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Results for “sensorimotor function”

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PubMed1998

Gastric mechanosensory and lower esophageal sphincter function in rumination syndrome.

Our hypothesis was that rumination syndrome is associated with gastric sensory and motor dysfunction. We studied gastric and somatic sensitivity, reflex relaxation of the lower esophageal sphincter (LES), and gastric compliance and accommodation postprandially and postglucagon. A barostatically controlled gastric bag and esophageal manometry were used to compare gastric sensorimotor functions and LES relaxation to gastric distension in 12 patients with rumination syndrome and 12 controls. During bag distensions, patients had greater nausea, bloating, and aggregate score, but not pain, compared with controls (P < 0.05). At 4 and 8 mmHg gastric distension, LES tone reduction was greater in patients than in controls (P < 0.05). Gastric compliance, accommodation to a standard meal, and response to glucagon were not different in patients and controls; however, 6 of 12 patients had no gastric accommodation; the latter patients had significantly greater pain perception during distension (P < 0.05) but normal somatic sensitivity compared with healthy controls. Rumination syndrome is characterized by higher gastric sensitivity and LES relaxation during gastric distension. A subgroup of patients also had absent postprandial accommodation.

Adolescent↗

PubMed2005

Effect of atorvastatin on spatial memory, neuronal survival, and vascular density in female rats after traumatic brain injury.

OBJECT: Atorvastatin administered after traumatic brain injury (TBI) induced by controlled cortical impact promotes functional improvement in male rats. Note, however, that parallel studies have not been performed in female rats. Therefore, the authors tested the effect of atorvastatin on TBI in female rats. METHODS: Atorvastatin (1 mg/kg/day) was orally administered for 7 consecutive days in female Wistar rats starting I day after TBI; control animals received saline. Modified neurological severity scores, the corner turn test, and the Morris water maze test were used to evaluate functional response to treatment. Rats were killed on Day 15 post-TBI, and brain tissue samples were processed for immunohistochemical staining. Atorvastatin administration after brain injury significantly promoted the restoration of spatial memory but did not reduce sensorimotor functional deficits. Treatment of TBI with atorvastatin increased neuronal survival in the CA3 region and the lesion boundary zone and prevented the loss of neuronal processes of damaged neurons in the hippocampal CA3 region but not in the lesion boundary zone on Day 15 after TBI. The protective effect of atorvastatin on the injured neurons perhaps is mediated by increasing the density of vessels in the lesion boundary zone and the hippocampus after TBI. CONCLUSIONS: . These data indicate that atorvastatin is beneficial in the treatment of TBI in female rats, although the effect may differ between sexes.

Administration, Oral↗

PubMedDate not supplied

Reflex modification and the detection of toxicant-induced auditory dysfunction.

There are numerous environmental chemicals that adversely impact sensory functioning in exposed populations. Test methods are needed that can rapidly and efficiently assess the potential of chemicals to induce sensory toxicity. Reflex modification of the startle response is a technique that provides rapid, objective and quantitative assessments of sensorimotor function. This procedure has been shown to be sensitive to a variety of neurotoxic compounds. Reflex modification can also provide independent estimates of chemical-induced alterations in both sensory and motor function. Future efforts should focus on expanding the use of this procedure in both the identification and characterization of neurotoxic chemicals.

Animals↗

PubMed1986

A psychobiologic analysis of cognitive failures. Structure and mechanisms.

Impairments in memory, learning, and related cognitive functions can vary in most psychiatric or neuropsychiatric disorders. Although many methods have been used to measure the presence and severity of cognitive symptoms, little progress has been made in defining and contrasting possible determinants of cognitive dysfunction. We propose a theoretical framework that describes impairments of higher mental functions in terms of both "extrinsic" noncognitive processes and "intrinsic" cognitive processes. The latter include effort (capacity) demanding processes; automatic processes; episodic (recent biographical) memory; and processes involved in accessing previously acquired knowledge. Noncognitive processes include sensitivity to reinforcement, activation, sensorimotor function, and mood. Each of these processes can be expressed at the time of information acquisition or retrieval from memory. Findings from clinical studies of patients suffering amnestic disorders, progressive dementias, and mood disorders illustrate the utility of such a model for understanding some of the determinants of cognitive dysfunction, for developing diagnostic tools, and for considering therapeutic strategies that may be useful in treating cognitive dysfunctions.

Alcohol Amnestic Disorder↗

PubMed2006

Behavioral and physiological methods for early quantitative assessment of spinal cord injury and prognosis in rats.

