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PubMed1999

Brain mapping in sedated infants and young children with passive-functional magnetic resonance imaging.

Functional magnetic resonance imaging (fMRI) in pediatric patients presents a unique set of problems due to the need for patient compliance, the frequent need for sedation and an early developmental status. A new method for using fMRI in sedated infants and young children is presented using passive stimuli focused on visual, sensorimotor and language functions. All of these stimuli are presented such that no patient interaction is required. Eight sedated children undergoing diagnostic MRI scans of the brain participated in these passive fMRI procedures. Cortical regions were identified using standard techniques applied to the blood-oxygen-level-dependent signal which is the basis for fMRI. The results support the feasibility of brain mapping in sedated children with passive fMRI techniques.

Anesthesia↗

PubMed2006

[Effects of transcranial magnetic stimulation on recovery of neural functions and changes of synaptic interface and dendritic structure in the contralateral brain area after cerebral infarction: experiment with rats].

OBJECTIVE: To evaluate the effects of transcranial magnetic stimulation (TMS) on the brain plasticity and its role in functional outcome in cerebral infarction. METHODS: Twenty male SD rats underwent suture of the unilateral middle cerebral artery (MCA) so as to establish focal cerebral infarction models and then were randomly divided into 2 equal groups: model group, to be reared in the original living state, and TMS group, given in addition TMS treatment 1 day after infarction 2 times per day and 30 pulses per time for 4 weeks. Twenty-eight days after the rats were killed. Four rats from each group underwent microscopy of the brain to measure the dendritic structure of the pyramidal cells quantitatively. Other 4 rats from each group underwent electron microscopy of the brain to measure the parameters of synaptic interface in the sensorimotor cortex. Neural function scoring was conducted 24 hours after the establishment of model and before being killed. RESULTS: There was no significant difference in the neural function 24 h after the establishment of models, however, 28 days after the score of neural function of the TMA group was 0.58 +/- 0.49, significantly lower than that of the model group (0.92 +/- 0.28, P < 0.05). The total dendritic length, number of dendritic branching points, and dendritic density in layer V pyramidal cells within the undamaged motor cortex of the TMS group were 898 microm +/- 127 microm, 6.6 +/- 1.5, and 0.75/microm +/- 0.19/microm, all significantly higher than those of the model group (788 microm +/- 112 microm, 5.8 +/- 1.5, and 0.60/microm +/- 0.16/microm, P < 0.05 or < 0.01). Electron microscopy showed that the synaptic curvatures and post-synaptic density of the TMS group were 1.06 +/- 0.08 and 64 +/- 13 respectively, both significantly higher than those of the model group (1.02 +/- 0.06 and 54 +/- 12 nm respectively, P < 0.05 and P < 0.01), and the synapse cleft width of the TMS group was 19.5 +/- 2.1, significantly narrower than that of the model group (23.3 +/- 2.3, P < 0.01). CONCLUSION: TMS promotes the improvement of neural functions of the rats with cerebral ischemia by the potential mechanism that TMS strengthen the compensatory roles of the synaptic interface and dendritic structure in the undamaged sensorimotor cortex area and increase synaptic plasticity.

Animals↗

PubMed2002

Technical aspects and utility of fMRI using BOLD and ASL.

Functional magnetic resonance imaging (fMRI) is an emerging methodology which provides various approaches to visualizing regional brain activity non-invasively. Although the exact mechanisms underlying the coupling between neural function and fMRI signal changes remain unclear, fMRI studies have been successful in confirming task-specific activation in a variety of brain regions, providing converging evidence for functional localization. In particular, fMRI methods based on blood oxygenation level dependent (BOLD) contrast and arterial spin labeling (ASL) perfusion contrast have enabled imaging of changes in blood oxygenation and cerebral blood flow (CBF). While BOLD contrast has been widely used as the surrogate marker for neural activation and can provide reliable information on the neuroanatomy underlying transient sensorimotor and cognitive functions, recent evidence suggests perfusion contrast is suitable for studying relatively long term effects on CBF both at rest or during activation. New developments in combining or simultaneously measuring the electrophysiological and fMRI signals allow a new class of studies that capitalize on dynamic imaging with high spatiotemporal resolution. This article reviews the biophysical bases and methodologies of fMRI and its applications to the clinical neurosciences, with emphasis on the spatiotemporal resolution of fMRI and its coupling with neurophysiology under both normal and pathophysiological conditions.

