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Abstract
Electroencephalogram is often used in determining the brain waves that are recorded in form of EEG signals. This waves are usually crucial in determining the brain’s activity level. Hence, a variety of these waves such as alpha, beta, delta and theta shows a variety of brain activity levels. Hence, in our experiment the brain waves that were recorded varied according to the activity which the subject was involved in. For instance, different EEG signals were recorded when the subjects brain’s waves were taken with their eyes closed or opened as well as involved in various activities such as a mental arithmetic or after hyperventilation.
This indicates that abnormalities in the brain functioning can be determined using this method which is easy to administer. Thus, it is often used in medical facilities to determine the presence of several brain abnormalities as well as the effects of some medications. However, people record different EEG signals according to their ages band medical conditions. However, this experiment effectively determined various brain waves according to the action the subjects were undertaking.
Introduction
The brain waves are mostly attributable to the brain’s electrical activities which are actually manifested due to the alternating potential differences that are usually found at the scalp surface (Pagana & Pagana, 2010). However, whenever such electrical activities are acquired by the use of scalp electrodes, the recorded potential differences usually leads to signals that are in time-continuous referred to as the electroencephalogram (EEG). Therefore, when considered from a physical point of view, it becomes necessary to model the obtained wave-like qualities of the electroencephalogram as a finite sum of the harmonic oscillations that are presented as discrete vibration rates that are central pace-maker triggered (Eimer & Kiss, 2010). Hence, the obtained brain-waves can analogously be interpreted just like the sound waves in acoustics consisting of the fundamental oscillations that are often superimposed by higher harmonics (Şenbil et al. 2002). Moreover, each of such partial tones are mainly characterized by two unique quantities, such as its frequency (“pitch”) as well as its amplitude (“loudness”).
Therefore, according to this model the brain-waves are usually composed of a “partial tones” series whose frequency range between 0.25 Hz and 64 Hz, however the total composition mostly depends on an individual’s state of consciousness, which include the state of wakefulness or at sleeping stages (Wackermann & Matouek, 1998). Therefore, the combination of these factors constitutes the electroencephalogram involved in measuring the brain waves effectively. Hence, a test that is readily available nowadays and crucial in providing the evidence on the functioning of the brain over a certain period of time (Fischbach & Dunning, 2009).
Thus, the EEG has been a reliable method that has been used in evaluating brain disorders. In addition, this method is most commonly used in showing the type as well as the location of the activity taking place in the brain during a seizure and also at normal times depending on the mental activity. Moreover, this method have also been consistently used in evaluating the brain functioning depending on the recorded activity as well as detecting the brain function problems such as the disorders that commonly affect the brain including tumours, coma, confusion or dementia, and so on (Eimer & Kiss, 2010). Hence, this method is widespread all over the world in determining the brain waves in different conditions and consciousness states.
The objective of this laboratory experiment being the determination of different brain waves recorded from the brain in the electroencephalogram under different activities such as awake or resting with eyes opened or closed (Pagana & Pagana, 2010). Hence, the recording of the brain’s activity mostly associated with the functioning neurons is presented as an electroencephalogram and has numerous applications in the neurology medicine and psychology. Therefore, the electroencephalogram mainly detects the brain’s activity within the scalp region (Fischbach & Dunning, 2009). Hence, the used electrodes usually receives activity from numerous neurons found within the brain. However, it is only at the time when there is synchronization of the input region with the electrical activity that occurs at the same time when you start distinguishing simple and periodic waveforms from the brain in the form of an electroencephalogram (Kaiser, 2006).
Literature review
Today, electroencephalogram is widely used in the medical practice and research in the correlation of the particular brain waves in different situations such as emotional states, sleep phases, psychological profiles as well as the ongoing mental processes. Therefore, from the electroencephalogram signals released it is possible to differentiate them in different categories such as alpha (α), beta (β), delta (δ), as well as theta (Θ) waves together with the spikes in case of epilepsy (Cook et al. 1998). Therefore, the recorded electroencephalogram signal is very closely related to a person’s level of consciousness. Hence, as the body activity increases, there is also a shift of the EEG to a higher frequency that is dominating and lower amplitude (Eimer & Kiss, 2010).
Thus, at times when the eyes are closed, the electroencephalogram is dominated by the alpha waves while when a person fall s asleep there is a decrease in the dominant EEG frequency. However, at certain phases of the sleep, referred to as the rapid eye movement (REM) sleep, dreams are experienced and the and there is an active movements of the eyes which is recorded (Fischbach & Dunning, 2009). Moreover, during the deep sleep there are large and slow deflections in the electroencephalogram resulting to the delta waves. Alternatively, the brain waves signals are directly proportional to the state of activity (Şenbil et al. 2002).
However, this method is not only used in the detection of the mental conditions but also it can be used to detect the brain activity in different conditions. For instance, previous research has clearly demonstrated that electroencephalogram can be used in distinguishing various brain activity at different conditions (Eimer & Kiss, 2010). Therefore, the hypothesis aimed to be tested by this experiment is that “different physical activities of the body results to recording of varied brain waves by the electroencephalogram such as alpha, beta, delta and theta”. Hence, this will be the hypothesis to be tested in this experiment.
Methods
Materials
v BIOPAC electrodes lead set (SS2LA/L)
v BIOPAC electrode gel and abrasive pad or alcohol prep or skin cleaner
v Three BIOPAC disposable vinyl electrodes per person
v Lyra swim cap or supportive wrap
v Lab table or cot and pillow
v Computer system
v BIOPAC Student Lab System
Procedure
The procedure of conducting an electroencephalogram involves four main stages such as the set up, calibration, data recording and the data analysis. The set up involves turning on the computer and plugging in the BIOPAC equipment. This is the followed by the positioning of the electrodes of the scalp of the participant. The electrodes leads are attached to the electrodes following the colour code. A supportive cap or wrap is usually placed on the subject’s in order to press the electrodes with a constant pressure against the scalp. The subject should then lie down while relaxed with her eyes closed for an estimated 5 minutes before recording. Then the Biopac Student Lab Program is started and allowed to record after a few settings.