Methods for reliable evaluation of spinal cord (SC) injury in rats at short periods (2 and 24 h) after lesion were tested to characterize the mechanisms implicated in primary SC damage. We measured the physiological changes occurring after several procedures for producing SC injury, with particular emphasis on sensorimotor functions. Segmental and suprasegmental reflexes were tested in 39 male Wistar rats weighing 250-300 g divided into three control groups that were subjected to a) anesthesia, b) dissection of soft prevertebral tissue, and c) laminectomy of the vertebral segments between T10 and L1. In the lesion group the SC was completely transected, hemisected or subjected to vertebral compression. All animals were evaluated 2 and 24 h after the experimental procedure by the hind limb motility index, Bohlman motor score, open-field, hot-plate, tail flick, and paw compression tests. The locomotion scale proved to be less sensitive than the sensorimotor tests. A reduction in exploratory movements was detected in the animals 24 h after the procedures. The hot-plate was the most sensitive test for detecting sensorimotor deficiencies following light, moderate or severe SC injury. The most sensitive and simplest test of reflex function was the hot-plate. The hemisection model promoted reproducible moderate SC injury which allowed us to quantify the resulting behavior and analyze the evolution of the lesion and its consequences during the first 24 h after injury. We conclude that hemisection permitted the quantitation of behavioral responses for evaluation of the development of deficits after lesions. Hind limb evaluation scores and spontaneous exploration events provided a sensitive index of immediate injury effects after SC lesion at 2 and 24 h. Taken together, locomotion scales, open-field, and hot-plate tests represent reproducible, quantitatively sensitive methods for detecting functional deficiencies within short periods of time, indicating their potential for the study of cellular mechanisms of primary injury and repair after traumatic SC injury.

Animals↗

PubMed1993

Geometrical approach to neural net control of movements and posture.

In one approach to modeling brain function, sensorimotor integration is described as geometrical mapping among coordinates of non-orthogonal frames that are intrinsic to the system; in such a case sensors represent (covariant) afferents and motor effectors represent (contravariant) motor efferents. The neuronal networks that perform such a function are viewed as general tensor transformations among different expressions and metric tensors determining the geometry of neural functional spaces. Although the non-orthogonality of a coordinate system does not impose a specific geometry on the space, this "Tensor Network Theory of brain function" allows for the possibility that the geometry is non-Euclidean. It is suggested that investigation of the non-Euclidean nature of the geometry is the key to understanding brain function and to interpreting neuronal network function. This paper outlines three contemporary applications of such a theoretical modeling approach. The first is the analysis and interpretation of multi-electrode recordings. The internal geometries of neural networks controlling external behavior of the skeletomuscle system is experimentally determinable using such multi-unit recordings. The second application of this geometrical approach to brain theory is modeling the control of posture and movement. A preliminary simulation study has been conducted with the aim of understanding the control of balance in a standing human. The model appears to unify postural control strategies that have previously been considered to be independent of each other. Third, this paper emphasizes the importance of the geometrical approach for the design and fabrication of neurocomputers that could be used in functional neuromuscular stimulation (FNS) for replacing lost motor control.

Animals↗

PubMed2002

Knowledge of object manipulation and object function: dissociations in apraxic and nonapraxic subjects.

An influential account of selective semantic deficits posits that visual features are heavily weighted in the representations of animals, whereas information about function is central in the representations of tools (e.g., Warrington & Shallice, 1984 ). An alternative account proposes that information about all types of objects-animate and inanimate alike-is represented in a distributed semantic architecture by verbal-propositional, tactile, visual, and proprioceptive-motor nodes, reflecting the degree to which these systems were activated when the knowledge was acquired (e.g., Allport, 1985 ). We studied a group of left hemisphere chronic stroke patients, some of whom were apraxic, with measures of declarative tool and animal knowledge, body part knowledge, and function and manipulation knowledge of artifacts. Apraxic (n=7) and nonapraxic (n=6) subjects demonstrated a double dissociation of performance on tests of tool and animal knowledge, suggesting that the apraxic group was not simply more severely impaired overall. Apraxics were relatively impaired in manipulation knowledge, whereas nonapraxics tended to be relatively impaired in function knowledge. Apraxics were also more impaired with body parts than nonapraxics. The association of gestural praxis, tool knowledge, body part knowledge, and manipulation knowledge suggests a coherent basis for the organization of semantic artifact knowledge in frontoparietal cortical regions specialized for sensorimotor functions, and thus provides support for the distributed architecture account of the semantic system.

