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PubMed1983

Stellate cells differentiate successively in the cat sensorimotor cortex during early postnatal ontogeny.

Golgi and Golgi-Kopsch techniques were used to investigate maturation of stellate and pyramidal cells and development of stellate-pyramidal connections in kittens of the following ages: 2, 7, 14, 21, 28 and 34 days. By two weeks, stellate cells in layer V have become mature. Layer III stellate cells with vertical axon ramifications are differentiated by 2-3 weeks of life and in 3-week-olds the horizontal spread of axon collaterals amounts to 1300 micrometer. Layer II stellate cells which are poorly developed n newborns acquire the greatest number of collaterals and a complex axon branching pattern by 4 weeks of age.

Animals↗
PubMed1990

High- and low-threshold calcium currents in neurons acutely isolated from rat sensorimotor cortex.

Neurons were isolated by papain treatment and trituration of the frontoparietal cortex of 14 to 28-day-old rats. Whole cell voltage clamp revealed a slowly inactivating high-threshold Ca2+ current, activated positive to -45 mV, and a transient low-threshold Ca2+ current, activated positive to -65 mV. The high-threshold current was more sensitive to block by Cd2+ and the low-threshold current was more sensitive to block by Ni2+. Replacement of Ca2+ by Ba2+ increased the high-threshold current and reduced the low-threshold current. The high-threshold current was enhanced by Bay K 8644 and reduced by nimodipine and omega-conotoxin. The low-threshold current was also reduced by nimodipine but was insensitive to Bay K 8644 and omega-conotoxin. The properties of the currents were consistent with different underlying Ca2+ channel types.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1991

Patterns of corticothalamic terminations following injection of Phaseolus vulgaris leucoagglutinin (PHA-L) in the sensorimotor cortex of the rat.

The morphology and spatial distribution of terminals emitted by corticothalamic axons originating from the rat motor cortex (as defined by intracortical microstimulations) were studied using Phaseolus vulgaris leucoagglutinin (PHA-L) as an anterograde tracer. After PHA-L injection in the face, forelimb or hindlimb motor cortical areas, small and densely packed boutons (about 1 micron in diameter), en passant and terminaux, were seen in the ventrolateral nucleus of the thalamus and, more sparsely, in the reticular nucleus, the nucleus ventrobasalis and the posterior nucleus of the thalamus. A separate projection with giant boutons (5-10 microns in diameter), en passant and terminaux, terminated in the posterior nucleus of the thalamus exclusively. Giant boutons originated from corticothalamic axons distinct from those providing small boutons. The corticothalamic projection originating from the motor cortex has basic organizational properties comparable to previous data obtained in the auditory and somatosensory corticothalamic projection systems.

Afferent Pathways↗
PubMed1992

Recovery of distal skills after neonatal lesion of the sensorimotor cortex in the cat.

The cytoarchitectonic cortical areas containing the cells of origin of the pyramidal tract were unilaterally removed from kittens during the first postnatal month. After 5 months, the distal skills of these operated animals were analyzed using a food retrieving task. After an initial deficit, cats achieved the same performance in grasping and wrist movement with the limb contralateral to the lesion as with the opposite limb. The duration of the deficit was dependent on age at the time of lesion. Recovery of distal skills after neonatal lesion is discussed with regard to the low degree of maturity of the corticospinal tract in newborn cat.

Aging↗
PubMed1991

Distribution of the calcium-binding proteins parvalbumin and calbindin-D28k in the sensorimotor cortex of the rat.

This study examined and compared the immunocytochemical distribution of the two calcium-binding proteins parvalbumin and calbindin-D28k in the primary motor and somatosensory areas of the rat neocortex. Parvalbumin-immunoreactive cells were found in all layers of the cortex except layer 1 and reached their peak density in the middle layers. The two cortical areas differed markedly in the number, cell size and morphology of immunoreactive cells. Parvalbumin-positive cells were more than twice as numerous in the somatosensory cortex compared to the motor cortex. In addition, the average size of their cell bodies was 25-30% larger in the somatosensory area. Parvalbumin cells in the motor area represented several classes of nonpyramidal cells, while the somatosensory cortex contained in addition many large cells with thick vertically oriented primary dendrites. Some of these cells resembled regular or inverted pyramidal neurons. Punctate neuropil labeling was much heavier in the upper layers of the somatosensory than in the motor cortex and was especially heavy in layer 4. Dense parvalbumin-positive perisomatic puncta surrounded large, unstained pyramidal cells in layer 5B of the motor cortex. Calbindin-D28k neuronal staining in both areas was confined to two populations. The most prominent was darkly labeled, small nonpyramidal cells confined to two bands in layers 2/3 and 5/6. There was also a lighter stained population composed of many pyramidal cells distributed throughout layers 2 and 3. In addition, the motor area contained a band of lightly stained, large pyramidal cells in layer 5B. Calbindin-D28k neuropil labeling was heaviest in layers 1 to 3. In contrast to parvalbumin, we found only minor differences in distribution, size and morphology of calbindin-D28k cell body or neuropil staining in the two cortical areas. Double-labeling immunocytochemistry showed that the large majority of immunoreactive cells contained only calbindin-D28k or parvalbumin, but a distinct population of multipolar cells in the upper layers of the somatosensory cortex contained both. The clear parcellation of parvalbumin immunoreactivity in the rat neocortex suggests that parvalbumin is preferentially associated with specific neuronal populations and terminals in the somatosensory cortex. The more general and homogeneous labeling of the upper layers of the cortex indicates that calbindin-D28k could be related to the relatively high density of calcium channels or N-methyl-D-aspartate receptors in the superficial layers of the rat cortex.