Calibration follows set up whereby it must be ensured that the electrode leads and electrodes bare properly placed and also the subject is relaxed. Calibration is then done after ensuring the connections are ok. The calibration data is then checked to ensure it is similar.
After calibration the recording is initiated whereby the recording is usually carried out when the subject is in a relaxed state with the eyes closed, eyes opened and closed again. The EEG signal is therefore recorded and extracted in terms of their rhythms such as alpha, beta, delta, and theta . However, in the second experiment the recording will be done for various activities such as eyes closed (to act as the control), during mental arithmetic, after hyperventilation and when eyes are opened. The recording should then be carried out for each of the activities in order to determine the brain activities that are then recorded by the machine. After recording the electrodes are then removed, followed by the peeling off and discarding of the electrodes since they are not reusable. The electrode gel residue is then washed thoroughly from the skin using water and soap.
The recorded data is then subjected to analysis whereby the analysis is conducted for all the procedure that take place such as when the eyes are closed, open and reclosed in the first experiment. However, in the second experiment the data is analysed for eyes closed (control), mental arithmetic, after hyperventilation as well as when the eyes are open.
Results Table
Discussion
As indicated in the above experiment an electroencephalogram is very useful since it is a test that is involved in measuring and recording the our brain’s electrical activity. This was made possible through the electrodes (special sensors) that are usually attached to the subject’s head as well as hooked by wires to a computer that is used in recording the EEG signals. Hence, the recorded results are then subjected to analysis which may take a while. There are several types of brain waves such as alpha, beta, delta and theta (Eimer & Kiss, 2010).
However, depending on the state of activity the subject is engaged in various signals are recorded. For instance, alpha waves usually have a frequency ranging between 8 to 12 cycles per second. These waves are actually present only in the waking state but only when the eyes are closed but in state of mental alertness. However, the alpha waves usually goes away at times when the eyes are open or at times of concentrating (Kaiser, 2006).
In addition, the beta waves usually posses a frequency ranging between 13 up to 30 cycles per second (Cook et al. 1998). However, the beta waves are mostly found when someone is alert or whenever the subject has taken some medicines in high doses, such as benzodiazepines. Moreover, the delta waves usually posses a frequency that is less than 3 cycles per second. However, these waves are mostly recorded only at times when a person is asleep or in young children. Finally, theta waves usually have a frequency ranging between 4 to 7 cycles per second mostly recorded when someone is also asleep or among the young children (Wackermann & Matouek, 1998).
Therefore, depending on the recorded EEG signals compared to the activity taking place it is possible to determine whether the signals are normal or abnormal. For instance, in adults who are awake the EEG signals mostly recorded are the alpha and beta (Şenbil et al. 2002). However, for normal signals the two sides of the brain arte supposed to portray same electrical activity patterns. Hence, in all the activities that were evaluated the EEG signals that were recorded ranged in the alpha and beta regions. This was mainly because they were all conducted at awake conditions both when the eyes were closed and opened while at the same time subjected to a variety of activities (Eimer & Kiss, 2010).
However, the abnormal signals are usually recorded for instance when the two sides of the brain indicates varied electrical activity patterns which may mean that there is a problem in that particular one side of the brain (Cook et al. 1998). Moreover, if the EEG shows spikes (sudden electrical activity bursts) or a sudden slowing in the brain waves in the brain it is an indication of a disease condition within the brain. Hence, this method can be used in pinpointing the exact location and type of conditions such as the brain tumour, epilepsy and stroke. Therefore, the recorded EEG signals between a normal person and a diseased one are totally different as it is also different in a normal person subjected to various activities (Fischbach & Dunning, 2009).
However, the EEG usually records the changes that occur in the brain waves that are not particularly not in just one area of the brain. Hence, the changes that may affect the entire brain thereby causing the entire change in the EEG signals (Kaiser, 2006). Moreover, if the EEG signals are dominated by the delta waves as well as numerous theta waves in an awake adults may mean that there is a brain injury or illness which is present or some medications may cause this. Therefore, in our experiment the recorded EEG signals indicated that the subjects brains were normally functioning since the recorded signals were comparable to the normal ones.
References
Cook, I.A., O’Hara, R., Uijtdehaage, S.H.J., Mandelkern, M. & Leuchter, A.F. (1998). Assessing the accuracy of topographic EEG mapping for determining local brain function. Electroencephalography and Clinical Neurophysiology, 107(6), 408-414.
Eimer, M., & Kiss, M. (2010). An electrophysiological measure of access to representations in visual working memory. Psychophysiology, 47(1), 197-200.
Fischbach, F.T. & Dunning, M.B. eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Kaiser, D. A. (2006). ELECTROENCEPHALOGRAPHY. Journal of Neurotherapy, 10(4), 75-79.
Pagana, K.D & Pagana, T.J. (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
Şenbil, N., Sonel, B., Aydin, Ö., & Gürer, Y. (2002). Epileptic and non-epileptic cerebral palsy: EEG and cranial imaging findings. Brain & Development, 24(3), 166.
Wackermann, J. & Matouek, M. (1998). From the ‘EEG age’ to a rational scale of brain electric maturation. Electroencephalography and Clinical Neurophysiology, 107(6), 415-421.
