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Results for “sensorimotor behavior”

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PubMed2004

The medial septum mediates impairment of prepulse inhibition of acoustic startle induced by a hippocampal seizure or phencyclidine.

The involvement of the septohippocampal system on the impaired sensorimotor gating induced by phencyclidine (PCP) or by an electrically induced hippocampal seizure was examined in behaving rats. An impaired sensorimotor gating, measured by prepulse inhibition (PPI) of the acoustic startle response, was observed following a hippocampal afterdischarge (AD) or systemic injection of PCP and was accompanied with an increase in hippocampal gamma waves (30-70 Hz). The medial septum infusion with muscimol (0.25 microg), a GABA(A) receptor agonist, 15 min prior to PCP or a hippocampal AD, prevented the impairment of sensorimotor gating and the increase in gamma waves. By itself, muscimol (0.25 microg) injection into the medial septum did not affect PPI, although it significantly suppressed spontaneous gamma waves. In order to identify subpopulations of neurons mediating the sensorimotor gating deficit and the hippocampal gamma wave increase, 0.14-0.21 microg of p75 antibody conjugated to saporin (192 IgG-saporin) was injected into the medial septum to selectively lesion the septohippocampal cholinergic neurons. Neither the PPI deficit nor the gamma wave increase induced by PCP or a hippocampal AD was affected by 192 IgG-saporin lesion of the medial septum. It is concluded that increase in neural activity in the medial septum participates in the impairment of sensorimotor gating and the increase in hippocampal gamma waves induced by PCP or a hippocampal AD. It is suggested that the GABAergic but not the cholinergic septohippocampal neurons mediate the sensorimotor gating deficit.

Animals↗
PubMed1981

Interanalyzer two-way neuronal connections during alimentary conditioning in cats.

Milk conditioned reflexes to low frequency electrostimulation of optic tracts was examined in four cats. Multineuronal activity from visual and sensorimotor cortical regions was recorded under conditions of chronic implantation. Intra- and interanalyzer interneuronal connections were statistically analyzed by constructing crosscorrelograms. The comparison of the results of interneuronal interaction in untrained and trained animals showed an increase of one-way and two-way connections both of intra- and interanalyzer types. Neurons characterized by intermediate amplitude spike, more than other neurons, changed their network properties and were enriched by incoming and outgoing connections in both visual and sensorimotor cortex of the trained animals. An increase in the total number of interneuronal connections after acquisition was due to an increase of connections from the sensorimotor to the visual analyzer.

Animals↗
PubMed2004

Schizophrenia-like behavioral changes after partial hippocampal kindling.

The effect of hippocampal kindling on behavioral changes following 10 and 21 hippocampal afterdischarges (ADs) or electrographic seizures was examined in behaving rats. As compared to control, non-stimulated rats, 21 but not 10 hippocampal ADs resulted in a decrease in social contact, an increase in social isolation, and an increase in climbing and chasing behavior tested in an open field 3 days after cessation of kindling. Porsolt forced swimming test was not different among the control, 10- or 21-AD groups of rats. A deficit in sensorimotor gating, measured by prepulse inhibition of an acoustic startle, was observed in kindled as compared to control rats at 2 weeks after 21 ADs, but not after 10 ADs. Similarly, methamphetamine (1 mg/kg i.p.) induced higher locomotor activity in kindled rats, as compared to controls, after 21 ADs but not after 10 ADs. Spontaneous locomotor activity in a novel cage, without drug administration, was not different between kindled and control rats. These findings suggest that behavioral alterations after repeated hippocampal electrographic seizures may be mediated by increased dopaminergic functions, which may also mediate the psychiatric symptoms in human epileptic patients.

Acoustic Stimulation↗
PubMed1997

The interface between dopamine neurons and the amygdala: implications for schizophrenia.

