Neurophysiology Practice Questions

Q: What are the effects of a lesion in Brodmann area 22?

Receptive aphasia. ***Receptive aphasia*** - A lesion in **Brodmann area 22**, specifically in **Wernicke's area**, leads to **receptive aphasia** (Wernicke's aphasia). - This condition is characterized by **impaired comprehension** of spoken and written language, **fluent but paraphasic speech**, and **poor repetition**. - This is the most comprehensive answer as it describes the entire clinical syndrome. *Expressive aphasia* - **Brodmann areas 44 and 45** (Broca's area) in the frontal lobe are associated with expressive aphasia (Broca's aphasia). - Patients have good comprehension but struggle to produce fluent speech, with effortful, telegraphic output. *Poor repetition of language* - While poor repetition is indeed a feature of Wernicke's aphasia, this option describes only one component of the syndrome rather than the complete clinical picture. - **Conduction aphasia** (from arcuate fasciculus lesions) is characterized by poor repetition with **relatively preserved** comprehension and fluent speech, distinguishing it from Wernicke's aphasia. - "Receptive aphasia" is the more complete answer. *Poor naming* - Difficulty with naming, or **anomia**, is a common feature across various types of aphasia, including both receptive and expressive aphasia. - It reflects disruption in language networks involving the **temporal and parietal lobes** but is not specific to Brodmann area 22 lesions.

Q: During polysomnography, which stage of sleep is represented by the marked areas when observing the following wave patterns? EOG (Electrooculography) EEG (Electroencephalography) EMG (Electromyography)

NREM I sleep. ***NREM I sleep*** - This stage is characterized by a transition from wakefulness to sleep, identifiable by the appearance of **slow eye movements** in the EOG and a reduction in EEG frequency with the presence of **theta waves**. - The EMG shows a decrease in muscle tone but without the complete atonia seen in REM sleep. *REM sleep* - **Rapid eye movements** are characteristic in the EOG, and the EEG shows **low-amplitude, mixed-frequency waves** similar to wakefulness. - The EMG would display profound muscle atonia, which is not evident in the provided tracing. *NREM II sleep* - This stage is marked by the presence of **sleep spindles** and **K-complexes** in the EEG, which are absent in the marked area. - Eye movements are generally absent, and muscle activity continues to be low. *NREM III sleep* - This is the deepest stage of sleep, characterized by **high-amplitude, slow-delta waves** (20-50% of the epoch) in the EEG. - Eye movements are typically absent, and muscle tone is very low but not completely absent.

Q: A woman with right-sided loss of sensations of both the upper and lower limb complains of shooting pain from her fingers to the right shoulder and a burning sensation when touching cold water. Motor functions are normal. Which of the following structures is likely to be involved?

Lateral spinothalamic tract. ***Lateral spinothalamic tract*** - The symptoms described, such as **loss of sensations**, **shooting pain** (neuropathic pain), and **burning sensation** with cold water (dysesthesia/allodynia), are characteristic of damage to the **spinothalamic tract**, which carries **pain and temperature** sensations. - Involvement of the **right-sided upper and lower limb** indicates a lesion affecting sensory pathways on the ipsilateral side of the body before decussation, or more commonly a contralateral lesion above the level of decussation for the specific tract. Given the symptoms affecting pain and temperature, the lateral spinothalamic tract is the primary candidate. *Anterior spinothalamic tract* - This tract primarily transmits **crude touch** and **pressure** sensations. - While loss of sensation is present, the prominent **shooting pain** and **burning sensation with cold water** are not typically associated with isolated anterior spinothalamic tract lesions. *Spinocerebellar tract* - This tract is responsible for transmitting **proprioceptive information** to the cerebellum for motor coordination. - Damage to the spinocerebellar tracts would manifest as **ataxia** and **incoordination**, not pain or loss of touch/temperature sensation, and motor functions are stated as normal in the patient. *Posterior column* - The posterior column (dorsal column-medial lemniscus pathway) transmits **fine touch**, **vibration**, and **proprioception**. - While a loss of sensation is present, the specific complaints of **shooting pain** and **burning sensation to cold water** are not characteristic of posterior column damage, which would typically present with deficits in discriminative touch, vibratory sense, and position sense.

Q: Which change in CSF production most directly affects intracranial pressure?

