Neurophysiology Practice Questions

Q: In a normal awake person at rest with eyes closed, EEG waves that are reduced on opening the eyes:

Alpha waves. ### **Explanation** The correct answer is **Alpha waves**. #### **1. Why Alpha Waves are Correct** * **Alpha waves (8–13 Hz)** are the characteristic rhythm of a **relaxed, awake adult** with **eyes closed**. They are most prominent in the **parieto-occipital** regions. * The phenomenon described in the question is known as **Alpha Block** or **Desynchronization**. When the person opens their eyes or engages in focused mental activity (like solving a math problem), the synchronized alpha rhythm is replaced by fast, irregular, low-voltage activity. This happens because visual input "breaks" the synchronized firing of cortical neurons. #### **2. Why Other Options are Incorrect** * **Beta waves (13–30 Hz):** These are seen during **active thinking**, alertness, or tension. Opening the eyes usually *increases* beta activity rather than reducing it. * **Theta waves (4–7 Hz):** These are normal in **children** or during **Stage N1 sleep** in adults. In an awake adult, they may indicate emotional stress or certain brain disorders. * **Delta waves (<4 Hz):** These are the slowest waves with the highest amplitude. They are characteristic of **deep sleep (Stage N3)** or infancy. Their presence in an awake adult signifies serious organic brain disease. #### **3. High-Yield Clinical Pearls for INI-CET** * **Mnemonic for EEG Frequencies:** **D**on't **T**ouch **A**ll **B**uttons (**D**elta < **T**heta 2 microvolts is recorded.

Q: Which wave is seen in the given EEG recording?

Delta waves. ***Delta waves*** - The highlighted EEG activity shows **large amplitude, low-frequency waves** (typically 0.5-4 Hz), which are characteristic of delta waves. - Delta waves are normally associated with **deep sleep** (NREM stage 3) or **pathological conditions** in awake adults, indicating significant brain dysfunction. *Alpha waves* - Alpha waves have a frequency range of **8-13 Hz** and typically appear when an individual is in a relaxed, awake state with eyes closed. - The waves in the image are much slower and higher in amplitude than typical alpha waves. *Beta waves* - Beta waves are characterized by a higher frequency range of **14-30 Hz** and are associated with active thinking, alertness, and concentration. - The observed activity is significantly slower and higher in amplitude than beta waves. *Epsilon wave* - The term "epsilon wave" is not a standard classification for EEG brain waves in the context of normal or common pathological activity, unlike alpha, beta, theta, and delta waves. - In cardiology, "epsilon wave" refers to a specific finding on an ECG in **Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)**, not an EEG.

Q: Name the interneuron marked X in colour purple involved in tetanus. (Recent NEET Pattern 2016-17)

Renshaw cell. ***Renshaw cell*** - The image depicts a **Renshaw cell (X)**, which is an **inhibitory interneuron** in the spinal cord, regulating motor neuron activity. - In tetanus, the toxin **tetanospasmin** inhibits the release of neurotransmitters (glycine and GABA) from Renshaw cells, leading to **uncontrolled muscle spasms**. *Basket cell* - **Basket cells** are found in the **cerebellar cortex** and hippocampus, playing a role in inhibiting Purkinje cell activity. - They are not located in the spinal cord gray matter in the position marked X. *Purkinje cell* - **Purkinje cells** are large, distinctive neurons found exclusively in the **cerebellar cortex**, crucial for motor coordination. - They are not present in the spinal cord and are not interneurons in the context of spinal reflexes. *Anterior horn cell* - **Anterior horn cells** are **motor neurons** whose cell bodies reside in the anterior horn of the spinal cord and directly innervate skeletal muscles. - They are not interneurons; rather, they are the target of regulation by interneurons like Renshaw cells.

Q: In the image shown below, which of the marked area is involved in relieving pain in response to massage?

Area A. ***A*** - Area A points to the **dorsal columns** (specifically the fasciculus gracilis and cuneatus) of the spinal cord, which carry **mechanoreceptive** and proprioceptive information. - Massage activates large diameter afferent fibers which transmit signals via the dorsal columns, inhibiting pain transmission through the **gate control theory of pain**. *B* - Area B points to the **dorsal horn** (specifically lamina I, II, and V), which is primarily involved in receiving and processing **nociceptive input**. - While integration of pain occurs here, it is not the primary pathway for the **modulatory effects of touch/pressure** from massage for pain relief. *C* - Area C indicates the **ventral horn** of the spinal cord, which contains **motor neurons** that control skeletal muscle activity. - It is involved in motor output, not directly in the sensory processing or modulation of pain signals from massage. *D* - Area D points to the **lateral white matter**, which contains various ascending and descending tracts, including the **spinothalamic tract** (primary pain pathway) and corticospinal tract. - While the spinothalamic tract carries pain signals, the direct pain-relieving effect of massage primarily involves activation of mechanoreceptors whose signals ascend via the dorsal columns.

