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Sensorimotor integration in the precentral gyrus: polysensory neurons and defensive movements.

The precentral gyrus of monkeys contains a polysensory zone in which the neurons respond to tactile, visual, and sometimes auditory stimuli. The tactile receptive fields of the polysensory neurons are usually on the face, arms, or upper torso, and the visual and auditory receptive fields are usually confined to the space near the tactile receptive fields, within about 30 cm of the body. Electrical stimulation of this polysensory zone, even in anesthetized animals, evokes a specific set of movements. The movements resemble those typically used to defend the body from objects that are near, approaching, or touching the skin. In the present study, to determine whether the stimulation-evoked movements represent a normal set of defensive movements, we tested whether they include a distinctive, nonsaccadic, centering movement of the eyes that occurs during defensive reactions. We report that this centering movement of the eyes is evoked by stimulation of sites in the polysensory zone. We also recorded the activity of neurons in the polysensory zone while the monkey made defensive reactions to an air puff on the face. The neurons became active during the defensive movement, and the magnitude of this activity was correlated with the magnitude of the defensive reaction. These results support the hypothesis that the polysensory zone in the precentral gyrus contributes to the control of defensive movements. More generally, the results support the view that the precentral gyrus can control movement at the level of complex sensorimotor tasks.

Anesthesia↗

Behavior-decrementing effects of low doses of haloperidol result from disruptions in response force and duration.

By using a factorial experimental design, the joint effects of two levels of sucrose reward, two levels of required force, and four levels of haloperidol dose (0. 0.04, 0.08, 0.16mg/kg) were examined for three measures of operant response: peak force, duration, and interresponse time. Even though a 24% sucrose reward led to more rapid acquisition of the operant than an 8% concentration during the drug-free response shaping period, neither the reward nor the required-force manipulations interacted with haloperidol dose during subsequent testing. Haloperidol had significant elevating effects on peak force and duration of response, while lengthening interresponse time. A within-session analysis revealed drug-related slowing of both response duration and interresponse time as the operant session progressed. Finally, dose effects on peak force and duration were apparent from the beginning of the session, but effects on interresponse time reached significance later in the session. Taken together the results downplay the importance of stimulus efficacy, anhedonia and required effort in accounting for haloperidol's behavior-decrementing effects. Instead, the results raise the possibility that the haloperidol-treated rats experienced difficulty in sensorimotor control of the operant response.

Journal Article↗

Scopolamine-induced alterations in predatory behaviour pattern in cats.

Predatory behaviour in its full pattern (i.e., following the mouse, killing it and consuming the carcass) was tested in semi-natural conditions in cats. Consumption of minced horse meat was tested as well. Centrally acting scopolamine hydrobromide injected i.p. did not suppress predatory motivation, since following the prey and killing it were preserved. The executory phase of predation (i.e., the killing grip) was severely disturbed and the consumption of the mouse as well as meat was totally inhibited. Peripherally acting scopolamine methylnitrate administered into another group of cats under the same conditions generally did not affect predatory pattern, though meat and mouse consumption was disturbed to some extent. It is concluded that central muscarinic involvement in predatory behaviour in cats is limited to sensorimotor control of jaw movements.

Animals↗

[A quantitative pharmaco-electroencephalographic analysis of the action of bromantane].

The action of the new stimulant bromantane on spectra power EEG on Fourier of sensorimotor cortex, dorsal hippocamp and lateral hypothalamus of left and right hemispheres of brain of rat in free behavior was investigated. Bromantane leads to decreases in the total and absolute powers of all frequency bands of EEG spectra, changes structural spectra in the cortex and in hippocamp--decreases the relative power of theta-band and increases the relative power of beta 1, 2-activity. The basic feature of bromantane's action is a two-phase effect (its maximum occurs 2-3 and 6-7 hours after administration), which remains up to 8 h of EEG recording. These data suggest that that bromantane has more marked and prolonged stimulant properties than other adamantane psychostimulants.

Amantadine↗

[Abnormalities in behavior in the oral and cervical area: reassurance breast-feeding. Considerations on sudden infant death].