A substantial amount of research has focused on the midbrain dopamine system and its role in emotional and motivational behaviors. In diseases in which dopamine function is compromised, patients exhibit a constellation of symptoms, suggesting that the dopamine system plays an important role in the integration of several functions. Subgroups of dopamine neurons receive information from limbic and association areas and project widely throughout cortex and striatum, including motor areas. A dorsal tier of dopamine neurons receive input from the ventral (limbic-related) striatum and from the amygdala and project widely throughout cortex. A more ventrally located group of dopamine cells receives input from both the limbic and association areas of striatum and projects widely throughout the striatum, including the sensorimotor regions. Through these projections, the limbic system has an enormous influence on dopamine output and can therefore affect the emotional and motivational "coloring" of a wide range of behaviors.

Amygdala↗
PubMed1977

Electroencephalographic correlates of prism adaptation in mentally retarded individuals.

Sensorimotor adaptation was studied in 23 institutionalized, mentally retarded individuals. This was achieved by recording the pattern of off-target pointing errors resulting from viewing through a 20-diopter prism. The results showed a wide range of individual differences in prism adaptation. The electroencephalogram (EEG) was also recorded from four scalp locations and analyzed by computer to determine EEG intensity, coherence, and phase angle. Correlations between EEG and behavioral scores of prism adaptation revealed a number of significant relationships, especially negative correlations between alpha intensity and prismatic adaptation. These results indicate that patterns of central nervous system activity are meaningful related to sensorimotor capabilities in retarded individuals.

Adaptation, Physiological↗
PubMed1999

Complete compensation in skilled reaching success with associated impairments in limb synergies, after dorsal column lesion in the rat.

Each of the dorsal columns of the rat spinal cord conveys primary sensory information, by way of the medullary dorsal column nucleus, to the ventrobasal thalamus on the contralateral side; thus the dorsal columns are an important source of neural input to the sensorimotor cortex. Damage to the dorsal columns causes impairments in synergistic proximal or whole-body movements in cats and distal limb impairments in primates, particularly in multiarticulated finger movements and tactile foviation while handling objects, but the behavioral effects of afferent fiber lesions in the dorsal columns of rodents have not been described. Female Long-Evans rats were trained to reach with a forelimb for food pellets and subsequently received lesions of the dorsomedial spinal cord at the C2 level, ipsilateral to their preferred limb. Reaching success completely recovered within a few days of dorsal column lesion. Nevertheless, a detailed analysis of high-speed video recordings revealed that rotatory limb movements (aiming, pronation, supination, etc.) were irreversibly impaired. Compensation was achieved with whole-body and alternate limb movements. These results indicate the following: (1) in the absence of the dorsal columns, other sensorimotor pathways support endpoint success in reaching; (2) sensory input conveyed by the dorsal columns is important for both proximal and distal limb movements used for skilled reaching; and (3) detailed behavioral analyses in addition to endpoint measures are necessary to completely describe the effects of dorsal column lesions.

Animals↗
PubMed2000

Niemann-Pick disease type C: two cases and an update.

We describe two patients with juvenile-onset Niemann-Pick disease type C (NPC) to illustrate the variable neurologic features of this condition. One presented with hypersplenism at age 10 and was misdiagnosed with Gaucher disease. He developed complex partial seizures in his teens but remained otherwise neurologically asymptomatic until his mid 30s. At age 45, he had mild dementia and dysarthria, vertical supranuclear ophthalmoplegia, axonal sensorimotor polyneuropathy, and cerebellar ataxia. The second patient presented with rapidly progressive dystonia at age 8, and mild hepatosplenomegaly, vertical supranuclear ophthalmoplegia, severe behavioral disorder, and dementia by age 14. The diagnosis of NPC was based on deficient cholesterol esterification and excessive lysosomal filipin staining in cultured skin fibroblasts. Current notions about diagnosis and pathogenesis of NPC are reviewed.

Adolescent↗
PubMed2005

Stimulus complexity dependent memory impairment and changes in motor performance after deletion of the neuronal gap junction protein connexin36 in mice.