Aged↗

PubMed2002

Persistent impairment of gait performances and working memory after bilateral common carotid artery occlusion in the adult Wistar rat.

BACKGROUND: The clinical and pathophysiological effects of a chronic reduction of cerebral blood flow in humans are not completely known. We investigated whether rats subjected to bilateral common carotid artery occlusion (bCCA-o) developed focal neurological deficits, gait dysfunction, and working memory alterations. METHODS: Eighteen male Wistar rats were subjected to bCCA-o, 13 were sham-operated. We assessed sensorimotor functions, gait on a 60 cm-long elevated bridge, and working memory (object recognition and Y maze tests) before and 30, 60, and 90 days after surgery. Histological analysis was performed in a subgroup of 10 rats. RESULTS: No rat showed sensorimotor alterations after surgery. Although gait performances of both bCCA-o and sham-operated rats declined over time, the differences reached statistical significance only for the bCCA-o group (mean+/-SE: 26.8+/-5.0; 22.4+/-4.9; 24.5+/-5.5 cm at 30, 60, and 90 days, respectively) in comparison with baseline (52.9+/-5.2 cm; P<0.05). At 60 and 90 days, bCCA-o rats in comparison with sham-operated rats showed decreased performances on object recognition (discrimination index: 0.15+/-0.03 vs. 0.29+/-0.05 at 60 days and 0.10+/-0.04 vs. 0.41+/-0.07 at 90 days; P<0.05) and on Y maze test (alternating rats: 9.9 vs. 85.7% at 60 days and 16.6 vs. 100% at 90 days; P<0.01). In none of the animals were cerebral infarcts detected. Selective neuronal necrosis was observed in the cortex and hippocampus of both bCCA-o and sham-operated rats without any obvious difference. CONCLUSIONS: bCCA-o in the Wistar rat induces persistent and progressive gait and working memory impairment without producing sensorimotor deficit or cerebral infarcts. This model may help to elucidate some physiopathological aspects of neurological impairment associated with states of cerebral chronic ischemia.

Animals↗

PubMed2000

Skilled forelimb reaching for pasta guided by tactile input in the rat as measured by accuracy, spatial adjustments, and force.

Rats are capable of reaching for food with a single forelimb, but since they locate the target of their reach using olfaction, it is unclear how they adjust their limb movement to compensate for errors. Although it is thought that their reaching movement is ballistic and can only be adjusted by trial and error, whether they can use haptic cues to aid in locating and identifying a target has not been examined. The present study addressed this question by allowing rats to reach through a slot for rigidly held pieces of uncooked pasta of varying thickness, which could be oriented vertically or horizontally from different points around the slot and which were attached to a force transducer. The tasks required that animals not only adjust their reach and grasp to the target's location but also identify the target based on its texture. Acquisition curves were made of head orientation, limb transport trajectories, number of attempts per success, paw orientation, breaking direction and force of the grasp. A haptic discrimination test used pasta and similar sized metal rods with different tactile properties as discriminanda. The results indicated that whereas postural orientation and limb transport trajectory were not modified as a function of target orientation, paw orientation and grasp force did vary as a function of the sensory qualities of the target object, and the rats could make a haptic discriminative choice of a target object. The results show that the rat is capable of adjusting paw movements using haptic information, suggesting that somatosensory features of sensorimotor control of limb and paw movements in carnivores and primates are shared by rodents. This commonality points to a conservation of motor control in mammals, explains some of the idiosyncratic features of rat reaching behavior, and confirms that rodents provide a good model for investigating sensorimotor functions.

Animals↗

PubMed2000

Spatial and associative learning deficits induced by neonatal excitotoxic hippocampal damage in rats: further evaluation of an animal model of schizophrenia.

Neonatal ventral hippocampal lesions in the rat result in post-pubertal onset of behavioural abnormalities, modelling some aspects of schizophrenia. We further assessed the behavioural effects of neonatal lesions in rats in a variety of cognitive tasks and in the prepulse inhibition (PPI) of startle response paradigm. Prepubescent, lesioned rats exhibited startle responses and PPI similar to controls whereas, at adulthood, they showed a deficit in PPI. Lesioned rats acquired both passive and active avoidance responses. However, compared to controls, they showed a deficit in passive avoidance retention and in acquisition of active avoidance responses. In a cued Morris water-maze task, lesioned rats demonstrated adequate sensorimotor functions and appropriate motivation to escape from water. However, they were impaired in place learning and in remembering the location of a submerged platform. In conclusion, neonatal ventral hippocampal lesions result in the post-pubertal emergence of long-lasting deficits in sensorimotor gating and in the capacity to acquire and retain information in tests of spatial and avoidance learning. Therefore, this neurodevelopmental model of schizophrenia seems to exhibit an interesting degree of validity in possibly simulating some cognitive impairments and sensorimotor gating deficits frequently observed in psychotic patients.

