Q.1 Which type of electrode is most commonly used for chronic intracortical recordings in neural prosthetic applications?
Surface (ECoG) electrode
Microwire electrode
Silicon Utah array
Depth macroelectrode
Explanation - Silicon Utah arrays consist of a grid of silicon shanks with multiple recording sites, providing stable long‑term recordings from cortical neurons, making them a standard choice for chronic intracortical neural prostheses.
Correct answer is: Silicon Utah array
Q.2 In a myoelectric prosthetic hand, the EMG signal is typically processed to extract which feature for control?
Peak frequency
Root mean square (RMS)
Phase angle
Signal entropy
Explanation - RMS provides a robust estimate of the EMG signal amplitude and is widely used to translate muscle activity into proportional control commands for prosthetic devices.
Correct answer is: Root mean square (RMS)
Q.3 Which of the following best describes a Brain‑Computer Interface (BCI) based on the motor imagery paradigm?
User imagines moving a limb, generating sensorimotor rhythms detected by EEG
User looks at flashing lights, inducing visual evoked potentials
User listens to tones, producing auditory evoked responses
User performs a mental arithmetic task, creating P300 potentials
Explanation - Motor imagery modulates sensorimotor rhythms (mu and beta bands) in the EEG, which are decoded by BCIs to infer intended movement without actual execution.
Correct answer is: User imagines moving a limb, generating sensorimotor rhythms detected by EEG
Q.4 What is the primary advantage of using functional electrical stimulation (FES) for gait rehabilitation in spinal cord injury patients?
It completely restores voluntary motor control
It reduces spasticity without any active movement
It activates paralyzed muscles to produce functional movements
It eliminates the need for assistive devices
Explanation - FES delivers electrical pulses to motor nerves, causing contractions of otherwise paralyzed muscles, enabling functional tasks such as walking.
Correct answer is: It activates paralyzed muscles to produce functional movements
Q.5 Which signal processing technique is most commonly used to remove power‑line interference (50/60 Hz) from neural recordings?
Band‑pass filtering between 300 Hz‑3 kHz
Notch filtering at 50/60 Hz
Wavelet denoising
Principal component analysis
Explanation - A narrow‑band notch filter attenuates the specific frequency of power‑line noise while preserving the rest of the neural signal spectrum.
Correct answer is: Notch filtering at 50/60 Hz
Q.6 In the context of neural prosthetics, what does the term "closed‑loop" refer to?
A system that records neural activity but does not provide feedback
A prosthetic that operates solely on pre‑programmed motions
A system that both reads neural signals and delivers sensory feedback to the user
A device that requires external power only during use
Explanation - Closed‑loop prostheses incorporate bidirectional communication: they decode motor intent and provide feedback (e.g., via sensory stimulation) to improve control and embodiment.
Correct answer is: A system that both reads neural signals and delivers sensory feedback to the user
Q.7 Which of the following materials is most biocompatible for long‑term implantation of neural electrodes?
Stainless steel
Gold
Silicone rubber
Platinum‑iridium alloy
Explanation - Platinum‑iridium exhibits excellent corrosion resistance, low impedance, and minimal tissue reaction, making it a preferred material for chronic neural interfaces.
Correct answer is: Platinum‑iridium alloy
Q.8 The 'P300' component used in many BCIs is best described as:
A sustained low‑frequency oscillation during motor imagery
An event‑related potential occurring approximately 300 ms after an oddball stimulus
A high‑frequency burst associated with visual stimulation
A slow cortical potential related to attention
Explanation - The P300 is an ERP that appears ~300 ms after a rare or significant stimulus in an oddball paradigm and is exploited for speller and selection BCIs.
Correct answer is: An event‑related potential occurring approximately 300 ms after an oddball stimulus
Q.9 What is the main purpose of using a common‑mode rejection ratio (CMRR) in amplifiers for neural signal acquisition?
To increase the gain of the desired signal
To suppress noise that appears equally on both input leads
To filter out high‑frequency components above 1 kHz
To convert analog signals to digital
Explanation - CMRR quantifies an amplifier's ability to reject common‑mode voltages, such as interference picked up equally by both electrodes, enhancing signal quality.
Correct answer is: To suppress noise that appears equally on both input leads
Q.10 Which rehabilitation technique combines robotic assistance with real‑time neural feedback to improve upper‑limb function after stroke?
Constraint-induced movement therapy
Mirror therapy
Hybrid assistive limb (HAL) training
Transcranial direct current stimulation (tDCS)
Explanation - HAL devices detect bio‑electric signals (e.g., EMG) from the patient and assist movement accordingly, providing closed‑loop assistance that promotes neuroplasticity.
Correct answer is: Hybrid assistive limb (HAL) training
Q.11 In cochlear implants, the electrode array is inserted into which part of the inner ear?
Vestibular duct
Scala tympani
Scala media
Cochlear nucleus
Explanation - The electrode array is placed in the scala tympani to stimulate the auditory nerve fibers close to the basal turn of the cochlea, preserving residual hearing and providing efficient stimulation.
Correct answer is: Scala tympani
Q.12 What is the primary function of a dorsal column stimulator in spinal cord injury rehabilitation?
To restore motor control directly
To provide analgesic pain relief
To enhance proprioceptive feedback for gait training
To stimulate bladder emptying
Explanation - Dorsal column stimulation can modulate sensory pathways, improving proprioceptive input that assists in relearning walking patterns after spinal cord injury.
Correct answer is: To enhance proprioceptive feedback for gait training
Q.13 Which decoding algorithm is most commonly used for translating spiking activity into continuous limb kinematics?
