Electroencephalography I PDF

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Lab Homework 1) Compare and contrast the waveforms (appearance of wave activity) of synchrony and alpha block. During synchrony, the alpha waves should be apparent. We would expect synchrony to occur during a relatively restful period of decreased concentration. Alpha waves would decrease when the person opens their eyes, especially if they are concentrating. This is called an alpha block. It is possible that merely opening the eyes was not enough mental stimulation to dramatically reduce alpha and increase beta waves. 2) Does synchronization of the alpha rhythm occur when the eyes are open or closed? Synchronization of the alpha rhythm occurs with eyes open.

3) Does the beta rhythm become more pronounced when the eyes are open or closed? Theoretically, the beta waves should become more pronounced when the eyes are open. However, they become even more pronounced when the mind is in concentration. 4) The amplitudes (height) of the waveforms are indicative of how much alpha activity is occurring in the subject. However, the amplitude values for beta do not reflect the amount of mental activity occurring with the eyes open. Please explain. Beta waves are characterized by lower amplitudes primarily because greater electrical activity of the cortex causes the average signal to be flatter. In other words, the increased positive and negative activity cancel each other on the average signal during increased mental functioning. 5) Examine the delta and theta rhythm. Is there an increase in delta and theta activity when the eyes are open? Try to explain your observation. Theta waves should decrease as a result of decreased relaxation during the eyes open condition. We would not expect much change in delta waves, which are usually most observable during deep sleep. 6) Briefly, what does the EEG signal represent? The EEG represents an average of the thousands to millions of action potentials occurring in the cortex below the electrode....