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Biomedical subjects

J Salamy

Publications and source records attributed to J Salamy.

6 recordsLinked to original sources
PubMed1984

EEG time and frequency domain measures of cerebral specialization.

Electroencephalographic (EEG) studies of lateralized cognitive functions have primarily relied upon measures of averaged evoked potentials (AEP) and power spectra (PS) to demonstrate hemispheric differences. The nature of the tasks appropriate to each of these methods of signal analysis generally require different cognitive activities and suggest different assumptions about cerebral specialization. This study investigated whether the tasks associated with either method were more likely to produce EEG asymmetries. Eighteen right-handed subjects participated in a three phase experiment which varied the amount of subject involvement in task performance. Phase I entailed passive listening to speech and nonspeech sounds. Phase II required active attention to speech and nonspeech sounds. Phase III involved a verbal matching task, a spatial rotations task, and a noncognitive control task. Auditory AEPs were measured in Phases I and II, and PS were measured in Phase II and III. EEG recordings were obtained from frontal and parietal areas of both hemispheres (F3, F4, P3, P4) referred to linked ears. Power spectra were derived from the 4-8, 8-13, and 13-20 Hz frequency bands at each lead. Despite statistically significant task and/or stimuli differences found in all three phases of study, essentially no task by lead interactions were obtained. That is, interhemispheric activity did not covary with differing stimuli and tasks. The absence of such interactions calls into question uncritical acceptance of a simple direct relation between task performance, EEG activity, and hemisphere specialization.

Acoustic Stimulation↗
PubMed1982

Physiological changes in hyperactive children following the ingestion of food additives.

This study attempted to determine if the ingestion of artificial food additives would produce detectable changes in autonomic and/or central nervous system activity in hyperactive children. A single-case experimental design was used which entailed the comparison of heart rate and electroencephalographic (EEG) measures for hyperactive and control children. The physiological measures were obtained prior to and following the ingestion of drinks containing food additives or placebos, which were administered in a double-blind, randomized, crossover procedure. The hyperactive children exhibited a greater degree of physiological activity following both the placebo and the drink containing food additives than did the control children. However, the magnitude of physiological changes in the hyperactive children were greater in response to ingestion of the additives than to placebo. These physiological findings are consistent with behavioural data indicating that some hyperactive children are adversely affected by food additives.

Alpha Rhythm↗
PubMed1980

Effects of morphine on sensory-evoked responses recorded from central gray, reticular formation, thalamus, hypothalamus, limbic system, basal ganglia, dorsal raphe, locus ceruleus, and pineal body.

Field potential recordings of acoustic and photic-evoked responses were obtained from 15 brain sites of freely behaving unanesthetized rats previously implanted stereotaxically with permanent electrodes. Several dosages of morphine (1, 5, 10, 30, and 50 mg/kg) were examined. The activities recorded from all the structures in this study, except the cochlear nucleus (CoN), were affected by morphine. Different sensitivities to morphine threshold were observed between structures, and several structures exhibited dose-related patterns (ventromedial hypothalamus (VMH), caudate nuucleus (CN), central gray (CG), hippocampus (Hipp), and lateral septum (Spt)). Several brain sites, after the initial dose of morphine, did not recruit more responses to subsequent doses of the drug, ie, exhibited all-or-none responses (pineal body (PB), medial thalamus (MTh), anterior hypothalamus (AH), mesencephalic reticular formation (MRF), and the dorsal raphe (DR)). In some structures, morphine induced increases in the response amplitudes, while in other sites decreases in response amplitudes were elicited. Biphasic responses, ie, increases in response amplitude after low doses of the drug and decreases in response amplitude after higher dosages, were also observed (VMH, CN, DR, CG, and MRF). The acoustic-evoked responses were affected by morphine more than the photic responses. The present observations indicated that 1) morphine exerts effects in many parts of the central nervous system (CNS); 2) some structures are more sensitive to morphine than others; 3) only a few structures exhibit dose-related patterns and, thus, may represent sites of direct morphine action; 4) some structures exhibit all-or-none responses; and 5) morphine depressed activity in some structures and increased activity in others, ie, morphine elicited different effects in different structures.

Acoustic Stimulation↗
PubMed1975

REM sleep and contingent negative variation development.

Three subjects demonstrated the ability to respond in a contingent negative variation (CNV) paradigm during rapid eye movement (REM) sleep. However, the CNV did not appear as it does in the waking state. This failure of the CNV to develop during REM sleep might be attributed to electrophysiological changes accompanying REM sleep.

Adult↗