Linear discriminant analysis (LDA)
Kalman filter
Support vector machine (SVM)
Hidden Markov model (HMM)
Explanation - The Kalman filter provides an optimal recursive solution for estimating continuous variables (e.g., limb position) from noisy neural spike counts.
Correct answer is: Kalman filter
Q.14 In peripheral nerve interfaces, the "cuff electrode" design is advantageous because:
It penetrates the nerve fascicles for high selectivity
It wraps around the nerve without penetrating tissue
It uses optical stimulation instead of electrical
It is only suitable for acute experiments
Explanation - Cuff electrodes are non‑invasive, circumferentially placed around a nerve, reducing tissue damage while providing reliable stimulation and recording.
Correct answer is: It wraps around the nerve without penetrating tissue
Q.15 Which of the following is a key limitation of surface electromyography (sEMG) for controlling multi‑degree‑of‑freedom prosthetic hands?
High spatial resolution
Low signal‑to‑noise ratio
Inability to detect deep muscle activity
Requirement of surgical implantation
Explanation - sEMG captures potentials from superficial muscles; deep muscle activity remains unrecorded, limiting the richness of control signals for complex prosthetic functions.
Correct answer is: Inability to detect deep muscle activity
Q.16 Which neuroplasticity mechanism is primarily targeted by repetitive transcranial magnetic stimulation (rTMS) in rehabilitation after stroke?
Long‑term potentiation (LTP)
Axonal sprouting
Myelination increase
Neurogenesis in the hippocampus
Explanation - rTMS can induce LTP‑like changes in cortical excitability, strengthening synaptic connections that support functional recovery.
Correct answer is: Long‑term potentiation (LTP)
Q.17 A common metric for assessing the performance of a neural prosthetic decoder is:
Mean absolute error (MAE)
Signal‑to‑noise ratio (SNR)
Bit error rate (BER)
Root mean square error (RMSE)
Explanation - RMSE quantifies the average magnitude of prediction errors between intended and decoded kinematic trajectories, widely used to evaluate decoder accuracy.
Correct answer is: Root mean square error (RMSE)
Q.18 In the context of retinal prostheses, the term "epiretinal" refers to:
Implantation on the inner surface of the sclera
Placement between the retinal pigment epithelium and photoreceptors
Positioning on the inner surface of the retina, adjacent to ganglion cells
Insertion into the optic nerve
Explanation - Epiretinal implants are placed on the vitreal side of the retina, stimulating retinal ganglion cells directly to bypass damaged photoreceptors.
Correct answer is: Positioning on the inner surface of the retina, adjacent to ganglion cells
Q.19 Which of the following best describes the principle of "sensory substitution" in neuroprosthetics?
Replacing a lost limb with a mechanical replica
Providing tactile feedback via vibration on the skin to convey visual information
Using auditory cues to replace proprioceptive signals
Stimulating the visual cortex to restore hearing
Explanation - Sensory substitution maps information from a lost sense (e.g., vision) onto another modality (e.g., touch) so the brain can interpret the substituted signals.
Correct answer is: Providing tactile feedback via vibration on the skin to convey visual information
Q.20 During functional electrical stimulation (FES) for hand grasp, which stimulation pattern is most effective for producing a smooth, natural grip?
Constant high‑frequency (100 Hz) pulse trains
Burst stimulation with variable amplitude
Low‑frequency (20 Hz) sinusoidal modulation
Single‑pulse stimulation at 1 Hz
Explanation - Burst patterns mimic the natural recruitment of motor units, allowing graded force production and smoother grip compared to constant high‑frequency stimulation.
Correct answer is: Burst stimulation with variable amplitude
Q.21 The term "neuroprosthetic" most accurately refers to:
Any device that replaces a damaged nerve with a synthetic conduit
An implanted system that records from or stimulates the nervous system to restore function
A wearable exoskeleton that assists movement without interfacing with the nervous system
A pharmacological treatment for neurodegenerative disease
Explanation - Neuroprosthetics interface directly with neural tissue to either read neural activity (recordings) or write information (stimulation) for therapeutic purposes.
Correct answer is: An implanted system that records from or stimulates the nervous system to restore function
Q.22 Which algorithm is commonly employed for classification of imagined hand gestures from EEG signals in non‑invasive BCIs?
K‑nearest neighbors (KNN)
Linear discriminant analysis (LDA)
Convolutional neural network (CNN)
Recursive least squares (RLS)
Explanation - LDA efficiently separates feature distributions of different imagined gestures and is computationally light, making it suitable for real‑time EEG‑based BCIs.
Correct answer is: Linear discriminant analysis (LDA)
Q.23 In a bidirectional prosthetic hand, which sensory modality is most often conveyed to the user via intraneural stimulation?
Temperature
Proprioception (position sense)
Auditory feedback
Visual cues
Explanation - Intraneural stimulation can evoke sensations related to limb position and movement, providing users with proprioceptive feedback essential for fine motor control.
Correct answer is: Proprioception (position sense)
Q.24 What is the purpose of using a "reference electrode" in a neural recording setup?
To amplify the recorded signal
To provide a stable ground potential against which other electrodes measure activity
To deliver stimulation currents
To increase the sampling rate
Explanation - A reference electrode ensures that the potential differences recorded by active electrodes are relative to a common, low‑noise point.
Correct answer is: To provide a stable ground potential against which other electrodes measure activity
Q.25 Which of the following best describes the concept of "motor cortex" somatotopy?
Motor neurons are randomly distributed across the cortex
Each body part is represented by a distinct, orderly region in the motor cortex
Only the hands have cortical representation
Somatotopy only exists in the sensory cortex
Explanation - Somatotopy refers to the orderly mapping of body parts onto the motor cortex, often illustrated by the motor homunculus.
