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PubMed1994

EEG rhythms of the sensorimotor region during hand movements.

The aim of this study was to determine what motor behaviors or conditions were associated with an increased occurrence of beta activity in the sensorimotor region of human subjects. EEG recordings were obtained from 8 electrodes symmetrically arranged around C3, with 3 cm interelectrode spacing. The electrode montage allowed calculation of the Laplacian operator at two positions, C3r and C3c, overlying the hand area of the motor cortex and of the somatosensory cortex, respectively. A variety of tasks involving right-hand movements of different levels of complexity, attention and preparation were performed. The corresponding EEG power spectra were subsequently computed for frequencies between 7 and 50 Hz. Repetitive hand movements alone (either drawing circles or writing one's signature) did not result in significantly increased beta activity in the sensorimotor region compared to relaxed conditions. However, both motor preparations and focused attention, whether movements were performed or not, were associated with an increase of high frequency beta activity (30-50 Hz) in the sensorimotor region. Therefore, the facilitatory effect of attention and motor preparation and not the functional activation of the sensorimotor cortex by hand movements was associated with an increase in synchronized fast beta activity.

Adolescent↗
PubMed2005

Retrograde study of hypocretin-1 (orexin-A) projections to subdivisions of the dorsal raphe nucleus in the rat.

A retrograde tracer, WGA-apo-HRP-gold (WG), was injected into each subdivision of the dorsal raphe (DR) nucleus, and subsequent orexin-A immunostaining was performed for the tuberal region of the hypothalamus in order to investigate orexin projections to the DR. Similar to previous studies, the majority of orexin-single-labeled neurons were observed at the dorsal half of the lateral hypothalamus (LH), the circle around the fornix, i.e., perifornical nucleus (PeF), and the area dorsal to the fornix. The present study reports that hypothalamic neurons exhibited differential projections to each subdivision of the DR. Following WG injections into rostral DR, WG-single-labeled cells were observed at the dorsal half of the LH as well as dorsomedial hypothalamic nucleus. The major input to the intermediate DR originates from the ventromedial portion of the LH, PeF, and the area dorsal to the PeF, whereas one to lateral wing DR derived from PeF as well as the ventrolateral portion of the LH. Following WG injections into caudal DR, WG-single-labeled cells were located at ventromedial LH and the ventrolateral portion of the posterior hypothalamus. Following WG injections into each DR subdivision, WG/orexin-double-labeled neurons were observed at LH, PeF, and the area dorsal to the PeF. Only a few double-labeled cells were observed in dorsomedial and posterior hypothalamic nuclei. Our observations suggest that various hypothalamic neurons differentially project to each subdivision of the DR, a portion of which is orexin-immunoreactive. These orexin-immunoreactive DR-projecting hypothalamic neurons might have wake-related influences over a variety of brain functions subject to DR efferent regulation, including affective behavior, autonomic control, nociception, cognition, and sensorimotor integration.

Animals↗
PubMed2006

Cancelling planned actions following mild traumatic brain injury.

Mild traumatic brain injury (mTBI) leads to a variety of attentional, cognitive, and sensorimotor deficits. An important aspect of behavior that intersects each of these functions is the ability to cancel a planned action. Thus, the purpose of this study was to determine the effects of mTBI on the ability to perform a countermanding saccade task. In this task, participants were asked to generate a saccade to a target appearing in peripheral vision, but to inhibit saccade execution if an auditory stop signal was presented. The delay between the appearance of the peripheral target and the presentation of the auditory stop signal was varied between 0 and 125ms. We found that the change in the probability of cancelling the saccade as a function of this delay was no different between participants with mTBI tested within 2 days of their injury and matched controls. However, saccadic reaction times and the stop signal reaction time were unexpectedly faster in the participants with mTBI and, furthermore, they inaccurately inhibited saccades during 15% of the trials with no stop signal. Taken together, this data suggests that the ability to cancel planned actions is subtly yet adversely affected by mTBI.

Adult↗
PubMed1998

Motor and somatosensory deficits following uni- and bilateral lesions of the cortex induced by aspiration or thermocoagulation in the adult rat.

