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PubMed1994

Pericruciate fibres to the red nucleus and to the medial bulbar reticular formation.

Extracellular single activity was recorded from pericruciate neurons in anaesthetized, paralysed, artificially ventilated cats. A total of 455 neurons were classified antidromically according to their sites of termination along the corticospinal tract and whether they sent collateral branches to the ipsilateral red nucleus and/or to the contralateral nucleus reticularis gigantocellularis. It was found that the majority of the branching fibres that reached the most caudal segments of the cord were fast conducting, while the slower branching axons tended to terminate at more rostral levels of the corticospinal tract. Most of the branching fibres terminated at bulbar and cervical levels (153/182: 84%), and the remaining ended at thoracic (21/182: 11.5%) and at lumbar (8/182: 4.4%) segments of the cord. The non-corticospinal, pyramidal tract fibres branched more (56%) than the corticospinal fibres (26.6%). Within the corticospinal neurons, the degree of branching decreased with distance along the spinal cord. While 57.5% of the pericruciate fibres that projected only as far as the pyramidal tract were slow conducting, the majority of the corticospinal neurons were fast conducting (74.6%). Both pyramidal tract and corticospinal neurons that sent branches to one or to the two sites tested were significantly faster conducting than the neurons which did not branch. A total of 101 corticorubral and corticobulbar neurons which did not respond to pyramidal tract stimulation was also recorded. The data can be of significance in the understanding of co-ordination of different muscles in order to couple movement and posture into a common act. The results are discussed from this point of view.

Animals↗

PubMed1996

Thalamic metbolism and corticospinal tract integrity determine motor recovery in stroke.

We studied the role of remote metabolic depressions and pyramidal tract involvement regarding motor recovery following a first hemiparetic ischemic stroke. In 23 patients the regional cerebral glucose metabolism (rCMRGlu) was measured with positron emission tomography and the location and spatial extent of the stroke lesions were assessed by magnetic resonance imaging. Motor impairment during the acute and chronic stages (4 weeks after stroke) was determined by a motor score and recordings of magnetic evoked motor potentials. Twelve patients recovered significantly, whereas 11 patients retained a disabling hemiparesis. In contrast to patients with good motor recovery, rCMRGlu was severely depressed in the thalamus on the lesion side in patients with poor motor recovery. This patient group also showed more severe damage to the pyramidal tract on magnetic resonance images and a more pronounced reduction of the magnetic evoked motor potential amplitude. Neither the size of the stroke lesions nor the spatial extent of the lesional and remote rCMRGlu depressions outside the thalamus correlated with the thalamic hypometabolism and the improvement of the motor score. We conclude that preservation both of parts of the pyramidal tract and of the thalamic circuitry is a major determinant for the quality of hand motor recovery following acute brain ischemia in the adult.

Adult↗

PubMed2003

Neurological diseases and accidental falls of the aged.

OBJECTIVE: To assess the influence of central and peripheral neurological diseases on the incidence of accidental falls of the aged. DESIGN: 1. Case-control study with cross-section at two years and 2. prospective study in a follow-up up to seven years thereafter. SETTING: Sample of a population study including all 589 inhabitants older than 70 years in three rural communities. PARTICIPANTS: 44 subjects with recurrent falls during two years' follow-up and 41 age and sex matched controls. MEASURES: Neurological diseases and evaluation, other diseases, and incidence of falls during the seven years' follow-up after the cross-section. RESULTS: Compared with the controls the fallers had more often multiple vascular lesions of the brain, extrapyramidal symptoms and signs as well as lumbar nerve root lesions. In the follow-up, cerebrovascular disease, especially with multiple lesions and residual signs of pyramidal tract lesion, Parkinson's disease, rigidity and hypokinesia were associated with increases risk of falling. In multivariate analysis signs of pyramidal tract lesion, rigidity and prior falls were predictors of falls. An increase in the incidence of falls was also associated with vascular lesion of the cerebellum, cerebral white matter hypodensity and cortical atrophy visible on CT. CONCLUSIONS: High incidence of falls was associated with chronic central nervous system diseases. Lumbar root lesions were more common among the fallers but did not increase the incidence of falls in the follow-up. Neurological diseases and evaluation, other diseases, and incidence of falls during the seven years' follow-up after the cross-section. Compared with the controls the fallers had more often multiple vascular lesions of the brain, extrapyramidal symptoms and signs as well as lumbar nerve root lesions. In the follow-up, cerebrovascular disease, especially with multiple lesions and residual signs of pyramidal tract lesion, Parkinson's disease, rigidity and hypokinesia were associated with increased risk of falling. In multivariate analysis signs of pyramidal tract lesion, rigidity, and prior falls were predictors of falls. An increase in the incidence of falls was also associated with vascular lesion of the cerebellum, cerebral white matter hypodensity and cortical atrophy visible on CT.

