beta- and alpha activity
Experiment was accomplished by:
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Teacher:
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Date:
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Subject's profile
Name: ... Height: ...
Age: ... Weight: ...
Gender: male / female
The aim of the experiment (brief definition in a few sentences)
Introduction (can be continued on a separate sheet if needed)
1. Mechanisms related to the generation of EEG, basics of the EEG recording, typical EEG waveforms (summary of the most important facts in regard to the analysis of the practical data)
2. Methods and materials (schematic enumeration)
3. Technical details of the practical exercises (preparation of the subject, settings of the recording system, explan-ation of the exercises)
A. Data and Calculations
After opening of the Lesson04 (EEGII) recording, the following signals can be seen on the display:channel 1(CH1) – recorded („raw”) EEG signal; channel 40 (CH40) – alpha activity(after digital filtering of the EEG signal);
channel 41 (CH41) – alpha rms.Alpha rms is the root mean square value of the signal within a window width of 0.25 seconds. This parameter provides a good characterization for the actual quantity of the alpha waves.
Attach the printouts from the magnified, analyzed recording segments to the lab record and note the number of the attachments.
1. Determination of the amplitude as well as frequency of alpha waves Name a segment from the EEG recording
when you expect highalphaactivity: ...
Number of the segment: ...
Analyze the signal seen onchannel 1 (recorded „raw” EEG signal). Magnify the selected section by theZoom cursor then set the amplitude of the signal by theDisplay/Autoscale Waveforms function.Use the following measurement windows:channel 1 (raw EEG) – p-p(peak-to-peak; this measurement shows the difference between the maximum and minimum amplitude value in the selected area);channel 1 (raw EEG) – delta T.Identify the consequtive alpha waves. Select an alpha wave by the I-beam cursor from the beginning of the wave to the peak of the wave. By this kind of selection, you can measure the amplitude of the wave. Then insert the value seen in thechannel 1 (raw EEG) p-pmeasurement window to the p-p (amplitude) line of the table below. After that, select the same alpha wave from the beginning to the end. Period time of the wave will apear in thechannel 1 (raw EEG) – delta Tmeasurement window. Insert this value to the table below. (Delta time can be negative if the se-lection had been made in a reverse order i.e. the end of the wave was selected first and the wave onset last). Repeat the above mentioned procedure to 7 different, consequtive alpha waves. Calculate frequency values from the period time values. Calculate the mean of the amplitude-, period- as well as frequency values.
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2. Determination of the amplitude as well as frequency of beta waves Name a segment from the EEG recording
when you expect highbetaactivity: ...
Number of the segment: ...
Analyze the signal seen onchannel 1 (recorded EEG signal). Analysis should be made in a similar way as in Ex-ercise 1.
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3. Effects of different interventions on the quantity of alpha waves
Analyze the signal seen onchannel 41 (alpha rms).Magnify the selected section by theZoomcursor then set the amplitude of the signal by theDisplay/Autoscale Waveformsfunction.Use the following measurement window:
channel 41 – mean.Take notice of the recorded EEG (channel 1) and select a 2-seconds-long part from every different recording segments (1st, 2nd, 3rd). Read the alpha rms values appearing on the measurement window and fill them into the table below.
When you select a part from the 1st (control) segment, pay attention to select a segment where several alpha waves can be seen in the recorded EEG (channel 1). In case of the 2nd segment (mental math), select that segment for the analysis which shows the data recorded immediately after the order to calculate (when the subject likely shows maximal mental activity). Take care to select artifact-free epochs. Alpha rms value of the first segment is the ref-erence (control). Calculate alpha rms diffref-erence between control and experimental stages (i.e. 2nd and 3rd segments).
4. Artifacts
Does the recording contain artifacts? Yes No
If artifacts are present in the recording, mark them on the printouts and reference them by numbers. Identify the
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B. Data summary and conclusions
1. Under which intervention did you observe the largest amount of alpha waves? Use the table at Exercise 3.
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2. Under which intervention did you observe the smallest quantity of alpha waves? Use the table at Exercise 3.
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3. How did the quantity of alpha waves change by the degree of attention?
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4. Based on the experimental results, did the subject pay attention to the mental math task?
yes no
5. Compare the EEG patterns recorded with eyes open or closed.
a) What kind of changes did you observe in the EEG when the subject's eyes were open?
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b) What happens to the functioning of the occipital lobe neurons when the subject's eyes are open?
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c) Give a definition describing the changes in the functioning of the the occipital lobe neurons when the subject's eyes are closed!
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d) When did you observe more pronounced beta activity?
eyes closed eyes open
C. Analysis of a healthy and a pathological EEG recordings
Compare the EEG recorded from a healthy subject (26 years old male with regular cortical activity) with the EEG originated from asubject with unknown medical condition(thus, he/she can be healthy, might suffer from some illnesses, can be a child or adult, etc). EEG was recorded using the international 10-20 system. Electrode configur-ation can be seen on Figure 1.
Use calibration bars indicated on the recordings to determine theamplitudeas well as thefrequencyof typical EEG waves. For the calculation, mark the start and end points of the analyzed segment on the recording (for example, an alpha spindle). Count the waves then measure the length of the analyzed segment. Calculate the duration of the segment in proportion to the time calibration bar. Then divide the number of the waves by the duration of the analysed segment to obtain the frequency of the given waves. [For example: time calibration indicates 25 mm as 1 second. The length of the selected epoch is 23 mm. Thus, the duration of the epoch is 0.92 s. If there were 10 waves in the selection, then the frequency is 10/0.92=10.87 Hz.]
There is no need to provide exact measurement on the frequency and amplitude of beta activity. Instead, indicate directly on the EEG recordings and also, in the table below the lead(s) where beta activity is clearly visible.
If artifacts are present in the recording, mark them on the printed recording and reference them by numbers.
Identify the types of the artifacts.
The healthy subject was in a supine position with closed eyes during the recording. Note that the subject with un-known medical condition is not certainly diseased.
Compare the EEG of the healthy subject with the subject with unknown medical condition.Give a detailed reasoning in the lab report about your opinion! It is not the medical accuracy of the diagnosis but the precision and depth of the analysis what will determine the rating of the lab record.
1. Identification of disordered waveforms on the recording of the subject with unknown medical condition:
a) name the type of the disordered waveforms and report the leads where those appeared.
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b) What was the cause of the appearance of the disordered waveforms?
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2. Identification of artifacts:
a) Did you observe artifacts in the recordings? If yes, on which leads?
recording of the healthy subject: ...
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recording of the subject with unknown medical condition:...
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b) What was the possible cause of these artifacts?
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3. Analysis of the recording belonging to a subject with unknown medical condition:
a) What do you think about the experimental conditions? Was the patient asleep or awake during the recording?Were the subject's eyes closed or open during the recording? Explain your answers!
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b) What is your opinion about the age of the unknown subject? Explain your answer.
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c) What is your opinion about the health status of the unknown subject? Explain your answer.
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