Clinical Neurophysiology Overview

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Questions and Answers

What is an example of an evoked response?

Mechanical stimulation of the skin

Visual stimulation of the eyes

Acoustic stimulation of the ears

Electrical stimulation of a peripheral nerve (correct)

Electrical recordings are the only way to measure the activity of neurons and muscle cells.

False

What are excitable cells?

Cells that can change their membrane potential to transmit information, including neurons and muscle cells.

The resting membrane potential is commonly abbreviated as ______.

RMP Signup and view all the answers

Match the types of stimulation with their corresponding applications:

Electrical stimulation = Peripheral nerve analysis Visual stimulation = Sensory pathway assessment Acoustic stimulation = Hearing and auditory processing Mechanical stimulation = Muscle contraction measurement Signup and view all the answers

Which tool is NOT used in clinical neurophysiology?

Acoustic tones Signup and view all the answers

Neurophysiology only examines the central nervous system.

False Signup and view all the answers

What occurs during the action potential (AP)?

A change in membrane potential that propagates an information signal along the cell. Signup and view all the answers

What happens to sodium channels during repolarization?

They close. Signup and view all the answers

The duration of an action potential (AP) is the same in all excitable cells.

False Signup and view all the answers

What is the role of the Na+/K+-ATPase during the refractory period?

It restores the resting state distributions of Na+ and K+ ions. Signup and view all the answers

During the ______ period, the membrane cannot generate a further action potential.

absolute refractory Signup and view all the answers

Match the following types of cells with the duration of their action potentials:

Nerve cells = 1 ms Muscle cells = 10 ms Heart muscle cells = 500 ms Signup and view all the answers

Which ions are predominantly affected during the action potential process?

Sodium and potassium Signup and view all the answers

Local anesthetics block calcium channels permanently.

False Signup and view all the answers

What is the all-or-none principle in action potentials?

An action potential is triggered only if the depolarization threshold is exceeded. Signup and view all the answers

Refractory periods help determine the maximal ______ rate of action potentials.

repetition Signup and view all the answers

Which component is responsible for stabilizing the membrane of excitable cells?

Extracellular calcium Signup and view all the answers

Which type of efferent fiber is responsible for innervating the main contractile muscle cells?

Aα-fibers Signup and view all the answers

Afferent Ia-fibers carry information about the absolute length of the muscle.

False Signup and view all the answers

What is the primary function of Ib-fibers?

They carry information about the tension in the tendons. Signup and view all the answers

The contractile elements within muscle spindles are called __________.

intrafusal muscle cells Signup and view all the answers

Match the following fibers to their functions:

Ia = Velocity of length change II = Absolute length Ib = Tension in tendons Aα = Main contractile muscle cells Signup and view all the answers

How do afferent fibers from the tendons protect muscles?

By inhibiting motoneurons Signup and view all the answers

The elastic center of intrafusal muscle cells helps preserve the sensitivity of the muscle spindle.

True Signup and view all the answers

What is the formula for signal-to-noise ratio (SNR)?

Psignal/Pnoise Signup and view all the answers

What is the role of α-motoneurons in muscle innervation?

They innervate the main contractile muscle cells. Signup and view all the answers

Electrocerebral silence has a typical SNR of 10:1.

False Signup and view all the answers

Afferent fibers from the spindle form the circuit for the __________ reflex.

deep tendon Signup and view all the answers

What is the typical SNR range for spontaneous activity in EMG?

5:1 - 10:1 Signup and view all the answers

Which fibers are part of the muscle spindle that measure the length of the muscle?

Aγ-fibers Signup and view all the answers

The typical SNR for CMAP in ENG is greater than ______:1.

<blockquote> 100 </blockquote> Signup and view all the answers

Match the following SNR values with their corresponding types:

Eng CMAP = > 100:1 EEG with EMG artifacts = < 1:10 Evoked Potentials (SEP/VEP) = 1:2 – 1:20 EMG Interference pattern = > 100:1 Signup and view all the answers

What does the evoked response from motor nerve stimulation called?

Compound muscle action potential (CMAP) Signup and view all the answers

The nerve conduction velocity is determined by the diameter of the fibers and their myelination.

True Signup and view all the answers

What should be done to ensure that nerve stimulation activates the whole motor pool?

Increase stimulus strength until no further increase in response is recorded. Signup and view all the answers

The ______ latency is observed to measure the time from stimulation to the response onset.

distal motor Signup and view all the answers

Match the following conduction velocities with their corresponding fiber classification:

100 m/s = Aα fibers 20 m/s = Aβ fibers 1 m/s = C fibers 75 m/s = Aγ fibers Signup and view all the answers

What factor makes it unreasonable to calculate nerve conduction velocity directly from stimulation to recording?

Synaptic delay Signup and view all the answers

Stimulation should occur with submaximal stimuli.

False Signup and view all the answers

What is the relationship between the distance between stimulation sites and latency difference?

Nerve conduction velocity is calculated by dividing the distance by the latency difference. Signup and view all the answers

Increasing the stimulus strength by 2 mA ensures that the stimulation is ______.

supramaximal Signup and view all the answers

Which of the following is associated with the slowest conduction velocity?

C fibers Signup and view all the answers

What primarily generates the EEG recordings?

