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Results for “sensorimotor function”

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At least 217 records · Page 12Linked to original sources

PubMed1986

Intrinsic 5HT-immunoreactive neurons in the spinal cord of the fetal non-human primate.

Serotonin (5HT) immunoreactive neurons were identified in the late-term fetal spinal cord of normal non-human primates. These neurons were distributed throughout the spinal cord, being concentrated in lamina X and the subjacent ventral median fissure, while their immunoreactive fibers and terminals innervated the zone surrounding the central canal and the ventral spinal artery. Even at this late fetal stage, the dorsal and ventral spinal gray matter was virtually devoid of any positive 5HT immunoreactivity, in contrast to that seen in the adult primate. These findings suggest that the intrinsic 5HT neurons of the primate during development may modulate CSF composition or provide cues for spinal cord differentiation rather than regulate sensorimotor functions as they do in the adult.

Animals↗

PubMed1994

The involvement of nucleus accumbens dopamine in appetitive and aversive motivation.

In recent years, considerable emphasis has been placed upon the putative role of nucleus accumbens dopamine systems in appetitive motivation and positive reinforcement. However, considerable evidence indicates that brain dopamine in general, and nucleus accumbens dopamine in particular, is involved in aspects of aversive motivation. Administration of dopamine antagonists or localized interference with nucleus accumbens dopamine systems has been shown to disrupt active avoidance behavior. In addition, accumbens dopamine release and metabolism is activated by a wide variety of stressful conditions. A review of the literature indicates that there are substantial similarities between the characteristics of dopaminergic involvement in appetitive and aversive motivation. There is conflicting evidence about the role of dopamine in emotion, and little evidence to suggest that the profound and consistent changes in instrumental behavior produced by interference with DA systems are due to direct dopaminergic mediation of positive affective responses such as hedonia. It is suggested that nucleus accumbens dopamine is involved in aspects of sensorimotor functions that are involved in both appetitive and aversive motivation.

Animals↗

PubMedDate not supplied

D-cycloserine, a novel cognitive enhancer, improves spatial memory in aged rats.

D-cycloserine, a partial agonist of the NMDA receptor-associated glycine site, can enhance cognition. The present experiment examines the behavioral effects of D-cycloserine on cognitive deficits in male Fischer-344 rats, 24 months old. Rats 24 months old (n = 42) received either vehicle or one of 3 doses of D-cycloserine prior to testing. Young rats, 4 months old (n = 13), received vehicle prior to testing. Place discrimination and repeated acquisition were tested in the water maze and a variety of sensorimotor tasks were given. Aging impaired performance in all tasks. D-cycloserine improved performance in place discrimination and repeated acquisition. No doses affected sensorimotor function. These results support the hypothesis that D-cycloserine has cognition enhancing properties and that it may be useful in treating disorders involving cognitive impairment.

Aging↗

PubMed1993

Surgical management of recurrent carpal tunnel syndrome.

An approach to the surgical management of recurrent carpal tunnel syndrome was evaluated in 30 patients with 35 involved wrists. This includes internal neurolysis of the median nerve and early post-operative mobilization of the wrist and fingers. The preferred surgical approach is through a second, more ulnar incision. Clinical assessment of sensorimotor function was converted into a numerical score ranging from zero (normal) to 9 (anaesthesia) and 10 (atrophy, severe). The average pre-operative score was mean 6.5 and median 7. At a mean follow-up of 23.5 months, the average post-operative score was mean 1.8 and median 0, a statistically significant improvement (P < 0.001).

Adult↗

PubMed1990

Selective neocortical and thalamic cell death in the gerbil after transient ischemia.