Correct answer is: Each body part is represented by a distinct, orderly region in the motor cortex
Q.26 Which of these is a major cause of signal degradation in chronic implanted neural electrodes?
Electrode material oxidation
Thermal noise increase
Gliosis and tissue encapsulation
Battery depletion
Explanation - The body's immune response leads to glial scar formation around electrodes, increasing impedance and reducing signal quality over time.
Correct answer is: Gliosis and tissue encapsulation
Q.27 A prosthetic leg that adapts its stiffness in response to ground reaction forces is an example of:
Passive orthosis
Open‑loop control system
Closed‑loop adaptive controller
Fixed‑gain proportional controller
Explanation - Sensors measure force, and the controller adjusts actuator stiffness in real time, forming a feedback loop that adapts to walking conditions.
Correct answer is: Closed‑loop adaptive controller
Q.28 Which type of neural signal is most commonly used for decoding intended speech from cortical activity?
Local field potentials (LFPs)
Single‑unit spikes
Electrooculogram (EOG)
Electrocardiogram (ECG)
Explanation - LFPs reflect summed synaptic activity over a small region and have shown robust correlations with speech articulation features, making them suitable for speech prostheses.
Correct answer is: Local field potentials (LFPs)
Q.29 In a neural prosthetic system, the term "latency" refers to:
The time delay between user intent detection and actuator movement
The total duration of a stimulation pulse
The frequency of the recorded neural signal
The lifespan of the implanted device
Explanation - Latency determines how quickly the prosthetic responds to decoded neural commands; low latency is crucial for naturalistic control.
Correct answer is: The time delay between user intent detection and actuator movement
Q.30 Which of the following is a common safety concern when delivering electrical stimulation to the peripheral nervous system?
Magnetic field interference
Electrochemical corrosion leading to tissue damage
Laser-induced heating
Acoustic cavitation
Explanation - Repeated stimulation can cause electrochemical reactions at the electrode–tissue interface, potentially harming surrounding tissues if not properly managed.
Correct answer is: Electrochemical corrosion leading to tissue damage
Q.31 Which clinical outcome measure is often used to evaluate the functional benefit of a hand prosthesis?
Six‑minute walk test
Box‑and‑Blocks test
Berg Balance Scale
Mini‑Mental State Examination
Explanation - The Box‑and‑Blocks test assesses manual dexterity and speed, making it suitable for measuring hand prosthesis performance.
Correct answer is: Box‑and‑Blocks test
Q.32 When designing a neural interface for recording, why is it important to keep the electrode impedance low (< 1 MΩ)?
Low impedance reduces thermal noise and improves signal quality
Low impedance ensures the device lasts longer battery life
Low impedance prevents the electrode from moving
Low impedance makes the device waterproof
Explanation - Lower impedance decreases Johnson noise and enhances the amplitude of recorded neural signals relative to background noise.
Correct answer is: Low impedance reduces thermal noise and improves signal quality
Q.33 A common method for providing tactile feedback in upper‑limb prostheses is:
Vibrotactile stimulation on the residual limb
Auditory beeps proportional to grip force
Visual LEDs indicating finger position
Temperature changes on the hand
Explanation - Vibrotactile actuators can deliver graded pressure cues to the skin, allowing the user to perceive grip force or contact events.
Correct answer is: Vibrotactile stimulation on the residual limb
Q.34 Which type of neural prosthetic is designed to restore bladder control in patients with spinal cord injury?
Cochlear implant
Sacral nerve stimulator
Deep brain stimulator
Retinal implant
Explanation - Sacral nerve stimulators deliver electrical pulses to the sacral nerves that control bladder storage and voiding functions.
Correct answer is: Sacral nerve stimulator
Q.35 In the context of neurorehabilitation, "task‑specific training" refers to:
General aerobic exercise unrelated to the target function
Practice of movements that closely mimic everyday activities
Passive stretching of muscles
Randomized motor tasks without feedback
Explanation - Task‑specific training leverages neuroplasticity by repeatedly performing functional tasks, enhancing the relearning of those specific actions.
Correct answer is: Practice of movements that closely mimic everyday activities
Q.36 What is the primary reason for using a "bipolar" recording configuration in neural electrophysiology?
To double the voltage amplitude
To eliminate common‑mode noise between two nearby electrodes
To increase the sampling frequency
To enable wireless transmission
Explanation - Bipolar recording measures the voltage difference between two closely spaced electrodes, canceling out noise that is common to both sites.
Correct answer is: To eliminate common‑mode noise between two nearby electrodes
Q.37 Which of the following is a characteristic of optogenetic neural stimulation compared to electrical stimulation?
Higher spatial specificity
Requires higher current amplitudes
Cannot be used in vivo
Produces more heat
Explanation - Optogenetics uses light‑sensitive ion channels, allowing activation of genetically targeted neurons with millisecond precision and fine spatial resolution.
Correct answer is: Higher spatial specificity
Q.38 In a motor neuroprosthesis, which type of control strategy maps neural firing rates directly to prosthetic joint velocities?
Proportional control
Velocity ramp control
Rate‑coding control
Finite‑state machine control
Explanation - Rate‑coding translates the instantaneous firing rate of recorded neurons into a proportional command, often used for joint velocity control.
Correct answer is: Rate‑coding control
Q.39 Which brain region is primarily targeted for deep brain stimulation (DBS) to alleviate Parkinsonian tremor?
Subthalamic nucleus (STN)
Primary visual cortex
Hippocampus
Cerebellar vermis
Explanation - STN DBS modulates pathological basal ganglia activity, reducing tremor and motor symptoms in Parkinson's disease.
Correct answer is: Subthalamic nucleus (STN)
Q.40 Which of the following best describes "muscle synergies" in the context of EMG‑based prosthetic control?
