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PubMed1984

Pyramidal control of skin potential responses in the cat.

Pyramidal command of Skin Potential Response (SPR) was investigated in 20 cats paralyzed by gallamine and under a halothane anaesthetic. For each animal, a transection of the medulla sparing only the pyramidal tract was carried out. The pyramidal tract and Mesencephalic Reticular Formation (MRF) were stimulated before and after the transection. Results taken before transection show that the SPR can be elicited from stimulation of the pyramidal tract and the MRF. After transection, stereotaxic stimulations of the pyramidal tract still evoked the SPR even after aspiration of the medullary tissue posterior to the section and overlying the pyramids. Control reticular stimulations with higher stimulus intensities failed to evoked the SPR. These results show that stimulation of the pyramidal tract can elicit the SPR independently of reticulospinal neurons. It is hypothesized that a group of corticospinal fibers could transmit volleys having autonomic activity on preganglionic autonomic neurons of the intermediate zone of the grey matter.

Animals↗
PubMed2003

Differential morphology of pyramidal tract-type and intratelencephalically projecting-type corticostriatal neurons and their intrastriatal terminals in rats.

Two types of corticostriatal projection neurons have been identified: 1) one whose intrastriatal arborization arises as a collateral of a projection to the ipsilateral brainstem via the pyramidal tract (PT-type); and 2) one that projects intratelencephalically to the cortex and striatum, in many cases bilaterally, but not extratelencephalically (IT-type). To assess possible functional differences between these two neuron types, we characterized their laminar location in the cortex, their perikaryal size, and the morphology of their intrastriatal terminals. IT-type neurons were retrogradely labeled by tetramethylrhodamine-dextran amine (RDA)3k injection into the contralateral striatum, whereas their intrastriatal terminals were labeled anterogradely by biotinylated dextran amine (BDA)10k injection into the contralateral motor or primary somatosensory cortex. To label PT-type neurons and their ipsilateral intrastriatal terminals retrogradely, BDA3k was injected into the pontine pyramidal tract. We found that IT-type neuronal perikarya are medium-sized (12-13 microm) and located in layer III and upper layer V, whereas PT-type perikarya are larger (18-19 microm) and most commonly located in lower layer V. At the electron microscopic level, the intrastriatal terminals of both corticostriatal neuron types made asymmetric synaptic contact with spine heads and less frequently with dendrites. IT-type axospinous terminals were characteristically small (0.4-0.5 microm) and regular in shape, whereas PT-type terminals were typically large (0.8-0.9 microm) and often irregular in shape. Perforated postsynaptic densities were common for PT-type terminals, but not IT-type. The clear differences between these two corticostriatal neuron types in perikaryal size and laminar location in the cortex, and in the size and shape of their intrastriatal terminals, suggest that they may differ in the nature of their influence on the striatum.

Animals↗
PubMed1976

Inhibitory potentials produced in cortical cells by stimulation of the lateral hypothalamus in rabbits.

(1) Intracellular potentials were recorded from pyramidal tract (PT) and non-pyramidal tract (non-PT) cells of the frontal cortex in urethane-anesthetized rabbits and the effects of electrical stimulation of the lateral hypothalamus (LH) were examined on the ipsilateral side. (2) Latencies of antidromic spikes of PT cells evoked by stimulation of the medullary pyramidal tract (PYR) had a unimodal distribution with the mean at 4.0 msec. The mean conduction velocity of the pyramidal tract fibers was 10.5 m/sec. (3) Prolonged IPSPs were produced in PT and non-PT cells by single shock stimulation of LH (LH-IPSP). They were significantly longer lasting than those produced by PYR stimulation (PYR-IPSP). (4) The latencies of LH-IPSPs ranged from 1.7 to 25.0 msec and were divided into two groups. The latencies of PYR-IPSPs had a unimodal distribution ranging from 2.5 to 30 msec. (5) In a few non-PT cells, a sequence of brief depolarization and prolonged hyperpolarization occurred in response to LH stimulation. (6) In some non-PT cells, EPSPs which occasionally resulted in spike discharges were observed after LH stimulation. However, no excitation of PT cells was observed by LH stimulation.