Decreased carbonic anhydrase activity. ***Decreased carbonic anhydrase activity*** - The **choroid plexus** produces CSF primarily through an active secretion process involving carbonic anhydrase. - Decreased activity of this enzyme directly reduces the formation of **bicarbonate ions** and **protons (H+)**, which are crucial for the active transport of Na+ and Cl- into the CSF, thereby lowering CSF production and subsequently **intracranial pressure**. *Decreased arachnoid granulation function* - This change would lead to a **decreased reabsorption** of CSF, which would *increase* intracranial pressure, not directly affect production to lower it. - Arachnoid granulations are responsible for the **resorption of CSF** into the venous system. *Increased choroid plexus blood flow* - While increased blood flow could potentially increase the delivery of substrates for CSF production, it is **not the most direct or primary determinant** of CSF production rate. - CSF production is predominantly an **active secretory process**, not a passive filtration process dependent solely on blood flow. *Increased osmotic gradient* - An increased osmotic gradient, if referring to a higher osmolality in the CSF compared to plasma, would tend to **draw water into the CSF**, potentially *increasing* CSF volume and intracranial pressure. - If referring to a gradient drawing water *out* of the CSF, it would *decrease* intracranial pressure but is not a primary mechanism of CSF production regulation.

Q: Which receptor type mediates the slow phase of synaptic transmission in autonomic ganglia?

Muscarinic (M1). ***Muscarinic (M1)*** - **M1 receptors** are **Gq-protein coupled receptors** that activate phospholipase C, leading to increased intracellular calcium and diacylglycerol, which mediates the slow excitatory postsynaptic potential in autonomic ganglia. - This activation results in a **slow depolarization** that prolongs the excitability of ganglionic neurons after the initial fast synaptic transmission. *Muscarinic (M3)* - **M3 receptors** are primarily found on **smooth muscle**, glands, and endothelium, mediating contraction, secretion, and vasodilation, respectively. - While also **Gq-protein coupled**, their role in autonomic ganglia is not the main mediator of the slow phase of synaptic transmission. *Muscarinic (M2)* - **M2 receptors** are **Gi-protein coupled receptors** mainly found in the heart, mediating decreased heart rate and contractility. - In autonomic ganglia, M2 receptors could have a modulatory role, but they are not responsible for the slow excitatory phase of synaptic transmission. *Nicotinic (N2)* - **Nicotinic N2 receptors** (also known as **NN or neuronal nicotinic receptors**) mediate the **fast excitatory postsynaptic potential** (EPSP) in autonomic ganglia by opening ion channels. - This leads to rapid depolarization and action potential generation, which is distinct from the **slower, prolonged phase** of transmission.

Q: Which muscle tendon is stretched in patellar tendon reflex?

Quadriceps femoris. ***Quadriceps femoris*** - The patellar tendon reflex is an example of a **stretch reflex**, where striking the patellar tendon directly stretches the quadriceps femoris muscle. - This stretch activates **muscle spindles** within the quadriceps, leading to its contraction and subsequent leg extension. *Biceps femoris* - The biceps femoris is part of the **hamstring muscle group**, located on the posterior aspect of the thigh. - Its primary action is **knee flexion** and hip extension, and it is not directly stretched during the patellar tendon reflex. *Semitendinosus* - The semitendinosus is also a **hamstring muscle** and functions in knee flexion and hip extension. - It is located medially on the posterior thigh and is not involved in the patellar tendon reflex arc. *Adductor magnus* - The adductor magnus is a large muscle on the **medial side of the thigh**, primarily responsible for **hip adduction**. - It is not directly stretched by tapping the patellar tendon and does not participate in the patellar reflex.

Q: The primary dopaminergic reward center in the brain is?

Ventral tegmental area. ***Ventral tegmental area*** - The **ventral tegmental area (VTA)** is a key component of the mesolimbic dopamine system, often referred to as the **reward pathway** in the brain. - It projects dopamine neurons to various areas, including the **nucleus accumbens** and prefrontal cortex, mediating feelings of pleasure and reward. *Hippocampus* - The **hippocampus** is primarily involved in **memory formation** and spatial navigation. - While it interacts with reward pathways, it is not the primary dopaminergic reward center itself. *Amygdala* - The **amygdala** is critical for processing **emotions**, particularly fear and aggression, and plays a role in emotional memory. - It modulates reward responses but is not the primary source of dopaminergic reward signaling. *Thalamus* - The **thalamus** acts as a **relay station** for sensory information, directing it to appropriate cortical areas. - It has diverse functions but is not recognized as the central dopaminergic reward area.