Independent activation of each motor unit
Coordinated activation patterns of groups of muscles
Random muscle firing unrelated to movement
Electrical cross‑talk between adjacent electrodes
Explanation - Muscle synergies represent low‑dimensional patterns that simplify control; extracting them from EMG can improve prosthetic command efficiency.
Correct answer is: Coordinated activation patterns of groups of muscles
Q.41 A major advantage of using a wireless telemetry system for implanted neural prostheses is:
Unlimited power supply
Elimination of infection risk from percutaneous connectors
Higher data bandwidth than wired connections
Reduced device size
Explanation - Wireless telemetry removes the need for trans‑skin leads, substantially lowering infection risk associated with long‑term implants.
Correct answer is: Elimination of infection risk from percutaneous connectors
Q.42 What does the term "neurotrophic factor" refer to in the context of neural prosthetic implants?
A type of electrical pulse waveform
A chemical that supports neuron survival and growth
A software algorithm for signal decoding
A mechanical component of the electrode
Explanation - Neurotrophic factors (e.g., BDNF, NGF) can be delivered locally to improve neuronal health around chronic implants.
Correct answer is: A chemical that supports neuron survival and growth
Q.43 Which of the following is the most common method for calibrating a myoelectric prosthetic hand before daily use?
Recording EMG while the user performs predefined grasps
Measuring skin temperature
Running a vision‑based hand tracking algorithm
Adjusting the battery voltage
Explanation - Calibration involves capturing EMG patterns associated with specific grasps to map them to prosthetic commands.
Correct answer is: Recording EMG while the user performs predefined grasps
Q.44 In a neural prosthetic for restoring hearing, the term "channel interaction" refers to:
Cross‑talk between adjacent electrode contacts causing overlapping stimulation fields
Interaction between auditory nerve fibers and the cochlea
Communication between the device and a smartphone
The effect of battery voltage on sound quality
Explanation - Channel interaction can degrade spectral resolution by causing overlapping activation of auditory nerve fibers.
Correct answer is: Cross‑talk between adjacent electrode contacts causing overlapping stimulation fields
Q.45 Which of the following best explains why spike‑sorting is necessary in intracortical recordings?
To increase the sampling rate
To separate action potentials from different neurons recorded on the same electrode
To convert analog signals into digital format
To filter out power‑line noise
Explanation - Spike‑sorting algorithms cluster waveforms to assign them to individual neuronal sources, allowing precise decoding of each neuron's activity.
Correct answer is: To separate action potentials from different neurons recorded on the same electrode
Q.46 The "cortical homunculus" is a visual representation of:
The distribution of blood vessels in the brain
Sensory and motor cortical areas mapped to body parts
The hierarchy of visual processing streams
The organization of the spinal cord
Explanation - The homunculus illustrates the somatotopic organization of the primary motor and somatosensory cortices.
Correct answer is: Sensory and motor cortical areas mapped to body parts
Q.47 When using transcranial direct current stimulation (tDCS) for motor rehabilitation, the anodal electrode is placed over the:
Contralateral motor cortex to increase excitability
Ipsilateral motor cortex to decrease excitability
Occipital lobe for visual enhancement
Cerebellum for balance improvement
Explanation - Anodal tDCS over the motor cortex of the affected limb increases neuronal excitability, facilitating motor learning.
Correct answer is: Contralateral motor cortex to increase excitability
Q.48 In a robotic exoskeleton for gait training, the term "assist‑as‑needed" control means:
The robot provides a constant torque regardless of user effort
The robot supplies assistance only when the user's performance falls below a threshold
The robot moves the user through a pre‑programmed trajectory
The robot disables assistance during the swing phase
Explanation - Assist‑as‑needed adapts support based on real‑time user effort, encouraging active participation and neuroplasticity.
Correct answer is: The robot supplies assistance only when the user's performance falls below a threshold
Q.49 Which of the following is a primary challenge when using surface EEG for high‑resolution neural prosthetic control?
High spatial resolution
Low signal amplitude and susceptibility to artifacts
Invasive surgery requirements
Long latency due to wireless transmission
Explanation - EEG signals are weak and contaminated by muscle, eye, and environmental noise, limiting fine‑grained control.
Correct answer is: Low signal amplitude and susceptibility to artifacts
Q.50 The "force‑feedback" modality in a prosthetic hand is typically delivered via:
Auditory tones
Vibrotactile stimulators on the residual limb
Visual display on a smartwatch
Temperature changes on the fingertip
Explanation - Vibratory actuators can encode grip force magnitude, enabling the user to sense how hard the prosthetic is gripping an object.
Correct answer is: Vibrotactile stimulators on the residual limb
Q.51 Which of the following best characterizes a "soft" neural interface?
Rigid silicon chips that penetrate the brain
Flexible polymeric electrodes that conform to tissue
Metallic wires implanted in the spinal cord
Glass micro‑electrodes with high stiffness
Explanation - Soft interfaces reduce mechanical mismatch with brain tissue, minimizing chronic inflammation and improving long‑term signal stability.
Correct answer is: Flexible polymeric electrodes that conform to tissue
Q.52 In a motor neuroprosthetic system, the term "decoder drift" refers to:
Gradual change in the relationship between neural signals and intended movements over time
Physical movement of the electrode array inside the brain
Battery voltage decreasing over time
Increase in stimulation intensity required for muscle activation
Explanation - Decoder drift occurs as neural signal characteristics evolve, requiring periodic recalibration to maintain accurate control.
Correct answer is: Gradual change in the relationship between neural signals and intended movements over time
Q.53 Which of the following is an example of a non‑invasive neural prosthesis?