Animals↗
PubMed1973

Input from muscle and cutaneous nerves of the hand and forearm to neurones of the precentral gyrus of baboons and monkeys.

1. The precentral bank of the Rolandic fissure of the cortical arm area has been explored with extracellular micro-electrodes in primates (baboons and monkeys) under nitrous oxide and oxygen anaesthesia, supplemented by small doses of Parkesernyl(R) and chloralose. The results in baboons and monkeys were the same.2. Single units were classified as pyramidal tract neurones or non-pyramidal tract neurones according to their antidromic responsiveness to stimuli applied in the dorsolateral funiculus at C1-2.3. Responses to electrical stimulation of the deep (motor) radial nerve, the deep palmar (motor) branch of the ulnar nerve, and the superficial (cutaneous) radial nerve could be recorded in the majority of neurones of the motor cortex provided that short trains of strong stimuli were used. Minimal responses to muscle nerve stimulation were observed in a few neurones at 1.4 x group I threshold, but most units reacted only with higher stimulus intensities (2-3 x group I threshold).4. The latencies to peripheral nerve stimulation were measured from the first peak of the incoming volley recorded at the root entry zone. The mean response latencies of pyramidal tract cells were between 20 and 25 msec; non-pyramidal tract cells were activated at slightly shorter mean latencies, the difference being significant for superficial radial nerve stimulation only (4 msec). These latencies are more than twice as long as those recorded in the postcentral gyrus, and the probability of discharge is lower than for postcentral neurones.5. A further difference between neurones of the postcentral and precentral gyrus is the pronounced convergence from different nerves and also from different modalities (cutaneous and muscle afferents) in units of the precentral cortex in contrast to units of the postcentral cortex.6. The high thresholds, necessary to activate precentral neurones by muscle nerve stimulation, make it unlikely that group I muscle afferents are involved. This is, furthermore, indicated by the lack of responsiveness to intravenous injection of succinylcholine which was, however, effective for driving neurones of the specific projection area for group I afferents, area 3a. The present experiments are consistent with the view that sensitivity of precentral neurones to muscle stretch (described in previous studies) is due to activation of secondary muscle spindle endings and their ascending pathways.7. The original hypothesis of a load compensating ;pyramidal reflex' with an oligosynaptic afferent contribution from the spindle primaries can be discarded. The present findings indicate that there is a feed-back from secondary muscle spindle afferents which, by way of a more complex pathway, can modulate the firing frequency of neurones in the motor cortex.

Animals↗
PubMed2006

Diffusion tensor imaging in acquired blind humans.

Retinal implants as a future possible therapy of blindness rely on an intact neural transmission from the retina to the primary visual cortex. By now it remains unknown, in how far the absence of afferent input in blindness affects also the organization of the optic radiation. Using diffusion tensor imaging (DTI), the non-invasive evaluation of large fiber tracts including the optic radiation has become possible. This method is sensitive to changes of the axonal state such as wallerian degeneration. We have compared DTI data from 6 acquired blind patients with those of a group of 11 healthy control subjects. Neither the relative anisotropy quotient of the visual fiber tract and the pyramidal tract showed a statistically significant difference between the blind patients and the control group nor did the absolute values of the relative anisotropy in the pyramidal tract and the visual fiber tract. There was no axonal degeneration of the optic radiation in late onset acquired blindness. With the optic pathways remaining intact, transmitting electric signals of retinal implants to the visual regions of the human brain seems to be possible even after decades of acquired blindness.

Adult↗
PubMed2003

Influence of dopamine on ventrolateral thalamic inputs in cat motor cortex.

