Frederick J. Bremner

Hinton diagrams: Viewing connection strengths in neural networks

A graphical analysis similar to that used by Hinton and Shallice (1991) was applied to the hair cells of a simulated auditory transducer. The graphical analysis made it apparent that there were hair cells that responded to a narrow range of frequencies, as would be predicted by the tonotopic organization of the real physiology. In short, this study demonstrates the efficacy of using graphic techniques to examine the nature of the autopoetic organization of the hidden layer of back-propagation networks.

Fourier analyses: A mathematical and geometric explanation

Fourier analyses are used in electrophysiological research to reduce EEG data to an interpretable, analyzable form. This article outlines the mathematical similarities and differences between Fourier transforms and fast Fourier transforms. A geometric explanation of the application of fast Fourier transforms and a Fourier series to theta-band EEG data is also included in this article.

Habituation of neuro-electric responses negative results

Abstract Brain waves recorded from electrodes permanently implanted in the hippocampi of white rats were spectrally analyzed in order to investigate neuro-electric changes occuring during presentation of a stimulus at regular intervals. Although the regular presentation of a stimulus is usually accompanied by the habituation of orientation responses the neuroelectric data recorded in this study did not show characteristics definable as habituation.

The effect of hours of food deprivation on hippocampal theta rhythm

Abstract Nine rats were chronically implanted in the hippocampus and habituated to a light stimulus for six consecutive hours. All Ss experienced habituation sessions at two levels of food deprivation, 3 and 22 hours, presented in a counterbalanced paradigm. Electroencephalographic data were recorded from the hippocampus during these habituations. These data were spectrally analyzed by an I.B.M. 360-44 computer, and the spectograms were then statistically examined by analyses of variance. The results indicated that Ss following 22 hours of food deprivation showed increased EEG activity in the hippocampal theta range (4–7 Hz), when compared to the theta of the Ss following a 3-hour deprivation period. The results were discussed in the light of theta rhythm as a measure of separate classes of attention.

Computer-managed inferential statistical analysis of EEG data

Much of the neuroelectrical/psychophysiologic research of the past has involved the use of “group-type” statistics. Often, this has resulted in large variances that make it difficult, if not impossible, to find significant differences. Using the INNOVATE technique of single-subject design, we are able to consistently demonstrate significant differences in EEG spectra related to experimental and clinical effects previously masked.

The effect of habituation and conditioning trials on hippocampal EEG

Comparison of hippocampal EEG during habituation of a neutral stimulus (CS), habituation of a reinforcing stimulus (US), and classical conditioning showed significantly different spectra for these three treatments. It was also demonstrated that spectra of hippocampal EEG data sampled randomly were different from those sampled immediately following either the CS or US.

The effect of methadone on hippocampal EEG

The following report concerns the effects of methadone on the hippocampal EEG both before and after electrical stimulation of the septum of cats. Initial effects of 3 mg/kg were investigated, as well as recovery trends of the EEG 6 hr after drug administration. A significant difference was found (p<0·042) in the post-stimulation condition using Hotelings T2 on the group power spectrum of 4 cats after initial injection of methadone when tested against that of 4 cats receiving saline injections. No significant differences were found in other conditions. Gross behavioral data were reported as collected on a 16 mm movie film taken of a cat with no electrodes implanted.

Identification of the precursors of hippocampal theta rhythm— A replication and extension

Abstract A cryoprobe was used to modify the functioning of the septal nucleus of several cats resulting in a change in reticular-formation-induced hippocampal theta rhythm. Control animals sustaining electrolytic lesions in the septum showed a similar effect. Changes in hippocampal EEG patterns resulting from electrical stimulation of the reticular formation combined with cryogenic cooling of the septum, lead the authors to hypothesize that the reticular formation may be mainly responsible for the 4–5 Hz. frequencies in the hippocampalgram.

EEG correlates of attention in humans

Abstract An attempt is made in this report to extend the Bremner attention model to human EEG data. Data are present which show changes predicted by the expectancy subset originally defined by animal EEG data. An additional subset, internal focus, is proposed and partially supported by changes in human EEG. It is suggested that this subset is unique to humans.

The effect of drive on attention

This study demonstrated that differences in drive level resulting from hours of deprivation are measurable by means of power spectral analysis of EEG data.