Electroencephalography (EEG) or brain imaging has come a long way since its inception more than 100 years ago. English physician Richard Caton discovered the existence of electrical currents in 1875 and later in the 1920s, Hans Berger was the first who recorded brain activity and coined the word electroencephalogram to describe brain electric potentials in humans. Four types of brainwaves are recorded according to frequencies; alpha, beta, theta and delta. EEG is used primarily in studying the properties of cerebral and neural networks in neurosciences:Michel et al 2004

EEG is used primarily in studying the properties of cerebral and neural networks in neurosciences (Michel et al 2004). It is used to monitor the neurodevelopment and sleep patterns of infants in the intensive care unit and ultimately enable physicians to use this information to improve daily medical care (Scher 2004). In epilepsy, EEG in used to map brain areas and to receive localization information that will be used prior to operation (Hamandi et al 2004).


The emergence of Neurofeedback or EEG biofeedback has expanded the application of EEG for both those with particular disorders or among healthy participants. The desired effects in Neurofeedback are achieved through self modification of brain electrophysiology. EEG frequencies in Neurofeedback can be controlled to influence certain cognitive performance and memory task (Vernon et al 2003). This was evident among musicians undergoing neurofeedback who improved their performances (Gruzelier et al 2003) and in children with learning disabilities (Tansey 1985). EEG biofeedback is also effective in treating psychological disorders such as attention deficit/hyperactivity disorder(ADHD) (Masterpasqua & Healey 2003), depression (Rosenfeld et al 1996), chronic anxiety disorder (Hardt & Kamiya 1978) and chronic alcoholics (Peniston & Kulkosky 1989) and neurological disorders like epilepsy (Walker & Kozlowski 2005) and severe cerebral palsy (Neuper et al 2003). Healthy participants have also been trained to control their brainwaves and learn mental relaxation through neurofeedback (Stolc et al 2003).

Certain limitations in EEG still need to be improved to attain better and more reliable results. For example, the variability according to age in which the frequencies of the basic waves are lower in children and persons above the age of 60. A person ?s condition during recording also plays a part in differentiated results and these conditions should be notely noted. It is also important for a therapy to be ongoing on the same individual as the effect of the training is cumulative. The effects of training are also highly specific to electrode placement and thus great care should be given to these aspects before any sort of training is carried out.

EEG is continued to be utilized in many aspects of modern medicine and new uses continue to emerge with wide proven benefits for both patients and practitioners.

References

Michel CM, Murray MM, Lantz G, Gonzalez S, Spinelli L, Grave de Peralta R. 2004. EEG source imaging. Clin Neurophysiol., 115(10):2195-222

Scher MS. 2004. Automated EEG-sleep analyses and neonatal neurointensive care. Sleep Med., 5(6):533-40

Hamandi K, Salek-Haddadi A, Fish DR, Lemieux L. 2004. EEG/functional MRI in epilepsy: The Queen Square Experience. J Clin Neurophysiol., 21(4):241-8.

Vernon D, Egner T, Cooper N, Compton T, Neilands C, Sheri A, Gruzelier. 2003. Internatinal J. Psychophysiology., 47:75-85

Gruzelier et al. 2003. Neurofeedback., 14:1221-24

Tansey MA. 1985. Brainwave signatures-An index reflective of the brain ?s functional neuroanatomy: Further findings on the effect of EEG sensorimotor rhythm biofeedback training on the neurologic precursors of learning disabilities. International J Psychophysiology., 3(2):85-99

Masterpasqua F, Healey KN. 2003. Neurofeedback in Psychological Practice. Professional Psy:Research and Practice., 34(6):652-6

Rosenfeld JP, Baehr E, Baehr R, Gotlib IH, Ranganath C. 1996. Preliminary evidence that daily changes in frontal alpha correlate with changes in affect in therapy sessions. International J. Psychophysiology., 23:137-141

Peniston EG, Kulkosky PJ. 1989. Alpha-theta brainwave training and beta-endorphin levels in alcoholics. Alcohol Clin Exp Res., 13(2):271-9

Walker JE, Kozlowski GP. 2005. Neurofeedback treatment of epilepsy. Child Adolesc Psychiatr Clin N Am., 14(1):163-76

Hardt JV, Kamiya J. 1978. Anxiety Change Through Electroencephalographic Alpha Feedback Seen Only in High Anxiety Subjects. Science., 201:79-81

Neuper C, Muller GR, Kubler A, Birbaumer N, Pfurtscheller G. 2003. Clinical application of an EEG based brain-computer interface: a case study in a patient with severe motor impairment. Clinical Neurophysiology., 114:399-409

Stolc S, Krakovska A, Teplan M. 2003. Audiovisual Stimulation of Human Brain. Linear and Nonlinear Measures. Measurement Science Review., 3(2):95-98