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L H Gold

Publications and source records attributed to L H Gold.

At least 73 records · Page 4Linked to original sources
PubMed1990

Application of entropy measures derived from the ergodic theory of dynamical systems to rat locomotor behavior.

Measures of complexity derived from ergodic theory of dynamical systems were developed and applied to an exemplary data set describing locomotor movements of rats in a bounded space. A symbolic dynamical system was obtained by partitioning the event space into equally probable partition elements, using a k-dimensional tree. The measures calculated from the symbolic sequences included the topological entropy (ht)--i.e., the rate of increase of all possible sequences with increasing sequence length--and the metric entropy (hm)--i.e., the rate of increase of all likely sequences with increasing sequence length. These measures were used to assess changes in rat locomotor behavior as recorded in the behavioral pattern monitor (BPM) that were induced by amphetamine (0.25, 0.50, 1.0, or 2.0 mg/kg) and 3,4-methylenedioxymethamphetamine (MDMA; 1.25, 2.5, 5.0, or 10.0 mg/kg). Amphetamine increased the mean activity, ht, and hm. MDMA resulted in a monotonic dose-response curve for activity but exhibited a biphasic dose response in ht and hm. In particular, some animals in the higher dose groups showed a ht in the range of the saline controls, whereas other animals exhibited a significantly reduced ht and a greater decrease in hm, suggesting that two different behavioral reactions coexist within the same higher dose range of MDMA. An important implication of our method is that, in applied ergodic measure-theoretic approaches, the partition that determines the elements of the symbolic dynamical system should not be specified a priori on abstract mathematical grounds but should be chosen relative to its significance with respect to the data set in question. Here, the animal constructs its own spatiotemporal partition in behavioral phase space.

3,4-Methylenedioxyamphetamine↗
PubMed1989

MDMA produces stimulant-like conditioned locomotor activity.

Daily administration of a drug in a distinctive environment establishes contingencies that support Pavlovian conditioning. Environmental cues that are paired with the drug injection and that predict the onset of drug action can become conditioned stimuli. Ultimately, the conditioned stimuli come to predict the availability of drug and develop the potential to engender conditioned drug responses. Various psychostimulant drugs can produce conditioned locomotion when tested in the presence of environmental cues that were repeatedly associated with the drug experience. The ability of amphetamine and cocaine to produce conditioned locomotion was demonstrated in the present study. Stimulant-like properties of methylenedioxy-methamphetamine (MDMA) have been reported in locomotor paradigms, drug discrimination procedures, and human subjective questionnaires. MDMA (5 mg/kg), paired for 5 days to a distinct environment signalled by the presence of a distinct odor, produced enhanced locomotion during a test probe with the odor alone indicating that MDMA can also produce conditioned locomotion. The observation that the stimulus properties of MDMA can also become associated with environmental cues supports the hypothesis that some of the behavioral effects of MDMA resemble those of other classical psychostimulants such as amphetamine and cocaine.

3,4-Methylenedioxyamphetamine↗
PubMed1989

A role for the mesolimbic dopamine system in the psychostimulant actions of MDMA.

Methylenedioxymethamphetamine (MDMA) is a phenylethylamine with a chemical structure that resembles both the amphetamines and mescaline and has both stimulant and perception altering properties. The stimulant properties of MDMA were assessed in photocell cages designed to measure locomotor activity in rats. MDMA, over a range of doses (2.5-10.0 mg/kg, SC) produced locomotor hyperactivity which lasted up to 4 h. Further studies examined the role of the mesolimbic dopamine system in the hyperactivity induced by MDMA. 6-Hydroxydopamine lesions of the Nucleus accumbens attenuated the locomotor response produced by MDMA. The well characterized attenuation of the locomotor response produced by amphetamine was also demonstrated in the same rats. The present study demonstrates similarities in the stimulant properties of MDMA and amphetamine, and also suggests that as with amphetamine, the locomotor activation associated with MDMA may involve the presynaptic release of dopamine in the region of the Nucleus accumbens. However, MDMA may have a more unusual pharmacological profile because of its longer duration of action, neurotoxic potential, and differences in the qualitative aspects of its psychoactive effects.

3,4-Methylenedioxyamphetamine↗
PubMed1989

Neurochemical mechanisms involved in behavioral effects of amphetamines and related designer drugs.

