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Biomedical subjects

R W Coger

Publications and source records attributed to R W Coger.

17 recordsLinked to original sources
PubMed1993

The N15 component of the brainstem auditory evoked potential: a measure of hippocampal activity in schizophrenics?

The negative wave component of the brainstem auditory evoked potential at approximately 15 ms has been found to be related to activity in the hippocampus. Since hippocampal abnormalities have been reported among schizophrenic patients, it is obvious that a reliable electrophysiological measure of hippocampal activity might be useful in the study of schizophrenia. For instance, it may be hypothesized that the N15 wave of the BAEP would be abnormally reduced in amplitude for schizophrenics compared to controls, based on the previously reported misalignment of neurons in the hippocampus for schizophrenics. The measurement of the N15 is complicated by the presence of a postauricular muscle reflex in some individuals. We attempted an analysis of the N15 wave based on distributional characteristics for schizophrenics and control subjects. The nature of the N15 wave is described and potential lines of investigation are proposed.

Adult↗
PubMed1990

Schizophrenia, corpus callosum, and interhemispheric communication: a review.

The literature suggests that some schizophrenic patients may have a dysfunction in the transfer of information between the two cerebral hemispheres via the corpus callosum (CC). The presence of an abnormally thickened CC in some schizophrenic patients and an abnormally thin CC in others suggests a possible anatomic basis for abnormal organization of cognitive functions in these patients resulting from either increased or decreased communication between the two cerebral hemispheres. The findings of the anatomic studies have suggested a connection between a thickened CC and both early onset and negative symptom patterns in schizophrenic patients. Similarly, onset of symptoms later in life and positive symptom patterns have been associated with a thinner CC. Behavioral and electrophysiological findings appear to support the idea that the same subgroups may be associated with opposite patterns of effective transfer of information between the cerebral hemispheres. Careful analysis of the transfer of information between the cerebral hemispheres for selected groups of schizophrenic patients and normal controls could provide important information about cerebral organization and possible mechanisms operative in schizophrenia.

Brain Mapping↗
PubMed1981

EEG differences between male alcoholics in withdrawal and those stabilized in treatment.

There is evidence that alcohol abuse and withdrawal produces cerebral impairment, some of which may be temporary and some permanent. This impairment has been found to be relatively specific in terms of brain areas affected. Recently our laboratory reported evidence that psychometrically measured impairment was systematically related to the energy in high frequency (beta-2) bands of the EEG. In the present study we attempted to determine the EEG patterns for male alcoholics undergoing withdrawal in comparison to patients who had been stabilized.

Alcohol Withdrawal Delirium↗
PubMed1980

Somatosensory evoked potentials and noxious stimulation in patients with intractable, noncancer pain syndromes.

Investigations of the evoked potentials (EPs) to noxious laser stimulation have indicated consistent strong linear relationships between subjective response (R), stimulus intensity (S), and EP amplitude (A). Thirty patients with chronic intractable benign pain syndromes (CIBPS) were tested to determine whether their patterns differed from previous studies with normal volunteers. Nearly half of the CIBPS patients were found to be relatively insensitive to acute pain stimuli. A large number were also found to show negative relationships between S and A. These differences from control subjects were considered of potential importance in their implications concerning the nature of chronic pain and its differences from the acute pain process.

Adult↗
PubMed1980

Data preprocessing applied to human average visual evoked potential P100-N140 amplitude, latency, and slope.

Data preprocessing, using principal components and Varimax rotation, was applied to 26 human average visual evoked potential (AVEP) variables representing bilateral amplitudes, latencies, and slopes from the P100 and N140 peaks. Five orthogonal factors, which accounted for about 80% of the variance, were found to describe the data from control subjects, stabilized alcoholics, and chronic nonparanoid schizophrenics. Tests of orthogonality and variance explained were employed to evaluate the results of the analysis.

Adult↗
PubMed1979

Electroencephalographic similarities between chronic alcoholics and chronic, nonparanoid schizophrenics.

We compared the EEG power spectral density patterns for chronic, nonparanoid schizophrenics and age-matched chronic alcoholic and control subjects. Bilateral precentral (F-T) and postcentral (C-O) derivations were used in the analysis. The nonparanoid schizophrenics and alcoholics showed increased low-frequency activity (0 to 6 Hz) in all derivations in comparison to the control subjects. Chronic alcoholics were found to have increased high-frequency activity primarily in the precentral derivations. Nonparanoid schizophrenics showed increased power in the high-frequency bands predominantly in the left precentral derivation. We discuss the implications of patterns of differences concerning the issue of nonspecificity of the EEG in psychiatry.

Adult↗
PubMed1979

Skin conductance conditioning with dyshidrotic eczema patients.

Thirty-three patients with dyshidrotic eczema were trained either to decrease or to increase the electrical conductivity of the skin. Skin conductance has been found to be related to epidermal water content as well as emotional variables, both of which have suggested links to eczema. Subjects trained to decrease skin conductance showed clinical improvement more often than the controls who were trained in the opposite direction. They also showed a significant decrease in measured conductance and anxiety. The controls showed increased anxiety and no significant changes in skin conductance level.

Adolescent↗
PubMed1978

EEG signs of brain impairment in alcoholism.

EEGs were recorded for two groups of chronic alcoholics who scored at opposite extremes on the Shipley Institute of Living Scale. The groups were matched in terms of age and drinking history variables and were compared to age-matched control subjects for left and right precentral (F-T) and postcentral (C-O) placements. Significant ANOVA findings were obtained primarily in high-frequency bands in the three group comparison. A significant linear trend was found for power as a function of degree of impairment from controls to moderately impaired alcoholics to severely impaired alcoholics in frequency bands above 14 Hz. The trend was most pronounced in the F-T derivations. Implications of the findings with respect to cortical atrophy in alcoholism are discussed.

Adult↗
PubMed1976

Alcoholism: averaged visual evoked response amplitude-intensity slope and symmetry in withdrawal.

Alcohol withdrawal has been characterized in terms of some EEG changes but seldom in terms of the averaged evoked response. Characteristics of the AER, such as amplitude, latency, and the least-squares slope of the AER amplitude as a function of stimulus intensity, have been found to change as a function of arousal and to separate some psychiatric groups. Seventeen alcoholics in withdrawal, 27 stabilized alcoholics, and 30 control volunteer subjects participated in an experiment to determine the changes in AER characteristics in withdrawal. Four stimulus intensities were presented to the subjects from a Grass PS 22 photostimulator with the flash sources 102 cm from the nasion. AER amplitude, the slope of the amplitude as a function of stimulus intensity, and bilateral symmetry scores were calculated for group comparison. Withdrawal and stabilized alcoholics were found to have significantly greater AER amplitudes at all intensity levels. Greater A-I slope from the right hemisphere and higher symmetry were found for withdrawal alcoholics than the other two groups.

Adult↗
PubMedDate not supplied

Attention deficit disorder in adults and nicotine dependence: psychobiological factors in resistance to recovery?

The addictive nature of nicotine appears to depend on a number of psychobiological factors. This study explores the psychoactive effects of nicotine in relationship to the particular dysphoric aspects of Attention Deficit Disorder as a coincident factor in nicotine dependence and resistance to treatment. The psychological and behavioral effects of nicotine directly correspond to reduction in symptoms of Attention-Deficit/Hyperactivity Disorder (ADHD) and the neurochemical effects of nicotine are qualitatively similar to stimulant medications used to treat ADHD. Aspects of the treatment of nicotine or other addictions in such comorbid situations are discussed in the context of self-medication.

Adult↗