The oral zone reflects the relational modalities of the child: the sensorimotor physiological and psychological behaviour is established according to the development of the facial sphere and its aero-digestive crossroads. In the baby, the mandibular equilibrium and position and the dimensions of the lower part of the face essentially depend upon praxic activities, which drive the mandibular and hyoid displacements. During the period of immaturity, the lingual area is brought into movement with each "sucking-swallowing" action that characterises breast-feeding: the mandibulo-hyoid swing is subordinate to the pharyngo-lingual complex. The analysis of this psycho-motor behaviour reveals imperfect and upsetting "mimics" that modify the balance of the jaw and of the hyo-lingual area during swallowing, which is the second phase of the reassurance breast-feed. The lingual ptosis causes congestion of the airways. These lax children, with a receding chin, are deformed by their oral habits. The clinical picture evidences the constitutional hyperlaxity by examining the parental group -the same facial dystrophies, the same habits resulting in various disorders of general or cervical statics. At the level of the temporomandibular joint, the dysfunction is also accompanied by claudication by mandibulo-hyo-lingual tipping. The general and cervical statics of the baby are thus affected in the course of sleep. It is during paradoxical sleep that the baby's head tips on to the thorax, due to the resultant atonia of the neck muscles. The head, insufficiently supported on its cervical pillar accentuates the asphyxial mechanism provoked by the tipping of the lingual area on the epiglottis.(ABSTRACT TRUNCATED AT 250 WORDS)

Deglutition Disorders↗

Random mutagenesis screen for dominant behavioral mutations in mice.

Large-scale mutagenesis and screening for altered phenotypes have been used effectively in many (lower) model organisms to identify mutations in genes that control biological processes. In the mouse, the cost of maintaining the large breeding colonies necessary to screen for recessive mutations makes it important to consider alternate approaches such as region-specific saturation mutagenesis or screening for mutations with a dominant mode of inheritance. In this article, a pilot screen for (semi)dominant visible and behavioral mutations in the mouse induced by a potent chemical mutagen, N-ethyl-N-nitrosourea (ENU), is described. An efficient protocol for ENU mutagenesis and strain-specific differences in the effect of mutagen on the sterility period and long-term survival are reported. In addition to a description of the screen for abnormal circadian wheel running activity that was used previously, the suitability of a high-throughput screen of mutagenized progeny in the Porsolt swim test, used to test the efficacy of antidepressant agents, and in the prepulse inhibition of the acoustic startle response, used to detect anomalies in sensorimotor gating, is tested. By demonstrating strain specific differences and prescreening 100 G1 progeny of mutagenized males, the feasibility of using these behavioral assays for a large-scale screen is illustrated. In this review, details of a mutagenesis screen for behavioral abnormalities are described and issues important in the initial characterization of novel ENU-induced mutations are considered.

Animals↗

Larger interregional synchrony is associated with greater behavioral success in a complex sensory integration task in humans.

Successful behavior depends on effective communication between distant brain regions. Moreover, disturbance of effective communication can cause neurological symptoms like apraxia, dyslexia or object agnosia. Interregional communication can be assessed by coherence analysis of synchronized neuronal oscillations, and has been referred to as synchrony or "binding". The concept of synchrony as a means of information coding is attractive, but its functional relevance has been challenged. We hypothesized that if synchrony is functionally relevant in humans, then more synchrony should determine better behavioral performance. Here, we show in a visuotactile integration task that the amount of low-frequency (7-13Hz), long-range electroencephalographic coherence between visual and sensorimotor cortex is significantly correlated with the level of performance. Trials with highest coherences were the most successful ones and vice versa in the absence of differences in regional activation measured as task-related spectral power. In summary, quantitatively linking the amount of long-range synchrony with the degree of behavioral success in humans, the present data suggest that the ability to generate topographically specific synchrony of high amplitude is functionally relevant for behavioral success. They also raise the possibility that the magnitude of regional activation is less representative of the efficacy of brain functioning than interregional synchrony.

Adult↗

Dopamine depletion causes fragmented clustering of neurons in the sensorimotor striatum: evidence of lasting reorganization of corticostriatal input.