Gap junction channels, composed of connexin (Cx) proteins, are conduits for intercellular communication and metabolic exchange in the central nervous system. Connexin36 (Cx36) is expressed in distinct subpopulations of neurons throughout the mammalian brain. Deletion of the Cx36 gene in the mouse affected power and frequency of gamma and sharp wave-ripple oscillations, putative correlates of memory engram inscription. Here, we present a behavioral analysis of Cx36-deficient mice. Activity patterns, exploratory- and anxiety-related responses were largely unaffected by elimination of Cx36, while sensorimotor capacities and learning and memory processes were impaired. Repeated testing on the rotarod suggested that the Cx36-deficient mice showed slower motor-coordination learning. After a retention interval of 24 h the Cx36-deficient mice showed habituation to an open-field, but failed to habituate to a more complex spatial environment (Y-maze). A more pronounced memory impairment was found when Cx36 knockout mice had to remember recently explored objects. Cx36-deficient mice were unable to recognize objects after short delays of 15 and 45 min. These data suggest that lack of Cx36 induces memory impairments that vary in dependence of the complexity of the stimuli presented. Our results suggest that neuronal gap junctions incorporating Cx36 play a role in learning and memory.

Analysis of Variance↗
PubMedDate not supplied

Patterns in the brain. Neuronal population coding in the somatosensory system.

The aim of this article is to review some basic principles of neural coding, with an emphasis on mechanisms of stimulus representation in ensembles of neurons. The theory of "across-neuron response patterns" (ANRPs), first suggested by Thomas Young (1802) and fully developed by Robert Erickson (1963-2000), is summarized and applied to the problem of coding in primary afferent fibers and cortical neurons of the somatosensory system. The basic premise of the theory is that precise information about stimulus features cannot be encoded by single neurons, but is encoded by patterns of activity across populations of neurons. Different stimuli produce uniquely different patterns of ensemble activity (ANRPs)-discrimination between two stimuli is based on the absolute difference in total amount of activity (neural mass difference) of the ANRPs for those stimuli. Review of the literature shows that ANRPs and related population codes can accurately represent and differentiate among various stimulus parameters that cannot be distinguished by single neurons alone. Finally, the behavior of neuronal ensembles can be used to account for the sensory-perceptual changes associated with plasticity of thalamocortical circuits following selective sensorimotor deprivation or experience.

Animals↗
PubMed2004

Gene expression profiling in the intact and injured brain following environmental enrichment.

An enriched environment promotes structural changes in both injured and intact brain and improves behavioral performance. In 2 different experimental approaches, the effects of enriched surroundings were analyzed utilizing DNA microarrays. First, gene expression patterns of the sensorimotor cortex and the hippocampus of noninjured adult rats with enriched housing were compared with analogous regions of rats kept in standard cages. Second, circumscribed infarcts affecting the forelimb area of the sensorimotor cortex were induced, and gene expression patterns of the non-necrotic ipsilesional as well as the contralesional homotopic cortex of rats (postlesionally enriched housing versus standard) were analyzed. In the intact brain, the hippocampus, which had 43 upregulations and 15 downregulations showed more changes than the sensorimotor cortex, which had 13 upregulations and 4 downregulations, indicating a greater responsiveness of the hippocampus to environmental stimuli. In the injured brain, enrichment led ipsilesionally to 28 downregulations and 14 upregulations, while in the contralesional cortex, upregulations prevailed with 46 upregulations and 13 downregulations. The larger number of genes responsive to enrichment in the contralesional cortex (59 gene regulations) as compared to the analogous area (i.e. sensorimotor cortex) of the intact brain (17 gene regulations) likely reflects increased susceptibility for plastic changes due to injury. With the exception of the perilesional cortex, similar functional groups of genes were differentially regulated in different brain regions/paradigms, suggesting basically similar molecular cascades being involved in reorganizing the brain following external stimuli. Many of the genes detected here correspond to molecular pathways known to be involved in neuroplasticity, whereas others provide new and hitherto unrecognized entry points.

Animals↗
PubMed2000

Differential effects of aging on the functions of the corpus callosum.