We have previously shown that lesions of the sensorimotor cortex induced by either thermocoagulation or aspiration produce different effects on axonal plasticity. We have now investigated whether these methods of lesion also influence the behavioral outcome. The behavioral effects of unilateral and bilateral lesions of the sensorimotor cortex induced by either aspiration or by thermocoagulation of pial blood vessels were examined in adult Sprague-Dawley rats. Rats were tested to determine limb use asymmetry by analyzing (1) coordinated forelimb placement and (2) paw use preference when rearing. Their responsiveness to somatosensory stimulation was tested by analyzing (1) the latency to remove sticky tape on the ventral surface of the paw, and (2) vibrissae-stimulated forelimb placing. Behavioral tests were performed prior to surgery and on day 4, 8, 12, 16, and 20 after surgery. Both unilateral lesions resulted in an over-reliance on the nonimpaired forelimb as early as 4 days after the surgery; functional recovery occurred after 16 days. Animals with bilateral lesions did not use either forelimb for support in postural support behaviors. However, this effect was more apparent in the animals with a thermocoagulatory lesion and, in contrast to the animals with an aspiration lesion, these animals did not show functional recovery. Animals with a unilateral aspiration, but not a thermocoagulatory lesion, showed a slowed response to tactile stimulation applied to the contralateral forelimb. After bilateral lesions, animals showed a slowed response to tactile stimulation applied to either forelimb at early time points after the lesion and recovery of function at later time points. These data indicate that, for the most part, lesions of the sensorimotor cortex by aspiration or thermocoagulation produce very similar effects on the behaviors examined in this study. However, unexpectedly, thermocoagulatory lesions induced a more severe (unilateral lesion) or prolonged (bilateral lesion) deficit in forelimb use than aspiration lesions. Conversely, the effect on tactile stimulation is more prominent after unilateral aspiration than thermocoagulatory lesions.

Animals↗
PubMedDate not supplied

["Animal hypnosis" and defensive dominant, behavioral aspect].

A stationary excitation focus produced in the sensorimotor cortex of a rabbit by rhythmic electrodermal paw stimulation was manifested in the reaction to a testing sound stimulus earlier indifferent for the animal. Regardless of the stimulated paw (left or right), reactions to the testing stimuli appeared approximately in the equal percent of cases (70.7% and 71.5%, respectively). After a single-trial induction of the "animal hypnosis" state, it was difficult to produce the dominant focus by simulation of the left paw, whereas the results of the right-paw stimulation did not differ from those obtained during control stimulation. Consequently, the influence of hypnosis on defensive stationary excitation foci in different hemispheres was not the same.

Acoustic Stimulation↗
PubMed1992

Microelectrophoretic application of kainic acid into the globus pallidus: disturbances in feeding behavior.

Body weight changes, food and water intake, and sensorimotor disturbances of male rats were studied after bilateral kainic acid-(KA) induced lesions of the globus pallidus (GP). To minimize the extent of damages, KA was applied electrophoretically by means of glass micropipettes (tip diameter of the pipettes was 10-15 microns). The neuron-specific damages of the GP resulted in aphagia and adipsia and rapid body weight decrease. Lesioned animals showed permanent motor disturbances but only temporary difficulties in the orientation toward sensory stimuli. Our data show that the selective destruction of the GP neurons results in a complex disorder that has motivational, (sensori)motor, and metabolic components.

Animals↗
PubMed1986

How does the limbic system assist motor learning? A limbic comparator hypothesis.

This paper offers a new hypothesis about how the limbic system might assist motor learning. It is proposed that interactions of limbic and sensorimotor-related systems are essential for learning what to do in a motor task (appropriate, relevant behavior) and how to do it best (motor skill). Limbic modulations of sensorimotor-related neural centers are envisaged to result from comparisons in various neural centers of converging inputs from the relevance-sensitive amygdala and from corollary, cortically-modulated recipients of amygdaloid information. Such comparisons of relatively 'raw' limbic inputs and their 'processed', corollary forms could be achieved in a side-loop manner resembling that in the cerebellum. This 'limbic comparator' hypothesis was prompted by studies of motor learning that show how monkeys develop skill only after gaining insight into appropriate, task-related behavior, and that inappropriate behavior during transition into the insightful state produces 'error' signals from the anterior cingulate cortex. Known sites of limbic projections that could serve corollary comparisons are examined with regard to their possible influence on motivation, appropriate, task-related behavior and motor skill. Anatomical and functional tests of convergence and comparison in sensorimotor-related neural centers are suggested in order to stimulate investigations of the limbic comparator hypothesis.