In animal models of transients ischemia, selective vulnerability and delayed neuronal death in the hippocampus have been extensively described. However, little is known about selective damage in the neocortex and the thalamus, even though deficits in sensorimotor function are common in humans surviving hypoxic/ischemic episodes. This study investigated the neurodegenerative effects of transient ischemia in the gerbil neocortex and thalamus with use of Cresyl Violet and silver impregnation staining methods. In addition, immunohistochemistry of an astrocyte-associated protein, glial fibrillary acidic protein, was used to assess the astrocytic response to ischemia. Pyramidal cells in layers 3 and 6 of somatosensory and auditory cortex were exceptionally sensitive to ischemia, whereas the neurons in layers 2, 4 and 5 were more resistant to ischemia. More pyramidal cells were killed in layer 3 than in layer 6. This bilaminar pattern of neuronal death developed after periods of ischemia ranging from 3 to 10 min and was identifiable at post-ischemic survival times of 6 h to one month. Somatodendritic argyrophilia in the neocortex was identified as early as 6-12 h after 5 min of ischemia. The greatest number of degenerating cortical neurons were stained two to four days after ischemia. With 10 min of ischemia, argyrophilic neurites and neurons were also found as early as 8 h after the occlusion. The most extensive damage was noted in the ventroposterior nucleus, the medial geniculate nucleus, and the intralaminar nuclei two to four days after ischemia. Thus, selective vulnerability and delayed neuronal death are evident in both the neocortex and the thalamus after transient ischemia. These regions need to be examined when considering the efficacy of potential neuroprotective drugs.

Animals↗

PubMed1990

Distribution of substance P-like immunoreactive fibres and terminals in the medulla oblongata of the human infant.

This study provides a detailed report of the distribution and density of substance P-like immunoreactive fibres and terminals within the human infant medulla. Seven brains with no signs of macroscopic alteration fixed usually within 24-48 h after death were used. Free floating transverse sections (50-60 microns) were then immunostained with a monoclonal antibody against substance P using the avidin-biotin-peroxidase technique. Morphologically three types of substance P-like immunoreactive fibres were observed: those with small varicosities of less than 1 micron, those with medium varicosities of 1-2 microns and those with large varicosities of 2-4 microns. Very dense substance P-like immunoreactivity was present within the spinal trigeminal nucleus, parts of the gracile and cuneate fasciculi and the paracommissural subnucleus of the solitary nucleus; dense substance P-like immunoreactivity was present within the dorsal nucleus of the vagus nerve, commissural, medial, dorsal, dorsolateral ventral and ventrolateral subnuclei of the solitary nuclear complex, parasolitary nucleus, raphe obscurus, inferior olivary complex (medial, dorsal, dorsomedial nuclei) and ventrolateral part of the dorsal reticular nucleus; moderate substance P-like immunoreactivity was present within the gelatinosus nucleus of the solitary tract, lateral reticular nucleus proper, intermediate reticular zone and parvocellular reticular nucleus; sparse substance P-like immunoreactivity was present within the hypoglossal nucleus, retroambigual nucleus and much of the reticular formation (dorsal, parvocellular, ventral gigantocellular, dorsal paragigantocellular nuclei): and very sparse substance P-like immunoreactivity was present within the nucleus ambiguus, medial vestibular nucleus and parts of the reticular formation (ventral, medial, gigantocellular, ventral gigantocellular, dorsal paragigantocellular nuclei). Substance P-like immunoreactivity was absent in the area postrema, intercalated nucleus, gracile and cuneate nuclei, in the epiolivary, subtrigeminal and parvocellular divisions of the lateral reticular nucleus, spinal vestibular nucleus, and in the solitary and pyramidal tracts. In several regions the substance P-like immunoreactive fibres formed distinct pericellular arrays around the somata and dendrites of neurons (hypoglossal nucleus, dorsal nucleus of the vagus nerve, retroambigual nucleus, intermediate reticular zone). The results indicate the high specificity of the localization of substance P in various structures of the brainstem and underline the presumed significance of this peptide in autonomic and sensorimotor functions of the brain.

Female↗

PubMed1993

Protective effects of SR 57746A in central and peripheral models of neurodegenerative disorders in rodents and primates.