Several structural imaging studies have revealed atrophy in regions of the corpus callosum due to normal aging. We examined the performance of young and senior adults on 2 behavioral measures of interhemispheric interactions to test for possible functional consequences of callosal decline. In a simple reaction time task, the efficiency of sensorimotor transfer was assessed by comparing response times from conditions that required interhemispheric transfer (e.g., the left hand responding to a right visual field light) to those from conditions that did not require transfer (e.g., the left hand responding to a left visual field light). Older adults were selectively slower when interhemispheric transfer was required. In the second task, participants matched letters presented within the same visual field or in opposite visual fields. This task is thought to index attentional functions of the corpus callosum, in particular, callosal contributions to resource allocation (Banich, 1998). For more difficult tasks, older participants showed a performance advantage on bilateral conditions requiring transfer compared to unilateral conditions that did not require transfer. This advantage equaled or exceeded that observed in younger adults. Together these results suggest that age does not have uniform effects on callosal function. Whereas sensorimotor functions show age-related decline, attentional functions of the corpus callosum may be relatively preserved and assume a more prominent role in the aging brain.

Adolescent↗
PubMed2002

Unilateral sensorimotor cortex lesions in adult rats facilitate motor skill learning with the "unaffected" forelimb and training-induced dendritic structural plasticity in the motor cortex.

In humans and other animals, sufficient unilateral damage to the sensorimotor cortex can cause impairments in the opposite forelimb and the development of a hyper-reliance on the nonimpaired limb. This hyper-reliance is adaptive to the extent that it contributes to functional compensation for lesion-induced impairments. We have found that unilateral lesions of the forelimb region of the sensorimotor cortex (FLsmc) in rats, or callosal transections, cause neurons of the opposite motor cortex to become exceptionally responsive to changes in forelimb behavior. This enhanced responsiveness might facilitate learning of compensatory strategies with the nonimpaired forelimb after unilateral FLsmc lesions. The possibility that these lesions facilitate learning with the nonimpaired forelimb was addressed in this study. Rats were required to learn a skilled forelimb reaching task after either unilateral FLsmc lesions or sham operations. The trained limb in animals with lesions was the nonimpaired limb. Compared with shams, rats with unilateral lesions had a greater rate of acquisition and asymptotic performance level on the task, which was especially evident on more difficult trials. Quantitative measures of microtubule associated protein-2 (MAP2) immunostained dendrites indicated an enhancement of training-induced dendritic cytoskeletal changes in the motor cortex opposite lesions. Thus, unilateral FLsmc lesions facilitate learning of at least some types of motor skills using the nonimpaired forelimb as well as some of the neuronal changes associated with this learning. This facilitation could be a substrate underlying behavioral compensation for unilateral FLsmc damage and may contribute to the phenomenon of learned nonuse of the impaired limb.

Adaptation, Physiological↗
PubMed2004

NMDA lesions in the medial prefrontal cortex impair the ability to inhibit responses during reversal of a simple spatial discrimination.

Although lesion studies suggest that the rat medial prefrontal cortex (mPFc) is involved in the process necessary for reversal of a particular set of contingencies, the nature of lesion-induced deficits is unclear. The involvement of rat mPFc in reversal of a simple spatial discrimination was examined in the present study. Our hypothesis was that lesion-induced deficits may reflect a failure to inhibit a learned instrumental response. Lister Hooded rats were trained on a spatial discrimination task (SD), which required a correct barpress matching the cue location, then they were trained on reversal of SD (SDR), which required a correct barpress opposite to the cue location. Rats with mPFc lesions showed a slower learning rate compared to the controls. However, behavior of the lesioned rats during early and later reversal differed. During the initial SDR, the lesioned rats showed a greater number of barpresses during the intertrial interval and a slightly higher percent correct responses than that of the controls. Our data suggest that damage to mPFc may produce a lack of response inhibition, leading to an increase in nondiscriminated bapresses, thereby yielding a 'facilitation' during early reversal. mPFc lesion did not affect either open field activity or prepulse inhibition (PPI), a frequently used measure of sensorimotor gating. Disruption of reversal learning following damage to mPFc is partly due to a failure to inhibit instrumental responses, rather than to disruption of other processes involved in sensorimotor gating or general activity.

Analysis of Variance↗
PubMed2004

Repeated quinpirole treatment increases cAMP-dependent protein kinase activity and CREB phosphorylation in nucleus accumbens and reverses quinpirole-induced sensorimotor gating deficits in rats.