Neuronal activity in several brain regions is modulated by dopaminergic inputs. When single neuronal activity/20 trials of single-pulse ventrolateral thalamic (VL) stimulation was extracellularly recorded in the in vivo, anesthetized cat motor cortex, iontophoretic application of dopamine (DA) elicited either suppression or, in a fewer instances, facilitation of evoked unitary responses. The predominant inhibition exerted by DA appeared to be consistent for successive trials, and a D(1), D(2), and D(1)/D(2) receptor antagonist restored the effect, thereby reflecting a possible coexistence of two DA receptors. By contrast, only a fewer neurons' response to DA displayed facilitation, which was not attenuated by DA antagonists. Moreover, subsequent trials with receptor agonist and antagonists induced inconsistent effects. Except for the jitters, single unit spikes showed invariant latency, which was constant during all recording parameters, and the mean latency remained unchanged. The modulatory effects mediated by DA did not reveal any substantial difference between short- and long-latency responses. Both pyramidal tract neurons and non-pyramidal tract neurons, determined on the basis of antidromic potentials from the pyramidal tract, responded to DA essentially in a similar manner. It appears that DA overall inhibits cat motor cortical neuronal activity in response to VL inputs. We propose that such DAergic inhibition of thalamocortical excitation in the motor cortex could be critical for ongoing sensorimotor transformation.

Animals↗
PubMed1997

[The diagnosis of amyotrophic lateral sclerosis supported by motor evoked potential and brain MRI studies].

A 57-year-old man developed severe muscle weakness and atrophy of the upper extremities within a five-month period. Neurological examination revealed severe weakness and atrophy in the scapular muscles and proximal and distal muscles of the upper extremities. Fasciculations were also observed in the various muscles of the upper extremities. There was neither muscle weakness, atrophy nor fasciculation in either his face, neck muscles or lower extremities. He had no pseudobulbar or bulbar signs. Tendon reflexes were mildly hyperactive in the jaw and lower extremities, and normal in the upper extremities. There were no pathological reflexes, spasticity or sensory disturbances. The needle EMG study revealed denervation potentials in all muscles of the upper extremities examined. The nerve conduction study revealed no findings of the conduction block. Cervical spine X-rays revealed the narrowing of the spinal foramens at the left C3/C4 and bilateral C4/C5, C5/C6, and C6/C7 intervertebral levels. In addition, magnetic resonance imaging (MRI) revealed compressions of the cervical cord at C4/C5 and C5/C6 intervertebral levels. These clinical and neuroradiological findings resembled those of the cervical spondylotic amyotrophy (CSA). However, the motor evoked potential (MEP) study revealed the pyramidal tract dysfunction above the levels of the pyramidal decussation. Furthermore, brain MRI revealed abnormal foci in both internal capsules which were characterized by hyperintense relative to cortical gray matter on T2-weighted images and still hyperintense to white matter on proton-density-weighted images. In addition, T2-weighted images demonstrated a low signal within the motor cortex and hyperintense lesions in the white matter of the precentral gyri. These MRI findings indicated the degeneration of the pyramidal tract and corresponded to those found in the patients with amyotrophic lateral sclerosis (ALS) which have been recently reported. It has been difficult to distinguish ALS from CSA. However, MEP and brain MRI studies were useful for distinguishing these two diseases in this patient. In addition, this patient showed typical MRI findings suggesting the degeneration of the pyramidal tract, although this patient had a relatively short course of illness and did not show obvious physical findings suggesting pyramidal tract dysfunction.

Amyotrophic Lateral Sclerosis↗
PubMed1990

[Neurological diseases in the aged].