Compounds possessing neurotrophic properties may represent a possible treatment for neurodegenerative disorders such as Alzheimer's disease. SR 57746A, 1-[2-(naphth-2-yl)ethyl]-4-(3-trifluoromethylphenyl)-1,2,5,6- tetrahydropyridine hydrochloride, is a new compound with neurotrophic activity in a number of in vitro preparations. The neurotrophic effects of this compound have been evaluated in vivo using four distinct rat models of neurodegeneration: transient global ischaemia produced by a four-vessel occlusion; septohippocampal lesion produced by injection of vincristine sulphate into the medial septum; sciatic nerve crushing; and acrylamide-induced peripheral neuropathy. Rats were administered vehicle or 2.5-10 mg/kg p.o. SR 57746A, after initiation of the degenerative process, then once daily for 10 days in the first two models, 16 days in the third and 26 days in the fourth model. Median scores for ischaemia-induced neuronal damage were reduced by 30-40% by SR 57746A treatment in hippocampal CA1, CA2, and CA3 regions, and in the dorsal striatum. Twelve days after intraseptal vincristine administration, there was a marked loss of septohippocampal cholinergic neurons, as indicated by reduced choline acetyltransferase activity in both the septum and hippocampus. SR 57746A dose-dependently reversed this reduction in both areas. These results were confirmed by histoenzymological evaluation of hippocampal acetylcholinesterase content. SR 57746A also reversed the loss of hippocampal choline acetyltransferase induced by intraseptal vincristine in marmosets. Behavioral deficits in these models (exploratory behaviour in the former and short-term social memory in the latter) were also significantly reduced by SR 57746A treatment. In the sciatic crush model, sensorimotor function improved more rapidly in rats treated with 10 mg/kg SR 57746A. In this same model, SR 57746A (10 mg/kg/day) also significantly increased the length of regenerated nerve eight days after the crush, as measured using the pinch test. Finally, SR 57746A retarded the onset, reduced the amplitude and accelerated the recovery of acrylamide-induced peripheral neuropathy. Thus, SR 57746A possesses notable neurotrophic activity in a variety of neurodegenerative models in vivo, suggesting that the compound may possess therapeutic potential for the treatment of neurodegenerative diseases.

Acetylcholinesterase↗

PubMed1981

Mesencephalic reticular formation stimulation effects on hypothalamic neuronal activity.

The effects of mesencephalic reticular formation (RF) single pulse, 0.5 msec and 0-500 microA, stimulation on lateral preoptic-lateral hypothalamic (LPA-LH) neuronal activity were determined in anesthetized rats. In addition, the effects of LH stimulation on neural activity in the RF and periaqueductal gray (PAG) were evaluated. Recordings from 117 neurons indicate reciprocal connections between the LPA-LH and the mesencephalon. Stimulation of the RF affected 70% of the LPA-LH neurons tested. Short latency decreases in activity predominated indicating an inhibitory synaptic input from the RF to the LPA-LH. Short latency increases in discharge frequency were observed infrequently. Stimulation of the LH affected only 32% of the mesencephalic neurons tested. Short latency decreases in activity were usually observed indicating reciprocal inhibitory synaptic connections between the LPA-LH and the RF and periaqueductal gray. Antidromic responses verified these interconnections and revealed relatively slow conduction velocities of approximately 1.0 m/sec. Results are discussed in terms of the involvement of the LPA-LH and RF in sensorimotor functions, spinal motor excitability, and ingestive behavior.

Action Potentials↗

PubMedDate not supplied

Behavioral and neurochemical sequelae in young rats of antenal hypoxia.

To test the hypothesis that perinatal hypoxia may have postnatal consequences via à vis learning memory, and neurochemical sequelae, we exposed pregnant Sprague-Dawley rats to 10.5% O2 for 4 h per day (0800-1200 h) or continuously from gestional day E15 to E20. On E20 we quantified ornithine decarboxylase activity and polyamine concentrations in fetal brain. We also conducted behavioral tests from postnatal day P3 to P110. Relatively mild antenatal hypoxia resulted in altered learning, memory, and delayed maturation of early developmental sensorimotor function. These behavioral changes disappeared at various postnatal ages, depending on the function. Perinatal hypoxia also altered the pharmacological response to dopaminergic drugs. In addition, antenatal hypoxia feminized a male nonreproductive sexual behavior, that of saccharin preference. Acute hypoxia also resulted in an increase in the enzyme ornithine decarboxylase and polyamines, which may affect brain development.

Animals↗

PubMed1993

Neural Darwinism: selection and reentrant signaling in higher brain function.