Animals↗

PubMed2005

Dimeric fibroblast growth factor-2 enhances functional recovery after focal cerebral ischemia.

PURPOSE: The purpose of this study was to examine the effects of dimerized basic fibroblast growth factor (dFGF), a novel engineered growth factor, in a model of functional recovery following focal cerebral infarction (stroke) in rats. METHODS: A focal stroke was made in mature male rats by occlusion of the middle cerebral artery (MCA). dFGF was administered by intracisternal injection at one and three days after stroke. Tests to evaluate sensorimotor recovery of the contralateral limbs were done during the next three weeks after stroke. RESULTS: dFGF significantly enhanced recovery of sensorimotor function in limb placing and body swing tests compared to vehicle treatment. There were no differences in body weight or infarct volume in dFGF- vs. vehicle-treated animals. CONCLUSIONS: dFGF represents a potential treatment to enhance functional recovery after stroke and offers several advantages over bFGF, including stability and independence from extracellular heparan sulfates.

Animals↗

PubMed1982

[Structural-functional reorganization of the brain after sequential removal of the regions of the motor cortex in cats and dogs].

It was shown in experiments on cats and dogs that the greater the mass of removed motor cortex on one side, the longer the time for restoring lost motor functions. Repeated ablations of the areas adjacent with the previously extirpated cortical zone after the restoration of motor functions, bring about the recurrence of the same disturbances. However the period of restoration after each repeated extirpation is perceptibly shorter. This means that repeated extirpations of cortical areas result in the activation of the mechanisms directed at the reorganization of the brain sensorimotor functions as a new integral system and providing for normalization of the motor functions.

Animals↗

PubMed2006

The influence of the novel 5-HT1A agonist R137696 on the proximal stomach function in healthy volunteers.

As fundic dysaccommodation represents one of the pathophysiological mechanisms underlying functional dyspepsia, gastric relaxant agents may serve as a new treatment of this disorder. Previous studies have suggested the involvement of 5HT1 receptors in the control of gastric tone. Our aim was to study the effect of R137696, a novel 5HT1A agonist, on fundus sensorimotor function in healthy volunteers. The effect of single oral doses (1-2 mg) R137696 was evaluated in a double-blind, placebo-controlled manner on fasting fundic volume, visceral perception, distension-evoked symptoms and fundic compliance in 21 healthy male subjects. R137696 increased the proximal stomach volumes in a dose-dependent manner. Distention-evoked symptoms or distention and discomfort threshold were not altered by R137696. A logistic regression model, characterizing the relationships between the volume and the visual analogue scale score for dyspeptic symptoms (nausea, fullness, discomfort, pain and satiety) as a sigmoidal curve, revealed that R137696 had no effect on distension-induced discomfort, fullness, pain and satiety compared to placebo. R137696 relaxes the gastric fundus in fasting conditions but has no effect on distension-evoked dyspeptic symptoms in healthy volunteers.

Adult↗

PubMedDate not supplied

Dynamical stability in the acquisition and performance of rhythmic ball manipulation: theoretical insights with a clinical slant.

Three experiments illustrate how a task-based approach and dynamical modeling of a perceptual-motor task can provide a useful framework for understanding functional and dysfunctional behavior. In the chosen task, subjects held a racket and bounced a ball rhythmically in the air with invariant ball amplitude. As such, the task could be cast into a mechanical model that encompassed the movements of the actor (racket) and the manipulandum (ball). In this form, the movement task is a dynamical system that displays dynamical stability, i.e., performance where perturbations die out by themselves. The hypothesis is that skilled actors seek to perform with this "passive" stability as it alleviates the control demands because perturbations do not require explicit corrections. In the experimental data, this strategy could be characterized by a single parameter, the acceleration of the racket at impact, which provided quantitative predictions. Experiment 1 established that subjects with normal sensorimotor functions indeed performed with racket acceleration values that were predicted to provide passive stability. Experiment 2 showed that subjects improved their skill over a course of 40 practice trials, as evidenced in decreased variability and accompanied by a change in racket acceleration toward values that provided optimal stability. In experiment 3, perturbations were applied and the subjects' adaptability was tested. When perturbations were large enough, subjects altered their racket timing to resume contact that provided stability. The results are discussed with their relevance to clinical contexts: How can such a task-based approach provide insights into the control of functional and dysfunctional movements? Can such behavioral results serve as a diagnostic tool? How can this approach to sensorimotor behavior stimulate physicians and therapists to progress therapeutic measures?