Firing during sensorimotor exam was used to categorize single neurons in the lateral striatum of awake, unrestrained rats. Five rats received unilateral injection of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle to deplete striatal dopamine (DA; >98% depletion, postmortem assay). Three months after treatment, rats exhibited exaggerated rotational behavior induced by L-dihydroxyphenylalanine (L-DOPA) and contralateral sensory neglect. Electrode track "depth profiles" on the DA-depleted side showed fragmented clustering of neurons related to sensorimotor activity of single body parts (SBP neurons). Clusters were smaller than normal, and more SBP neurons were observed in isolation, outside of clusters. More body parts were represented per unit volume. No recovery in these measures was observed up to one year post lesion. Overall distributions of neurons related to different body parts were not altered. The fragmentation of SBP clusters after DA depletion indicates that a percentage of striatal SBP neurons switched responsiveness from one body part to one or more different body parts. Because the specific firing that characterizes striatal SBP neurons is mediated by corticostriatal inputs (Liles and Updyke [1985] Brain Res. 339:245-255), the data indicate that DA depletion resulted in a reorganization of corticostriatal connections, perhaps via unmasking or sprouting of connections to adjacent clusters of striatal neurons. After reorganization, sensory activity in a localized body part activates striatal neurons that have switched to that body part. In turn, switched signals sent from basal ganglia to premotor and motor neurons, which likely retain their original connections, would create mismatches in these normally precise topographic connections. Switched signals could partially explain parkinsonian deficits in motor functions involving somatosensory guidance and their intractability to L-DOPA therapy-particularly if the switching involves sprouting.

Adrenergic Agents↗

Neurological and behavioral outcomes of focal cerebral ischemia in rats.

BACKGROUND AND PURPOSE: The aim of this study was to investigate the neurobehavioral consequences of focal ischemia in rats. METHODS: We induced permanent occlusion of the left middle cerebral artery in 14 Sprague-Dawley rats, and used 13 sham-operated rats as controls. During surgery, brain temperature and body temperature were kept at normothermia. Neurobehavioral studies (neurological examination, passive avoidance task, Y maze test, and modified open-field test) were carried out 4 days after ischemia before killing the rats to evaluate histological damage. RESULTS: Ischemia induced large infarcts in the cortex (138.6 +/- 8.5 mm3) and caudate-putamen (48.8 +/- 2.6 mm3) and, compared with sham-operated rats, produced a dramatic neurological deficit (p less than 0.001) characterized by sensorimotor dysfunctions and hemiplegia. Memory retention was significantly (p less than 0.05) impaired in the passive avoidance task, but neither vigilance and exploratory behavior measured in the modified open-field test nor working memory evaluated in the Y maze test were disturbed. Infarct size was not correlated with the neurological or behavioral deficits. CONCLUSIONS: This lack of correlation indicates the necessity of carrying out parallel histological, neurological, and behavioral studies in any assays of new drugs using this model of focal ischemia.

Animals↗

Abnormal tactile experience early in life disrupts active touch.

The importance of early tactile experience in the development of discriminative somatomotor function was assessed by examining the proficiency and movement strategies of rats raised without normal sensory inputs provided by their mystacial vibrissae. Infant-trimmed animals had their whiskers clipped daily from birth to 45 d of age, after which they were allowed to regrow for 60-70 d before initiation of behavioral training, which lasted as long as several months. Adult-trimmed animals had their whiskers trimmed for comparable periods during adulthood. Rats were tested on one of two tactile discriminations, rough versus smooth or rough versus rough, that differed with respect to the overall size of their surface features. Whisker movements during task performance were examined in detail using video-based motion analysis software. Infant-trimmed animals performed rough versus smooth discriminations as well as adult-trimmed rats or normally reared animals. Except for one subject, infant-trimmed rats were severely impaired in their ability to distinguish rough versus rough surfaces. Deficits persisted in spite of months of training with the regrown vibrissae. The animals that failed to master this task displayed whisking patterns that notably lacked frequencies in the normal range of 6-12 Hz. Thus, abnormal tactile experience early in life substantially, and perhaps permanently, impairs sensorimotor integration underlying active touch.