Deep brain stimulator
Utah intracortical array
Transcranial magnetic stimulation (TMS) device for motor recovery
Spinal cord epidural stimulator
Explanation - TMS induces currents in the cortex without penetrating the skull, classifying it as a non‑invasive neural interface.
Correct answer is: Transcranial magnetic stimulation (TMS) device for motor recovery
Q.54 When designing a neural prosthetic for a pediatric user, which factor is most critical?
Device weight
Battery size
Ability to accommodate growth and skull development
Color of the device
Explanation - Pediatric implants must adapt to anatomical changes as the child grows to avoid complications and maintain functionality.
Correct answer is: Ability to accommodate growth and skull development
Q.55 The principle of "Hebbian learning" (cells that fire together wire together) is often utilized in which type of neural prosthetic training?
Closed‑loop sensory feedback training
Passive movement therapy
Randomized stimulation protocols
Pharmacological drug trials
Explanation - Providing timely sensory feedback linked to motor intent strengthens synaptic connections, leveraging Hebbian plasticity for functional recovery.
Correct answer is: Closed‑loop sensory feedback training
Q.56 Which metric is used to quantify the information transfer rate (ITR) of a BCI system?
Bits per trial
Bits per minute
Bits per electrode
Bits per voltage
Explanation - ITR measures the speed and accuracy of a BCI in bits per minute, reflecting how quickly a user can communicate or control a device.
Correct answer is: Bits per minute
Q.57 A neural prosthesis that restores limb movement by stimulating the peripheral nerves directly is called:
Central pattern generator implant
Peripheral nerve interface
Spinal cord stimulator
Brain‑stem implant
Explanation - Peripheral nerve interfaces provide bidirectional communication with the nerves that innervate the limb, enabling motor control and sensory feedback.
Correct answer is: Peripheral nerve interface
Q.58 Which of the following is NOT a typical component of a neurorehabilitation robot?
Actuator (motor)
Force/torque sensor
Electroencephalography (EEG) cap
Hydraulic pump
Explanation - Most rehabilitation robots use electric actuators; hydraulic pumps are uncommon due to size, weight, and control complexity.
Correct answer is: Hydraulic pump
Q.59 In the context of neural signal acquisition, the term "sampling theorem" (Nyquist) states that the sampling frequency must be at least:
Twice the highest frequency component of interest
Equal to the highest frequency component
Half the highest frequency component
Ten times the highest frequency component
Explanation - According to Nyquist, to avoid aliasing the sampling rate must be at least twice the maximum signal frequency.
Correct answer is: Twice the highest frequency component of interest
Q.60 Which of the following best describes the purpose of "gain scheduling" in prosthetic control algorithms?
Changing controller parameters based on operating conditions such as speed or load
Increasing the voltage supplied to the motor
Scheduling battery recharge cycles
Adjusting the visual display brightness
Explanation - Gain scheduling adapts controller gains in real time to maintain performance across different dynamic regimes.
Correct answer is: Changing controller parameters based on operating conditions such as speed or load
Q.61 What is the main advantage of using a "floating micro‑electrode" design for chronic brain implants?
It eliminates the need for any fixation hardware
It reduces micromotion-induced tissue damage by allowing movement with the brain
It provides higher electrical stimulation currents
It can be powered wirelessly
Explanation - Floating electrodes move with brain tissue, minimizing shear forces that cause inflammation and scar formation.
Correct answer is: It reduces micromotion-induced tissue damage by allowing movement with the brain
Q.62 Which rehabilitation outcome measure assesses the ability to walk 10 meters as quickly as possible?
Timed Up‑and‑Go (TUG) test
Six‑Minute Walk Test (6MWT)
10‑Meter Walk Test (10MWT)
Berg Balance Scale
Explanation - The 10MWT evaluates gait speed over a short distance, commonly used to gauge functional ambulation.
Correct answer is: 10‑Meter Walk Test (10MWT)
Q.63 In a neural prosthetic system, what does the term "latency jitter" refer to?
Variability in the time delay between command generation and actuator response
Average delay from stimulus to perception
Fluctuation in battery voltage
Changes in electrode impedance over time
Explanation - Latency jitter can degrade control smoothness and predictability, especially in fast‑acting prosthetic movements.
Correct answer is: Variability in the time delay between command generation and actuator response
Q.64 Which of the following is a common method for providing visual feedback to a BCI user during a cursor control task?
Auditory tones indicating direction
A moving dot on a screen representing cursor position
Vibration on the arm
Temperature change on the fingertip
Explanation - Visual feedback of cursor position allows the user to adjust neural activity to steer the cursor toward targets.
Correct answer is: A moving dot on a screen representing cursor position
Q.65 What is the primary physiological basis for detecting motor intent from the motor cortex using intracortical electrodes?
Changes in local field potential (LFP) power
Spiking activity of pyramidal neurons
Blood oxygen level‑dependent (BOLD) signals
Magnetic field fluctuations
Explanation - Individual action potentials from motor cortex pyramidal cells encode precise movement intentions, providing high‑resolution control signals.
Correct answer is: Spiking activity of pyramidal neurons
Q.66 Which of the following best describes a "feedforward" control strategy in prosthetic devices?
Using sensory feedback to adjust motor commands in real time
Predicting required actuator outputs based on a model of the user's intent without waiting for feedback
Applying a constant torque regardless of user input
Randomly varying motor commands to prevent adaptation
Explanation - Feedforward control anticipates necessary actions, relying on prior knowledge rather than real‑time sensory data.
Correct answer is: Predicting required actuator outputs based on a model of the user's intent without waiting for feedback
Q.67 In a functional electrical stimulation (FES) system for standing, which muscles are typically targeted?