Subsynaptic potentials in the uppermost layer of the cortex Signup and view all the answers

Which frequency band in the EEG is primarily associated with cortical inhibition?

Alpha band Signup and view all the answers

The ascending reticular activating system (ARAS) primarily regulates which aspects of neural function?

Consciousness and attention Signup and view all the answers

What does beta activity in the EEG indicate?

Cortical activation focusing attention Signup and view all the answers

Which statement accurately describes the relationship between frequency bands and synaptic activity in the EEG?

Lower frequency bands express cortical inhibition from various modulating influences. Signup and view all the answers

Which of the following symptoms is NOT a cardinal sign of Parkinson's disease?

Hyperactivity Signup and view all the answers

What is the primary target for deep brain stimulation (DBS) in Parkinson's disease?

Subthalamic nucleus (STN) Signup and view all the answers

What type of recording shows potential input data in the context of DBS?

Local field potentials (LFP) Signup and view all the answers

Which of the following strategies is NOT aimed at reducing adverse effects during DBS?

Repetitive shock therapy Signup and view all the answers

In the context of Parkinson's disease, what physiological change occurs due to the loss of dopaminergic neurons?

Hyperactivity of the subthalamic nucleus Signup and view all the answers

What symptom is associated with the bradykinesia aspect of Parkinson's disease?

Impaired facial expression Signup and view all the answers

Which of the following best describes the role of the vestibulocerebellum?

Maintenance of posture and equilibrium Signup and view all the answers

Which of the following is NOT considered an adverse effect of deep brain stimulation?

Memory enhancement Signup and view all the answers

What is the primary focus of neurophysiology?

The function of the nervous system Signup and view all the answers

Which of the following techniques is primarily used for analyzing the electrical activity of single neurons?

Intracellular microelectrode recordings Signup and view all the answers

What type of electrical activity does the electromyogram (EMG) primarily measure?

Electrical activity of muscle cells Signup and view all the answers

How is the assessment of heart-rate variability most commonly extracted from ECG recordings?

By measuring the intervals between heartbeats Signup and view all the answers

What does spontaneous electrical activity in the nervous system refer to?

Unprovoked electrical signals Signup and view all the answers

Which of the following statements about neurophysiological findings is accurate?

Knowledge of nervous system architecture is often crucial for interpretation. Signup and view all the answers

Which of the following describes the electroencephalogram (EEG)?

An assessment of brain's spontaneous electrical activity Signup and view all the answers

In clinical practice, which measurement is typically excluded from neurophysiology despite its relevance?

Electrocardiogram (ECG) Signup and view all the answers

Which physiological characteristic is primarily analyzed using patch clamp techniques?

Single neuron ionic currents Signup and view all the answers

What effect does a decrease in the diameter of the motor nerve branches have on action potential propagation velocity?

Propagation velocity decreases correspondingly. Signup and view all the answers

In neuromuscular junctions, what is the primary role of the synapse known as the motor end plate?

To facilitate signal transmission with a delay. Signup and view all the answers

Which of the following best defines a motor unit?

A single motoneuron and all muscle fibers it innervates. Signup and view all the answers

What is the impact of changing the polarity during direct nerve stimulation when recording responses?

It can cause an increased latency of the recorded responses. Signup and view all the answers

What defines the relationship between the size of motor units and the muscles demonstrating well-graded force development?

Smaller motor units contribute to finer control. Signup and view all the answers

What type of current is typically used to stimulate nerves with bipolar electrodes?

Square-wave current. Signup and view all the answers

When recording from a nerve with many fibers, what shape do the recorded responses typically differ from?

Biphasic or triphasic shape. Signup and view all the answers

What is a common misconception about the anodal block during nerve stimulation?

It is a fictional concept in neurophysiology. Signup and view all the answers

What is the relationship between the distance between stimulation sites and the latency difference?

Increased distance results in increased latency difference. Signup and view all the answers

What is the purpose of an electrode's cathode placement during nerve stimulation?

To ensure depolarization occurs where needed. Signup and view all the answers

What is the primary characteristic of sensory nerve conduction in carpal tunnel syndrome?

Slowing of the median sensory nerve conduction Signup and view all the answers

What treatment is recommended for carpal tunnel syndrome with minor symptoms?

Splinting during the night Signup and view all the answers

Which of the following symptoms is most commonly associated with cubital tunnel syndrome?

Weakness of the hand Signup and view all the answers

What is a common diagnostic procedure for carpal tunnel syndrome when nerve conduction studies are inconclusive?

Ultrasound of the wrist Signup and view all the answers

How is muscle atrophy in cubital tunnel syndrome typically evaluated?

Comparison of muscle strength with both hands Signup and view all the answers

What is a specific finding in nerve conduction tests that indicates Guyon's canal syndrome?

Prolongation of distal motor latency Signup and view all the answers

What is the surgical intervention for carpal tunnel syndrome referred to in the content?

Open or endoscopic decompression Signup and view all the answers

Which nerve root levels are primarily involved in muscle atrophy associated with cubital tunnel syndrome?

C8-T1 Signup and view all the answers

What distinguishes the symptoms of Guyon's canal syndrome from cubital tunnel syndrome?