Accidental Falls↗

PubMed1980

Specific and non-specific multiple unit activities during pentylenetetrazol seizures. I. Animals with 'encéphale isolé'.

The present report describes the sequence of activation and deactivation of multiple unit activities (MUA) in the brain stem reticular formation and pyramidal tract, in relation to the clinical seizure and electroencephalographic and electromyographic tonic-clonic discharges induced by pentylenetetrazol (PTZ), in cats immobilized by high spinal transection ('encéphale isolé'). Threshold doses of PTZ (20 mg/kg i.v.) produced the following events: (1) Significant increase in mesencephalic and pontine MUA, anticipating 2 (+/- 1) sec the clinical and electromyographic seizures and 5 (+/- 2) sec the onset of EEG and pyramidal tract tonic-clonic discharges. (2) A further increase in mesencephalic and pontine reticular MUA and electromyogram MUA at the onset of EEG and pyramidal tract tonic-clonic discharges. (3) Significant decrease of EEG spike activity and pyramidal tract MUA to levels below the control period 16 (+/- 8) sec later, while mesencephalic and pontine MUA and electromyogram remained very high. Results suggest that (i) PTZ-induced seizures start in the brain stem reticular formation and propagate to muscles by at least two different pathways: a pyramidal and an extrapyramidal pathway; (ii) that inhibition of seizure activity may start at the cortical level.

Action Potentials↗

PubMed2002

History of the extensor plantar response: Babinski and Chaddock signs.

The testing of reflexes involving the lower extremities is a pivotal part of the modern neurological examination. The normal response to noxious stimulation of the foot is plantar flexion of the toes, causing them to curl downward toward the undersurface of the foot. In 1896, Joseph Babinski described an extensor toe response that he claimed was a consistent finding among patients with pyramidal tract lesions of the cortex, subcortex, brain stem, or spinal cord. He considered it a distinct sign of organic disease and found it to be absent in cases of hysterical weakness. Charles Gilbert Chaddock admired the work of Babinski and described a modification of the Babinski technique, demonstrating that stimulation of the lateral surface of the foot could induce the same type of toe extension in patients with pyramidal tract lesions. The two reflexes are complementary, and each can occur without the other, although both are usually present in cases of pyramidal tract impairment. Although these two reflexes are the most commonly described pathological reflexes indicative of pyramidal tract disruption, the names of other celebrated neurologists are also linked to the study of extensor toe signs, each having identified a variant of the Babinski sign.

History, 19th Century↗

PubMed2003

Clinicotopographical correlation of corticospinal tract stroke: a color-coded diffusion tensor imaging study.

UNLABELLED: Background- Small capsular strokes are difficult to assess with regard to the precise location and the extent of pyramidal tract damage with conventional brain imaging. Color-coded diffusion tensor imaging (CDTI) provides a means to visualize the course of the corticospinal tract within the white matter. In addition to T2-weighted MRI, diffusion-weighted MRI and CDTI were used to analyze the topographical patterns of small lacunar corticospinal tract strokes. METHODS: We examined 15 patients with pyramidal tract strokes in the subacute phase (days 3 to 7). Lesions were identified on diffusion-weighted MRI and superimposed on CDTI images. The anatomic location and pattern of the lesion were visualized on CDTI with regard to the corticospinal tract and subsequently compared with the clinical presentation. In addition, infarct areas were evaluated with quantitative parameters: mean diffusivity and lattice anisotropy index of lesions were determined. RESULTS: We identified 5 different patterns of corticospinal tract stroke falling into 2 clinical subgroups: (1) those with marked deficits and minor improvement (6/15) and (2) those with good recovery (9/15). Group 1 had long lesions centered in the pyramidal tract, involving the basal ganglia (anterior choroidal artery); group 2 lesions were very small and/or located anteriorly and medially (periventricular anterior choroidal artery territory; thalamogeniculate, tuberothalamic, and lateral striate branches). Lesions showed a significant increase of mean diffusivity and decrease of lattice anisotropy. CONCLUSIONS: CDTI allows in vivo differentiation of distinct subcortical stroke subtypes. Improved anatomic definition of lesion localization using CDTI may help in better establishing the prognosis for patients after subcortical stroke.