In this paper, I described clinical and basic problems on neurology of the aged patients. These studies have been done in various institutions with many co-workers. 1) A PET study revealed some age differences on CBF, CMRO2, or CMRgl. But these results are not so rigid in which much of individual variations should be considered in interpretation. Calendar age is not always compatible to biological age. 2) Saccular aneurysms in the brain artery were found in 7.3% of 1200 routine autopsy series of the aged subjects. Aneurysms with external diameter exceeding 6 mm had been fatally ruptured in 14 (78%) of 18 subjects. 3) Variations of the pyramidal crossing are found responsible for bizarre clinical manifestations. Non-crossing component was more prominent in the right pyramidal tract; consequently, right pyramidal tracts including ventral and lateral one seemed to have more extensive representation in the spinal cord level. 4) I123-IMP SPECT study showed a reduced uptake in the area 4 or area 4-6 of the ALS patients. 5) I introduced a new simplified Wartenberg's maneuver, which is useful for detection of subtle pyramidal dysfunctions. 6) Cases with central pontine myelinolysis and those of paraneoplastic syndrome were presented with an emphasis on their patho-chemical mechanisms. 7) Lewis-Sumner syndrome showing multifocal persistent conduction block is not rare in the aged, in which we have already had some useful therapeutic methods. 8) Dementia complicated with neurodegenerative disease was discussed on its clinical and chemical features of mental disturbances. In ALS-dementia, CSF-homovanilic acid reduced significantly than in the control and L-dopa was effective in some patients. 9) Vascular and Alzheimer-type dementias were presented and discussed on their pathogenetic mechanism according to our recent studies with review of literature.

Adolescent↗
PubMed1989

Selective elimination of axons extended by developing cortical neurons is dependent on regional locale: experiments utilizing fetal cortical transplants.

In adult rats, cortical neurons that extend an exon through the pyramidal tract (a major subcortical efferent projection of the neocortex) are limited to layer V of about the rostral two-thirds of the neocortex. In neonates, however, pyramidal tract neurons are distributed throughout the neocortex, but all of those found in certain areas, such as the posterior occipital region (including primary visual cortex) selectively lose their pyramidal tract axon (Stanfield et al., 1982) yet maintain axon collaterals to other subcortical targets (O'Leary and Stanfield, 1985). To determine if the regional location of a developing pyramidal tract neuron critically influences the maintenance or elimination of the axon collaterals it initially extends, pieces of cortex from embryonic day 17 (E17) rat fetuses (exposed to 3H-thymidine on E15) were transplanted heterotopically into the cortex of newborn (PO) rats; rostral cortex was placed into the posterior occipital region (R----O), or posterior occipital cortex into a rostral cortical locale (O----R). The retrograde tracers Fast blue (FB) and Diamidino yellow (DY) were used to assay for the presence of specific populations of cortical projection neurons within the autoradiographically identified transplants. In terms of the extension and maintenance of pyramidal tract axons, the transplanted neurons behave like the host neurons of the recipient cortical region rather than like those of their site of origin. At P40, following FB injections into the pyramidal decussation on P34, pyramidal tract neurons are labeled within the O----R transplants, but none can be labeled within R----O transplants, although in the same R----O cases transplanted neurons are labeled by an injection of DY in the superior colliculus. However, at P13 pyramidal tract neurons can be identified within the R----O transplants, as well as in the host occipital cortex, following injections made on P9, a period when the distribution of pyramidal tract neurons in normal rats is widespread (Stanfield and O'Leary, 1985b). In a second series of host rats, on P34 FB was injected in the pyramidal decussation of the O----R cases, or in the superior colliculus of the R----O cases, and in both groups DY was injected into the region of contralateral cortex homotopic for the new location of the transplant. On P40, in both the O----R and R----O transplants, many neurons singly labeled with FB or DY are found, but no double dye-labeled cells are seen.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2005

'Importance sampling' in MS: use of diffusion tensor tractography to quantify pathology related to specific impairment.