Numbness in the fourth and fifth fingers Signup and view all the answers

Which treatment strategy is ineffective if carpal tunnel syndrome symptoms are major or refractory to initial therapy?

Night splinting Signup and view all the answers

Match the components of the basal ganglia pathways with their respective functions:

Striatum = Input from the cortex Globus pallidus interna = Output to thalamus Substantia nigra pars reticularis = Output to thalamus GPe = Indirect pathway modulation Signup and view all the answers

Match the types of dopamine receptors with their effects in the striatum:

D1 receptors = Excitation D2 receptors = Inhibition Dopaminergic projections = Modulation of pathways Str -> SNret/GPi = Direct pathway function Signup and view all the answers

Match the phases of cortical stimulation response with their descriptions:

First phase = Inhibition of thalamocortical projections Second phase = Disinhibition and movement release Third phase = Inhibition stopping movement release Delay = Increased activity after first phase Signup and view all the answers

Match the pathways with their corresponding outcomes:

Direct pathway = Facilitation of thalamocortical projections Indirect pathway = Inhibition of thalamocortical projections Disinhibition = Facilitation of impulse transmission Thalamic output = Influenced by basal ganglia activity Signup and view all the answers

Match the anatomical features of the basal ganglia with their specific roles:

Striatum = Major input structure Substantia nigra = Dopaminergic modulation Globus pallidus = Regulates output to thalamus STN = Component of indirect pathway Signup and view all the answers

Match the types of evoked responses with their corresponding stimulation methods:

Electrical stimulation = Contraction of innervated muscles Visual stimulation = Assessing visual pathways Acoustic stimulation = Testing auditory pathways Mechanical stimulation = Measuring bladder pressure Signup and view all the answers

Match the neurophysiological tools with their applications:

Calcium imaging = Studying metabolic processes in neurons fMRI = Examining brain activity Electrical recordings = Measuring neuronal activity Mechanical transducers = Assessing muscle contractions Signup and view all the answers

Match the types of cells with their primary characteristics:

Neurons = Information processing via action potentials Muscle cells = Contraction in response to stimulation Secretory cells = Secretion of neurotransmitters Excitable cells = Change in membrane potential Signup and view all the answers

Match the physiological terms with their definitions:

Resting Membrane Potential (RMP) = Baseline membrane potential of cells Action Potential (AP) = Membrane change during signal propagation Neurophysiology = Study of nerve functions and pathways Clinical Neurophysiology = Application of neurophysiological techniques in humans Signup and view all the answers

Match the types of neurophysiology with their primary focus:

Peripheral neurophysiology = Assessment of peripheral nerve diseases Central neurophysiology = Study of the central nervous system Autonomous neurophysiology = Diagnosis of autonomic nervous system disorders Clinical neurophysiology = Diagnostic and therapeutic applications in humans Signup and view all the answers

Match the types of reflex pathways with their characteristics:

Stretch reflex = Monosynaptic reflex action Withdraw reflex = Polysynaptic reflex action Tendon reflex = Protection from muscle injury Neural reflex = Response via neuronal connections Signup and view all the answers

Match the types of ion channels with their roles during action potential:

Sodium channels = Depolarization phase Potassium channels = Repolarization phase Calcium channels = Neurotransmitter release Chloride channels = Inhibitory postsynaptic potentials Signup and view all the answers

Match the definitions with their corresponding physiological processes:

Excitability = Ability of cells to generate action potentials Conductivity = Propagation of electrical signals along neurons Neuromuscular transmission = Communication between nerves and muscles Synaptic transmission = Transfer of signals across synapses Signup and view all the answers

Match the type of muscle fiber with its primary function:

Aα-fibers = Innervate main contractile muscle cells Aγ-fibers = Innervate contractile elements of muscle spindles Ia-fibers = Carry information of velocity of length change II-fibers = Carry information about absolute length Signup and view all the answers

Match the type of sensory fiber with its corresponding origin:

Ia-fibers = Muscle spindle Ib-fibers = Tendon receptors Aα-fibers = α-motoneurons Aγ-fibers = γ-motoneurons Signup and view all the answers

Match the reflex pathway with its associated function:

Deep tendon reflex = Assesses muscle spindle afferents Inhibitory reflex = Protects muscle from damage Voluntary movement = Modifies reflex circuit Length change reflex = Monitors muscle length alterations Signup and view all the answers

Match the component of muscle spindles with its description:

Intrafusal muscle cells = Contractile elements within spindles Extrafusal muscle cells = Outer muscle cells responsible for contraction Elastic center = Preserves sensitivity of the receptor Contractile ends = Compensate for length changes during contraction Signup and view all the answers

Match the afferent fiber type with their specific role:

Ia-fibers = Velocity of length change II-fibers = Absolute muscle length Ib-fibers = Tension in tendons Afferent fibers = Establish synaptic contacts with motoneurons Signup and view all the answers

Match the type of nerve fiber with its conduction velocity:

Aα-fibers = Fastest conduction velocity Aγ-fibers = Moderate conduction speed Ia-fibers = Intermediate conduction velocity Ib-fibers = Slowest conduction speed Signup and view all the answers

Match the following types of refractory periods with their characteristics:

Absolute refractory period = Membrane cannot generate a further action potential Relative refractory period = Depolarization threshold is increased Refractory period = Determines maximal AP repetition rate Resting state = Ions return to resting state distributions Signup and view all the answers

Match the following cell types with their action potential duration:

Nerve cells = Usually lasts 1 ms Muscle cells = Lasts about 10 ms Heart muscle cells = Can last up to 500 ms CNS neurons = Can exhibit slow calcium spikes Signup and view all the answers

Match the term with its corresponding definition in muscle innervation:

Electroneurography = Measures nerve conduction Afferent fibers = Sensory signals to CNS Efferent fibers = Motor signals from CNS Muscle spindles = Receptors measuring muscle length Signup and view all the answers

Match the ion channels with their roles during an action potential:

Sodium channels = Open during depolarization Potassium channels = Open during repolarization Calcium channels = Influence plateau phase in heart muscles Na+/K+ - ATPase = Returns ions to resting distributions Signup and view all the answers

Match the type of fiber with the aspect of muscle they innervate:

Aα-fibers = Main contractile elements Aγ-fibers = Intrafusal muscle components Ia-fibers = Muscle spindle receptors Ib-fibers = Tendon tension receptors Signup and view all the answers

Match the sensory fiber type with the information it carries:

Ia-fibers = Velocity of muscle length change Ib-fibers = Tension in tendons II-fibers = Absolute muscle length Aγ-fibers = Contractile information to spindles Signup and view all the answers

Match the following terms with their definitions related to action potentials:

All-or-none principle = Action potential independent of stimulus current Depolarization threshold = Minimum potential to trigger an AP Voltage-dependent inactivation = Occurs during refractory periods Calcium spikes = Provide driving force for sodium spikes in CNS Signup and view all the answers

Match the following drugs with their effects on ion channels:

Local anesthetics = Block sodium channels reversibly Calcium channel blockers = Inhibit calcium influx Potassium channel blockers = Prolong depolarization phase Sodium channel activators = Increase ease of depolarization Signup and view all the answers

Match the following phases of action potential with their characteristics:

Depolarization = Sodium influx raises membrane potential Repolarization = Potassium efflux lowers membrane potential Plateau phase = Caused by voltage-gated calcium channels Refractory phase = Limits frequency of action potentials Signup and view all the answers

Match the following cellular activities with their respective ions:

Sodium (Na+) = Rising phase of action potential Potassium (K+) = Falling phase of action potential Calcium (Ca++) = Prolonged plateau phase in cardiac myocytes Sodium-potassium pump = Restoration of resting ion concentrations Signup and view all the answers

Match the following anatomical features of neurons with their functions:

Dendrites = Receive synaptic input Axon = Conducts action potentials away from the cell body Synapse = Site of neurotransmitter release Myelin sheath = Increases conduction velocity of action potentials Signup and view all the answers

Match the following physiological concepts with their implications in excitable cells:

Increased extracellular calcium = Raises depolarization threshold Absolute refractory period = Prevents immediate second action potential Relative refractory period = Requires stronger stimulus for second action potential Ion channel inactivation = Contributes to the timing of action potentials Signup and view all the answers

Match the EEG frequency bands with their corresponding frequency ranges:

Gamma = > 31 Hz Beta = 13 – 30 Hz Alpha = 8 – 12 Hz Theta = 4 – 7 Hz Signup and view all the answers

Match the EEG findings with their descriptions during normal conditions:

Alpha waves = Regular and individual-specific frequency Beta waves = Dominated by beta-activity in all channels Theta waves = Increased during some sleep stages Delta waves = Pathologically slowed EEG activity Signup and view all the answers

Match the factors affecting normal EEG findings with their descriptions:

Individual factors = Variability due to personal characteristics Age = Can influence EEG patterns External stimuli = Environmental influences on EEG Degree of attention = Contributes to changes in frequency bands Signup and view all the answers

Match the abnormal EEG conditions with their potential causes:

Pathologically slowed EEG = Elevated intracranial pressure Burst-suppression EEG = Severe brain dysfunction Electrocerebral silence = Criteria for diagnosing brain death Focal abnormalities = Circumscribed slowing or epileptic activity Signup and view all the answers

Match the EEG activity changes with their triggers:

Alpha activity = Blocked by eye opening Beta activity = Observed during drowsiness Theta activity = Dominates during sleep stages Delta activity = Increases pathology of consciousness Signup and view all the answers

Match the EEG frequencies with their typical characteristics:

Gamma = Associated with cognitive processing Beta = Indicates active concentration or engagement Alpha = Calm, relaxed state often present with closed eyes Delta = Slow-wave activity during deep sleep Signup and view all the answers

Match the abnormal EEG patterns with their implications:

Alpha-coma = Absence of alpha waves with normal background Focal slowing = Localized brain injury or lesions Electrocerebral silence = Potential indication of brain death Burst suppression = Severe neurologic impairment Signup and view all the answers

Match the EEG states with their resting conditions:

Awake = Presence of alpha and beta activity Non-REM sleep = Presence of theta and delta activity REM sleep = Active brain function with eye movements Drowsy state = Transitional phase before deeper sleep Signup and view all the answers

Match the EEG findings with their locations in the brain:

Alpha rhythm = Accentuated over occipital and temporal lobes Central mu rhythm = Prominent in the central region Beta waves = Widespread across all channels Theta waves = Commonly seen during emotional turmoil Signup and view all the answers

Match the stimulus factors with their effects on EEG activity:

Eye opening = Blocks alpha waves Eyes closed = Restores alpha activity Drowsiness = May induce beta and alpha planes intermittently Straining = Can introduce EMG artifacts in the recording Signup and view all the answers

What are the frequency ranges for the Delta and Beta EEG bands?

