Where is the primary reward center located in the brain?

Nucleus Accumbens. ***Nucleus Accumbens*** - The **nucleus accumbens** is a crucial part of the **ventral striatum** and is a primary component of the brain's **reward system**. - It plays a central role in processing motivation, pleasure, and reinforcement learning, especially regarding **reward-seeking behaviors**. *Amygdala* - The **amygdala** is primarily involved in processing **emotions**, especially fear and anxiety [2]. - While it interacts with reward pathways, its main role is not as the primary reward center but rather in emotional learning and memory [2]. *Hippocampus* - The **hippocampus** is critical for **memory formation** and spatial navigation [1]. - It plays a role in contextual memory related to rewards but is not the primary site for reward processing itself [1]. *Cerebellum* - The **cerebellum** is largely involved in **motor control**, coordination, balance, and fine-tuning movements. - While it has been implicated in certain cognitive functions, it is not considered part of the brain's primary reward system.

Q: Noradrenaline is the major neurotransmitter in?

Postganglionic sympathetic fibers, except in sweat glands. **Postganglionic sympathetic fibers, except in sweat glands** - **Noradrenaline** (norepinephrine) is the primary neurotransmitter released by most **postganglionic sympathetic nerve fibers**. - An important exception is the **sweat glands**, where postganglionic sympathetic fibers release **acetylcholine**. *Postganglionic parasympathetic fibres* - **Acetylcholine** is the major neurotransmitter released by all **postganglionic parasympathetic fibers**. - These fibers are part of the "rest and digest" system, mediating responses like reduced heart rate and increased digestive activity. *Autonomic ganglia* - **Acetylcholine** is the neurotransmitter released by both sympathetic and parasympathetic **preganglionic neurons** onto nicotinic receptors in the autonomic ganglia. - These ganglia act as relay stations, where preganglionic neurons synapse with postganglionic neurons. *Preganglionic autonomic fibres* - All **preganglionic sympathetic** and **preganglionic parasympathetic fibers** release **acetylcholine** as their neurotransmitter. - These fibers originate in the central nervous system and synapse in autonomic ganglia.

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

CSF pressure is increased in all except -

Accepted Answer

Forced inspiration

Answer

Valsalva manoeuvre

Answer

Crying

Answer

Coughing

Question 2

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 3

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 4

Which receptor is primarily associated with Brain-Derived Neurotrophic Factor (BDNF)?

Accepted Answer

TrkB receptor (Tropomyosin receptor kinase B)

Answer

TrkC receptor (Tropomyosin receptor kinase C)

Answer

TrkA receptor (Tropomyosin receptor kinase A)

Answer

p75NTR receptor (Low-affinity neurotrophin receptor)

Question 5

Which is not an extrapyramidal tract?

Accepted Answer

Corticospinal tract

Answer

Reticulospinal tract

Answer

Tectospinal tract

Answer

Rubrospinal tract

Question 6

Feed forward inhibition synapse is seen in:

Accepted Answer

Cerebellum

Answer

Medulla

Answer

Basal ganglia

Answer

Hypothalamus

Question 7

Which of the following statements about cerebellar neuronal connections is correct?

Accepted Answer

Climbing fibers originate from the inferior olivary nucleus and project to Purkinje cells.

Answer

Mossy fibers provide inhibitory input to granule cells.

Answer

Climbing fibers provide inhibitory input to Purkinje cells.

Answer

Mossy fibers originate only from the pontine nuclei and synapse with Purkinje cells.

Question 8

Where is the primary reward center located in the brain?

Accepted Answer

Nucleus Accumbens

Answer

Amygdala

Answer

Hippocampus

Answer

Cerebellum

Question 9

Noradrenaline is the major neurotransmitter in?

Accepted Answer

Postganglionic sympathetic fibers, except in sweat glands

Answer

Postganglionic parasympathetic fibres

Answer

Autonomic ganglia

Answer

Preganglionic autonomic fibres

Question 10

While walking or standing, posture is maintained by?

Accepted Answer

Cerebellum

Answer

Basal ganglia

Answer

Hypothalamus

Answer

Amygdala

Neurophysiology — MCQs

Neurophysiology — MCQs

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