The motor activation produced by psychomotor stimulants has been long associated with the midbrain dopamine systems. While focused stereotyped behavior produced by high doses of indirect sympathomimetics is blocked by removal of dopamine terminals in the corpus striatum (Creese and Iversen 1975), the locomotor activation produced by low doses of indirect sympathomimetics is blocked by removal of dopamine terminals in the region of the nucleus accumbens (Kelly et al. 1975). This dopaminergic substrate for psychostimulant effects appears selective for the indirect sympathomimetics in that dopamine lesions to the region of the nucleus accumbens do not block caffeine, scopolamine, heroin, or CSF-induced locomotor activation (Swerdlow and Koob 1985; Vaccarino et al. 1986). The neurochemical sites for psychomotor stimulant reward are likely to be the presynaptic dopamine terminals located in the region of the nucleus accumbens, frontal cortex, and other forebrain structures that originate in the ventral tegmental area. Note, however, that intracranial self-administration of cocaine is elicited from the frontal cortex, but not from the nucleus accumbens (Goeders and Smith 1983). Thus, concomitant activation of structures other than the nucleus accumbens may be an important part of the circuitry involved in initiation of cocaine intravenous self-administration, as has been hypothesized for the opiates (Smith and Lane 1983; Smith et al. 1982). In addition, these neuropharmacological studies provide evidence to show that, in the rat, the neural/neurochemical substrates for processing the reinforcing and stimulant properties of psychomotor stimulants may be similar, if not identical. Parallel manipulations using dopamine receptor antagonists and 6-OHDA lesions produce parallel results. How far this parallelism continues in further processing is under current investigation; however, such an overlap brings additional impetus to earlier hypotheses relating reinforcement and motor function (Glickman and Schiff 1967). The motor activation produced by MDMA and MDE has similarities to classic psychostimulants, but also some important differences. In the BPM system, the stimulant-like properties of these drugs were reflected in significant increases in horizontal locomotor activity measured across a wide dose range. Interestingly, medium to high doses of MDMA or MDE produced a transient decrease in horizontal locomotion for the first 10 minutes, followed by a sustained increase. The increase in holepokes and rearings that typically accompanies the increase in ambulation seen with amphetamine itself or other indirect sympathomimetics (Geyer et al. 1986) was not observed with MDMA or MDE.(ABSTRACT TRUNCATED AT 400 WORDS)

Amphetamines↗
PubMed1988

Methysergide potentiates the hyperactivity produced by MDMA in rats.

Although some substituted amphetamines, like MDA, produce a combination of sympathomimetic stimulation and perceptual alterations, the psychoactive qualities of MDMA are less distinctive. MDMA binds to serotonergic receptors and has been shown to potently deplete brain serotonin concentrations. Biochemical and behavioral evidence suggests that MDMA may also act on the dopamine system. The present study explored the effects of blocking serotonin receptors on MDMA and amphetamine induced locomotor hyperactivity in rats. Locomotor activity was measured in photocell cages for 120 minutes following injection of methysergide (0, 2.5, 5, 10 mg/kg) or methysergide in combination with amphetamine (0.5 mg/kg) or MDMA (10 mg/kg). Methysergide, which had no effect on its own, significantly potentiated the locomotor hyperactivity produced by MDMA but not amphetamine. Thus, the intrinsic serotonergic agonist properties of MDMA may actually counteract the indirect sympathomimetic effects thought to be responsible for the locomotor hyperactivity MDMA produces.

3,4-Methylenedioxyamphetamine↗
PubMed1988

The role of mesolimbic dopamine in conditioned locomotion produced by amphetamine.

Daily administration of psychomotor stimulants in a distinctive environment can impart on the environment stimulantlike properties. Rats injected with amphetamine (0.75 mg/kg, sc) daily for 5 days exhibited a robust unconditioned locomotor response, measured in photocell cages, and showed a conditioned locomotor response when treated with saline on the 6th day. This conditioned locomotor response was found to be significantly attenuated by 6-hydroxydopamine (6-OHDA) lesions of the nucleus accumbens when the lesion was made either pre- or postconditioning. Similarly, although rats with 6-OHDA lesions of the nucleus accumbens exhibited a robust supersensitive unconditioned locomotor hyperactivity in response to apomorphine (0.1 mg/kg, sc), they did not show a conditioned response on the test day. These results suggest that the mesolimbic dopamine system may be responsible for both the unconditioned and conditioned locomotor responses to psychomotor stimulant drugs. Further, conditioned locomotion depends on a critical interaction between the physiological release of presynaptic dopamine and occupation of postsynaptic receptors.

Animals↗
PubMed1988

Stimulant and hallucinogenic behavioral profiles of 3,4-methylenedioxymethamphetamine and N-ethyl-3,4-methylenedioxyamphetamine in rats.

The effects of methylenedioxymethamphetamine (0.63-10.0 mg/kg) and N-ethyl-methylenedioxyamphetamine (1.0-10.0 mg/kg) on locomotor and investigatory responses of rats were measured in the Behavioral Pattern Monitor system, a system designed to measure both the quantity and quality of behavioral activity. Horizontal locomotion was increased considerably by these compounds in a dose-related manner. This hyperactivity was accompanied by an initial decrease in investigatory holepokes and rearings followed by a subsequent increase at the highest doses tested. Rats injected with these phenylethylamine derivatives also exhibited thigmotaxis and a tendency to avoid the center of the experimental chamber, a behavioral profile similar to hallucinogen-like drugs. Consequently, a disruption of the spatial patterns of locomotion was also observed. Analyses of these patterns revealed an increasing tendency toward more stereotyped, predictable locomotor paths with increasing dose. Rats circled around the perimeter of the chamber with individual animals demonstrating a predominant though not completely consistent direction of rotation. The methylenedioxymethamphetamine-induced increase in locomotion remained significantly elevated up to 4 hr after injection at a 10 mg/kg dose, whereas other aspects of motor activity returned to base-line levels more rapidly. Thus, methylenedioxymethamphetamine and N-ethyl-methylenedioxyamphetamine seem to possess both psychomotor stimulant properties and elements of a hallucinogen-like behavioral profile.