Brain Diseases↗

PubMed2005

The neuroscience of grasping.

People have always been fascinated by the exquisite precision and flexibility of the human hand. When hand meets object, we confront the overlapping worlds of sensorimotor and cognitive functions. We reach for objects, grasp and lift them, manipulate them and use them to act on other objects. This review examines one of these actions--grasping. Recent research in behavioural neuroscience, neuroimaging and electrophysiology has the potential to reveal where in the brain the process of grasping is organized, but has yet to address several questions about the sensorimotor transformations that relate to the control of the hands.

Animals↗

PubMed1993

Tethered cord syndrome: an unusual cause of adult bladder dysfunction.

Tethered cord syndrome is a complication of spinal dysraphism. The tethering of the cord does not permit the normal cranial migration of the conus within the vertebral canal and this results in neural dysfunction due to a traction neuropathy. Although this condition commonly presents in childhood, less severe degrees of tethering may remain asymptomatic until adult life. The clinical features, imaging and management of 5 adults with this condition are reviewed. Both urological and neurosurgical intervention are aimed at preservation of function as, unlike the sensorimotor deficit that commonly complicates this condition, improvement in bladder function is uncommon following cord release.

Adolescent↗

PubMed2005

Intracerebral hemorrhage in the iron-deficient rat.

BACKGROUND AND PURPOSE: Iron contributes to brain injury after intracerebral hemorrhage (ICH). Because ICH may occur in the context of iron deficiency anemia (IDA), a common nutritional disorder, the purpose of this study was to determine whether IDA in rats affects brain edema, functional behavior, and changes in brain iron-handling proteins after ICH. METHODS: Six-week-old male rats (n=75) were randomized to non-IDA or IDA groups and provided iron-sufficient or -deficient diets, respectively. After 1 month, 100 microL autologous blood was infused into the right basal ganglia (BG). Brains removed at days 1, 3, 7, and 28 after ICH were assessed for regional brain water content and BG transferrin and transferrin receptor concentrations (Western blotting). Sensorimotor measures of functional recovery were assessed. RESULTS: Brain water content was increased for IDA versus non-IDA in injured cortex and BG at day 3 (P<0.05). IDA rats had impaired left forepaw placing and more asymmetric forelimb use versus non-IDA after ICH (P<0.05). Transferrin and transferrin receptor concentrations in the BG were increased for IDA versus non-IDA within the first week (P<0.05). CONCLUSIONS: Rats with IDA have greater brain edema, poorer sensorimotor outcome, and a greater expression of iron regulatory proteins than non-IDA rats after ICH, suggesting brain iron status is a determinant of injury severity and recovery.

Anemia, Iron-Deficiency↗

PubMed2006

Post-movement beta rebound is generated in motor cortex: evidence from neuromagnetic recordings.

Voluntary movements are accompanied by amplitude changes in cortical rhythms presumably as a result of functional activation of sensorimotor areas. Recently, the location of the neural generators involved in increasing power within the beta (15-30 Hz) frequency band following movement (post-movement beta rebound, PMBR) has come into question [Parkes, L.M, Bastiaansen, M.C.M, Norris, D.G., 2006. Combining EEG and fMRI to investigate the post-movement beta rebound. NeuroImage 29, 685-696.]. We used the synthetic aperture magnetometry (SAM) spatial filtering method to identify the time course and location of oscillatory changes within the beta and mu (8-14 Hz) frequency bands during the performance of voluntary movements. Neuromagnetic activity was recorded from 10 adult subjects during abduction of the right index finger. Changes in beta and mu source power were calculated for periods during and following movement, relative to pre-movement baseline activity. Decreases in beta band activity (event-related desynchronization, ERD) were observed during movement, with a strong increase (PMBR) beginning 230+/-170 ms following movement, lasting for 680+/-170 ms. Mu band ERD was observed both during and following movement, with little to no post-movement rebound. Beta and mu ERD were localized bilaterally to the hand region of postcentral gyrus whereas PMBR was localized bilaterally to the hand region of precentral gyrus (motor cortex). Both PMBR and beta ERD were strongest contralateral to the side of movement. These results provide further evidence that movement influences independent cortical rhythms in sensorimotor areas, and confirm previous reports of precentral generators of PMBR in the region of motor cortex, with postcentral generators of beta and mu ERD during movement.