Q: The following electrical recording is known as:

Visual evoked potential (VEP). ***Visual evoked potential (VEP)*** - The image displays a checkerboard pattern stimulus and recordings from electrodes placed on the scalp, which are characteristic components of a **visual evoked potential** test. - The graph shows a "Normal recording" and a "Multiple sclerosis recording," indicating how demyelination affects the conduction time of visual pathways, a key application of VEP studies. *Electroencephalogram (EEG)* - An EEG records the brain's **spontaneous electrical activity** over time, typically showing rhythms like alpha, beta, theta, and delta waves. - While it uses scalp electrodes, it does not involve specific sensory stimulation like a checkerboard pattern to evoke a response. *Electromyogram (EMG)* - An EMG measures the electrical activity of **muscles** in response to nerve stimulation or during voluntary contraction. - It involves needle electrodes inserted into muscles and is used to diagnose muscle and nerve disorders, not visual pathway integrity. *Nerve conduction study (NCS)* - An NCS measures how fast electrical signals travel along **nerves** in the limbs to assess their function. - It typically involves stimulating a peripheral nerve and recording the response from a muscle or nerve further along the pathway, which is distinct from the visual pathway assessment shown.

Q: A polysomnography is performed on a patient. Based on the provided EEG, EOG, and EMG findings, which stage of sleep is indicated? (Image: img-182.jpeg)

NREM 2. ***NREM 2*** - This stage is characterized by the presence of **sleep spindles** (bursts of brain activity) and **K-complexes** (large, slow waves) on the EEG. - The EOG typically shows **no significant eye movement**, and the EMG registers **lower muscle tension** compared to wakefulness or NREM 1. *NREM 1* - This initial stage of sleep is marked by the appearance of **theta waves** on the EEG and a reduction in alpha wave activity. - The EOG often shows **slow, rolling eye movements**, and the EMG indicates slightly **reduced muscle tone** compared to the wake state. *NREM 3* - Often referred to as **deep sleep** or slow-wave sleep, this stage is characterized by a significant presence of **delta waves** (high amplitude, low frequency) on the EEG, comprising 20-50% of the epoch. - Eye movements are **minimal or absent** on EOG, and muscle tension on EMG is **lower** than in NREM 2 but still present. *REM* - This stage is distinguished by **rapid eye movements** (REMs) observed on the EOG and a characteristic **sawtooth pattern** or low-voltage, mixed-frequency activity on the EEG. - A key feature of REM sleep is **atonia** (paralysis of skeletal muscles), resulting in the **lowest muscle tone** on the EMG, often appearing as a flat line.

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.

Question 1

In a normal awake person at rest with eyes closed, EEG waves that are reduced on opening the eyes:

Accepted Answer

Alpha waves

Answer

Theta waves

Answer

Beta waves

Answer

Delta waves

Question 2

Which wave is seen in the given EEG recording?

Accepted Answer

Delta waves

Answer

Alpha waves

Answer

Beta waves

Answer

Epsilon wave

Question 3

Name the interneuron marked X in colour purple involved in tetanus. (Recent NEET Pattern 2016-17)

Accepted Answer

Renshaw cell

Answer

Basket cell

Answer

Purkinje cell

Answer

Anterior horn cell

Question 4

In the image shown below, which of the marked area is involved in relieving pain in response to massage?

Accepted Answer

Area A

Answer

Area B

Answer

Area C

Answer

Area D

Question 5

The following electrical recording is known as:

Accepted Answer

Visual evoked potential (VEP)

Answer

Electroencephalogram (EEG)

Answer

Electromyogram (EMG)

Answer

Nerve conduction study (NCS)

Question 6

A polysomnography is performed on a patient. Based on the provided EEG, EOG, and EMG findings, which stage of sleep is indicated? (Image: img-182.jpeg)

Accepted Answer

NREM 2

Answer

NREM 1

Answer

NREM 3

Answer

REM

Question 7

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 8

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 9

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 10

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

Neurophysiology — MCQs

Neurophysiology — MCQs

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