Biceps brachii and triceps brachii
Quadriceps, gluteus maximus, and gastrocnemius
Deltoid and pectoralis major
Forearm flexors and extensors
Explanation - These lower‑limb muscles generate the extension and stability needed to achieve and maintain a standing posture.
Correct answer is: Quadriceps, gluteus maximus, and gastrocnemius
Q.68 Which of the following is a key advantage of using a “soft robotics” exosuit for gait rehabilitation?
Higher torque output than rigid exoskeletons
Lightweight and minimally restrictive to natural movement
Ability to deliver deep brain stimulation
Built‑in AI for autonomous navigation
Explanation - Soft exosuits conform to the body, providing assistance without impeding natural gait dynamics.
Correct answer is: Lightweight and minimally restrictive to natural movement
Q.69 The term "cortical re‑mapping" in neuroprosthetic training refers to:
Physical relocation of the implant within the brain
Changes in the cortical representation of body parts due to learning or injury
Re‑programming the decoder software
Adjusting the electrode impedance
Explanation - Cortical re‑mapping reflects neuroplastic reorganization, often targeted during BCI training to improve control.
Correct answer is: Changes in the cortical representation of body parts due to learning or injury
Q.70 Which of the following is a typical frequency band used for decoding motor intention from EEG?
Delta (0.5‑4 Hz)
Theta (4‑8 Hz)
Mu (8‑13 Hz)
Gamma (> 30 Hz)
Explanation - The mu rhythm (sensorimotor rhythm) is modulated during motor imagination and execution, making it a common feature for EEG‑based motor BCIs.
Correct answer is: Mu (8‑13 Hz)
Q.71 In a neural prosthetic for speech, which type of cortical area is primarily targeted for decoding?
Primary visual cortex
Broca's area (speech production)
Primary auditory cortex
Motor cortex leg representation
Explanation - Broca's area is involved in planning and producing speech, providing neural signals that can be decoded for speech prostheses.
Correct answer is: Broca's area (speech production)
Q.72 Which of the following best defines the term "neuroprosthetic latency budget"?
The total allowable time from neural intent detection to prosthetic action for naturalistic control
The amount of battery life remaining in the device
The maximum stimulation amplitude permitted
The number of electrodes that can be used simultaneously
Explanation - Latency budget encompasses sensing, processing, and actuation delays; staying within this budget is essential for smooth, intuitive prosthetic operation.
Correct answer is: The total allowable time from neural intent detection to prosthetic action for naturalistic control
Q.73 When using a neural cuff electrode on a peripheral nerve, the stimulation selectivity is primarily determined by:
Cuff thickness
Electrode contact geometry and spacing
Battery voltage
Wireless transmission frequency
Explanation - Design of contacts (size, shape, spacing) influences the ability to selectively activate specific fascicles within the nerve.
Correct answer is: Electrode contact geometry and spacing
Q.74 In the context of brain‑machine interfaces, the term "population vector" refers to:
A vector representing the average firing direction of a group of neurons
The physical location of the implanted electrode array
The magnetic field generated by neuronal activity
The voltage output of a single neuron
Explanation - Population vectors sum the directional tuning of many neurons to estimate intended movement direction.
Correct answer is: A vector representing the average firing direction of a group of neurons
Q.75 Which of the following is a common clinical metric used to assess the effectiveness of a lower‑limb prosthetic after amputation?
K-level classification
MRC muscle strength grading
Fugl‑Meyer Assessment
Barthel Index
Explanation - K-levels (0‑4) describe a patient's functional mobility and are used to prescribe appropriate prosthetic components.
Correct answer is: K-level classification
Q.76 What is the primary purpose of using a "bias‑tee" in a neural stimulation circuit?
To block DC components while allowing AC stimulation pulses
To increase the stimulation amplitude
To convert digital signals to analog
To store energy for the next pulse
Explanation - A bias‑tee separates AC stimulation currents from DC bias, protecting tissue and preventing electrode corrosion.
Correct answer is: To block DC components while allowing AC stimulation pulses
Q.77 In a prosthetic hand, "haptic rendering" typically involves:
Generating auditory cues for grip force
Providing force feedback through tactile actuators
Displaying visual icons on a screen
Changing the temperature of the hand
Explanation - Haptic rendering creates the sensation of touch or pressure, usually via vibration or pressure devices on the user's skin.
Correct answer is: Providing force feedback through tactile actuators
Q.78 Which of the following best explains why deep learning models are increasingly used for decoding neural signals?
They require less data than traditional methods
They can automatically learn complex, non‑linear feature representations
They are always faster to run on embedded hardware
They do not need any preprocessing of the signals
Explanation - Deep neural networks can capture intricate patterns in high‑dimensional neural data, improving decoding accuracy over linear models.
Correct answer is: They can automatically learn complex, non‑linear feature representations
Q.79 When assessing the durability of an implanted neural electrode, which property is most critical?
Optical transparency
Corrosion resistance
Magnetic susceptibility
Color stability
Explanation - Electrodes must resist degradation in the ionic environment of the body to maintain performance over years.
Correct answer is: Corrosion resistance
Q.80 Which of the following is a typical symptom addressed by a spinal cord stimulation (SCS) neuroprosthesis?
Hearing loss
Chronic neuropathic pain
Visual field deficits
Tremor in Parkinson's disease
Explanation - SCS delivers low‑frequency pulses to the dorsal columns, modulating pain pathways and reducing neuropathic pain sensations.
Correct answer is: Chronic neuropathic pain
Q.81 In the design of a neural prosthetic for upper‑limb reach, the "inverse kinematics" algorithm is used to:
Predict muscle activation patterns from joint angles
Convert desired hand position into joint angle commands
Measure the electrical resistance of the electrode
Generate visual feedback for the user
Explanation - Inverse kinematics computes the joint configuration needed to achieve a target end‑effector position, essential for controlling prosthetic arms.
