Biomedical subjects

G Z Rosenstein

Publications and source records attributed to G Z Rosenstein.

3 recordsLinked to original sources

PubMed2002

A new technique for the analysis of background and evoked EEG activity: time and amplitude distributions of the EEG deflections.

OBJECTIVES: The EEG during background activity and that evoked in response to sensory stimuli (evoked potential, EP) has traditionally been studied by averaging and by frequency analysis. These obscure trial to trial variability. A new analysis technique is presented here which leads to single trial analysis and to insight into the mechanisms of EP generation. METHODS: This technique is based on the identification of the EEG deflections recorded on the scalp before (background) and immediately after visual stimuli. A statistical description of the time and amplitude distributions of these deflections is defined and leads to the differentiation between background and evoked activity. RESULTS: In response to stimuli, the time and amplitude of ongoing deflections (background) are re-organized (time locking) and amplified, generating the EP. Not all stimulus trials are accompanied by an appropriate response. Separate analysis of those single trials that do contain a response deflection provides information on the exact timing, variability, amplitude, etc., of those EEG deflections which contribute to the EP. CONCLUSIONS: New EEG analysis techniques are described which provide single trial EP analysis and insight into mechanisms of EP generation.

Acoustic Stimulation↗

PubMed1994

Single P100 visual evoked potential analyses in man.

Standards evoked potential averaging leads to a loss of information inherent in the moment to moment variability of the amplitude and latency of single evoked potentials. In order to extract this information, attempts were made to develop procedures which would allow recording of single visual evoked potentials in at least a selected group of subjects. In 11 out of 25 non-selected subjects, 43% to 86% of all stimuli (reversal checkerboard pattern elicited single visual evoked potentials (VEP) which were recognized as such by a group of independent observers. The mean amplitude and latency obtained by directly measuring the peak to peak amplitudes and peak latencies of these single VEPs (arithmetic averaging) were compared to those obtained following conventional time-locked averaging of the same data. During long-term continuous stimulation, the arithmetic averaged VEPs increased in amplitude to a steady state while the time-locked averages of the same sets of responses decreased in amplitude. This reduction was found to be closely related to the latency jitter. It may provide a better understanding of the phenomenon of habituation. This finding was confirmed in model single VEPs obtained by summing on-going pre-stimulus EEG activity with a time-locked average VEP stationary wave form. The variability of the true single VEPs was found to be less than the variability of the model single VEPs. The latency and amplitude parameters of the true single VEPs were strongly correlated with each other while those of the model single VEPs were not. These findings show that single VEPs have an inherent variability which may reflect brain processing.

Adult↗

PubMedDate not supplied

Cause of catecholamine distribution change in the schizophrenic brain.

The existence of an additional or augmented (in comparison with the norm) inner source of electrical stimulation of the reward system (hypothalamic in particular) is discussed as a possible cause for catecholamine distribution change in the schizophrenic brain. Our previously described model of behavioral disorders was based on this idea and several important conclusions were deduced from it, including the theory of illusion formation in norm versus pathology. The unexpected possibility of applying the same model to the problem of catecholamines in the schizophrenic brain indicates a path towards a unified theory of schizophrenia.

Brain Chemistry↗