Delta is < 4 Hz and Beta is 13 – 30 Hz. Signup and view all the answers

How does lateral inhibition contribute to the localization of a damaging stimulus?

Lateral inhibition enhances the contrast of impulses, limiting propagation to only the afferent signals from the damaged site. Signup and view all the answers

How does eye opening affect Alpha EEG activity?

Alpha activity is blocked by eye opening and restored after eye closing. Signup and view all the answers

What are potential causes of pathologically slowed EEG activity?

Causes include elevated intracranial pressure and pathologically impaired consciousness. Signup and view all the answers

What role do small interneurons play in the neural circuitry related to pain stimuli?

Small interneurons establish inhibitory contacts that facilitate lateral inhibition, contributing to pain processing. Signup and view all the answers

Explain how the convergence-divergence circuitry functions in response to sensory input like a pain stimulus.

This circuitry acts like an amplifier, allowing for a quick orientation response to potentially harmful stimuli. Signup and view all the answers

What distinguishes the Alpha rhythm in an EEG?

The Alpha rhythm is very regular, specific to the individual, and accentuated over the occipital and temporal lobes. Signup and view all the answers

What does 'electrocerebral silence' indicate in an EEG?

Electrocerebral silence may indicate brain death and requires careful validation to avoid false results. Signup and view all the answers

In the context of clinical neurophysiology, what is a significant challenge in extracellular recordings?

Extracellular recordings often have a poor signal-to-noise ratio due to the large distance between excitable cells and the recording electrodes. Signup and view all the answers

Why is it important to consider the relationship between stimulus strength and activation of the motor pool?

Proper stimulation strength ensures that the entire motor pool is activated for effective muscle response. Signup and view all the answers

What is the consequence of setting recording electrodes too far from excitable cells in neurophysiological studies?

It leads to a large distance affecting the signal quality, resulting in a complex relationship between the extracellular field and cellular activity. Signup and view all the answers

Describe the significance of time-dependent voltage changes in the context of electrophysiological recording.

These changes reflect the activity of excitable cells and are crucial for understanding their functional state. Signup and view all the answers

What factors influence the nerve conduction velocity, and how do they relate to fiber diameter?

Nerve conduction velocity depends on the diameter of fibers and their level of myelination, with larger, myelinated fibers conducting faster. Signup and view all the answers

What nerve is compressed in meralgia paresthetica?

The lateral femoral cutaneous nerve. Signup and view all the answers

What are the roles of the Inner Helmholtz plane (IHP) and Outer Helmholtz plane (OHP) in the electrode-electrolyte interface?

IHP forms the closest layer of solvent molecules to the electrode, while OHP encompasses additional layers where ionic distribution changes occur. Signup and view all the answers

What are two common symptoms of polyneuropathy?

Weakness and burning pain. Signup and view all the answers

What is the primary mechanism behind distal axonopathy?

Interrupted function of peripheral nerves. Signup and view all the answers

Describe the composition and function of mixed nerves.

Mixed nerves contain both efferent motor fibers and afferent sensory fibers, allowing for the conduction of signals to and from the central nervous system. Signup and view all the answers

What is the significance of pseudounipolar ganglion cells in nerve fiber anatomy?

Pseudounipolar ganglion cells have their somata outside the spinal cord and allow sensory fibers to bypass the cell body, facilitating rapid signal transmission. Signup and view all the answers

What do F-waves signify in neurophysiology?

They indicate the response of alpha motor neurons after antidromic stimulation. Signup and view all the answers

What does the H-reflex reflect in the nervous system?

It reflects the monosynaptic reflex circuit of spinal stretch reflexes. Signup and view all the answers

How do the spinal roots contribute to nerve function?

Spinal roots consist of afferent fibers in the dorsal roots and efferent fibers in the ventral roots, mediating sensory and motor pathways between the CNS and peripheral tissues. Signup and view all the answers

Name one inherited cause of polyneuropathy.

Charcot-Marie-Tooth disease. Signup and view all the answers

Explain the role of the skin interface in electrode measurements.

The skin interface serves as a barrier for electrical signals, affecting the accuracy and quality of electrode recordings during electroneurography. Signup and view all the answers

What types of fibers are involved in the spinal nerve structure?

The spinal nerve comprises both sensory afferent fibers and motor efferent fibers, along with vegetative fibers for autonomic functions. Signup and view all the answers

Which acquired condition is often associated with polyneuropathy?

Diabetes mellitus. Signup and view all the answers

Discuss the anatomical locations of somata for afferent somatosensory nerves.

The somata of afferent somatosensory nerves are located in the spinal ganglions, positioned outside the spine or within the foramina of the vertebral column. Signup and view all the answers

What is the typical progression pattern of polyneuropathy symptoms?