Correct answer is: Convert desired hand position into joint angle commands
Q.82 Which of the following best characterizes a "myoelectric" prosthetic hand?
It uses brain‑derived signals to control movement
It is driven by surface EMG signals from residual muscles
It relies on foot pedal controls
It is powered solely by solar energy
Explanation - Myoelectric prostheses detect EMG from remaining limb muscles to generate proportional control signals for the hand.
Correct answer is: It is driven by surface EMG signals from residual muscles
Q.83 What does the term "neuro‑rehabilitation" primarily refer to?
Surgical implantation of neural prostheses
Physical therapy that incorporates neural plasticity principles
Prescription of antiepileptic medication
Genetic engineering of neurons
Explanation - Neuro‑rehabilitation leverages activity‑dependent plasticity to restore function after nervous system injury.
Correct answer is: Physical therapy that incorporates neural plasticity principles
Q.84 Which of the following is a key factor influencing the resolution of a retinal prosthesis?
Number of electrode contacts per square millimeter
Battery capacity of the external processor
Color of the device housing
Length of the surgical incision
Explanation - Higher electrode density enables finer stimulation patterns, improving visual resolution for the user.
Correct answer is: Number of electrode contacts per square millimeter
Q.85 In the context of functional electrical stimulation for gait, the term "phase‑specific" stimulation means:
Stimulating continuously throughout the gait cycle
Delivering pulses only during specific phases (e.g., stance or swing)
Changing the frequency of stimulation every minute
Adjusting the electrode polarity randomly
Explanation - Phase‑specific FES aligns stimulation with the natural timing of muscle activation, improving gait symmetry and efficiency.
Correct answer is: Delivering pulses only during specific phases (e.g., stance or swing)
Q.86 Which of the following is a standard method for evaluating the classification accuracy of a BCI decoder?
Cross‑entropy loss
Confusion matrix analysis
Root mean square error (RMSE)
Signal‑to‑noise ratio (SNR)
Explanation - A confusion matrix displays true vs. predicted class counts, from which accuracy, precision, recall, and other metrics are derived.
Correct answer is: Confusion matrix analysis
Q.87 Which brain region is most commonly targeted for recording speech articulation intent in invasive BCIs?
Primary visual cortex
Primary motor cortex (hand area)
Broca's area (inferior frontal gyrus)
Posterior parietal cortex
Explanation - Broca's area is involved in language production and shows activity correlated with speech planning, making it suitable for speech prostheses.
Correct answer is: Broca's area (inferior frontal gyrus)
Q.88 Which of the following best describes the term "sensory substitution" in neuroprosthetics?
Using visual cues to replace auditory feedback
Providing tactile feedback on the skin to convey information from a lost sense
Replacing a limb with a robotic prosthesis
Transplanting donor nerves into the stump
Explanation - Sensory substitution maps information from a deficient modality (e.g., vision) onto another (e.g., touch) so the brain can interpret the new signals.
Correct answer is: Providing tactile feedback on the skin to convey information from a lost sense
Q.89 In a closed‑loop FES system for hand opening, the feedback sensor typically measures:
Skin temperature
Grip force or finger joint angle
Ambient light level
Heart rate
Explanation - Feedback of force or position allows the controller to adjust stimulation intensity to achieve the desired hand opening without overshoot.
Correct answer is: Grip force or finger joint angle
Q.90 Which of the following is a potential benefit of using a "micro‑LED" array for optogenetic stimulation in a neural prosthetic?
Reduced heat generation compared to fiber‑optic light sources
Increased stimulation depth beyond 10 mm
Elimination of the need for genetic modification
Ability to deliver electrical stimulation simultaneously
Explanation - Micro‑LEDs can be integrated close to target tissue, delivering light efficiently with lower power and minimal heating.
Correct answer is: Reduced heat generation compared to fiber‑optic light sources
Q.91 When evaluating a neural prosthetic arm, the "degrees of freedom" (DOF) refers to:
Number of batteries the device contains
Number of independent movement axes the prosthesis can control
Number of electrodes implanted in the brain
Number of software updates per year
Explanation - DOF denotes the distinct ways the prosthetic can move (e.g., wrist flex/extension, grip, pronation), influencing functional capability.
Correct answer is: Number of independent movement axes the prosthesis can control
Q.92 Which of the following best explains why a high‑density electrode array can improve decoding performance in motor BCIs?
It reduces the overall power consumption
It captures a larger population of neurons, providing richer information
It eliminates the need for signal filtering
It automatically corrects for electrode drift
Explanation - More recording sites increase spatial coverage and neuron count, enhancing the statistical power for decoding intended movements.
Correct answer is: It captures a larger population of neurons, providing richer information
Q.93 Which of the following is a common method for providing proprioceptive feedback in a bidirectional arm prosthesis?
Electrical stimulation of the median nerve
Auditory tone modulation
Visual indicator lights on the device
Temperature changes on the skin
Explanation - Targeted electrical stimulation of peripheral nerves can evoke sensations of joint position, delivering proprioceptive feedback to the user.
Correct answer is: Electrical stimulation of the median nerve
Q.94 Which of the following best describes the term "neuroprosthetic "cortical" implant"?
An implant placed on the scalp surface
A device implanted within the cerebral cortex to record or stimulate neurons
A peripheral nerve cuff electrode
A spinal cord stimulator
Explanation - Cortical implants reside in the brain tissue, directly interfacing with cortical neurons for high‑resolution communication.