Animals↗
PubMed2006

Sensorimotor gating deficits in adults with autism.

BACKGROUND: Prepulse inhibition (PPI) is an operational measure of sensorimotor gating and is impaired in a family of neuropsychiatric disorders characterized by abnormalities of inhibitory function. Adults with autistic disorder (AD) exhibit clinical features of inhibitory deficits, such as restrictive and repetitive behaviors, that may be explained by deficits in sensorimotor gating. METHODS: Acoustic startle reactivity, habituation, and PPI (30-, 60-, 120-msec interstimulus intervals) were assessed in 14 adult men diagnosed with AD and 16 typically developing normal comparison (NC) participants. All participants were administered measures of intelligence and frontal-executive functioning. RESULTS: Adults with AD exhibited significantly less PPI in the 60-msec condition than NC participants, which was correlated with increased ratings of restricted and repetitive behaviors. The groups did not differ on measures of startle amplitude or overall habituation. There was, however, a significant group-by-block habituation effect. Furthermore, PPI was not related to intelligence but was moderately associated with performance on a measure of frontal-executive functioning. CONCLUSIONS: Adults with AD have sensorimotor gating deficits similar to other neurodevelopmental disorders, implicating a failure of normal inhibitory regulation of sensory, motor, and attentional mechanisms. Thus, PPI deficits may be indirectly linked to one of the hallmark features of AD.

Acoustic Stimulation↗
PubMed2003

Sensorimotor deficits in a unilateral intrastriatal 6-OHDA partial lesion model of Parkinson's disease in marmoset monkeys.

Animal studies investigating the efficacy of neurotrophic factors as treatments for Parkinson's disease (PD) ideally require partial dopamine (DA) lesion models. The intrastriatal 6-hydroxydopamine (6-OHDA) lesion model may be suitable for this purpose. Although this model has been well characterized in rodents, it has not previously been used in monkeys. The goal of the present study was to characterize the behavioral effects of unilateral injections of 6-OHDA in the basal ganglia of common marmoset monkeys (Callithrix jacchus). Cell counts from tyrosine hydroxylase immunochemistry 5 months postlesion revealed DA cell loss in the substantia nigra on the lesioned side to approximately 46% of relative to the unlesioned side. 6-OHDA lesioned monkeys showed a variety of behavioral deficits. Apomorphine induced rotation and simple sensorimotor measures (head position bias and PD disability rating score) were most affected by the lesion. The largest deficits were seen at 1 or 2 weeks postsurgery but had recovered by week 10. 6-OHDA lesioned monkeys took longer to complete a more complex sensorimotor staircase task. At 3.5 months postlesion, 6-OHDA monkeys also showed deficits on an object retrieval task designed to measure sensorimotor planning and skilled hand use. alpha-Methyl-p-tyrosine, a tyrosine hydroxylase inhibitor, reinstated those deficits which had undergone recovery in the lesioned animals and also exacerbated the deficits on the staircase task. This model has potential in assessing treatments for PD aimed at curtailing disease progression such as continuous delivery of neurotrophic factors.

Animals↗
PubMed2000

An associational model of birdsong sensorimotor learning II. Temporal hierarchies and the learning of song sequence.