They usually begin in the hands and feet and may progress to the arms and legs. Signup and view all the answers

What role does assessment with somatosensory evoked potentials play in diagnosing peripheral nerve issues?

It may provide helpful insights into nerve function. Signup and view all the answers

What type of signals do mixed nerves primarily transmit?

Mixed nerves primarily transmit both sensory signals from peripheral receptors to the CNS and motor signals from the CNS to skeletal muscles. Signup and view all the answers

How do efferent motor fibers function in relation to muscle contraction?

Efferent motor fibers extend from motoneurons in the CNS to voluntary muscles, triggering muscle contractions through the release of neurotransmitters at the neuromuscular junction. Signup and view all the answers

What distinguishes myelinopathy from other types of polyneuropathy?

Myelinopathy is specifically caused by a loss of myelin. Signup and view all the answers

Why are vegetative fibers typically not assessed electrophysiologically in mixed nerves?

Vegetative fibers are primarily involved in autonomic functions, which are not usually reflected in standard electrophysiological assessments in clinical practice. Signup and view all the answers

What are the main parts of the neuron involved in action potential propagation?

The main parts involved are the soma, axon, axon hillock, and dendrites. Signup and view all the answers

How does myelin affect the speed of action potential propagation?

Myelin increases the speed of action potential propagation by reducing membrane capacitance and increasing membrane resistance. Signup and view all the answers

What is the role of nodes of Ranvier in axonal signaling?

Nodes of Ranvier allow for the saltatory conduction of action potentials, enabling faster transmission along myelinated axons. Signup and view all the answers

What initiates the release of neurotransmitters at the synapse?

The arrival of an action potential at the axon terminal triggers the opening of Ca++ channels, which causes neurotransmitter release. Signup and view all the answers

Describe the primary method of signal transmission between neurons.

Signal transmission between neurons primarily occurs chemically via neurotransmitters at synapses. Signup and view all the answers

What factors influence the conduction velocity of nerves?

Conduction velocity is influenced by the diameter of the axon, temperature, and the myelination of the fibers. Signup and view all the answers

What does the term 'saltatory conduction' refer to?

Saltatory conduction refers to the process where action potentials jump from one node of Ranvier to the next along myelinated axons. Signup and view all the answers

How does the diameter of an axon affect action potential speed?

A larger axon diameter generally results in faster propagation of action potentials due to lower internal resistance. Signup and view all the answers

What ensures that two neurons do not connect electrically?

Two neurons typically do not connect electrically due to the presence of synapses, which facilitate chemical communication. Signup and view all the answers

What is the significance of the action potential's all-or-none principle?

The all-or-none principle indicates that an action potential either occurs fully or not at all, ensuring reliable signal transmission. Signup and view all the answers

What does neurophysiology primarily study?

Neurophysiology studies the function of the central, peripheral, and autonomic nervous systems. Signup and view all the answers

What historical approach has dominated the field of neurophysiology?

The field has been dominated by the analysis of electrical activity of neurons. Signup and view all the answers

What is spontaneous electrical activity in neurophysiology exemplified by?

Spontaneous electrical activity is exemplified by the electroencephalogram (EEG). Signup and view all the answers

How does an electromyogram (EMG) relate to neurophysiology?

An EMG records the electrical activity of voluntarily innervated muscle cells. Signup and view all the answers

Why can knowledge of the nervous system architecture be important in neurophysiology?

Knowledge of architecture is often mandatory to interpret neurophysiological findings. Signup and view all the answers

What are voltage-clamp and patch-clamp techniques used for in neurophysiology?

They are used for sophisticated analysis of single neurons' electrical activity. Signup and view all the answers

What role does heart-rate variability play in neurophysiology?

Heart-rate variability, assessed from ECG recordings, analyzes the autonomic nervous system. Signup and view all the answers

What characterizes the distinction between EEG and ECG in terms of neurophysiology?

EEG focuses on brain activity, while ECG predominantly assesses heart activity. Signup and view all the answers

What are the main types of acute peripheral nerve lesions?

The main types are neurapraxia, axonotmesis, and neurotmesis. Signup and view all the answers

How does temperature affect motor nerve conduction studies?

Lower temperatures can lead to increased latency and decreased amplitude in nerve conduction. Signup and view all the answers

What happens during the regeneration process in neurapraxia?

Regeneration occurs with shorter distances between Ranvier nodes, leading to decreased nerve conduction velocity (NCV). Signup and view all the answers

What occurs when a neurotransmitter opens sodium channels in the postsynaptic membrane?

It causes depolarization, resulting in an excitatory postsynaptic potential (EPSP). Signup and view all the answers

In the context of motor nerve conduction, what is meant by distal motor latency?

Distal motor latency refers to the time interval between stimulation and response at a distal nerve site. Signup and view all the answers

What characterizes chronic peripheral nerve damage compared to acute injuries?

Chronic damage typically involves repetitive degeneration of the myelin sheath and axonal damage due to reduced blood flow. Signup and view all the answers

How does an inhibitory postsynaptic potential (IPSP) affect the postsynaptic neuron?

It causes hyperpolarization, making it less likely to generate an action potential. Signup and view all the answers

What is the significance of the axon hillock in neural signaling?

The axon hillock is where action potentials are first generated, influenced by the summation of EPSPs and IPSPs. Signup and view all the answers

Which factors can lead to difficulties in stimulating nerves during conduction studies?