Aged↗

PubMed1986

Corticospinal facilitation of hand muscles during voluntary movement in the conscious monkey.

1. The method of spike-triggered averaging has been used to detect a direct influence of pyramidal tract neurones on the activity of hand and forearm muscles in conscious monkeys trained to perform repetitive movements of the hand and fingers. Gross electromyograms (e.m.g.s) from individual muscles were rectified and synchronously averaged with respect to the discharge of single, antidromically identified pyramidal tract cells in the 'hand' area of the pre-central gyrus. 2. The presence in an average of a post-spike facilitation which could be revealed reproducibly from successive epochs of recording and was clearly larger than the biggest fluctuations seen in pseudo-randomly triggered averages of the same e.m.g. data, was taken to indicate a direct cortico-motoneuronal excitatory influence. 3. 55% of cortical neurones analysed showed post-spike facilitation in one or more recorded muscle and 7% showed post-spike suppression. In terms of the total number of muscle-neurone combinations analysed, the proportions showing post-spike effects were 18 and 1% respectively. These figures have been influenced by the pre-selection of neurones for analysis according to restrictive criteria. The neurones selected (a) were recorded at cortical loci where weak intracortical microstimulation could evoke finger movements, (b) could be activated antidromically at short latency by medullary pyramidal tract stimulation, (c) showed natural discharge activity which was clearly modulated in relation to voluntary finger movements, and (d) were located in the anterior bank of the central sulcus. The results provide some evidence to vindicate these criteria. 4. The strongest post-spike facilitation observed had a peak which was 42% higher than the average pre-spike level of e.m.g. activity, but most were within the range 5-20%. Facilitation peaks below about 3% could not have been resolved from the 'noise' in the averages. The mean latency from cell discharge in the cortex to the start of the post-spike facilitation was 11.2 ms (range 7.4-17.2) for intrinsic hand muscles and 9.8 ms (range 4.1-15.0) for forearm muscles. These latencies were compared with the latencies of responses to intracortical microstimulation and to stimulation of the medullary pyramidal tract. 5. Evidence was obtained suggesting that the latency for cortico-motoneuronal activation of an individual motor unit was commonly subject to considerable variability and that different motor units of a muscle could be facilitated by the one cortical neurone at different latencies. These factors are thought to contribute to an elongation of the time course of post-spike facilitation.(ABSTRACT TRUNCATED AT 400 WORDS)

Action Potentials↗

PubMed1985

Stimulus- and amino acid-induced calcium and potassium changes in rat neocortex.

