Question

Which statement about alpha waves is NOT true?

Select one:

a. Alpha waves tend to be strongest when the subject has his eyes open and is alert.

b. Alpha waves may be expected to be stronger in outgoing subjects (extroverts).

c. Typical frequencies vary from 8-13 Hz.

d. Females tend to have higher mean frequencies than males.

e. Alpha waves are smaller when signals are desynchronized.

Answer 1

Answer: option (1) is the correct answer. The given statement in option (1) is not true - Alpha waves tend to be strongest when the subject has his eyes open and is alert.

Alpha waves

Brain is a bustling hub of electrical activity. This is due to the fact that the cells in brain, called neurons, use electricity to communicate with each other. When a group of neurons sends an electrical signal to another group of neurons, we call those brain waves. This is because a computer-generated electroencephalogram (EEG) test that detects and measures the electrical activity in your brain actually creates a picture that looks like a wavelike pattern.

There are five basic types of brain waves that range from very slow to very fast. Alpha waves fall in the middle of that series of waves. Your brain produces these waves when you are awake but not really concentrating on any one thing. Your brain produces these waves when you are not focusing too hard on anything in particular. Whatever you are doing, you are probably feeling relatively calm and relaxed. These waves measure between 8 and 12 Hz.

In general, the alpha rhythm is the prominent EEG wave pattern of an adult who is awake but relaxed with eyes closed. Each region of the brain has a characteristic alpha rhythm but alpha waves of the greatest amplitude are recorded from the occipital and parietal regions of the cerebral cortex. Results from various studies indicate that:

1. Hyperventilation (breathing abnormally quickly and deeply) causes the gas composition of the blood to change. During hyperventilation, the carbon dioxide levels of the blood fall, pH levels increase, and blood pressure decreases. These effects of hyperventilation are associated with changes in brainwave activity. With hyperventilation, the overall electrical activity of the brain increases, with the amplitude of the alpha rhythms often increases as well.

2. Females tend to have higher mean frequencies of alpha waves than males, although the differences are small.

3. Alpha wave amplitudes are likely to be higher in “outgoing” and “extroverted” subjects.

4. Alpha wave amplitudes vary with the subject's attention to mental tasks performed with the eyes closed.

5. Alpha waves are smaller when signals are desynchronized. A higher degree of alertness caused by opening one’s eyes is associated with the attenuation of alpha rhythm, which is supplanted by desynchronized low voltage activity.

6. In general, amplitudes of alpha waves diminish when subjects open their eyes and are attentive to external stimuli. Thus, instead of getting the wave-like synchronized pattern of alpha waves, desynchronization occurs. Although some subjects trained in relaxation techniques can maintain high alpha amplitudes even with their eyes open.

7. Amplitudes increase when subjects are less alert