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Biomedical subjects

J M Stapleton

Publications and source records attributed to J M Stapleton.

35 records · Page 2Linked to original sources
PubMed1989

Effective pharmacotherapy of alcoholic amnestic disorder with fluvoxamine. Preliminary findings.

Ten patients with alcoholic chronic organic brain disease were categorized as having alcohol amnestic disorder, or Korsakoff's psychosis (n = 6), dementia associated with alcoholism (n = 3), or compensated alcoholic liver disease (n = 1). All patients had severe deficits in memory for recently acquired information (episodic memory). Patients with alcohol dementia also showed global intellectual decline, including decreased performance on measures of semantic (knowledge) memory and reduction in levels of cerebrospinal fluid somatostatin. In a 4-week double-blind crossover design, the serotonin-uptake blocker fluvoxamine maleate (100 to 200 mg/d) was found to improve episodic memory in only the patients with alcohol amnestic disorder. These improvements in memory were significantly correlated with reductions in levels of cerebrospinal fluid 5-hydroxyindoleacetic acid, suggesting that facilitation of serotonergic neurotransmission may ameliorate the episodic memory failure in patients with alcohol amnestic disorder.

Aged↗
PubMed1988

Alcohol intoxication reduces visual sustained attention.

Effects of alcohol intoxication on visual sustained attention were studied using a vigilance task entailing detection of degraded target stimuli. Data were obtained in separate sessions under four ethanol doses, ranging from 0 (placebo) to 1.05 g/kg lean body weight, with periodic maintenance dosing of 0.12 g/kg. Intoxication lowered the overall level of detection performance, and in addition produced dose-related increases in the rate of performance decrement over time. Analysis of performance data using techniques derived from Signal Detection Theory indicated that the decrements were due specifically to alterations in perceptual sensitivity. Examination of eye movements and blinks indicated that the effects of ethanol were not mediated peripherally. Rather, alcohol appears to have deleterious effects on central processing capacity and the availability of capacity over time. The alcohol-related failure of sustained attention may contribute to increased accident risk in tasks requiring continuous performance.

Adult↗
PubMed1988

Treatment of alcoholic organic brain syndrome with the serotonin reuptake inhibitor fluvoxamine: a preliminary study.

The chronic effects of fluvoxamine (200 mg per day for 4 weeks) were studied in ten alcoholic organic brain syndrome patients in a double-blind cross-over design. Complete neuropsychological evaluation was performed as well as measurement of neurochemical changes in CSF. Fluvoxamine produced a small but significant improvement in memory performance. An analysis of fluvoxamine minus placebo difference scores showed a significant correlation between memory functioning and CSF 5HIAA levels. Alcohol amnestic syndrome patients who had the highest blood levels of fluvoxamine demonstrated the largest changes in CSF 5HIAA and improvement in memory performance under fluvoxamine. These findings implicate a role of serotonergic mechanisms in alcoholic organic brain syndrome and suggest that with individual titration of the drug dose, fluvoxamine might be a clinically useful agent in the treatment of this syndrome.

Aged↗
PubMed1988

Acute effects of ethanol on motor performance and movement-related brain potentials.

The acute effects of ethanol on skilled motor functions were examined in male social drinkers, under four doses ranging from 0 (placebo) to 1.05 g/kg lean body weight. The movement entailed a forewarned choice transitive motion of the arm and hand, aimed at a flanking target. Performance measures disclosed only small effects of ethanol on speed and accuracy of movement. The simultaneously-recorded movement-related brain potentials disclosed decreased involvement of frontal and posterior brain areas, suggesting that ethanol disrupted the planning and regulation of movement despite the overall preservation of reaction speed.

Contingent Negative Variation↗
PubMed1987

Endogenous potentials evoked in simple cognitive tasks: depth components and task correlates.

Depth event-related potentials in humans were studied during a series of simple cognitive tasks. The previously reported finding of large, polarity-reversing potentials in medial temporal lobe (MTL) during tasks which evoke P3 at the scalp was confirmed. Within the latency range of the scalp N2/P3, at least two depth components were identified which are consistent across patients, and topographically distinct. They have task correlates similar to P3 in that they are larger to rare attended tones than to frequent or ignored tones and are present to rare omitted stimuli.