Local changes in extracellular concentration of calcium ions, [Ca2+]o, and potassium ions, [K+]o, elicited through ionophoretic applications of the excitatory amino acids glutamate (Glu) and aspartate (Asp) or through cortical surface stimulations were measured in the rat motor cortex using paired ion-selective microelectrodes. Glu or Asp applications produced dose-dependent decreases in [Ca2+]o from a base line of 1.25 mM to as low as 0.08 mM and increases in [K+]o from 2.8 mM to as high as 13.3 mM. These ionic changes were accompanied by negative DC potential shifts of up to 15 mV. [K+]o changes were practically constant in all cortical layers, whereas [Ca2+]o changes were variable with depth, showing two localized marked maximums. One was observed in the superficial layers, 150-300 microns below cortical surface and the second at 1,100-1,300 microns, in a region corresponding roughly to layer V. Application of tetrodotoxin (TTX) onto the cortical surface abolished stimulus-evoked ionic changes, whereas amino acid-induced [Ca2+]o changes remained practically unaltered, and [K+]o changes were reduced by 20% on average. Selective degeneration of the pyramidal tract neurons was induced by performing chronic lesions of the pyramidal tract at the bulbar level. In these conditions, laminar profiles of amino acid-induced [Ca2+]o changes were considerably altered in the corresponding motor cortex. The maximum Ca2+ changes were then reduced by two-thirds, and the [Ca2+]o signals were practically constant throughout the cortex. Local cobalt (Co2+) or manganese (Mn2+) applications could abolish amino acid-evoked [Ca2+]o changes, whereas most of the [K+]o changes persisted. gamma-Aminobutyric acid applications could decrease [Ca2+]o signals to a large extent, whereas [K+]o changes were diminished by only 15-25% on average. These results show that the putative neurotransmitters Glu and Asp induce significant changes in [Ca2+]o and [K+]o in the rat cerebral cortex and indicate the possible origin of the ion fluxes in terms of neuronal elements and ionic channels: in particular, they indicate that the major part of the amino acid-induced [Ca2+]o maximum decreases can be ascribed to Ca2+ movements through channels located very likely on the pyramidal tract neurons in the motor cortex. They also indicate that significant reductions of the extracellular space volume occur during excitatory amino acid applications.

Amino Acids↗

PubMed1998

Subcortical frontal lesions on MRI in patients with motor neurone disease.

MRI was performed in 32 patients with motor neurone disease (26 men and 6 women, aged 40-77 years) and in a control group of 21 subjects. Of the patients studied, 19 had definite and 11 probable amyotrophic lateral sclerosis (ALS) and two had progressive bulbar palsy. In 10 patients there were asymmetrical bilateral foci of increased signal intensity on proton-density and T2-weighted images, confined to the white matter. Two patients had only cortical frontal atrophy and slightly increased ventricular size, whereas 20 had normal MRI. The focal lesions were not confined to corticospinal tracts, but were also observed in subcortical frontal areas. While the lesions along the corticospinal tracts correspond to pyramidal tract degeneration, the subcortical foci correlate with degeneration of the frontal bundles and indicate generalised involvement of the central nervous system.

Adult↗

PubMed2005

Neuropathologic characteristics of brainstem lesions in sporadic Creutzfeldt-Jakob disease.

We investigated whether the brainstem is affected by the pathologic process of sporadic Creutzfeldt-Jakob disease (sCJD), with particular attention to brainstem atrophy, neuronal loss, pyramidal tract degeneration, and prion protein (PrP) deposition, in 33 patients with sCJD. Brainstem atrophy, particularly in the pontine base, was relatively prominent in patients with disease of unusually prolonged duration. Neuronal loss and pyramidal tract degeneration were also identified in some but not all patients with prolonged disease. Neuronal loss was relatively prominent in the pontine nucleus and less so in the substantia nigra and inferior olivary nucleus; motor nuclei of the brainstem tegmentum were well preserved. PrP deposition was present in the brainstem in all patients, and was identified predominantly in the substantia nigra, quadrigeminal body, pontine nucleus, and inferior olivary nucleus. PrP deposition was less prominent in the red nucleus and tegmentum of the pons and medulla oblongata. PrP deposition occurred least or not at all in the pyramidal tract. The density of PrP deposition in the sCJD brainstem was not associated with disease duration or neuronal degeneration until the late stage. Our results show that atrophy, neuronal loss, and pyramidal tract degeneration occur in the sCJD brainstem, particularly in patients with an unusually prolonged disease course. These findings are not associated directly with PrP deposition and may reflect end-stage sCJD. No VV1, VV2, or MV2 cases were included in our study; however, we suggest that widespread and relatively stereotypic PrP deposition is a consistent pathologic feature of sCJD, at least in MM1 sCJD patients. Although accumulation of PrP in the brainstem appears to be an early pathologic event in sCJD, and may remain into the late disease stage, the brainstem remains relatively resistant to the pathologic process of sCJD.