Adult↗

PubMed2004

Human neural stem/progenitor cells, expanded in long-term neurosphere culture, promote functional recovery after focal ischemia in Mongolian gerbils.

Transplantation of human neural stem cells (NSCs) is a promising potential therapy for neurologic dysfunctions after the hyperacute stage of stroke in humans, but large amounts of human NSCs must be expanded in long-term culture for such therapy. To determine their possible therapeutic potential for human stroke, human fetal neural stem/progenitor cells (NSPCs) (i.e., neurosphere-forming cells) were isolated originally from forebrain tissues of one human fetus, and expanded in long-term neurosphere culture (exceeding 24 weeks), then xenografted into the lesioned areas in the brains of Mongolian gerbils 4 days after focal ischemia. Sensorimotor and cognitive functions were evaluated during the 4 weeks after transplantation. The total infarction volume in the NSPC-grafted animals was significantly lower than that in controls. Approximately 8% of the grafted NSPCs survived, mainly in areas of selective neuronal death, and were costained with antibodies against neuronal nuclei antibody (NeuN), microtubule associated protein (MAP-2), glial fibrillary acidic protein (GFAP), and anti-2'3' cyclic nucleotide 3'-phosphodiesterase (CNPase). Synaptic structures between NSPCs-derived neurons and host neurons were observed. Furthermore, gradual improvement of neurologic functions was observed clearly in the NSPC-grafted animals, compared to that in controls. Human NSPCs, even from long-term culture, remarkably improved neurologic functions after focal ischemia in the Mongolian gerbil, and maintained their abilities to migrate around the infarction, differentiate into mature neurons, and form synapses with host neuronal circuits. These results indicate that in vitro-expanded human neurosphere cells are a potential source for transplantable material for treatment of stroke.

Animals↗

PubMed1997

Event-related coherence and event-related desynchronization/synchronization in the 10 Hz and 20 Hz EEG during self-paced movements.

To investigate the activity of cortical regions in the control of movement, we studied event-related desynchronization/synchronization (ERD/ERS), event-related coherence (ERC), and phase coherence in 29-channel EEGs from 9 subjects performing self-paced movements of the right index finger. Movement preparation and execution produced ERD over the sensorimotor areas at 10 Hz and 20 Hz, followed by ERS. ERD corresponded spatiotemporally to an increase in coherence over the frontocentral areas. For both frequency bands, ERD began over the left sensorimotor areas and became bilateral at the time of movement onset. The coherence increase with frontal areas began in the left central areas and became symmetrical after EMG onset. The ERD and coherence increase was longer at 10 Hz than at 20 Hz. Phase coherence at 10 Hz showed a lead of anterior regions to posterior regions throughout the time period, and at 20 Hz showed a tendency toward zero phase delay corresponding with the movement. EEG desynchronization parallels functional coupling over sensorimotor and frontal areas. Event-related coherence and phase coherence findings implicate the frontal lobes in control of movement planning and execution. The involvement of different frequency bands with different timings may represent parallel changes in the cortical network.

Adult↗

PubMed1993

Epileptic negative myoclonus.

Five patients with partial epilepsy of diverse etiology insidiously developed action-activated jerks. The disorder was limited to one arm in two patients and to the legs in another, and was multifocal in the remaining two. Each jerk was related to an EMG silent period lasting 100 to 400 msec, causing a lapse followed by resumption of posture. Simultaneous EEG-EMG recording showed each postural lapse to be time-locked with a sharp or spike and slow-wave transient over the contralateral sensorimotor cortex, where almost continuous paroxysmal activity occurred. The three patients who were able to cooperate during neurologic evaluation also exhibited motor neglect in the most affected body segment and decreased awareness of the disorder. In three patients, the phenomenon was medically resistant, and in two of them it was continuous and could be defined as epilepsia partialis continua. In the other two, medical treatment induced remission of EEG, motor, and neuropsychological abnormalities. This disabling movement disorder can be classified as "epileptic negative myoclonus" and may result from focal-discharge-related transient disruption of cortical function in the sensorimotor cortex.