Specific neurological impairments in multiple sclerosis (MS) are dependent on the pathology in clinically eloquent areas of the central nervous system. We aimed to use diffusion tensor fiber tracking to identify the pyramidal tracts and corpus callosum in MS patients, measure the apparent diffusivity within the tracts, and evaluate whether this would correlate with relevant disability scores. Dual-echo and diffusion tensor magnetic resonance imaging (DT-MRI) brain scans were obtained from 29 patients with relapsing remitting MS, and 13 age and gender matched normal controls. Voxels from pyramidal tracts and corpus callosum were automatically identified using a tractography based algorithm. Mean apparent diffusion coefficient (ADC(av)) was measured for these tracts. Scores of Expanded Disability Status Scale (EDSS) and Paced Auditory Serial Addition Test (PASAT) were obtained. The median EDSS score was 2.5 (inter-quartile range 2-3.25). The ADC(av) in the pyramidal tracts (p=0.02) and corpus callosum (p=0.0004) in patients was significantly higher than in controls. Pyramidal tracts ADC(av) was correlated with pyramidal FSS (r=0.5, p=0.008). Corpus callosum ADC(av) was correlated with PASAT (r=-0.58, p=0.001). Global T2 lesion volume did not correlate with the EDSS, but correlated with ADC(av) of the pyramidal tracts (r=0.6, p=0.0007) and corpus callosum (r=0.8, p<0.0001). T2 lesion volume within the pyramidal tracts and corpus callosum correlated with ADC(av) in the pyramidal tracts (r=0.6, p=0.0009) and corpus callosum (r=0.65, p=0.0002) respectively, but not with pyramidal FSS or PASAT score. DT-MRI quantifies pathology in specific white matter tracts and may increase the specificity of MRI in monitoring progression of motor and cognitive deficits in MS.

Acoustic Stimulation↗
PubMed2006

Pathological heterogeneity of the precentral gyrus in Pick's disease: a study of 16 autopsy cases.

This report concerns the upper motor neuron involvement in 16 autopsy cases of Pick disease with Pick bodies, including 11 cases reported by us previously. Prominent, circumscribed atrophy of the precentral gyrus, conspicuously in the lower portion, was noted in one case. Loss of Betz cells and astrocytosis of the precentral gyrus layer V were encountered in 15 cases (94%) and eight cases (50%), respectively. Appearance of Pick bodies and ballooned neurons in the precentral gyrus layer V was confirmed in seven cases (44%). Degeneration of the pyramidal tract in the medulla oblongata was noted in all 15 cases in which this structure was examined. Pyramidal signs were observed in four (67%) of the six cases that were neurologically sufficiently examined: hyperreflexia in four cases (67%), spasticity in one case (17%). Babinski sign was not encountered in any of the six cases. In all four cases having pyramidal signs, degeneration of the pyramidal tract was observed. In contrast, two cases having degeneration of the pyramidal tract did not develop pyramidal signs. In Pick's disease with Pick bodies, obvious involvement of the precentral gyrus and pyramidal tract was not previously noticed. Furthermore, we suggest that pyramidal signs in Pick's disease with Pick bodies have been underestimated.

Aged↗
PubMed2004

Ipsilateral actions of feline corticospinal tract neurons on limb motoneurons.

Contralateral pyramidal tract (PT) neurons arising in the primary motor cortex are the major route through which volitional limb movements are controlled. However, the contralateral hemiparesis that follows PT neuron injury on one side may be counteracted by ipsilateral of actions of PT neurons from the undamaged side. To investigate the spinal relays through which PT neurons may influence ipsilateral motoneurons, we analyzed the synaptic actions evoked by stimulation of the ipsilateral pyramid on hindlimb motoneurons after transecting the descending fibers of the contralateral PT at a low thoracic level. The results show that ipsilateral PT neurons can affect limb motoneurons trisynaptically by activating contralaterally descending reticulospinal neurons, which in turn activate spinal commissural interneurons that project back across to motoneurons ipsilateral to the stimulated pyramidal tract. Stimulation of the pyramids alone did not evoke synaptic actions in motoneurons but potently facilitated disynaptic EPSPs and IPSPs evoked by stimulation of reticulospinal tract fibers in the medial longitudinal fascicle. In parallel with this double-crossed pathway, corticospinal neurons could also evoke ipsilateral actions via ipsilateral descending reticulospinal tract fibers, acting through ipsilaterally located spinal interneurons. Because the actions mediated by commissural interneurons were found to be stronger than those of ipsilateral premotor interneurons, the study leads to the conclusion that ipsilateral actions of corticospinal neurons via commissural interneurons may provide a better opportunity for recovery of function in hemiparesis produced by corticospinal tract injury.

Animals↗
PubMed1987

Intrinsically directed pruning as a mechanism regulating the elimination of transient collateral pathways.