Variation and selection within neural populations play key roles in the development and function of the brain. In this article, I review a population theory of the nervous system aimed at understanding the significance of these processes. Since its original formulation in 1978, considerable evidence has accumulated to support this theory of neuronal group selection. Extensive neural modeling based on the theory has provided useful insights into several outstanding neurobiological problems including those concerned with integration of cortical function, sensorimotor control, and perceptually based behavior.

Animals↗

PubMed1995

Hypnotic catalepsy-induced changes of regional cerebral glucose metabolism.

In an attempt to elucidate the physiological basis of hypnosis, we investigated the changes of whole-brain and regional cerebral glucose metabolism, from a state of resting wakefulness to a hypnotized state with whole-body catalepsy, using positron emission tomography and the 2[18F]fluorodeoxyglucose method in 15 highly hypnotizable adults. Neither the random order of study conditions nor any of the other experimental factors had a measurable effect, and there was no statistically significant global activation or metabolic depression. However, repeated measures analysis of variance revealed a statistically significant heterogeneity of symmetric regional responses: Mainly the occipital areas, including visual and paravisual cortex, became relatively deactivated, while some metabolic recruitment was found in structures involved in sensorimotor functions. The observed pattern of changes of regional cerebral activity corresponds with the shift of attention away from normal sensory input that hypnosis is known to produce.

Adult↗

PubMed1998

Diagnosis and rehabilitation strategies for patients with hysterical hemiparesis: a report of four cases.

Conversion disorder is a psychological disturbance that produces subconscious alterations in sensorimotor function. Hysterical hemiparesis is a relatively rare, and difficult to diagnose, form of conversion disorder presenting as unilateral motor weakness with or without sensory deficits. We report four patients who required inpatient rehabilitation for hysterical hemiparesis, a diagnosis for which there is little information regarding rehabilitation management. In all cases, an extensive acute care evaluation including multiple imaging studies failed to identify a new neurologic lesion. All patients had rapid functional improvement using functional and behavioral therapies and extensive psychosocial support (mean length of stay of 11 days; mean Functional Independence Measure [FIM] gain of 22; mean discharge FIM of 112), consistent with other published reports of rehabilitation of conversion disorder. Evaluation of these cases reveals consistencies regarding presentation, psychosocial history, and rehabilitation course that can aid clinicians in making the diagnosis. Rehabilitation strategies for hysterical hemiparesis are reviewed.

Activities of Daily Living↗

PubMed1998

Impaired spatial navigation learning in transgenic mice over-expressing heme oxygenase-1.

Transgenic mice expressing heme oxygenase-1 (HO-1) using the neuron-specific enolase promoter were impaired in learning the Morris water maze compared to nontransgenic littermates. The memory of the HO-1 mice for the location of the platform was similarly impaired when tested using a probe trial after 7 training blocks, but performance on visible platform trials was similar for both groups of mice. Importantly, both HO-1 and nontransgenic mice had normal sensorimotor function, and performed the same on a Y-maze alternation task, highlighting the specificity of memory deficit in the spatial navigation task. These results suggest that carbon monoxide, one product of HO-1 activity, interferes in the development of spatial navigation memory, and may play a role in normal memory function.

Animals↗

PubMed1999

Lubeluzole shows neuroprotective effects in an "in-vitro"-model for neuronal lesions in the chicken retina.

In this study, the isolated chicken retina was used as an "in-vitro"-model for investigation of neuronal lesions to show the neuroprotective effects of lubeluzole. Lubeluzole is a neuroprotective compound that has been shown to stereoselectively rescue sensorimotor function and reduce infarct size in photochemical stroke models in rats. In the retina, the typical cell swelling of a developing lesion is accompanied by a very strong intrinsic optical signal (IOS), occurring simultaneous with the electrical signal which is based on changes in light scattering. In the presented model, lesions were elicited electrically with a tungsten microelectrode (0.1 MOmega). The degree of damage was evaluated with optical methods by measuring area and brightness of the affected tissue. Lubeluzole was much more effective in reducing the growth of the lesions than its R-isomer. However, both compounds enhanced the possibility of the neuronal tissue to recover after excitotoxic stimuli.

Animals↗

PubMedDate not supplied

Developmental stress disrupts habituation but spares prepulse inhibition in young rats.