Understanding the neural mechanisms underlying serially ordered behavior is a fundamental problem in motor learning. We present a computational model of sensorimotor learning in songbirds that is constrained by the known functional anatomy of the song circuit. The model subsumes our companion model for learning individual song "syllables" and relies on the same underlying assumptions. The extended model addresses the problem of learning to produce syllables in the correct sequence. Central to our approach is the hypothesis that the Anterior Forebrain Pathway (AFP) produces signals related to the comparison of the bird's own vocalizations and a previously memorized "template." This "AFP comparison hypothesis" is challenged by the lack of a direct projection from the AFP to the song nucleus HVc, a candidate site for the generator of song sequence. We propose that sequence generation in HVc results from an associative chain of motor and sensory representations (motor --> sensory --> next motor. ) encoded within the two known populations of HVc projection neurons. The sensory link in the chain is provided, not by auditory feedback, but by a centrally generated efference copy that serves as an internal prediction of this feedback. The use of efference copy as a substitute for the sensory signal explains the ability of adult birds to produce normal song immediately after deafening. We also predict that the AFP guides sequence learning by biasing motor activity in nucleus RA, the premotor nucleus downstream of HVc. Associative learning then remaps the output of the HVc sequence generator. By altering the motor pathway in RA, the AFP alters the correspondence between HVc motor commands and the resulting sensory feedback and triggers renewed efference copy learning in HVc. Thus, auditory feedback-mediated efference copy learning provides an indirect pathway by which the AFP can influence sequence generation in HVc. The model makes predictions concerning the role played by specific neural populations during the sensorimotor phase of song learning and demonstrates how simple rules of associational plasticity can contribute to the learning of a complex behavior on multiple time scales.

Animals↗
PubMed2003

Whisking as a "voluntary" response: operant control of whisking parameters and effects of whisker denervation.

The rat's ability to vary its whisking "strategies" to meet the functional demands of a discriminative task suggests that whisking may be characterized as a "voluntary" behavior--an operant--and like other operants, should be modifiable by appropriate manipulations of response-reinforcer contingencies. To test this hypothesis we have used high-resolution, optoelectronic "real-time" recording procedures to monitor the movements of individual whiskers and reinforce specific movement parameters (amplitude, frequency). In one operant paradigm (N = 9) whisks with protractions above a specified amplitude were reinforced (Variable Interval 30 s) in the presence of a tone, but extinguished (EXT) in its absence. In a second paradigm (N = 3), rats were reinforced on two different VI schedules (VI-20s/VI-120s) signaled, respectively, by the presence or absence of the tone. Selective reinforcement of whisking movements maintained the behavior over many weeks of testing and brought it under stimulus and schedule control. Subjects in the first paradigm learned to increase responding in the presence of the tone and inhibit responding in its absence. In the second paradigm, subjects whisked at significantly different rates in the two stimulus conditions. Bilateral deafferentation of the whisker pad did not impair conditioned whisking or disrupt discrimination behavior. Our results confirm the hypothesis that rodent whisking has many of the properties of an operant response. The ability to bring whisking movement parameters under operant control should facilitate electrophysiological and lesion/behavioral studies of this widely used "model" sensorimotor system.

Animals↗
PubMed2000

Vasotocin stimulates appetitive responses to the visual and pheromonal stimuli used by male roughskin newts during courtship.

It is now well established that vasotocin (AVT) and its mammalian homologue vasopressin influence various social behaviors in vertebrates, but less is known about the mechanisms through which these peptides modulate behavior. In male roughskin newts, Taricha granulosa, AVT stimulates a courtship behavior, amplectic clasping. Three general explanations for how AVT affects male courtship behavior have been considered: by enhancing a central state of sexual motivation, by affecting sensorimotor integration mechanisms in individual sensory modalities, or by influencing a nonspecific state of attention, arousal, or anxiety. AVT administration enhanced appetitive responses to visual and olfactory sexual stimuli, as would be expected if AVT affects a state of sexual motivation that affects behavioral responses to sexual stimuli regardless of the sensory modality in which they are processed. However, AVT selectively enhanced responses to female olfactory stimuli (sex pheromones), but similarly enhanced responses to female and food-related visual stimuli (worms), thus questioning the utility of such a motivational mechanism, as responses to female stimuli were not selectively enhanced in all sensory modalities. We therefore propose that exogenous AVT independently influences olfactory processes associated with orientation/attraction toward a female sex pheromone and visual processes associated with orientation/attraction toward a visual feature common to females and worms. In further experiments AVT administration failed to stimulate feeding behavior but did decrease locomotor activity. Thus, AVT does not stimulate courtship behavior in this species by enhancing the animals' general state of attention or by decreasing general anxiety, as responses to nonsexual, attractive stimuli were not uniformly enhanced, nor by stimulating general arousal, as activity levels did not increase. Rather, the data support the conclusion that AVT affects courtship by influencing specific sensorimotor processes associated with behavioral responses to individual releasing stimuli, which suggests a mechanistic framework for understanding socially motivated behavior is this species.