Animals↗

Comparison of the parental behavior of pair-bonded female and male prairie voles (Microtus ochrogaster).

The behavior of primiparous lactating prairie voles (Microtus ochrogaster) and their mates individually interacting with pups was continuously assessed for 45 min after a 2-h parent-litter separation on days 3-4 and 10-11 postpartum. Both sexes were highly parental after reunion with the young, and their general pattern of behavior consisted of bouts of quiescence interspersed with bursts of heightened activity. Lactating females spent more time than males in contact with pups, and more time being quiescent, most often in the kyphotic (upright crouched) nursing posture. Even in the absence of nipples upon which the pups could suckle, males also displayed kyphosis, although for shorter durations than females. Males spent more time, however, huddled over the litter in a hunched position than their mates. In accordance with their decreased quiescence, male voles licked and carried pups more and were more exploratory than females. Compared with the first week postpartum, bouts of kyphosis were shorter during the second week postpartum for both sexes, while laying prone on the pups increased. Males spent less time licking and more time carrying older pups than younger ones, and were more exploratory during the second week postpartum. Sex differences in the parental behavior of prairie voles may reflect differences in the somatosensory stimulation that females and males receive from pups. Furthermore, the display of kyphosis by male voles indicates that the sensorimotor organization of this posture in voles differs from that of lactating rats, which require suckling stimulation for its regulation.

Aging↗

Reversible inactivation of the medial septum or nucleus basalis impairs working memory in rats: a dissociation of memory and performance.

Lidocaine-induced inactivation of the medial septum immediately after training or prior to testing in a delay radial-arm maze task produced deficits in spatial working memory that reflected impaired acquisition of the task. Injection of lidocaine into the nucleus basalis magnocellularis produced a profile of behavioral changes that indicated that temporary inactivation of this structure impaired the behavioral expression of information already stored in working memory. This appears to reflect an impairment in processes that are required for performance (i.e., attention, motivation, sensorimotor function) of the task but not for retrieval of stored information. Site-specific inactivation of the basal forebrain should help to reveal the involvement of its component structures in different aspects of cognitive function.

Analysis of Variance↗

Neurobehavioral development, adult openfield exploration and swimming navigation learning in mice with a modified beta-amyloid precursor protein gene.

The processing of beta-amyloid precursor protein (betaAPP) and its metabolites plays an important role in the pathogenesis of Alzheimer's disease (AD) and Down's syndrome. The authors have reported elsewhere that a targeted mutation resulting in low expression of a shortened betaAPP protein (betaAPP(delta/delta)) entails reduced learning abilities. Here the authors investigate whether these effects were caused by postnatal developmental actions of the altered protein. The authors examined 35 mice carrying the betaAPP(delta/delta) mutation for somatic growth and sensorimotor development during the first 4 postnatal weeks (pw) and compared them with 31 wildtype litter-mates. Thereafter, the same mice were tested at about 10 weeks of age for openfield behavior and for swimming navigation learning. Mutant mice showed both transient and long-lasting deficits in development. Body weight deficit started to emerge at postnatal day (pd) 12, peaked with a 15.1% deficit at pd 27 and lasted until pw 33-37. Significant transient deficits in mutant mice during sensorimotor development were observed in three time windows (pd 3-10, pd 11-19 and pd 20-27), long-lasting effects, manifest at pw 8-12 and pw 33-37, emerged at any of the three periods. In the adult mice, exploratory activity of betaAPP mutants in the openfield arena was severely reduced. In the Morris water maze task, mutant mice showed moderate escape performance deficits during the acquisition period but no impairment in spatial memory. The authors conclude that a defective betaAPP gene impairs postnatal somatic development, associated with transient as well as long-lasting neurobehavioral retardation and muscular weakness. Comparison with earlier data suggests that early postnatal handling may attenuate some of the non-cognitive performance deficits in the water maze. Further, the manifestation and time course of behavioral yet not neuropathological symptoms in betaAPP mutant mice resemble in some aspects those of the human Down's syndrome.