Difficulties can arise from thick subcutaneous tissue, deep nerve courses, and irradiation of the stimulus to neighboring nerves. Signup and view all the answers

What are the differences in nerve conduction velocity (NCV) associated with axonotmesis and neurotmesis?

Axonotmesis shows decreased NCV and partial nerve block, while neurotmesis results in a total block and loss of neuron function. Signup and view all the answers

What is 'divergence' in the context of neural circuitry?

Divergence refers to a single presynaptic axon establishing synaptic connections with multiple postsynaptic neurons. Signup and view all the answers

How does the amplitude of a nerve conduction study change during axonotmesis?

Initially, the amplitude decreases due to the disruption of axons. Signup and view all the answers

Describe the process of convergence in neural networks.

Convergence occurs when multiple presynaptic axons connect to a single postsynaptic neuron, enhancing the signal strength. Signup and view all the answers

Why is sensory nerve conduction often unsuccessful with skin stimulation?

Sensory nerve conduction studies may fail because pure sensory nerves have limited response at the skin level. Signup and view all the answers

How does the convergence-divergence circuitry function in response to a new sensory input?

It acts like an amplifier, quickly processing and enhancing the response to potentially harmful stimuli. Signup and view all the answers

What is the main clinical indication for neurotmesis?

The main indication for neurotmesis is surgical reconstruction due to complete nerve disruption. Signup and view all the answers

Why do EPSPs and IPSPs last longer than action potentials?

They involve gradual changes in ionic permeability that persist beyond the rapid spike of an action potential. Signup and view all the answers

How many synaptic relays are typically involved in the somatosensory pathway?

Typically, there are three synaptic relays from the periphery to the primary sensory cortex. Signup and view all the answers

What reflects the dynamic nature of information processing in neural networks?

The adaptation of postsynaptic potentials to changing inputs illustrates the complex information processing. Signup and view all the answers

What role do subsynaptic membranes play in a neuron?

They are critical sites for neurotransmitter reception and shaping the postsynaptic potentials. Signup and view all the answers

What is the role of the striatum in the direct pathway of the basal ganglia?

The striatum facilitates thalamocortical projections by disinhibiting the globus pallidus interna and substantia nigra pars reticularis. Signup and view all the answers

Explain how dopaminergic projections from the substantia nigra affect the striatum.

Dopaminergic projections from the substantia nigra modulate striatal activity, with D1 receptors promoting excitation and D2 receptors leading to inhibition. Signup and view all the answers

What are the phases of the triphasic response observed during cortical stimulation?

The triphasic response includes an initial increase in activity leading to inhibition, a decrease indicating disinhibition, and a final increase that results in inhibition stopping movement release. Signup and view all the answers

Describe the function of the indirect pathway in the basal ganglia.

The indirect pathway inhibits thalamocortical projections through a sequence of connections from the striatum to the globus pallidus externus and then to the subthalamic nucleus. Signup and view all the answers

What effect does the activation of D1 and D2 receptors in the striatum have on thalamocortical transmission?

Activation of D1 receptors facilitates transmission, while D2 receptors inhibit it, balancing excitation and inhibition within the striatum. Signup and view all the answers

What is the primary function of the basal ganglia in motor control?

The basal ganglia primarily control the initiation and termination of movements. Signup and view all the answers

Describe the role of the extrapyramidal system in muscle movement.

The extrapyramidal system modulates voluntary movements through polysynaptic projections and continually inhibits spinal reflexes. Signup and view all the answers

How are the basal ganglia and the thalamus related in the context of neural pathways?

The basal ganglia are located adjacent to the thalamus and are embedded in complex motor loops that interact with it. Signup and view all the answers

What processes are modulated by the basal ganglia besides voluntary movement?

The basal ganglia also modulate procedural learning, conditional learning, eye movements, cognition, and emotion. Signup and view all the answers

What constitutes the primary role of the N.oculomotorius and N.abducens during intraoperative monitoring?

They are monitored to assess the integrity of cranial nerves that control eye movements. Signup and view all the answers

Describe the characteristics of muscle spindle afferent fibers.

Muscle spindle afferent fibers measure muscle length and adjust muscle tone. Signup and view all the answers

What does EMG stand for, and what does it measure in intraoperative monitoring?

EMG stands for electromyography, and it measures the electrical activity of muscle cells. Signup and view all the answers

In the context of motor pathways, how does the basal ganglia influence reflex arcs?

The basal ganglia usually inhibit reflex arcs to modulate spinal cord reflex activity. Signup and view all the answers

What is the significant role of the cranial nerves monitored during surgery?

Monitoring cranial nerves during surgery helps ensure their functionality is preserved and prevents postoperative complications. Signup and view all the answers

How do the basal ganglia contribute to the stability of movements?

The basal ganglia help stabilize movements by coordinating muscle activity and ensuring smooth transitions. Signup and view all the answers

Which of the following is a cardinal sign of Parkinson's disease?

Rigidity Signup and view all the answers

Deep brain stimulation (DBS) can only be used when all medication options have been exhausted.

False Signup and view all the answers

What is the main neurotransmitter affected in Parkinson's disease?