Animals↗
PubMed1992

Neuroethological evaluation of audiogenic seizures and audiogenic-like seizures induced by microinjection of bicuculline into the inferior colliculus. I. Effects of midcollicular knife cuts.

Audiogenic seizures (AS) are a model of generalized tonic-clonic seizures. The inferior colliculus (IC) and the GABAergic neurotransmission seems to be the most critical site and neurotransmitter system, respectively, of the auditory midbrain involved in AS origin and development. Thus, audiogenic-like seizures are evoked by GABAA antagonists such as bicuculline (BIC). Wistar audiogenic AS resistant (R) rats were sham-transected through the midcollicular line and microinjected with IC bicuculline (BIC; 80 ng/0.2 microliters) (n = 8); transected through the midcollicular line and microinjected with IC saline 0.9% (n = 8); transected through the cortex above the midcollicular line and microinjected with IC BIC (n = 3); transected through the midcollicular line up to 6.0 mm depth and microinjected with IC BIC (80 ng/0.2 microliters or 120 ng/0.3 microliters (n = 8). Wistar AS susceptible (S) rats were submitted to cortical transections (n = 8) and midcollicular transections (n = 7). Animals were studied by means of an ethological method before and after microinjections and/or transections in order to evaluate possible pathways in the AS-like evoked seizures. Bicuculline-evoked seizures were very similar to those evoked by acoustic stimulation, but lacked the tonic-clonic component. No modification in animal behavior was observed in the presence of sound, once the AS-like behavior was initiated. A small percentage of the animals, however, presented procursive behavior which was increased by sound. The IC BIC-evoked patterns were almost totally blocked by midcollicular but not cortical transections. Furthermore, midcollicular but not cortical transections blocked the tonic-clonic component of AS in genetically S animals without modifying the wild running component. These data suggest that the inferior colliculus-superior colliculus connection may be involved in the sensorimotor transduction necessary for AS-like behaviors.

Acoustic Stimulation↗
PubMed1997

A study of cognitive development and behavior problems in mentally retarded children.

Cognitive development in seventy-one mentally retarded children (19 autistic, 52 non-autistic; aged 7-19 years) from a school for handicapped children was studied, using Ohta's scale for evaluating cognitive development level based on language comprehension (Ohta's stage), and other developmental scales. Behavior problems were also examined. The present study reports on the utility of Ohta's stage in non-autistic children, and the relationship between cognitive development level and behavior problems in mentally retarded children. In non-autistic children, there were temporal correlations between Ohta's stage and other development scales (a standard developmental test, speech development, symbolic play development, imitation development), suggesting that in non-autistic children as well, Ohta's stage may serve well as a scale for cognitive development, and reflect symbolic representational functioning. In non-autistic children, most behavior problems in feeding, elimination and sleeping, hyperkinesis, hypokinesis, stereotyped behaviors, self-injurious behavior and licking were closely associated with cognitive development level, and were more often noted in children of lower cognitive development level rather than only in the severely mentally retarded children. Some behavior problems may often occur in the sensorimotor period and hardly occur in the symbolic representational period.

Adolescent↗
PubMed2001

Evidence for distinct beta resonance frequencies in human EEG related to specific sensorimotor cortical areas.