Adult↗

Periventricular noradrenergic systems are critical for angiotensin-induced drinking and blood pressure responses.

Deficits in experimentally induced drinking and pressor responses after administration of 6-hydroxydopamine (6-OHDA) into the lateral cerebral ventricle (LCV) have been reported. Questions have arisen, however, as to whether these effects are due to non-specific actions of the neurotoxin and, if specific, whether the depletion of dopamine (DA) or of norepinephrine (NE) is the critical factor for producing the impairments. In the present report methods to deplete brain catecholamine (CA) differentially were employed in order to test the hypothesis that central 6-OHDA injections act on brain CA substrates per se to produce behavioral and physiological response deficits to angiotensin II (ANG II) challenges. The findings support the interpretation that forebrain dopamine is essential for the mediation of sensorimotor integration involved in response to acute homeostatic stressors. In addition, the outcome identifies an important role for forebrain noradrenergic systems in the mediation of ANG II-elicited drinking and blood pressure responses.

Angiotensin II↗

Mass-related traumatic tissue displacement and behavior: a screen for treatments that reduce [corrected] harm to bystander cells and recovery of function.

In this study, we focused on a preclinical model of brain compression injury that has relevance to pathological conditions such as tumor, hematoma, blood clot, and intracerebral bony fragment. We investigated behavioral impairment as a result of rapid-onset small mass, and the factors involved in lesion formation and neuroplasticity. An epidural bead implantation method was adopted. Two sizes (1.5 mm and 2.0 mm thick) of hemisphere-shaped beads were used. The beads were implanted into various locations over the sensorimotor cortex (SMC--anterior, middle and posterior). The effects of early versus delayed bead removal were examined to model clinical neurosurgical or other treatment procedures. Forelimb and hind-limb behavioral deficits and recovery were observed, and histological changes were quantified to determine brain reaction to focal compression. Our results showed that the behavioral deficits of compression were influenced by the location, timing of compression release, and magnitude of compression. Even persistent compression by the thicker bead (2.0 mm) caused only minor behavioral deficits, followed by fast recovery within a week in most animals, suggesting a mild lesion pattern for this model. Brain tissue was compressed into a deformed shape under pressure with slight tissue damage, evidenced by pathological evaluation on hematoxylin and eosin (H&E)- and TUNEL-stained sections. Detectable but not severe behavioral dysfunction exhibited by this model makes it particularly suitable for direct assessment of adverse effects of interventions on neuroplasticity after brain compression injury. This model may permit development of treatment strategies to alleviate brain mass effects, without disrupting neuroplasticity.

Animals↗

Alterations in dendritic morphology of prefrontal cortical and nucleus accumbens neurons in post-pubertal rats after neonatal excitotoxic lesions of the ventral hippocampus.

Neonatal ventral hippocampal (nVH) lesions in rats result in adult onset of a number of behavioral and cognitive abnormalities analogous to those seen in schizophrenia, including hyperresponsiveness to stress and psychostimulants and deficits in working memory, sensorimotor gating and social interaction. Molecular and neurochemical alterations in the prefrontal cortex (PFC) and nucleus accumbens (NAcc) of nVH-lesioned animals suggest developmental reorganization of these structures following neonatal lesions. To determine whether nVH lesions lead to neuronal morphological changes, we investigated the effect of nVH lesion on dendritic structure and spine density of pyramidal neurons of the PFC and medium spiny neurons of the NAcc. Bilateral ibotenic acid-induced lesion of the VH was made in Sprague-Dawley pups at postnatal day 7 (P7); and at P70, neuronal morphology was quantified by modified Golgi-Cox staining. The results show that length of basilar dendrites and branching and the density of dendritic spines on layer 3 pyramidal neurons were significantly decreased in rats with nVH lesions. Medium spiny neurons from the NAcc showed a decrease in the density of dendritic spines without significant changes in dendritic length or arborization. The data, comparable to those observed in the PFC of schizophrenic patients, suggest that developmental loss of excitatory projections from the VH may lead to altered neuronal plasticity in the PFC and the NAcc that may contribute to the behavioral changes in these animals.

Age Factors↗