Adolescent↗

PubMed2001

Behavioral effects induced by acute exposure to benzo(a)pyrene in F-344 rats.

Polycyclic aromatic hydrocarbons (PAHs) are highly persistent environmental pollutants which pose potential adverse effects on human health. Benzo(a)-pyrene (B(a)P) is the prototypical representative of these widely dispersed lipophylic contaminants. (B(a)P) exposure in experimental animals results in an array of tissue- and organ-specific responses including carcinogenicity, teratogenicity, reproductive and immunotoxicity. However, no previous studies have examined the potential neurobehavioral toxicity of B(a)P in vivo. The present study was conducted to investigate the behavioral effects induced by single oral doses of (B(a)P) in 8-week-old male and female F-344 rats. Rats were exposed to 0, 12.5, 25, 50, 100 and 200 mg/kg of B(a)P by oral gavage. Motor activity measurements and the functional observational battery (FOB) were used to assess behavioral changes induced by B(a)P at 2, 4, 6, 8, 10, 12, 24, 48, 72 and 96 h post treatment. Statistical analyses revealed significant (p <0.001) dose, sex and time interactions. (B(a)P) doses ranging from 25 to 200 mg/kg produced a significant suppression (up to 60%) in four motor activity parameters: horizontal activity, total distance, stereotype and vertical activity in both sexes within 2 and 4h of dosing. B(a)P treated male and female animals also showed significant (p <0.001) changes in neuromuscular, autonomic, sensorimotor and physiological functions within 2 and 4h post B(a)P administration except in the 12.5 mg/kg treatment group. The 12.5 mg/kg dose did not produce significant (p > 0.05) behavioral toxicity in either males or females. All treated animals (25-200 mg/kg) recovered from the toxic effects of B(a)P by 72 h. Significant (p < 0.05) gender differences were noted in FOB test measures with males displaying greater sensitivity to B(a)P. These data suggest that motor activity and FOB measurements can be used as indices to detect B(a)P neurotoxicity.

Journal Article↗

PubMed2005

Differential modulation in human primary and secondary somatosensory cortices during the preparatory period of self-initiated finger movement.

To elucidate the mechanisms underlying sensorimotor integration, we investigated modulation in the primary (SI) and secondary (SII) somatosensory cortices during the preparatory period of a self-initiated finger extension. Electrical stimulation of the right median nerve was applied continuously, while the subjects performed a self-initiated finger extension and were instructed not to pay attention to the stimulation. The preparatory period was divided into five sub-periods from the onset of the electromyogram to 3000 ms before movement and the magnetoencephalogram signals following stimulation in each sub-period were averaged. Multiple source analysis indicated that the equivalent current dipoles (ECDs) were located in SI and bilateral SII. Although the ECD moment for N 20 m (the upward deflection peaking at around 20 ms) was not significantly changed, that for P 30 m (the downward deflection peaking at around 30 m) was significantly smaller in the 0- to -500-ms sub-period than the -2000- to -3000-ms sub-period. As for SII, the ECD moment for the SII ipsilateral to movement showed no significant change, while that for the contralateral SII was significantly larger in the 0- to -500-ms sub-period than the -1500- to -2000-ms or -2000- to -3000-ms sub-period. The opposite effects of movement on SI and SII cortices indicated that these cortical areas play a different role in the function of the sensorimotor integration and are affected differently by the centrifugal process.

Adult↗

PubMed2005

Assessment of recovery in the hemiparkinson rat: drug-induced rotation is inadequate.

