Electroencephalogram Alpha

Glucocorticoids have important effects on the nervous system. Adrenal insufficiency causes marked slowing of the alpha rhythm of the electroencephalogram and is associated with depression. Increased amounts of glucocorticoids often produce behavioral disturbances in humans initially insomnia and euphoria and subsequently depression. Large doses of glucocorticoids may increase intracranial pressure (pseudotumor cerebri). 

Figure i. Records taken from a cat chronically prepared with electrodes to record the eye movements (EOG), the electroencephalogram from both sides of the skull (EEG), and the activity of the neck muscles (NMG). The animal was kept in an air-conditioned, sound-attenuated room supplied with a oneway mirror for observation. The records were taken while the animal was awake and active (top left), awake and resting (top right—note alpha waves), just dropped off to sleep (middle left —note "spindles"), in deeper sleep (middle right—note slow waves in EEG) in still sounder sleep (bottom left—note very slow waves), and in paradoxical sleep (bottom right—arousal pattern in EEG). (Note eye movements in awake animal and in paradoxical sleep). Note also reduced electrical muscle activity in paradoxical sleep. Calibrations vertical line at top middle = 100 microvolts (or o.oooi volt), horizontal line = l second. Original from author s laboratory. 

Figure 2. The effect of LSD-25 on the electroencephalogram of the normal unrestrained cat. Recording modes as indicated by connections and electrode position on cortex of cat brain in upper part of picture. Record 4 is derived from hypothalamus. A (control) animal is in quiet waking state. Note alphalike waves in three cortical leads. B records twenty minutes after LSD-25 (15 jug/kg) had been administered into peritoneal cavity, which leads to disappearance of alphas and to arousal pattern. Calibration in microvolts and seconds as indicated (From Bradley and Elkes, 1953). P. B. Bradley and T. Elkes, "The Effects of Some Drugs on the Electrical Activity of the Brain," Brain, Vol. 80, 1957. Reprinted by permission of the authors and the publisher.

Alpha electroencephalogram EEG that shows 8-13 Hz waves (alpha waves) in all... 

The effects of the BZs on the electroencephalogram (EEG) resemble those of other sedative/hypnotic agents, including decreased alpha activity and increased low-voltage fast activity, especially beta activity (Rail, 1990). Their effects on sleep are also similar to those of other CNS depressants and provide a window into the dysfunctions they produce (Rail, 1990). 

Neuroleptic drugs cause slowing of alpha rhythm and increased synchronization and amplitude with superimposed sharp fast activity. They also induce discharge patterns in the electroencephalogram similar to those associated with epileptic seizures of the tonic-clonic generalized or focal types (SED-11,108 168). 

Headache, drowsiness, and dizziness are common with niridazole (2,4,5). More severe neuropsychiatric symptoms are more frequent in patients with liver disease, especially those with portosystemic shunts, in whom the drug bypasses the liver (6). Symptoms in these cases include insomnia, anxiety, depression, confusion, hallucinations, and convulsions the reactions may prove fatal. The electroencephalogram can show slowed alpha rhythms, beta waves, and theta waves, as well as sharp wave and spike forms with niridazole (7). A single case of acute cortical necrosis was recorded in the much older literature, but was probably coincidental (SED-8, 691) (8). Agitation can occur in patients with abnormal liver function. 

Gross neurobehavioral effects, such as disturbances of equilibrium and coordination, occur in humans following acute exposure to 1,1,1-trichloroethane concentrations between 1,000 and 2,000 ppm (Stewart et al. 1961, 1969, 1975 Torkelson et al. 1958). These effects are more obvious at higher exposure concentrations (Torkelson et al. 1958). An increase was noted in the amplitude of alpha activity in electroencephalograms from individuals acutely exposed to moderate concentrations of 1,1,1-trichloroethane (Stewart et al. 1975). The significance of this effect is unknown, especially since it persisted for several days, but it occurred at an exposure level that... 

The effects of benzodiazepines on the waking electroencephalogram (EEC) resemble those of other sedative-hypnotic drugs. Alpha activity is decreased but there is an increase in low-voltage fast activity. Tolerance occurs to these effects. 

One promising psychophysiological measure is electrical brain activity as measured by electroencephalogram (EEG). The EEG represents fluctuations in voltage recorded from the scalp that fall between 1 and 40 Hz. This frequency range is often subdivided into narrower bands named delta (1-3 Hz), theta (4-7 HzX alpha (8-13 Hz), and beta (13-20 Hz). 

When eyes are closed the sine-wave-shaped large-amplitude alpha rhythm appears in the scalp potentials, of which frequency fluctuates within a frequency range 8-13 Hz, and this almost periodic waveform is clearly seen in the spontaneous electroencephalogram. The instantaneous frequency is defined from the interval between consecutive zerocrossing points. Its power spectral density is found to be of 1// in a certain range of the Fourier frequency. It is another example of 1// fluctuations of biological rhythm phenomena. When a subject is in a... 

Slow alpha activity on electroencephalogram (mean bone lead = 26 pg/g, mean CBLI = 546 pg-years/dL). 

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