Dopamine Signup and view all the answers

In Parkinson's disease, the loss of neurons occurs primarily in the substantia nigra pars __________.

compacta Signup and view all the answers

Match the following symptoms of Parkinson's disease with their descriptions:

Akinesia = Difficulty in initiating movements Bradykinesia = Slowness of movement Tremor = Involuntary shaking Rigidity = Stiffness of muscles Signup and view all the answers

What is the first line of therapy for managing Parkinson's disease?

L-Dopa and Dopaminagonists Signup and view all the answers

Phase amplitude coupling (PAC) is a technique used in DBS optimization to enhance stimulation outcomes.

True Signup and view all the answers

List one potential adverse effect of deep brain stimulation (DBS).

Infections Signup and view all the answers

What does neurophysiology primarily study?

The function of the nervous system Signup and view all the answers

The electrocardiogram (ECG) is typically included in neurophysiological assessments.

False Signup and view all the answers

What is a common technique used to record spontaneous electrical activity in the nervous system?

Electroencephalogram (EEG) Signup and view all the answers

Neurophysiology examines not only the central but also the and nervous systems.

peripheral, autonomous Signup and view all the answers

Match the following neurophysiological techniques with their primary use:

EEG = Recording spontaneous brain activity EMG = Recording muscle electrical activity Patch clamp = High-resolution single neuron analysis Voltage clamp = Controlling the membrane potential of a neuron Signup and view all the answers

Which technique is used to analyze single neurons?

Patch clamp Signup and view all the answers

Spontaneous electrical activity can include measurements from muscle cells.

True Signup and view all the answers

The analysis of the electrical activity of ______ has historically dominated neurophysiology.

neurons Signup and view all the answers

What are the electrical measurements typically used in neurophysiology called?

Electrodes Signup and view all the answers

Which of the following statements is true regarding neurophysiological findings?

They require an understanding of nervous system architecture. Signup and view all the answers

What is one primary function of the basal ganglia?

Control of voluntary movements Signup and view all the answers

The extrapyramidal system consists of only pyramidal tracts.

False Signup and view all the answers

What is the role of the basal ganglia in motor control?

Initiation and termination of movements Signup and view all the answers

The _______ are a group of subcortical nuclei involved in procedural and habit learning.

basal ganglia Signup and view all the answers

Match the following types of monitoring with their applications:

N.oculomotorius = Eye movement control N.abducens = Lateral eye movement N.vagus = Autonomic functions N.VII = Facial expression control Signup and view all the answers

Which electrode position corresponds to the front of the brain?

F Signup and view all the answers

Midline electrode positions are indicated by even numbers.

False Signup and view all the answers

What are the potential differences measured by EEG?

Electrical activity between pairs of electrodes. Signup and view all the answers

The __________ electrode position refers to the area of the brain near the ears.

A Signup and view all the answers

Which type of montage is described as more sensitive?

Reference Signup and view all the answers

Match the following EEG montages with their characteristics:

Bipolar = Localizes signals better Reference = More sensitive to distance Average reference = Uses multiple electrodes for baseline Laplacian = Enhances spatial resolution Signup and view all the answers

What is the primary disadvantage of bipolar montages?

Less sensitive than reference montages Signup and view all the answers

The Laplacian montage is primarily used for long-distance signal monitoring.

False Signup and view all the answers

What determines how the electrical activity is recorded in EEG?

The way electrodes are connected to the amplifiers. Signup and view all the answers

The __________ montages typically use an ear as a reference point.

Ipsilateral Signup and view all the answers

What is the key factor that leads to a decrease in nerve conduction velocity (NCV) in the case of neurapraxia?

Segmental degeneration of the myelin sheath Signup and view all the answers

Axonotmesis is characterized by complete disruption of the entire nerve.

False Signup and view all the answers

What is the term for the degeneration that occurs with complete nerve disruption?

Neurotmesis Signup and view all the answers

In chronic nerve damage, the repeated degeneration and regeneration of the ______ sheath occurs.

myelin Signup and view all the answers

Match the type of nerve lesion with its characteristic:

Neurapraxia = Segmental degeneration of myelin Axonotmesis = Disruption of axons with intact sheaths Neurotmesis = Complete nerve disruption Chronic damage = Repetitive degeneration of myelin Signup and view all the answers

What is a common pitfall that can affect nerve conduction studies?

Deep, intramuscular nerve course Signup and view all the answers

Amplitude can be easily assessed due to its consistent variability across stimulation sites.

False Signup and view all the answers

What is the typical regeneration rate for axonal repair in case of axonotmesis?

1 mm/day Signup and view all the answers

The ______ is used to measure the time from stimulation to the response onset in nerve conduction studies.

distal motor latency Signup and view all the answers

Which condition does NOT typically involve nerve entrapment syndromes?

Neurapraxia Signup and view all the answers

Study Notes

Evoked Responses

After a stimulus, the evoked response is an approach to analyzing the nervous system.
It's used to evaluate the connections between neurons. (neural pathways)

Electrical Stimulation

This involves applying a stimulus to a peripheral nerve.
It triggers a muscle contraction in the area innervated by the nerve.
Other than electrical current, techniques like visual, acoustic, mechanical, and magnetic stimulation can also be used to test sensory and motor pathways.