Recovery from apomorphine-induced rotational behavior was compared to sensorimotor and motor function in hemiparkinsonian rats receiving intrastriatal grafts of astrocytes expressing recombinant tyrosine hydroxylase (TH) or control beta-galactosidase (beta-gal). Rats received unilateral intranigral infusions of 6-hydroxydopamine (6-OHDA). Animals with large lesions, as determined by apomorphine-induced rotation, received grafts of astrocytes into the denervated striatum. Behavioral recovery was assessed on days 14-16 post-transplantation using apomorphine-induced rotation, somatosensory neglect, and reaching for pellets using the Montoya staircase method. Rats that received transplants of TH-transfected astrocytes showed a 34% decrease in rotational behavior, but no consistent recovery of somatosensory neglect or skilled reaching. Post-mortem histological analyses revealed survival of grafted astrocytes in host striatum and expression of TH at 17 days post-transplantation. We suggest that TH-expressing astrocytes may reverse post-synaptic dopamine (DA) receptor supersensitivity; however, sensorimotor and motor abilities are not restored due to a failure by TH-expressing astrocytes to reestablish dopaminergic circuitry. The present results demonstrate the need to utilize a variety of sensory and motor behavioral tests that cohesively provide greater interpretability than a single behavioral measure used in isolation, such as drug-induced rotational behavior, to assess the efficacy of experimental gene therapies.

Animals↗

PubMedDate not supplied

Long-term treatment of male F344 rats with deprenyl: assessment of effects on longevity, behavior, and brain function.

L-Deprenyl (selegiline) was chronically administered to male Fischer 344 rats via their drinking water beginning at 54 weeks of age (estimated daily dose: 0.5 mg/kg/day). Beginning at 84 weeks of age, the rats were behaviorally evaluated using a sensorimotor battery, a motor-learning task, and the Morris water maze. At 118 weeks of age, cerebellar noradrenergic function was evaluated in the surviving rats using in vivo electrochemistry. The rats were then sacrificed to measure brain monoamine oxidase activity and perform quantitative autoradiography to evaluate the effect of chronic deprenyl treatment on beta-adrenergic receptors in the cerebellum, alpha 2-adrenergic receptors several brain regions, and D1 and D2 dopamine receptors in the striatum. Deprenyl treatment reduced brain monoamine oxidase B activity by 85%, but had no effect on brain monoamine oxidase A. A clear effect of chronic deprenyl treatment upon longevity was not observed. Several measures of CNS function were altered in the deprenyl-treated animals: 1) spatial learning in the Morris water maze was improved; 2) electrochemical signals recorded following local application of NE were reduced, and the responsiveness to the reuptake blocker nomifensine was enhanced, in the cerebellum; 3) beta-adrenergic receptor binding affinity was increased in the cerebellum; 4) alpha 2-adrenergic receptor density was increased in the inferior colliculus; and 5) striatal D1 dopamine receptor density was reduced but binding affinity was enhanced. In contrast, chronic deprenyl treatment did not cause changes in: 1) sensorimotor function, as evaluated by balance beam, inclined screen, or wire hang tasks; 2) motor learning; 3) alpha 2-adrenergic receptor density in any region examined except for the inferior colliculus, or binding affinity in any region examined; or 4) striatal D2 dopamine receptor number or affinity. Thus, long-term oral administration of deprenyl extended the functional life span of rats with respect to cognitive, but not motor, performance.

Animals↗

PubMed1998

Mapping of the central sulcus with functional MR: active versus passive activation tasks.

PURPOSE: Our purpose was to assess the pattern of functional MR activation obtained with a passive sensory versus an active sensorimotor hand stimulus paradigm. METHODS: Eight functional MR runs, four with an active sensorimotor (sponge-squeezing) task and four with a passive sensory (palm-finger brushing) reception, were acquired for each of 10 healthy volunteers. Activation maps were generated by thresholding cross-correlation maps. Regions of interests (ROIs) were drawn around the precentral and postcentral gyri on T1-weighted images according to established anatomic criteria, and the number of activated pixels inside the ROIs was ascertained. Displacement of the sensorimotor and sensory activation centroids within the ROIs from the central sulcus as well as from each other was measured. RESULTS: Active sensorimotor stimulation produced a significantly greater number of activation pixels than did passive sensory stimulation. Run-to-run variability was equivalent between sensorimotor and sensory activation tasks. On average, the sensorimotor and sensory activation centroids were located in the postcentral gyrus, and their spatial locations were not significantly different. CONCLUSION: Active and passive activation tasks produce largely equivalent results. Presurgical mapping of the sensorimotor area can be performed with functional MR imaging using a passive palm-finger brushing task in patients who are physically unable to perform active finger-tapping or hand-squeezing sensorimotor activation tasks.

Adult↗

PubMed2003

Triggering of protective stepping for the control of human balance: age and contextual dependence.