Stress has long been recognized as a factor that contributes to the induction of schizophrenia and results in abnormal sensorimotor functioning and information processing. Patients with schizophrenia show disrupted habituation and prepulse inhibition of the acoustic startle response. This study examined the effects of maternal isolation in rats on the habituation of startle and PPI to assess the potential impact of developmental stress on schizophrenic symptomatology. Evaluation of performance in young adulthood (3-4 months) revealed a disruption of habituation in the isolated group; response amplitude increased over time. PPI was not altered. These results suggest that the disruption of habituation may involve acute effects of elevated stress hormones on neuronal functions. In contrast, disturbance of PPI may require an accrual of neuronal insult and damage to ultimately undermine neurologic function, possibly through impact on N-methyl-D-aspartate-mediated transmission. An analysis of effects at middle age is planned to address this possibility.

Acoustic Stimulation↗

PubMed1989

Afferents and efferents of the vestibular nuclei: the necessity of context-specific interpretation.

A synopsis of physiological and anatomical results is presented that leads to the conclusion that experimental data have to be interpreted in a context meaningful for the system investigated. For example, since there is an obvious spatial relationship between semicircular canals and extraocular muscles, the interdependence between the three-neurone-arc circuitry, and vestibular and visual signals follows quite naturally from a common geometry inherent in the sensory and motor periphery. It is emphasized that signals related to compensatory eye movements have to be interpreted within a vestibular/eye muscle frame of reference. By the same argument, when dealing with the head-neck movement system, the appropriate reference frame will have to be applied to arrive at a meaningful interpretation of related sensorimotor functions. Thus, in general terms, each system has to be interpreted within its own meaningful biological context.

Animals↗

PubMed1987

An hypothesis about redundancy and reliability in the brains of higher species: analogies with genes, internal organs, and engineering systems.

The phenomena of behavioral resistance to massive brain damage and behavioral recovery from brain damage suggest there is redundancy in neural tissue. This paper uses basic concepts from probability theory and reliability engineering, as a first step toward more rigorously establishing the plausibility of the redundancy hypothesis. Exponential effects in the relevant formulas lead to results that are intuitively surprising. Thus, within a broad range of parametric assumptions related to lifespan and number of neurons or neural subsystems, it appears that the human brain may be at least twice as large as it would have to be for short-term survival. Simple reliability models suggest that redundancies are in parallel connections of smallest subsystems, such as individual neurons. Other implications of the basic formulas concern the relation between backed-up subsystem reliability and lifetime usage frequency for each subsystem, and the evolution of approximately equal allocation of lifetime reliability among components of a system. In addition, the paper briefly reviews more complex reliability engineering approaches. Redundancy as a reason for neural mass action is compared to other theoretical reasons for mass action in sensorimotor function and learning. Relationships of the present hypothesis to other theories of recovery from brain damage and to theories of regressive trophic phenomena in ontogeny are briefly discussed; it is suggested that as stages of ontogeny progress, both redundancy and flexibility in simpler behavioral functions are traded away for a larger, more differentiated repertoire of complex functions and memories.

Animals↗

PubMed1999

Suck and spit, don't blow: orbital emphysema after decompression surgery.

PURPOSE: To describe the occurrence of vision-threatening orbital emphysema in patients awakening from orbital decompression surgery and to assess risk factors and preventive measures. DESIGN: Small noncomparative case series. PARTICIPANTS: Three patients undergoing bilateral orbital two-wall decompression experienced significant orbital emphysema associated with persistent coughing and Valsalva at the time of extubation. INTERVENTION: In two patients, symptoms resolved with simple observation, whereas one patient required sedation, topical anesthesia around the endotracheal tube, and needle decompression of trapped air. MAIN OUTCOME MEASURES: Visual acuity, pupils, visual fields, and sensorimotor examination. RESULTS: No patient experienced a permanent deficit of visual or sensorimotor function. CONCLUSIONS: Acute orbital emphysema can occur after orbital decompression surgery despite the large bony opening created. Violent coughing spells at the time of extubation are more common in patients with a history of heavy tobacco use and may be causative. Opening the periorbita may be another specific predisposing risk factor. Knowledge of this dangerous phenomenon, along with appropriate perioperative management, may prevent this complication from occurring.

Acute Disease↗