PubMed Health⌕ Search

Biomedical subjects

R G Bickford

Publications and source records attributed to R G Bickford.

6 recordsLinked to original sources
PubMed1978

The relationship of head size to alpha frequency with implications to a brain wave model.

Analogies between brain waves and waves in physical systems suggest that EEG frequency may be partly determined by cortical surface area. Since a number of other physiological and anatomical parameters probably influence EEG frequency, only a weak correlation is to be expected. A study was made of 159 subjects, some of whom had either very large or very small heads. A single number representing head size was determined as the cube root of three linear measurements. Several characteristic EEG frequencies were determined for each subject by means of Fourier analysis. The data indicate that alpha frequency is significantly correlated with head size: larger heads tend to produce slower alpha rhythms. It was also shown that alpha frequency tends to be lower in all subjects above roughly age 60. Subjects above produced significantly less alpha rhythm than the younger group. It is suggested that analogies between brain waves and physical waves may explain a number of phenomena which are typical of EEG.

Adolescent↗
PubMed1976

Effect of flurazepam on sleep spindles and K-complexes.

In this research, a quantitative study of the EEG from 5 subjects permitted a detailed analysis of the effect of 30 mg of flurazepam administered over 7 nights. Four placebo baseline nights and 3 placebo withdrawal nights were also recorded. For 4 of the subjects, a nondrug and nonplacebo follow-up record was obtained 4 to 6 weeks later. The subjects were 4 females, 1 male, age range 23-42. All complained of either sleep onset greater than 45 min, sleep length of less than 6 h, or two or more sleep awakenings. Compressed spectral analysis yielded a computer-generated somnogram on each of the 15 nights of sleep, and an automated spindle detector was used to count and measure the duration of spindle bursts with frequencies of 12.25-15.5 c/sec on baseline nights 3 and 4, drug nights 1, 2, 3 and 7, on the 3rd withdrawal night, and on the 4-6 week followup record. K-complexes were scored visually on the 4th baseline and 7th drug nights. There were no significant differences in spindle rate per minute among baseline nights and the follow-up record. By the 2nd drug night, spindle rate had significantly increased over the baseline rate. Linear contrast analysis indicated there was a significant increase of spindle rate over drug nights. All 5 subjects showed this pattern of increase. In contrast to the increase in spindle activity, the rate per minute of K-complexes significantly decreased during drug administration.

Adult↗
PubMed1976

Visual and auditory evoked responses during penicillin-induced generalized spike-and-wave activity in cats.

In 13 healthy adult cats chronically implanted with parasagittal electrodes applied to the dural surface, curarization was performed and baseline recordings of the visual evoked response (VER), auditory evoked response (AER), and brainstem auditory evoked response (BAER) were made. Following the procedure of Prince and Farrell (1969), the animals were then given intramuscular doses of 300,000 to 500,000 U/kg of penicillin with the subsequent development of diffuse, bilaterally symmetrical, photosensitive spike-and-wave discharges in the EEG from 1 to 1 1/2 hr later and concomitant facial myoclonus, arrest of movement, and "absence-like" staring in non-curarized animals. The VER, AER, and BAER were monitored at 15-min intervals for several hours during which time the VER consistently decreased in amplitude up to the time at which the first spike-and wave bursts could be elicited by photic stimulation, approximately 1 hr after injection, after which all early components (0-200 msec) of the VER were progressively increased from 150 to 300% until spontaneous spike-and-wave bursts were consistently recorded (1 1/2-2 hr). Coincident with this change, a marked increase in late components (200-500 msec) was also observed. Both th early diminution and later augmentation of the VER were equally observable in visual and nonvisual cortex. Changes in the AER were also recorded with the development of this model, and were similar to those of the VER but of a lesser degree. The amplitudes of waves I through V of the BAER were found to increase from 28 to 88% maximal at 1 1/2 hr following penicillin injection. These data and the similarity of this model to human petit mal epilepsy argue against increased inhibitory impulses to the visual system during the ictal discharge being responsible for the subjective loss of visual information during petit mal absence. If the amplitude of the evoked response is directly related to the functional integrity of a sensory system, this suggests that the impairment of sensory input, or absence, during spike-and-wave paroxysm is due to interference with sensory processing rostral to the brainstem ascending auditory pathway, and probably does not occur in primary sensory cortex but rather in cortical or subcortical association tracts.

Animals↗