Cognition↗
PubMed1987

Endogenous potentials after anterior temporal lobectomy.

The scalp topography of endogenous potentials was studied in patients who had previously undergone unilateral anterior temporal lobectomy (ATL). These excisions include medial temporal lobe (MTL) structures that have been shown to generate large potentials during tasks that evoke P3 at the scalp. Following right or left ATL, patients showed no differences from unoperated control subjects in overall amplitude of P3 or any other potential measured. The topography of P3 was very similar in both ATL groups and the control subjects, with no differences in laterality. These results suggest that the MTL is not the major generator of the P3 recorded at the scalp in the tasks studied here.

Adult↗
PubMed1987

Endogenous potentials evoked in simple cognitive tasks: scalp topography.

The scalp topography of endogeneous potentials was studied during a series of simple cognitive tasks in the auditory modality. P3 and Slow Wave showed the expected task correlates of being larger to rare than to frequent tones, and larger when attended than ignored, but N2 was not clearly measurable due to overlap with P2 and P3. Overall, across all task conditions, P3 was larger at sites over the right hemisphere than the left, particularly for sites near the midline (F3, F4, C3, C4, P3, P4). P3 was present (though smaller) to rare omitted stimuli in a tone series, as well as to tones presented at long, random intervals (3 to 9 s) in a simple counting task. P3 was very large to novel, unique, nontarget auditory stimuli, and had a somewhat different distribution to these stimuli than to targets, suggesting a difference in the underlying intracranial generators. Except for these novel nontarget sounds, P3 showed a consistent topography across tasks in spite of differences in amplitude.

Adolescent↗
PubMed1987

Alcohol intoxication in humans: effects on vigilance performance.

Effects of ethanol on vigilance in tasks requiring continuous performance are reviewed. Evidence is presented to indicate that ethanol has adverse effects on both the overall level of performance and the rate of performance decrement over time. The effects on performance level are attributed to nonspecific sedative properties of ethanol whereas the effects on rate of decrement are interpreted as a more specific loss in cognitive processing capacity.

Alcoholic Intoxication↗
PubMed1986

Human medial temporal lobe potentials evoked in memory and language tasks.

Lesion evidence indicates that the human medial temporal lobe (MTL) makes an important contribution to Recent Memory formation and retrieval very soon after a stimulus item is encountered. For verbal materials, this contribution is lateralized to the language dominant hemisphere. Evoked potentials recorded from the MTL during verbal recognition memory display two late endogenous components. Both show differences between repeated target words and non-repeated distractor words. The first component is usually negative and has an average latency of 460 msec. It is also observed in lexical decision and picture naming tasks. This component is similar in latency, morphology, and task correlates to the scalp-recorded N4 potential. This 'MTL-N4' is smaller in amplitude to words recognized as repeats and is largest in amplitude in the left MTL. The second component is usually positive and has an average latency of 620 msec. It is similar in morphology and MTL topography to the P3-like component evoked at 360 msec to rare tones in auditory discrimination tasks. This 'MTL-P3' is larger in amplitude to words recognized as repeats. Both components are of very large amplitude and invert polarity over short distances within the MTL. Hence, they appear to be locally generated in the MTL. The extent to which volume conduction of these MTL potentials contribute to scalp-recorded EPs is unclear. The MTL-N4 might be involved with memory formation and retrieval processes, and the MTL-P3 might index completion of the detection-recognition cycle.

Adult↗
PubMed1986

Interictal spike-wave complexes in the human medial temporal lobe: typical topography and comparisons with cognitive potentials.