Animals↗
PubMed2004

Functional lateralization of the sensorimotor cortex in patients with schizophrenia: effects of treatment with olanzapine.

BACKGROUND: Earlier cross-sectional studies with functional magnetic resonance imaging (fMRI) in treated patients with schizophrenia have reported abnormalities of cortical motor processing, including reduced lateralization of primary sensory motor cortex. The objective of the present longitudinal study was to evaluate whether such cortical abnormalities represent state or trait phenomena of the disorder. METHODS: Seventeen acutely ill, previously untreated patients were studied after 4 weeks and after 8 weeks of olanzapine therapy. Seventeen matched healthy subjects served as control subjects. All subjects underwent two fMRI scans 4 weeks apart during a visually paced motor task using a simple periodic block design. Functional magnetic resonance imaging data were analyzed in Statistical Parametric Mapping (SPM99). Region of interest analyses were used to determine a laterality quotient (an index of lateralization) of motor cortical regions. RESULTS: The fMRI data indicated that patients had reduced activation of the primary sensory motor cortex at 4 weeks but not at 8 weeks; however, the laterality quotient in the primary sensory motor cortex was reduced in patients at both time points. CONCLUSIONS: These results suggest that some cortical abnormalities during motor processing represent state phenomena, whereas reduced functional lateralization of the primary sensory motor cortex represents an enduring trait of schizophrenia.

Adolescent↗
PubMed2004

NMDA receptor-dependent long-term potentiation is dependent on low-voltage-activated calcium currents in the sensorimotor cortex of cats.

The role of low-voltage-activated (LVA) calcium channels in the expression of long-term potentiation (LTP) was examined by intracellular recording in slices from cat agranular cortex. In the normal solution, LTP was induced, and the potentiation of low-threshold rebound potential was evoked by negative current injection. In the cells, in which resting membrane potential was depolarized, the incidence of LTP was very low. LTP was blocked completely in the presence of NMDA receptor antagonist or 50-100 microM nickel. It was suggested that LVA calcium channels function downstream of NMDA receptor-dependent signaling.

2-Amino-5-phosphonovalerate↗
PubMed2006

Generators and temporal succession of giant somatosensory evoked potentials in cortical reflex myoclonus: epicortical recording from sensorimotor cortex.

OBJECTIVE: To clarify the generator mechanism of giant somatosensory evoked potentials (giant SEPs) and the hyperexcitability of primary somatosensory and motor cortices (SI and MI). METHODS: In a patient with intractable focal seizures manifesting cortical reflex myoclonus of the left foot, giant SEPs to left tibial nerve stimulation were epicortically recorded as a part of presurgical evaluation with subdural electrodes. RESULTS: In the single pulse SEPs, enlarged P1-N1 components were observed at the foot area of the SI and MI (86.5-258.8 microV, respectively), and the peak latencies were always shorter at SI than at MI by 6 ms. Similar findings were obtained for peroneal and sural nerve stimulation. In the paired pulse SEPs, the second response was less suppressed, as compared to other interstimulus intervals (ISIs), with ISIs of 40 and 200 ms both at SI and MI. CONCLUSIONS: In this particular patient, cortical hyperexcitability to somatosensory stimuli seems to originate from SI but subsequently both SI and MI are responsible for the generation of giant SEPs and cortical reflex myoclonus. SIGNIFICANCE: Somatosensory and primary motor cortices both generated enhanced early cortical components of SEPs, most likely by enhancing the latter by the former.

Adult↗
PubMed2006

Effect of hindlimb suspension on activation and MHC content of triceps brachii and on the representation of forepaw on the sensorimotor cortex.