Q: Which of the following has small representation in somatosensory area of cerebral cortex -

Trunk. ***Trunk*** - The representation size in the **somatosensory cortex** is proportional to the **density of sensory receptors** and the importance of sensory feedback from that body part, not its physical size. - The trunk, while large in physical size, has a relatively **sparse distribution of specialized sensory receptors** compared to areas like the hands, lips, or tongue, thus leading to a smaller cortical representation. *Lips* - The lips have an **extremely high density of touch receptors** and are critical for fine sensory discrimination, speech, and feeding. - This high sensory innervation results in a **very large representation** in the somatosensory cortex. *Thumb/fingers* - The thumb and fingers are crucial for **fine motor manipulation**, complex tactile exploration, and detailed sensory feedback. - They possess a **very rich supply of mechanoreceptors**, leading to a disproportionately large cortical area dedicated to their sensation. *Tongue* - The tongue is vital for **taste perception, speech articulation**, and manipulating food during chewing and swallowing. - Its diverse sensory functions and high receptor density ensure a **significant representation** within the somatosensory cortex.

Q: Which of the following is not carried in dorsal column of spinal cord:

Heat sensation. ***Heat sensation*** - **Heat sensation** is primarily transmitted via the **spinothalamic tracts** (specifically the lateral spinothalamic tract), not the dorsal column. - The spinothalamic tracts are responsible for transmitting **pain** and **temperature** information. *Vibratory sense* - **Vibratory sense** is a type of mechanoreception and is indeed carried by the **dorsal column-medial lemniscus pathway**. - This pathway is responsible for several forms of discriminative touch and proprioception. *Proprioception* - **Proprioception**, the sense of body position and movement, is a key sensory modality transmitted through the **dorsal column**. - It involves information from **muscle spindles** and **Golgi tendon organs**. *Touch* - While "touch" is a broad term, **discriminative touch** (e.g., fine touch, two-point discrimination) is carried in the **dorsal column**. - **Crude touch** (non-discriminative touch) is transmitted via the **anterior spinothalamic tract**.

Question 1

A patient is experiencing phantom limb pain after the amputation of the right limb. What is observed on a PET scan in a patient with phantom limb pain?

Accepted Answer

Neighboring cortical areas extending into the hand representation area

Answer

Expansion of right somatosensory cortex

Answer

Expansion of hand representation in the left somatosensory cortex into neighboring areas

Answer

General expansion of left somatosensory cortex

Question 2

What are the effects of a lesion in Brodmann area 22?

Accepted Answer

Receptive aphasia

Answer

Expressive aphasia

Answer

Poor repetition of language

Answer

Poor naming

Question 3

During polysomnography, which stage of sleep is represented by the marked areas when observing the following wave patterns?

EOG (Electrooculography)
EEG (Electroencephalography)
EMG (Electromyography)

Accepted Answer

NREM I sleep

Answer

REM sleep

Answer

NREM II sleep

Answer

NREM III sleep

Question 4

A woman with right-sided loss of sensations of both the upper and lower limb complains of shooting pain from her fingers to the right shoulder and a burning sensation when touching cold water. Motor functions are normal. Which of the following structures is likely to be involved?

Accepted Answer

Lateral spinothalamic tract

Answer

Anterior spinothalamic tract

Answer

Spinocerebellar tract

Answer

Posterior column

Question 5

Which change in CSF production most directly affects intracranial pressure?

Accepted Answer

Decreased carbonic anhydrase activity

Answer

Decreased arachnoid granulation function

Answer

Increased choroid plexus blood flow

Answer

Increased osmotic gradient

Question 6

Which receptor type mediates the slow phase of synaptic transmission in autonomic ganglia?

Accepted Answer

Muscarinic (M1)

Answer

Muscarinic (M3)

Answer

Muscarinic (M2)

Answer

Nicotinic (N2)

Question 7

Which muscle tendon is stretched in patellar tendon reflex?

Accepted Answer

Quadriceps femoris

Answer

Biceps femoris

Answer

Semitendinosus

Answer

Adductor magnus

Question 8

The primary dopaminergic reward center in the brain is?

Accepted Answer

Ventral tegmental area

Answer

Hippocampus

Answer

Amygdala

Answer

Thalamus

Question 9

Which of the following has small representation in somatosensory area of cerebral cortex -

Accepted Answer

Trunk

Answer

Lips

Answer

Thumb/fingers

Answer

Tongue

Question 10

Which of the following is not carried in dorsal column of spinal cord:

Accepted Answer

Heat sensation

Answer

Vibratory sense

Answer

Proprioception

Answer

Touch

Neurophysiology — MCQs

Neurophysiology — MCQs

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