Human stepping is a commonly executed control strategy for maintaining standing balance in the natural environment. Aging changes in the initiation triggering of both voluntary (longer latency) and perturbation-induced (shorter latency) stepping are associated with falling, and are a complex function of altered sensorimotor, neuromuscular, and cognitive system factors. The aim of this study was to determine the effect of contextual uncertainty about balance stability on the triggering of protective stepping in young and older individuals. Subjects initiated forward stepping during simple reaction time and waist-pull perturbation conditions with and without contextual uncertainty about balance stability. The results showed that, regardless of age, the initiation timing for triggering both voluntary and induced stepping was delayed substantially (100-300 ms) by the presence of balance uncertainty, and that age-associated timing differences were exacerbated with contextual uncertainty. The initiation timing of the first step liftoff for perturbation-induced stepping did not reflect entirely an immediate necessity or last resort strategy to balance instability determined directly by specific sensory input, but rather a decision to step. Moreover, the time to liftoff onset for perturbation-induced stepping was similar for the old and young with contextual certainty, and occurred 130 ms earlier for the old than for the young when balance stability was uncertain. Overall, we concluded that older individuals can retain a residual capacity to sustain stationary standing stability as a function of the prevailing task conditions, and that the reduced timing threshold with age may involve a pre-selected strategy triggered earlier by non-specific event-related sensory input rather than specific movement-related information.

Acoustic Stimulation↗

PubMed1995

Suppression of ponto-geniculo-occipital waves by neurotoxic lesions of pontine caudo-lateral peribrachial cells.

Ponto-geniculo-occipital waves precede rapid eye movement sleep and play an important role in triggering and maintaining rapid eye movement sleep. Ponto-geniculo-occipital waves have been implicated in several important functions such as sensorimotor integration, learning, cognition, development of the visual system, visual hallucination, and startle response. Peribrachial area neurons have long been thought to play a key role in the triggering of ponto-geniculo-occipital wave. However, the exact location within the peribrachial area for triggering pontine ponto-geniculo-occipital wave has not been unequivocally demonstrated. In an attempt to address this issue, kainic acid was microinjected (1.0 micrograms) unilaterally into the caudo-lateral peribrachial area of four cats in order to destroy the cell bodies located in that region and thus to study the effects of their destruction upon waking-sleep states and ponto-geniculo-occipital waves. The kainic acid produced a small spherical area of nerve cell loss and/or gliosis centered on the stereotaxic coordinates of P: 4.0, L: 4.5, and H: -2.5. The maximum diameter of that spherical area of cell loss was 0.9 mm. Unilateral lesioning of the caudo-lateral peribrachial area decreased ponto-geniculo-occipital waves during rapid eye movement sleep by 85% ipsi-laterally and 15% contralaterally in the lateral geniculate body without significantly changing the amounts of time spent in wake, slow-wave sleep, and rapid eye movement sleep. These results suggest that the caudo-lateral peribrachial area cells are critical to the genesis of ponto-geniculo-occipital waves, and provide compelling evidence that the different parts of the peribrachial area have quite different roles in the generation of discrete rapid eye movement sleep signs. We propose that caudo-lateral peribrachial cells exert an excitatory influence on rostral peribrachial cells, which then directly activate the ponto-geniculo-occipital waves that are recorded in the lateral geniculate body. Results of this study are not only important to understand the mechanisms generating ponto-geniculo-occipital waves but also could be used as an experimental tool to study the functions of this wave.

Animals↗

PubMed1981

Infants at risk for schizophrenia. The Jerusalem Infant Development Study.

The development of infants born to parents with serious mental disorders was followed up from birth through the first year of life. An individual-differences approach to statistical analysis. Multidimensional Scalogram Analysis (MSA), was shown to be an effective statistical procedure for examining heterogeneous psychiatric populations. The MSA revealed the existence of a subgroup of infants born to schizophrenics who repeatedly performed poorly in motor and sensorimotor areas of functioning during their first year of life. These infants were especially vulnerable to external insults, and many had low to low-normal birth weights. These findings, taken together with similar findings from other investigations, add support to the hypothesis that these infants may have a genetically determined neurointegrative deficit.

Adult↗