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Biomedical subjects

H K Hopkins

Publications and source records attributed to H K Hopkins.

15 recordsLinked to original sources
PubMed1979

Visual scanning and matching dysfunction in brain-damaged patients with drawing impairment.

Visual matching and visual exploration were examined in 7 normal subjects and 20 brain-damaged patients with drawing impairment measured by the Bender Gestalt Visual-Motor Test. Right brain-damaged patients made significantly more errors of rotation and integration than left brain-damaged patients. Selecteded Bender figures were also used as stimuli for both visual matching and visual exploration tests. The ability to match Bender figures was found to be impaired in right but not left brain-damaged patients. All patients showed eye movement and fixation patterns different from those normals. Patients essentially had more fixations and shorter fixation durations. Significant intercorrelations were found between the total Bender Gestalt score and visual matching and visual exploration scores. These findings indicate that visual matching and visual exploration measures can be used to evaluate perceptual impairment in individuals who do not have adequate motor responses or where impaired motor responses may confound interpretations about visual cognitive impairment.

Adult↗
PubMed1978

Are there schizophrenics for whom drugs may be unnecessary or contraindicated?

This study reports that there are schizophrenics who do relatively well long term without the routine or continuous use of antipsychotic medication. Specially selected young males undergoing an acute schizophrenic episode were followed, after hospitalization, for up to three years. While hospitalized they were assigned randomly to either placebo or chlorpromazine treatment. Many unmedicated-while-in-hospital patients showed greater long-term improvement, less pathology at follow-up, fewer rehospitalizations and better overall function in the community than patients who were given chlorpromazine while in the hospital. Factors related to post-hospital outcome were good premorbid history and short-lived paranoid characteristics. Considerations which may have an effect on the successful management of acute schizophrenic patients not on medication are mentioned. The findings underline the need for further study of how to utilize antipsychotic medication more selectively in the treatment of schizophrenia.

Adolescent↗
PubMed1975

Phenothiazine effects on cerebral-evoked potentials and eye movements in acute schizophrenics.

An investigation was made of the effects of phenothiazine medication on the averaged visual-evoked potentials (AVEP) and on eye movements in hospitalized, young, acute schizophrenic patients. These results were compared with those of normal subjects who were not given medication. AVEP measures included maximum amplitude (Am), frequency of peaks (FOP'S), variability (V) and peak latencies for an early negative peak (N1) and a later positive peak (P6). Eye movement measures included percent of time looking at a stimulus slide, percent of time looking at a figure on the slide, the number of fixations and the percent of cells entered in which fixations occurred. For schizophrenics off and on phenothiazine medication, there were no consistently significant drug effects on any measure except frequency of peaks. Schizophrenics compared to normals had lower amplitudes, greater frequency of peaks, greater variability and lower eye movement scores.

Acute Disease↗
PubMed1973

Tobacco and evoked potential.

Significant changes were found in two indices of the averaged visual evoked potentials in nine smokers after 12 and 36 hours of abstinence and after resumption of smoking. There was a decrease of the amplitude envelope accompanying withdrawal and an increase with resumption of smoking. These changes are consistent with the contention that tobacco increases arousal. Amplitude changes were found in a specific component of the evoked potential occurring between 100 and 125 milliseconds after the onset of the flash. The latter changes suggest the possibility that smoking selectively enhances the perceptiont of weak stimuli.

Adult↗
PubMed1971

Phenothiazine effects on auditory signal detection in paranoid and nonparanoid schizophrenics.

The differential effects of phenothiazine medication on auditory signal detection performance were compared in two types of schizophrenic subjects and in normal subjects. With increasing phenothiazine dosage a decrease in efficiency of signal detection performance occurred among nonparanoid schizophrenics and an increase in efficiency occurred among paranoid schizophrenics. These and related findings were interpreted in terms of differences in neuropsychological response and information processing characteristics in the two types of schizophrenics. The primary deficit in information processing in nonparanoid schizophrenics may be related primarily to their hypersensitivity to sensory stimuli, whereas in paranoids it may be related primarily to their impaired focusing of attention. Phenothiazines appear to decrease sensitivity to stimuli in nonparanoids but increase the ability to focus attention in paranoids. The possibility of treatment regimens which take into account the differential effects of phenothiazine medication was suggested.

Adult↗
PubMed1970

Evoked response and behavior in cats.

Electroencephalographic averaged evoked responses to flashing lights of four different intensities were recorded in ten cats and correlated with behavior. Animals showing a high degree of exploratory behavior, aggressiveness, and activity and little withdrawal showed relatively large increases in amplitude of the averaged evoked response with increases of stimulus intensity. Those showing opposite behavioral traits had small increases or decreases of average evoked response amplitude with increases of stimulus intensity. These findings are compatible with those reported for human subjects. Inference is made about a neurophysiological mechanism for stimulus intensity modulation.

Aggression↗