Biomechanical Phenomena↗

PubMed1982

Monitoring of cortical somatosensory evoked potentials to determine the safety of sacrificing the anterior cerebral artery.

Cortical somatosensory evoked potentials (SSEPs) reflect the functional integrity of somatosensory pathways from the site of stimulation to the primary somatosensory cortex. We used intraoperative monitoring of cortical SSEPs to determine whether the right anterior cerebral artery (RACA), the major feeding vessel of a large arteriovenous malformation (AVM), could be sacrificed without compromising sensorimotor function in the left lower extremity. The SSEPs recorded after test occlusion of the RACA showed preservation of the initial cortical positivity, and the RACA was divided. The AVM was excised completely, and the patient suffered no neurological deficit.

Adult↗

PubMed2003

Angiotensin II accelerates functional recovery in the rat sciatic nerve in vivo: role of the AT2 receptor and the transcription factor NF-kappaB.

The AT2 receptor regulates several functions of nerve cells, e.g., ionic fluxes, cell differentiation, and axonal regeneration, but also modulates programmed cell death. We tested the hypothesis that angiotensin II (ANG II) via its AT2 receptor not only promotes regeneration but also functional recovery after sciatic nerve crush in adult rats. ANG II (10(-7), 10(-9), 10(-11) M) applied locally via osmotic minipumps promoted functional recovery with maximal effects after the lowest concentration. The toe spread distance as a parameter for re-innervation after 20 days was significantly (P<0.01) greater (10.2+/-10.27 mm) compared with the control group (8.73+/-0.16 mm). The response to local electrical stimulation (return of sensorimotor function) was reduced to 14.6 days vs. 17.9 days in the control group (P<0.01). The AT2 receptor antagonist PD 123319 administered alone or in combination with ANG II completely prevented the ANG II-induced recovery, whereas the AT1 receptor antagonist losartan had no effect. Furthermore, ANG II induces, via the AT2 receptor, activation of the transcription factor NF-kappaB in Schwann cells. Histological criteria, morphometric analyses, and electron microscopy confirmed the functional data. These results are the first to present direct evidence for an involvement of the AT2 receptor and NF-kappaB in peripheral nerve regeneration.

Angiotensin II↗

PubMed1998

Age-dependent neurobehavioral plasticity following forebrain dopamine depletions.

The differential neurobehavioral effects of forebrain dopamine (DA) depletions in neonatal and adult rats are reviewed. In contrast to the severe and long-lasting parkinsonian sensorimotor deficits seen in rats sustaining large DA depletions as adults, rats comparably depleted as neonates are spared from these gross behavioral deficits. While DA released from residual striatal DA terminals remains necessary for the gradual recovery of sensorimotor function in rats lesioned as adults and the sparing from deficits in rats lesioned as neonates, the specific roles of D1- and D2-like receptors differ between the two age groups. Coactivation of striatal D1 and D2 receptors by residual DA is necessary for the expression of sensorimotor behavior in rats depleted of DA as adults (and in intact rats) whereas activation of either D1 or D2 receptors is sufficient for these behaviors in rats depleted of DA as neonates. We discuss the D1/D2 modulation of several important markers for striatal transmission (acetylcholine release from interneurons, induction of c-fos, and the expression of GAD65 mRNA in striatal efferents) as potential mechanisms underlying this striking age-dependent plasticity following forebrain DA depletions.

Aging↗

PubMed1990

Effects of temperature on nervous system: implications for behavioral performance.

Temperature change has a major impact on the function of the nervous system and its components, including altering synaptic gain and changing synaptic and conduction delays. Although many animals are subject to changes in body temperature, the degree of temperature change actually experienced by many poikilotherms is not well documented. The fact that many animals continue to exhibit coordinated sensorimotor function during changes in body temperature indicates that some form of temperature compensation has occurred within the nervous system. Compensations may occur automatically (opposing effects of temperature offsetting each other), they may be an inherent property of closed-loop systems, or they may be effected by more sophisticated control mechanisms such as those of the vertebrate cerebellum.

Action Potentials↗