Clinical Science Questions and Answers – Electroencephalography

This set of Clinical Science test focuses on “Electroencephalography”.

1. The placement of the sensors on the cranium in order to take EEG is called ________
a) Montage
b) Cranial Cap
c) Electrode Placement
d) Electrode Cap
View Answer

Answer: a
Explanation: The placement of the electrodes on the cranium in order to take the EEG is the montage. The placement can involve 21 electrodes. In order to ensure the correct placement of the electrodes, a cap with perforations at the correct locations is used. This cap is the cranial cap or the montage cap. When taking the EEG, the sensors or the electrodes are plugged in the respective perforations and the signal is acquired.

2. The frequency of the waves acquired when the person is in an alert and wakeful state is _______
a) 4 – 8 Hz
b) 8 – 13 Hz
c) 13 – 30 Hz
d) > 30 Hz
View Answer

Answer: c
Explanation: When a person is alert and properly awake, the waves obtained are beta waves. These waves range from 13 – 20 Hz. The alpha waves (8 – 13 Hz) are obtained when a person is asleep. Theta waves (4 – 8 Hz) are found when the person is sitting idle or in children. Sometimes, these waves are generated when the person is about to fall asleep. Gamma waves (> 30 Hz) are found when a person is doing an intense mental activity or is multitasking.

3. The electrode gel is used to _________
a) reduce skin resistance
b) increase skin resistance
c) moisturize the skin
d) cause skin flaking
View Answer

Answer: a
Explanation: The electrodes that acquire the signal can cause damage to the skin as well. This is because while acquiring the signal, there is heat production which can cause burning if the signal acquisition is of a long duration. Thus, the electrode gel is used to reduce the skin resistance so that prolonged signal acquisition can take place.

4. EEG is the recording of the _________
a) signal from axons of the pyramidal cells
b) signal from the dendrites of the pyramidal cells
c) cyton secretions
d) axon secretions
View Answer

Answer: b
Explanation: Pyramidal cells are those which are close to the surface of the cranium. Dendrites are the extension of cytons, i.e. the cell body of neurons. The dendrites take the impulses, the impulses enter the cyton, travel through the axon and reach the axon terminal from where they are transmitted further.

5. When a person moves his arms and legs, the EEG is generated from _______
a) Temporal Lobe
b) Parietal Lobe
c) Occipital Lobe
d) Frontal Lobe
View Answer

Answer: d
Explanation: The brain is divided into various areas called the Broca’s areas. These areas process and control the various actions of the body. Area 4 is situated in the Frontal Lobe and this area is responsible for the motor functions of the body. It is the highest center for motor activity.
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6. When an EEG is taken from the Occipital Region of the brain, what signal will cause the maximum amount of noise?
a) EOG
b) EMG
c) ECG
d) EEG from other parts of the brain
View Answer

Answer: a
Explanation: EOG stands for electrooculogram and it the signal that is taken from the eye. The occipital lobe is the center for eye movements so if an EEG is being taken from the Occipital Lobe, the incoming signals from the eyes (EOG) will act as noise to them.

7. Which of the following conditions will give slow waves with high amplitude?
a) Hypoglycemia
b) Hypothermia
c) Hypocapnia
d) Low Glucocorticoids
View Answer

Answer: c
Explanation: Hypocapnia is a condition when the levels of carbon dioxide go lower than the normal levels. This is due to deep or rapid breathing. This state is also called as hyperventilation. Hypoglycemia is the condition when the blood sugar goes low while hypothermia is the condition when the body temperature has gone down. Glucocorticoids are important to the immune system. When conditions like Hypoglycemia, hypothermia or low glucocorticoids happen, the body is actively trying to raise their quantity so the brain signals are high. However, in case of less carbon dioxide, the brain reduces activity to set the balance. Thus, the signals received are slow and of low frequency.

8. Certain natural processes interrupt the normal alpha waves. This process is called as alpha block or ________
a) disruption
b) beta introduction
c) asynchronization
d) desynchronization
View Answer

Answer: d
Explanation: When the normal alpha waves are disrupted, the process is desynchronization. In this process, a beta wave gets introduced and persists for a while until the activity is ongoing.