Sensorimotor gating, which is severely disrupted in schizophrenic patients, can be measured by assessing prepulse inhibition of the acoustic startle response (PPI). Acute administration of D2-like receptor agonists such as quinpirole reduces PPI, but tolerance occurs upon repeated administration. In the present study, PPI in rats was reduced by acute quinpirole (0.1 mg/kg, s.c.), but not following repeated quinpirole treatment once daily for 28 days. Repeated quinpirole treatment did not alter the levels of basal-, forskolin- (5 microM), or SKF 82958- (10 microM) stimulated adenylate cyclase activity in the nucleus accumbens (NAc), but significantly increased cAMP-dependent protein kinase (PKA) activity. Phosphorylation of cAMP response element-binding protein (CREB) was significantly greater in the NAc after repeated quinpirole treatment than after repeated saline treatment with or without acute quinpirole challenge. Activation of PKA by intra-accumbens infusion of the cAMP analog, Sp-cAMPS, prevented acute quinpirole-induced PPI disruption, similar to the behavioral effect observed following repeated quinpirole treatment. Thus, repeated quinpirole treatment increases NAc PKA activity and CREB phosphorylation, and this neuroadaptive response might facilitate the recovery of sensorimotor gating in schizophrenia.

Acoustic Stimulation↗
PubMed1999

Role of an enriched environment on the restoration of behavioral deficits in Lurcher mutant mice.

Lurcher mutant mice, characterized by massive degeneration of the cerebellar cortex, and normal littermate controls were reared from birth either in standard conditions or in an enriched environment. The effects of this manipulation on motor functions, landmark water maze learning, exploration, and anxiety were evaluated at 3 months of age. Under standard conditions, Lurcher mutants were impaired in comparison to controls on tests of sensorimotor function and had altered exploratory tendencies. The enriched housing improved the motor coordination of Lurcher mutants and decreased the number of trials before reaching criterion in the landmark water maze. In addition to its effects in Lurcher mutants, enriched rearing also increased some behavioral abilities in normal mice. It is hypothesized that enriched housing altered brain morphology or neurochemistry in both normal and cerebellar-damaged animals.

Animals↗
PubMedDate not supplied

Unilateral cortical spreading depression in the rat: effects on feeding, drinking and other behaviors.

The effects of unilateral cortical spreading depression (CSD) on feeding, drinking and other behaviors were studied in rats. CSD waves were elicited by a microinjection of KC1 solution through an implanted cannula. The animal's behavior and slow potential changes (SPC) accompanying CSD were then simultaneously monitored for 20 min. Intensive face grooming was observed while the CSD wave-front propagated across the sensorimotor cortex. Animals commenced their first feeding or drinking shortly after the invasion of the negative SPC into the frontal cortex of Krieg's area 6 and 10 [14] had reached its maximum height. A two-way switching effect between the first feeding or drinking and quiescence (freezing) and a close relationship between their onsets were observed. The results are discussed specifically in relation to cortico-hypothalamic pathways.

Animals↗
PubMed2004

Environmental enrichment-behavior-oxidative stress interactions in the aged rat: issues for a therapeutic approach in human aging.

The effects of environment enrichment on motor activity, exploration, and cognitive performances were studied in aged rats. Both nonimpaired (NI) and impaired (I) rats were submitted to daily training in a complex-enriched environment (cEE) for 60 days. Animals were examined at spatial water maze task, passive avoidance test, open-field test, and sensorimotor coordination tasks (bridges test and Marshall scales). At the end of experiments, animals were killed for brain biochemical determinations (gluthatione content and specific-ChAT activity). Results after the first evaluation (before training) corroborate that the aged rat population showed a heterogeneity in behavioral patterns like that observed in humans. Also, cEE modified exploration activity, cognition, motor functions, and biochemical markers in both NI and I groups, but changes reached significant relevance for the last group. It is significant that neurotrophins, "novo" synthesis of neurotransmitters, and oxidative stress levels may mediate the observed changes, indicating that the aged brain still has appreciable plasticity in response to well-manipulated environmental stimulation. Finally, our results also support the novel concepts and programs in prevention/reduction both in incidence/severity and outcome of age-associated neurodegenerative conditions.

Aging↗