Neurophysiology Practice Questions

Q: Which of the following is an example of explicit memory?

Semantic. ***Semantic*** - **Semantic memory** is a type of **explicit memory** that stores general knowledge and facts about the world, such as the capital of France or the meaning of words. - It is a form of **declarative memory** because it involves conscious recall of information. *Procedural* - **Procedural memory** is a type of **implicit memory** involving the recall of how to do things, like riding a bike or tying a shoelace. - This type of memory is often acquired through repetition and is not consciously recalled in the same way as explicit memories. *Nondeclarative* - **Nondeclarative memory** is another term for **implicit memory**, which includes procedural memory, classical conditioning, and priming. - It is characterized by unconscious recall and influences behavior without conscious awareness. *Working* - **Working memory** is a system for temporarily holding and manipulating information needed for cognitive tasks. - While it involves conscious processing, it is distinct from long-term explicit memories that are *stored* and *retrieved*; it's more about active maintenance than long-term recall.

Q: Alpha block on EEG is typically observed during which of the following activities?

Concentrating. ***Concentrating*** - **Alpha rhythm** (8-13 Hz) is strongest in the **posterior regions** of the brain during quiet wakefulness with closed eyes. - When a person opens their eyes or engages in mental activity like concentrating, the alpha rhythm **attenuates or disappears**, a phenomenon known as alpha blocking or **alpha desynchronization**. *Sleep* - During sleep, the EEG activity changes from alpha to slower rhythms like **theta** (4-7 Hz) and **delta** (0.5-3 Hz), along with the appearance of sleep spindles and K-complexes. - **Alpha waves diminish** significantly or are entirely absent, substituted by these other waveforms. *Seizures* - Seizures are characterized by **abnormal, hypersynchronous neuronal activity**, which manifests on EEG as abrupt changes in frequency, amplitude, and morphology, such as **spikes and sharp waves**, or generalized spike-and-wave discharges. - While alpha rhythms might be present in the interictal period, the ictal phase shows distinct, abnormal activity, not normal alpha blocking. *None of the options* - This option is incorrect because alpha block is a well-described phenomenon associated with specific mental states. - **Concentrating** directly causes the attenuation of alpha rhythms.

Q: Bilateral ablation of which of the following structures results in the inability to form long-term memories?

Hippocampus. ***Hippocampus*** - The **hippocampus** is a crucial brain structure involved in the consolidation of short-term memories into **long-term memories**, particularly declarative (facts and events) memory. - Bilateral ablation of the hippocampus results in **anterograde amnesia**, the inability to form new long-term memories after the injury, while remote memories may remain intact. *Amygdala* - The **amygdala** is primarily involved in processing and regulating **emotions**, especially fear and aggression, and in emotional memory. - While it contributes to emotionally charged memories, its bilateral damage does not typically cause the inability to form new general long-term memories. *Cingulate gyrus* - The **cingulate gyrus** plays a role in various functions including emotion, learning, and memory, but it's more involved in the emotional component of memory and **attention**. - Its bilateral ablation would not primarily result in a complete inability to form new long-term memories, but rather could affect emotional responses and learning. *Hypothalamus* - The **hypothalamus** is essential for maintaining **homeostasis**, regulating functions like body temperature, hunger, thirst, and hormone release. - While it influences motivated behaviors that can impact memory, its direct ablation does not primarily lead to a deficit in long-term memory formation.

Q: Which of the following substances cannot cross the blood-brain barrier?

Large protein molecule. ***Large protein molecule*** - The **blood-brain barrier (BBB)** is formed by tight junctions between endothelial cells, which restrict the passage of large molecules. - Large protein molecules **cannot easily diffuse** across these tight junctions and active transport mechanisms for such molecules are limited. *Glucose* - Glucose is essential for the brain's metabolism and actively crosses the BBB via **glucose transporters (GLUT1)** found on endothelial cells. - This active transport ensures a continuous supply of energy to the brain. *Oxygen* - Oxygen is a **small, lipid-soluble gas** that readily diffuses across the cell membranes of the BBB endothelial cells. - Its passage is crucial for **neuronal aerobic respiration**. *Lipophilic drug* - **Lipid-soluble (lipophilic) drugs** can easily dissolve in the lipid bilayer of the BBB endothelial cells and passively diffuse across the barrier. - This property is often exploited in drug design to target the central nervous system.

Q: Which one of the following phenomena is closely associated with slow-wave sleep?

Sleepwalking. ***Sleepwalking*** - **Sleepwalking** (somnambulism) is a **parasomnia** that typically occurs during **slow-wave sleep (SWS)**, particularly in stages N3. - During SWS, the brain waves are slow, and the body's motor systems can still be active, leading to complex behaviors like walking while asleep. *Dreaming* - While dreams can occur in all sleep stages, **vivid and elaborate dreams** are most strongly associated with **REM (rapid eye movement) sleep**. - Dreams in **SWS** tend to be less vivid, more fragmented, and less emotionally charged. *Atonia* - **Atonia**, or muscle paralysis, is a hallmark feature of **REM sleep**, which prevents individuals from acting out their dreams. - In contrast, **muscle tone is typically maintained** during slow-wave sleep. *Irregular heart rate* - An **irregular heart rate** can be a feature of **REM sleep**, where autonomic nervous system activity is highly variable alongside rapid eye movements. - During **slow-wave sleep**, physiological functions such as heart rate tend to be **slowed and regular**, reflecting deep relaxation.