9. Which of the following processes will cause desynchronization?
i. Thinking
ii. Snoring
iii Mathematical Calculation
iv. Eye opening after sleep
v. Sleeping
vi. Clapping
vii. Sneezing
a) iii, iv & vi
b) i, ii, iii, iv, v, vi & vii
c) i & iv
d) ii, vi, & vii
View Answer

Answer: a
Explanation: Mathematical Calculation, Eye opening after sleep and Clapping are actions that gain our attention after a period of inattention. Thinking is a proper prolonged process and generates a long line of beta waves while calculations can be of short duration and so can cause desynchronization.

10. Sleep spindles are found __________ of the sleep.
a) first phase
b) second phase
c) third phase
d) fourth phase
View Answer

Answer: b
Explanation: Sleep spindles are found in the second stage of sleep. According to sleep sciences, consciousness is classified by Rapid Eye movement (REM), Non – Rapid Eye Movement (NREM) and wakefulness. NREM is the stage of proper deep sleep and the sleep spindles along with Kappa Waves are observed in this period.

11. Abnormal sleep spindles can indicate _______
a) Cerebral Palsy
b) Meningitis
c) Epilepsy
d) Paralysis
View Answer

Answer: c
Explanation: Scientists over long research have a reason to believe that sleep spindles are a way for the brain to convert short term memory into long term and therefore enhance learning. Often times, when the body does minute physical movement, sleep spindles are also generated. So, it is said that the body is learning in sleep. Thus, when sleep spindles of epileptic patients are seen, they show an abnormal trend.

12. Which wave can help point out the place of a brain tumor?
a) Alpha waves
b) Beta waves
c) Delta waves
d) Gamma waves
View Answer

Answer: c
Explanation: Delta waves have a frequency of less than 4 Hz. When a person is at rest, they will normally give alpha waves whose lowest range is 8 Hz. Thus, if there is a tumor formation, we can assume that a tumour is blocking the signal and so the electrode at the specific region reads a delta wave instead of an alpha wave when even though the other parts of the brain is giving an alpha wave.

13. Narcolepsy is a condition in which a person has excessive sleepiness during daytime as they are unable to regulate their sleep cycle. It’s a neurological disorder and can be traced with the help of an EEG. What kind of EEG can be expected in this kind of disorder?
a) Alpha waves with short bursts of Beta waves
b) Alpha Waves with short burst of Gamma waves
c) Alpha Waves with short bursts of sleep spindles
d) Continuous alpha waves
View Answer

Answer: c
Explanation: The brain normally gives alpha waves while deep sleep produces sleep spindles. When a person is suffering from narcolepsy they will have a deep burst of sleep which causes the sleep spindles to occur. Thus the presence of sleep spindles in the period of wakefulness can indicate narcolepsy.

14. An EEG for seizure is characterized by ___________
a) low amplitude, high frequency waves
b) high amplitude, low frequency waves
c) high amplitude, high frequency waves
d) low amplitude, low frequency waves
View Answer

Answer: c
Explanation: When a seizure occurs, the EEG shoots, giving a high frequency high, amplitude output. This is because, during a seizure, the brain activity becomes extremely high that the signals are generated faster than they are processed and dispersed. Since the brain is not able to send out signals fast enough or rather the body is not able to act on the signals fast enough, shaking, trembling or other physical outlets may happen.

15. What is the term used for portable EEG?
a) Travel EEG
b) Ambulatory EEG
c) Personalized EEG
d) Transport EEG
View Answer

Answer: b
Explanation: Ambulatory EEG is the one in which a person wears an EEG cap where the receiving electrodes are placed. The machine is strapped to the waist of the person and a continuous monitoring of the EEG can be done. This is useful for those who need long monitoring for diagnosis and treatment. This provides portability and comfort to the patient.

16. The following is the diagrammatic representation of _______ montage.
Find the placement of the electrodes from the given diagram
a) 10 – 20 %
b) 20 – 40 %
c) 40 – 60 %
d) 60 – 80 %
View Answer

Answer: a
Explanation: The placement of the electrodes on the cranium is called as the montage. The 10 – 20% is an internationally accepted standard for the placement of electrodes. The 10 and 20 stand for the distance between the adjacent electrodes is actually 10% or 20% of the total distance of the front-back or right-left length of the skull.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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