Correct answer is: A device implanted within the cerebral cortex to record or stimulate neurons
Q.95 In a neural prosthetic system, the "sampling rate" of 30 kHz is primarily chosen to:
Match the frequency of human heartbeats
Capture the fast dynamics of neuronal action potentials
Reduce power consumption
Synchronize with Bluetooth transmission
Explanation - Action potentials have durations of ~1 ms; a 30 kHz sampling rate provides sufficient temporal resolution to accurately record spike waveforms.
Correct answer is: Capture the fast dynamics of neuronal action potentials
Q.96 Which of the following is a major challenge when using surface EMG for controlling a multi‑finger prosthetic hand?
High inter‑subject variability in signal amplitude
Inability to record any muscle activity
Excessive power consumption of the electrodes
Requirement for surgical implantation
Explanation - Surface EMG signals vary widely across users and electrode placements, making consistent multi‑finger control difficult without extensive calibration.
Correct answer is: High inter‑subject variability in signal amplitude
Q.97 Which of the following best defines the term "neuro‑plasticity" in the context of rehabilitation?
The ability of neural tissue to change its shape
The capacity of the nervous system to reorganize connections in response to experience
The rigidity of synaptic connections after injury
The electrical resistance of neural tissue
Explanation - Neuro‑plasticity underlies functional recovery, as repeated training can strengthen or form new synaptic pathways.
Correct answer is: The capacity of the nervous system to reorganize connections in response to experience
Q.98 When implementing a real‑time decoder for a BCI, which computational approach is most suitable for minimizing latency?
Batch processing of recorded data after the trial
Using lightweight linear models such as LDA or ridge regression
Training a deep convolutional network on a GPU during operation
Running a full Monte‑Carlo simulation for each sample
Explanation - Linear models have low computational overhead, allowing rapid inference essential for low‑latency BCI control.
Correct answer is: Using lightweight linear models such as LDA or ridge regression
Q.99 Which of the following clinical tests assesses upper‑limb dexterity and is often used to evaluate prosthetic hand performance?
9‑Hole Peg Test
Timed Up‑and‑Go (TUG)
Six‑Minute Walk Test
Berg Balance Scale
Explanation - The 9‑Hole Peg Test measures fine motor coordination and speed, making it suitable for assessing hand prostheses.
Correct answer is: 9‑Hole Peg Test
Q.100 Which of the following is the most common cause of "electrode migration" after chronic implantation?
Magnetic resonance imaging (MRI) exposure
Mechanical forces from brain pulsations and tissue movement
Battery depletion
Software firmware updates
Explanation - Micromotion of brain tissue can gradually shift implanted electrodes, leading to signal loss or changes in stimulation location.
Correct answer is: Mechanical forces from brain pulsations and tissue movement
Q.101 In a neuroprosthetic system for lower‑limb exoskeleton control, the term "assistive torque" refers to:
The torque generated by the user's muscles alone
The torque supplied by the exoskeleton actuators to aid movement
The torque measured by the onboard gyroscope
The torque needed to power the battery
Explanation - Assistive torque is the additional rotational force the exoskeleton provides to support or augment the user's intended motion.
Correct answer is: The torque supplied by the exoskeleton actuators to aid movement
Q.102 Which of the following best describes the purpose of a "ground" electrode in a neural recording system?
To increase the signal amplitude
To provide a reference point that reduces common‑mode noise
To deliver therapeutic stimulation currents
To power the recording hardware
Explanation - The ground electrode stabilizes the electrical environment, helping to cancel out interference common to all recording sites.
Correct answer is: To provide a reference point that reduces common‑mode noise
Q.103 In the context of neural prostheses, the term "signal‑to‑noise ratio (SNR)" is important because:
Higher SNR indicates more reliable detection of neural events
SNR determines the battery life of the device
SNR is directly related to the weight of the implant
Low SNR improves the comfort of the prosthesis
Explanation - A high SNR means the neural signal stands out clearly above background noise, essential for accurate decoding and stimulation.
Correct answer is: Higher SNR indicates more reliable detection of neural events
Q.104 Which of the following is a primary advantage of using a "modular" architecture in neural prosthetic hardware?
Reduced need for software updates
Ease of swapping or upgrading individual components without redesigning the whole system
Increased weight for better stability
Elimination of the need for power management
Explanation - Modularity allows developers to replace or improve specific parts (e.g., amplifiers, stimulators) while keeping the rest of the system unchanged.
Correct answer is: Ease of swapping or upgrading individual components without redesigning the whole system
Q.105 Which of the following best explains why a prosthetic hand might use "force‑sensing resistors (FSRs)" at the fingertips?
To detect temperature changes
To measure the applied grip force for feedback control
To generate electrical stimulation pulses
To store energy during grasp
Explanation - FSRs change resistance with applied pressure, providing real‑time grip force data that can be fed back to the controller or user.
Correct answer is: To measure the applied grip force for feedback control
Q.106 In a neural prosthetic system, a "low‑pass filter" set at 300 Hz is typically used to:
Remove high‑frequency noise while preserving action potentials
Amplify the neural signal
Convert analog signals to digital
Increase the sampling rate
Explanation - A low‑pass filter attenuates frequencies above the cutoff, eliminating high‑frequency artifacts while keeping the spike band (typically up to 300 Hz).
Correct answer is: Remove high‑frequency noise while preserving action potentials
Q.107 Which of the following is a common method for reducing motion artefacts in surface EMG recordings?
Increasing the electrode size
Applying a high‑pass filter at 20 Hz
Using adhesive conductive gel and secure electrode placement
Operating the system at a higher temperature
Explanation - Good skin preparation and stable electrode attachment minimize movement‑induced artefacts in EMG signals.
Correct answer is: Using adhesive conductive gel and secure electrode placement