Q: A 72-year-old woman with insomnia participates in a sleep study. As part of the study protocol, she has EEG leads attached, then goes to sleep. At one point during the evening, 12-16 Hz sleep spindles and K-complexes are observed. Which stage of sleep is associated with this pattern?

Stage 2. ***Stage 2*** - **Sleep spindles** (12-16 Hz bursts) and **K-complexes** (high-amplitude negative deflection followed by a positive component) are the definitive EEG markers of **Stage 2 non-REM sleep**. - This stage represents a deeper level of sleep than Stage 1, where the body begins to relax more, and eye movements cease. *REM* - **REM sleep** is characterized by low-voltage, mixed-frequency EEG activity resembling wakefulness, along with **rapid eye movements** and muscle atonia. - While dreaming is prevalent during REM, **sleep spindles** and **K-complexes** are notably absent. *Stage 1* - **Stage 1 (N1 non-REM sleep)** is the transition from wakefulness to sleep, marked by the disappearance of alpha waves and the appearance of **theta waves** (3-7 Hz). - It does not contain **sleep spindles** or **K-complexes**, which are characteristic of deeper sleep stages. *Stage 3* - **Stage 3 (N3 non-REM sleep)**, commonly known as **deep sleep** or **slow-wave sleep**, is defined by the presence of **delta waves** (0.5-2 Hz) accounting for 20% or more of the EEG. - Although it is a deeper stage of sleep, **sleep spindles** and **K-complexes** are not the primary defining features; **delta wave activity** predominates.

Q: Renshaw cell inhibition is a typical example of inhibition:

Recurrent. ***Recurrent*** - **Renshaw cells** are inhibitory interneurons in the spinal cord that receive excitatory input from **alpha motor neurons** and then in turn inhibit those same alpha motor neurons. - This forms a **negative feedback loop** that is characteristic of recurrent inhibition, helping to regulate motor neuron firing. *Direct* - This typically refers to inhibition where a neuron directly inhibits another neuron without an intermediary, which is not the case for Renshaw cells. - In direct inhibition, the inhibitory neuron forms a synapse directly onto the target cell's dendrites or soma to reduce its excitability. *Indirect* - Indirect inhibition generally involves an excitatory neuron activating an inhibitory interneuron, which then inhibits the target neuron. - While Renshaw cells are interneurons, the key characteristic here is the feedback *to the originating neuron*, which makes it specifically recurrent rather than just generally indirect. *Presynaptic* - **Presynaptic inhibition** occurs when an inhibitory neuron (or another neuron) reduces the amount of neurotransmitter released from the presynaptic terminal of another neuron. - Renshaw cells exert their inhibitory effect postsynaptically on the motor neurons, not by modulating neurotransmitter release from their presynaptic terminals.

Question 1

Which of the following is an example of explicit memory?

Accepted Answer

Semantic

Answer

Procedural

Answer

Nondeclarative

Answer

Working

Question 2

Alpha block on EEG is typically observed during which of the following activities?

Accepted Answer

Concentrating

Answer

Seizures

Answer

Sleep

Answer

None of the options

Question 3

Bilateral ablation of which of the following structures results in the inability to form long-term memories?

Accepted Answer

Hippocampus

Answer

Amygdala

Answer

Cingulate gyrus

Answer

Hypothalamus

Question 4

Which of the following statements *most* accurately describes the medial lemniscus system?

Accepted Answer

Transmits proprioceptive and fine touch sensations from the body

Answer

Conveys pain and temperature sensations

Answer

Integrates with the spinothalamic tract

Answer

Primarily processes crude touch and pressure sensations

Question 5

Which of the following substances cannot cross the blood-brain barrier?

Accepted Answer

Large protein molecule

Answer

Glucose

Answer

Oxygen

Answer

Lipophilic drug

Question 6

Which one of the following phenomena is closely associated with slow-wave sleep?

Accepted Answer

Sleepwalking

Answer

Dreaming

Answer

Atonia

Answer

Irregular heart rate

Question 7

A 72-year-old woman with insomnia participates in a sleep study. As part of the study protocol, she has EEG leads attached, then goes to sleep. At one point during the evening, 12-16 Hz sleep spindles and K-complexes are observed. Which stage of sleep is associated with this pattern?

Accepted Answer

Stage 2

Answer

REM

Answer

Stage 1

Answer

Stage 3

Question 8

Renshaw cell inhibition is a typical example of inhibition:

Accepted Answer

Recurrent

Answer

Presynaptic

Answer

Indirect

Answer

Direct

Neurophysiology — MCQs

Neurophysiology — MCQs

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