Ten of 16 patients with complex partial epilepsy displayed an interictal spike-slow wave sequence with characteristic morphology and depth voltage topography. This 'typical slow wave' (TSW) lasted 300-600 msec, was usually largest and negative in the anterior hippocampus, and positive in the amygdala. Simultaneous recordings from ipsilateral cingulate, supplementary motor, orbitofrontal, and lateral temporal cortices, as well as from the contralateral medial temporal lobe (MTL), revealed only small, apparently volume-conducted, wave forms. Simultaneously recorded multiunit activity within the focal MTL was profoundly inhibited during the TSW. The TSW propagated to the scalp, producing a large widespread positivity. A large endogenous potential with similar latency range and task correlates as the scalp-P3 was recorded from the MTL to infrequent tones in a simple discrimination task. This 'depth-P3' had very similar polarity and relative amplitude across MTL sites, as was observed for the TSW at the same electrode contacts. However, at more superficial intracranial sites, the TSW was relatively smaller than the P3. Similarly, from MTL to surface, the P3 was found to decrement about half as much as the TSW decrements. This evidence suggests that the surface P3 is generated, but in part only, by the MTL.

Adolescent↗
PubMed1986

Effects of alcohol and other psychotropic drugs on eye movements: relevance to traffic safety.

The effects of alcohol and other psychotropic drugs on eye movements are reviewed with particular attention to the possible relevance of these effects for traffic safety. Alcohol has been shown to have diverse effects, including reduction of the velocity of both saccadic and smooth pursuit eye movements, increased saccadic latency, impairment of convergence and induction of nystagmus. These effects probably contribute to impaired visual information processing, which reduces driving ability. Barbiturates have been reported to produce effects similar to alcohol, and the effects of benzodiazepines and opioids seem to be more limited but still substantial. Marihuana has relatively little effect on eye movements.

Accidents, Traffic↗
PubMed1985

Human medial temporal-lobe stimulation disrupts both formation and retrieval of recent memories.

Disrupting medial temporal-lobe (MTL) activity for less than a second, either during the initial presentation of a complex scene or when it is presented again 1 min later, severely impairs recognition at the second presentation. MTL disruption during both presentation and recognition periods produces further impairment. These results are not consistent with views limiting MTL function solely to encoding or solely to retrieval mechanisms.

Amygdala↗
PubMed1979

Morphine and naloxone's effects on sexual behavior of the female golden hamster.

The effects of morphine and naloxone were observed after administration to female golden hamsters (Mesocricetus auratus). Large doses of morphine, 80 mg/kg, consistently produced sedation and behavioral depression of responses to nociceptive stimuli. Smaller doses of morphine (e.g., 10 mg/kg), that produced few other behavioral changes, suppressed a measure of female sexual responding. The suppressive effects on sexual behavior were reversed by 4 mg/kg of naloxone. Morphine administered intracerebroventricularly had little effect on sexual responding, even at doses which produced other side effects. Doses of 4 and 8 mg/kg of naloxone in opioid-naive subjects did not reliably alter sexual responding up to 2 hr after administration. These observations lead to the suggestion that morphine produces effects which are incompatible with full sexual functioning in female hamsters.

Animals↗
PubMedDate not supplied

Dose-related effects of ethanol on visual sustained attention and event-related potentials.

The effects of acute ethanol intoxication on visual sustained attention were investigated in male social drinkers. Four doses ranging from 0 (placebo) to 1.05 g/kg lean body weight, with periodic maintenance dosing of 0.12 g/kg, were given in separate sessions. The task required subjects to monitor a series of blurred digits presented singly at a rate of one per sec and to respond to occasional (p = 0.25) target digits with a speeded button press. Detection performance deteriorated as a function of both dose and time on task. In addition, the factors of dose and time on task interacted to produce a more rapid performance decrement under the higher doses. Early event-related potential (ERP) components (N1 and P2) were not greatly affected, suggesting that the performance decrement reflects central rather than peripheral factors. Later components related to cognitive appraisal processes (N2, P3), in contrast, varied in both amplitude and latency. Ethanol yielded dose-related delays in N2 and P3 latencies, which paralleled reaction time increases. The amplitude of N2 also decreased over time on task, and P3 amplitude decreased both as a function of dose and time on task. ERP and performance data were interpreted as demonstrating an adverse effect of ethanol on central processing capacity.

Adult↗