The aims of this work were to analyze the effects of a chronic (14 days) increase in the functional demand imposed on the triceps brachii and to evaluate the changes of the cortical representation of forelimb to this increased activity. The activation of triceps brachii was obtained by the hindlimb unloading (HU) model. Electromyographic activity changed from a phasic to a tonic pattern. Response amplitude increased during the first days of hyperactivity and then stabilized at an intermediate level. A transient decrease (-13% to -36% on day 2) in the mean frequency of motor units was observed. Content in myosin heavy chain of muscle fibers showed a reduction in IIb+IIx fibers in HU rats, whereas IIa+IIx fibers were more numerous. Thus, fibers tend to be more resistant to fatigue. Taken together, these observations reveal a dual plastic process. First, the nervous system reacts immediately to an environmental change, and second it reorganizes its motor command to impose a pattern of activity that is more adapted to a postural function. The extent of the cortical forelimb representation was delimited by oxidase histochemistry. No differences were detectable between control and HU animals for the period corresponding to enlarged receptive fields in the HU condition. Our observation lends support to our hypothesis that activation patterns contribute to the maintenance of neuronal properties in the somatosensory cortex. Moreover, the new tonic pattern resulting from the long contact of the paw with the floor may contribute to the adaptation of the central control of motoneuronal activity.

Animals↗
PubMed2005

Magnetic resonance spectroscopy study of proton metabolite level changes in sensorimotor cortex after upper limb replantation-revascularization.

We aimed to investigate the changes in proton metabolite levels at the motor and somatosensory cortex by magnetic resonance spectroscopy (MRS) after upper extremity replantation or revascularization. Nine patients who referred to our clinic suffering from major total (two) and subtotal (seven) amputation of the upper extremity were enrolled in this study. Mean time value between the injury and operation was 5.1 h. Mean follow-up period or mean time between the injury and MRS analysis was 26.2 months (ranging from 7 to 41 months). Voxels (TR: 2000; TE: 136 ms) were placed onto locations in the bilateral precentral and postcentral cortex area of the cerebral hemispheres that represent the upper extremity. Contralateral sides of the brain hemisphere that represent the injured extremity were accounted as control groups. Metabolite ratios [NAA (N-acetyl aspartate)/Cr (creatine) and Cho (choline)/Cr] of the motor and somatosensory cortex were calculated. The NAA/Cr and Cho/Cr metabolite ratios between the two groups were found to be insignificant, and these results may indicate that there is no remarkable somatosensorial cortex disruption or demyelination in these patients. Fifty-six percent of patients were found as functional according to Chen's scale.

Adolescent↗
PubMed2004

Functional MR imaging of language, memory, and sensorimotor cortex.

fMR imaging is a versatile technology that allows for the noninvasive identification of sensory, motor,and cognitive functions that may be impaired by surgical resection. fMR imaging provides the capacity to probe several brain functions, and when results are uncertain, to repeat or modify them. There are some limitations, MR contraindications to scanning, motion, and cooperation among them. Yet for most patients fMR imaging provides a reliable way to lateralize language dominance and to guide localization of language functions. Memory paradigms lag behind language in practical application, but the impediments to its utility will likely be resolved in the near future.

Brain Mapping↗
PubMed2002

A new pneumatic vibrator for functional magnetic resonance imaging of the human sensorimotor cortex.

The aim of the study was to implement a vibrotactile stimulator using functional magnetic resonance imaging (fMRI). A fMRI compatible vibration device consisting of a pneumatically driven dual membrane pump was developed. Brain activation during 50 Hz vibrotactile stimulation of the right hand-palm were compared to a right 2 Hz finger-to-thumb-tapping in ten healthy, right-handed male volunteers. The vibration paradigm showed a comparable activation pattern with respect to finger-to-thumb-tapping in the contralateral perirolandic region. The advantage of the new vibration device is the possibility to elicit the vibratory-tonic-reflex due to the higher amplitude in context with the high frequency than established devices. This reflex is considered to be responsible for the activation in the primary motor cortex and the current paradigm might prove useful in future neurosurgical planning in patients with perirolandic lesions.

Adult↗
PubMed1998

Differential magnetic resonance signal change in human sensorimotor cortex to finger movements of different rate of the dominant and subdominant hand.

Functional magnetic resonance tomography (fMRI) analysis of unimanual and bimanual sequential movements in righthanders showed the following effects. First, a rate-dependent activation of the somato-motor cortex was confirmed, with faster movement rates producing higher activation both in terms of signal intensity and number of activated voxels. Second, the right hemisphere showed more activation than the left hemisphere during unimanual tasks. Third, during bimanual movements, the left hemisphere showed greater activation than the right hemisphere. Finally, while the left hemisphere showed a marked change in activation patterns from unimanual to bimanual task, the right hemisphere activation patterns were not sensitive to task changes. The hemispheric asymmetries suggest substantial left hemisphere involvement in the coordination of bimanual tasks.

Adult↗