In neonatal cats, neurons in frontoparietal areas of the cerebral cortex have axons which branch, some collaterals project transiently to the cerebellum, whereas others project by way of the pyramidal tract to the brainstem and spinal cord and persist into the adult. If cerebrocerebellar collaterals are eliminated simply because they are exuberant, then experimentally removing the collaterals in the pyramidal tract should cause the normally ephemeral projections to the cerebellum to persist. To test this hypothesis, the pyramidal tract was cut unilaterally at the pontomedullary junction in 5-9-postnatal-day-old (PND) cats, and 35-68 days later the frontoparietal cortex ipsilateral to the pyramidotomy was injected with tritiated amino acids. From the end of the lesioned pyramidal tract, labeled axons were traced into pathways that descended aberrantly into the caudal medulla and spinal cord, but there was never any transported label in the cerebellum. In a second series of experiments, the fluorescent dye Fast blue (FB) was injected into the spinal cord (2-5 PND) prior to cutting the contralateral pyramidal tract (9-12 PND) to determine if the pyramidotomy caused the axotomized cortical neurons to die. There were no neurons labeled with FB in the frontoparietal cortex on the side of the pyramidotomy, but many retrogradely labeled neurons were present contralaterally in the cortex, suggesting that the pyramidotomy caused the death of all axotomized cortical neurons. In a final set of experiments, FB was injected into the spinal cord and the cerebellar cortex was ablated (2-3 PND) prior to cutting the pyramidal tract (9-72 PND). Cerebellar decortication results in the persistence of cerebrocerebral projections to the partially deafferented deep nuclei, therefore injections of Nuclear yellow (NY) or Diamidino yellow (DY) were made later (32-86 PND) into the cerebellar nuclei on the side of the decortication to determine if these projections persist in pyramidotomized cats. After pyramidotomies at 9 PND, there were no neurons labeled with fluorescent dyes in the ipsilateral frontoparietal cortex, indicating that the cerebrocerebellar collaterals, even under experimental conditions which normally cause them to persist, could not sustain the axotomized cortical neurons. Pyramidotomies at 24 PND or later did not cause all axotomized neurons to die since neurons labeled with FB were present in the ipsilateral cortex. These findings suggest that during development of corticosubcortical pathways there is a hierarchical.(ABSTRACT TRUNCATED AT 400 WORDS)

Amidines↗
PubMed1998

A quantitative study of the progress of myelination in the rat central nervous system, using the immunohistochemical method for proteolipid protein.

The temporal changes in intensity of myelination of the nervous pathways in 0 to 42-day-old Wistar rats were quantitatively analyzed by immunohistochemistry with anti-proteolipid protein and compared with that obtained by immunohistochemistry with anti-myelin basic protein. Immunohistochemistry was performed on paraffin-embedded tissue according to the standard ABC technique. Intensity of myelination was examined by an image analyzing system. We analyzed nine nervous pathways: corpus callosum, optic tract, internal capsule, spinal tract of the trigeminal nerve, inferior cerebellar peduncle, cerebellar white matter, pyramidal tract, medial longitudinal fasciculus, and cuneate fasciculus. The presence of immunoreactive fibers for proteolipid protein (PLP) in the spinal tract of the trigeminal nerve, medial longitudinal fasciculus and cuneate fasciculus was noted on postnatal day 0. Those of the corpus callosum, inferior cerebellar peduncle, cerebellar white matter, pyramidal tract and internal capsule were noted on day 7, and that of optic tract on day 14. The time required to reach the intensity of myelination of day 42 was day 14 for the cuneate fasciculus, day 21 for the spinal tract of the trigeminal nerve, inferior cerebellar peduncle and medial longitudinal fasciculus, day 28 for the optic and pyramidal tracts, day 35 for the corpus callosum and day 42 for the internal capsule and cerebellar white matter. The appearance of immunoreactive fibers for PLP was usually earlier than that for myelin basic protein (MBP) and the pattern of difference between PLP and MBP can be classified into three groups: (1) their time of appearance and progress are almost the same, as in the optic tract; (2) the appearance and progress of PLP occurs earlier than those of MBP, as in the pyramidal tract; (3) the appearance of PLP occurs earlier than that of MBP, but their progress is the same. Our findings revealed that the time of appearance and progress of myelination as measured by PLP are different among the nervous pathways, and that there is also a difference between PLP and MBP. This difference between PLP and MBP may indicate a functional difference between them.