3,4-Methylenedioxyamphetamine↗
PubMed1986

Complications associated with thoracocentesis.

In order to determine the spectrum and frequency of complications associated with thoracocentesis, we decided to audit prospectively all thoracocentesis performed in the medical service at our institution. Over a ten-month interval, 125 procedures were performed. We identified 114 (91 percent) prospectively, 11 retrospectively by a computer-assisted review of discharge summaries. Forty-six percent of the procedures were complicated by at least one adverse occurrence. Complications considered major occurred in 14 percent, minor in 33 percent. The major complications included 14 pneumothoraces (three required tube thoracostomies and one percutaneous aspiration), one splenic laceration, one sheared-off catheter, and one pneumohemothorax. The minor complications included pain in 28, persistent cough in 14, dry taps in 16, and subcutaneous fluid collections in four patients. We conclude that thoracocentesis can carry the risk of frequent morbidity even when a lecture and printed guidelines on performing thoracocentesis have been given and experienced individuals are in attendance during the performance of the procedure. Our study suggests a portion of this morbidity may be from poor technique, inability to adequately identify landmarks, and improper utilization of a needle-catheter apparatus. Suggestions for correction of these problems are made.

Humans↗
PubMed1983

d-Amphetamine in squirrel monkeys of different social status: effects on social and agonistic behavior, locomotion, and stereotypies.

The influences of social status on amphetamine-induced behavioral effects in squirrel monkeys were investigated. Social status was determined by constructing a sociogram. d-Amphetamine (0.3--1.0 mg/kg orally, 0.3 and 0.6 mg/kg IM) increased stereotyped head movements and reduced the time spent in the sitting posture in all monkeys (N = 25) regardless of sex, age, or social status. The high levels of locomotor activity in dominant and juvenile monkeys were decreased at higher amphetamine doses (0.6 mg/kg IM, 0.6 and 1.0 mg/kg orally), whereas the same doses increased locomotion in otherwise less active subdominant and submissive animals. Low doses of amphetamine (0.1, 0.3 mg/kg) decreased the incidence of agonistic behavior initiated by dominant monkeys, and higher doses (0.6, 1.0 mg/kg) caused these monkeys to change from predominant initiators of agonistic behavior into recipients. At 2 h after amphetamine administration (0.3 mg/kg IM), the high levels of locomotor behavior had returned to baseline, the social isolation began to disappear, and the disrupted agonistic behavior of dominant monkeys returned to control levels, yet the stereotyped head movements continued to occur with high frequency. In half of the monkeys, amphetamine produced a large increase in distress-like vocalizations. Amphetamine-mediated motor stereotypies may be mediated by mechanisms different than those responsible for agonistic behavior. The selective changes in agonistic behavior by dominant monkeys when challenged with amphetamine may reflect a status-related functional alteration of catecholaminergic processes upon which the drug acts.

Agonistic Behavior↗
PubMed1982

Redundant lumbar nerve root syndrome: myelographic features.

Nine patients with redundant lumbar nerve root syndrome were identified using positive-contrast myelography, seven with metrizamide and two with iophendylate. Serpiginous intradural filling defects occurred in conjunction with a complete or partial extradural block and spinal stenosis. These redundant nerve roots were seen on the cephalic side of the block. Eight of the nine patients had pseudoclaudication. One case was found incidentally during a cervical myelogram. This series is presented to demonstrate the characteristic myelographic pattern that should be recognized and differentiated from tortuous intradural blood vessels. Possible causes are discussed.

Adult↗
PubMed1981

Case report. Bilateral cerebellar venous angioma.

A case of posterior fossa venous angioma involving both cerebellar hemispheres and responsible for a subarachnoid hemorrhage is reported. The computed tomographic appearance was characteristic and closely corresponded to the angiographic findings. One of the draining veins of this angiomatous lesion had a transpontine course.

Adult↗
PubMed1980

Vertebrobasilar injuries following cervical manipulation.

Four cases of brainstem stroke syndromes followed mechanical cervical manipulation; vascular injury was confirmed angiographically. A comprehensive review of the literature on vertebrobasilar injuries disclosed the various mechanisms of injury and pathogenesis of subsequent vascular complications following cervical manipulation. Emphasis is given to the potentially devastating neurological complications, particularly in view of the increasing utilization of chiropractic therapy.

Adult↗
PubMed1980

Combined embolization and operation in the treatment of cervical arteriovenous malformations.

The effectiveness of a combined approach of embolization and operation for cervical vascular malformations is stressed. Lesions that seem to be inoperable may have their blood flow sufficiently reduced by preoperative embolization to allow surgical extirpation. Polyvinyl alcohol foam is an ideal embolic agent; not only may it be used preoperatively, but its permanency allows it to be used for primary therapy.

Adolescent↗