OBJECTIVE: We studied event-related synchronization (ERS) of beta rhythms related to voluntary movement vs. stimulation of upper and lower limbs. The aim of this study was to investigate whether the frequency of the beta response is related to specific regions within the sensorimotor strip. METHODS: Self-paced movement and electrical stimulation of the dominant hand and foot/leg was investigated in 10 right-handed volunteers. The electroencephalogram was recorded from closely spaced electrodes over central areas and processed time-locked to movement-offset or stimulation. In order to identify the dominant frequency of the induced beta oscillations, time-frequency maps were calculated using the continuous wavelet transformation. For the specific beta frequency bands, the band power time courses were analyzed by quantifying the event-related (de-)synchronization (ERD/ERS). RESULTS: Both limb movement and somatosensory stimulation induced bursts of beta oscillations appearing within 1 s after movement/stimulation with a clear focus close to the corresponding sensorimotor representation area. The peak frequency was significantly lower over the hand area (below approximately 20 Hz) than at mid-central sites overlying the foot representation area (above approximately 20 Hz). But no difference was found between movement and stimulation of the respective limb. CONCLUSIONS: Analyzing the frequency of induced beta activity revealed concomitant oscillations at slightly different frequencies over neighboring cortical areas. These oscillations might be indicative for a resonance-like behavior of connected sub-networks in sensorimotor areas.

Adult↗
PubMed1995

A behavioral assessment of Ts65Dn mice: a putative Down syndrome model.

Mice which are trisomic for only the human chromosome (Chr) 21-homologous segment of mouse Chr 16 (segmental trisomy), including a portion of the Down syndrome region of human Chr 21, have recently been developed. Since these segmentally trisomic mice, designated Ts(17(16))65Dn, survive to adulthood, they may represent a mouse model for the study of Down syndrome. A partial characterization of their behavioral phenotype was undertaken by evaluating the sensorimotor reflexes, exploration, locomotor activity, emotionality and spatial learning in 16 male Ts65Dn mice (TS) and 16 control (CO) littermates. No sensorimotor deficits appeared in TS compared to CO mice. By contrast, head-dipping behaviour in the hold board was increased in TS mice with respect to the CO group, showing a higher repetition rate of previously explored holes. Crossings in the open field and total arm entries in the plus maze were higher in TS than in the CO group during the dark phase of the light-dark (LD) cycle under red light, but not during the light phase of the LD cycle under white light. Entries into the open arms of the plus maze were increased overall in TS mice when compared to CO mice, but no differences were found in time spent in the open arms. TS mice showed impaired place learning in the Morris water maze, whereas they were able to reach the same performance as CO animals in cued learning. Thus, absence of sensorimotor deficits, increased exploration, hyperactivity under certain experimental conditions and a moderate impairment of spatial learning were the principal characteristics observed in TS mice compared to their CO littermates.

Animals↗
PubMed1992

Chronic infusion of GABA into the nucleus basalis magnocellularis or frontal cortex of rats: a behavioral and histological study.

In order to determine the influence of the nucleus basalis magnocellularis (NBM) on the sensorimotor function of the frontal cortex (FCx) of the rat, GABA at various concentrations (10, 50 or 100 micrograms.microliters-1) was administered into these structures. GABA was infused for four consecutive days after which saline was infused for another four. On the contralateral side the order of administration was reversed. Each structure received GABA while its homologous on the contralateral side received saline. Before, during and after drug infusion, the animals were weighted and their performance in two non-reinforced behavioral tasks (beam walking and spontaneous rotation) was examined. When GABA was infused into the FCx, a dose-dependent and reversible sensorimotor deficit was observed along with a behavioral withdrawal syndrome upon GABA discontinuation. When GABA was administered into the NBM, a reversible sensorimotor deficit was observed only when GABA was infused at the highest concentration. In this case no behavioral changes were observed upon GABA discontinuation. Histologically, a gliosis was observed in the NBM in which GABA was infused at the two highest concentrations without saline pretreatment; these effects were not observed when GABA was infused without saline pretreatment into the FCx. In relation to our previous findings, these results suggest that i) the FCx is directly involved in the expression of sensorimotor functions, while the influence of the NBM on these functions appears only after severe subcortical damage, ii) a GABA withdrawal syndrome is observed following GABA administration in the FCx but not in the NBM, and iii) "tonic" effects of GABA are dose-related and partially dependent upon pretreatment conditions and the brain region infused.

Analysis of Variance↗