Age Factors↗
PubMed1989

Absence of impulse activity in cortical neurons with transient projections to the cerebellum.

During the second postnatal week of development in cats, neurons in layer V of the primary sensorimotor cortex project transiently, by way of collaterals of pyramidal tract axons, to the cerebellum. All cerebrocerebellar collaterals are subsequently eliminated, while the collaterals in the pyramidal tract persist into the adult. To determine if the transience of the projection to the cerebellum could be due to the lack of functional activity in cerebrocerebellar projection neurons, single-unit extracellular recordings were made from neurons in the primary somatosensory cortex (S-I) in 8-14-day-old kittens. Projection neurons were identified by their antidromic activation from pyramidal tract or cerebellum. Collision experiments confirmed that some neurons had collateral projections to both structures. Recordings from both generally anesthetized as well as locally anesthetized, but awake preparations, indicated that pyramidal tract and cerebrocerebellar projection neurons never fired action potentials spontaneously or were orthodromically activated following stimulation of the medial lemniscus. Stimulation of the medial lemniscus did synaptically activate neurons in the cortex, but these were always located superficial to the antidromically activated projection neurons. These findings indicate that pyramidal tract and/or cerebrocerebellar S-I projection neurons are physiologically silent during the period of development that cortical axons are transiently present in the cerebellum, suggesting that cerebrocerebellar projections may be eliminated because of the lack of impulse activity.

Animals↗
PubMed2002

Frontotemporal dementia with cerebral intraneuronal ubiquitin-positive inclusions but lacking lower motor neuron involvement.

A case of frontotemporal dementia with cerebral intraneuronal ubiquitin-positive, tau- and alpha-synuclein-negative inclusions is reported. A 50-year-old female patient exhibited mental changes; however, no clinical evidence of motor neuron disease was detected in her 11-year history. Neuronal loss and spongiform changes were mainly found in the frontotemporal cortices. Degeneration of the pyramidal tract was observed. Depletion of Betz cells was observed, whereas motor neurons of the hypoglossal nuclei and spinal anterior horn were well preserved. Immunohistochemically, intraneuronal ubiquitin-positive, tau and alpha-synuclein -negative inclusions were present in the small neurons of the dentate gyrus, frontal cortices and putamen. Neither Betz cells nor the anterior horn cells contained any inclusions. Fragmentation of the Golgi apparatus was visible only in 2.2% of anterior horn cells. A large number of tau-positive glial structures lacking argyrophilia were seen in the area of the frontopontine tract in the cerebral peduncle. The pyramidal tract lesions of the present case may be based on frontal lobe degeneration with spread of lesions to the motor cortex. Except for the pyramidal tract lesions, our case is similar to cases of motor neuron disease-inclusion dementia.

Brain↗
PubMed1983

The crossed upgoing toe sign: a clinical study.

We compared the crossed upgoing toe sign with the plantar response as an indicator of pyramidal tract dysfunction in 125 normal subjects and 192 patients with neurological disorders. A positive crossed upgoing toe sign was associated significantly with a partial pyramidal tract lesion in the contralateral cerebral hemisphere with a frequency similar to that of Babinski's sign. Unlike Babinski's sign, however, the positive crossed upgoing toe sign was lost when pyramidal weakness was severe enough to produce paralysis of voluntary dorsiflexion of the great toe, and it was found only rarely with pyramidal tract lesions of the spinal cord. The crossed upgoing toe sign has little value as a sensitive indicator of a pyramidal tract lesion. It is potentially of limited value as an aid in determining the level of a pyramidal tract lesion (cerebral hemisphere versus spinal cord), but its usefulness is seriously impaired by the high frequency of false positive signs in normal subjects and patients with other neurological disorders.

Adolescent↗