Aged↗

PubMed2003

Diffusion tensor imaging for long-term follow-up of corticospinal tract degeneration in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a predominantly clinical and electromyographic diagnosis. Conventional MRI reveals atrophy of the motor system, particularly the pyramidal tract, in the advanced stages but does not provide a sensitive measure of disease progression. Three patients with different principal symptoms of ALS, i.e., with predominant involvement of the upper (UMN) or lower (UMN) motor neurons, or bulbar disease, respectively, underwent serial clinical examination including lung function tests, conventional MRI, and diffusion tensor imaging (DTI). MRI demonstrated changes in of the pyramidal tract without measurable variation on follow-up. The patient with UMN involvement showed remarkable progressive loss of diffusion anisotropy in the pyramidal tract. DTI might be useful, together with clinical follow-up, as an objective morphological marker in therapeutic trials.

Amyotrophic Lateral Sclerosis↗

PubMed1998

[Clinical application of multi-shot diffusion EPI in neurological disease].

Using the multi-shot EPI method we investigated the clinical application of diffusion weighted imaging (DWI) in the diagnosis of neurological disease. The multi-shot method provided better susceptibility artifact-free DWI than the single-shot method particularly in the region of the posterior cranial fossa. DWI using the multi-shot EPI method readily shows the pyramidal tract extending from the internal capsule to the brainstems which is inaccessible by the conventional single-shot EPI method, and providing three-dimensional and distinct images of pyramidal tract changes in amyotrophic lateral sclerosis or cerebral infarction with pyramidal tract disturbance. Our findings suggest that the use of DWI with the multi-shot EPI method would provide a technique for the easy diagnosis and evaluation of various neurological diseases.

Amyotrophic Lateral Sclerosis↗

PubMed1979

Intracellular synaptic potentials of primate motor cortex neurons during voluntary movement.

An intracellular recording technique was applied to the precentral motor cortex of the unanesthetized, chronically behaving monkey. Postsynaptic potentials, responsible for an initiation of the voluntary movement, were recorded. In total, 22 pyramidal tract neurons (PTNs) and 40 non-pyramidal tract neurons (non-PTNs) were successfully penetrated in 5 monkeys while the monkey was performing a flexion-extension wrist movement after a visual cue (reaction time, 200--350 msec). The neurons showed a negative membrane potential shift of at least 30 mV for more than 30 sec. A slowly rising PSP appeared 80--180 msec after the visual cue, and was 70--180 msec prior to an onset of the movement. Spike activities were superimposed upon this slow PSP with 20--80 msec rise time and 2--6 mV depolarization (8 PTNs and 6 non-PTNs). Since these depolarizations were variable in magnitude and latency, these were considered to be summated potentials of small EPSPs and hidden IPSPs. Membrane resistance was measured from an IR drop by a hyperpolarizing current (1.2 X 10(-9) A) passed through a recording electrode, and was 3.5 +/- 1.7 Momega in 18 PTNs and 4.5 +/- 2.5 Momega in 28 non-PTNs. There was a linear relationship in PTNs between membrane resistance and antidromic latency from the pontine pyramid. Because of the time course of PSPs, their possible dendritic origins were discussed.

Animals↗

PubMed1982

Selective retrograde transport of D-aspartate in spinal interneurons and cortical neurons of rats.

Retrograde labeling of neuronal elements in the brain and spinal cord has been investigated by autoradiographic techniques following injections of D-[3H]aspartate (asp), [3H] gamma-aminobutyric acid (GABA) or horseradish peroxidase (HRP) in the medulla and spinal cord of rats. Twenty-four hours after D-[3H]asp injections focused upon the cuneate nucleus, autoradiographic labeling is present over fibers in the pyramidal tract, internal capsule and over layer V pyramids in the forelimb representation of the sensorimotor cortex. After [3H]GABA injections in the same nucleus no labeling attributable to retrograde translocation can be detected in spinal segments, brain stem or cortex. Conversely, injections of 30% HRP in the cuneate nucleus label neurons in several brain stem nuclei, in spinal gray and in layer V of the sensorimotor cortex. These observations give further support to the proposed existence of a selective retrograde transport of D-[3H]asp and are consistent with the available evidence which indicates that the corticodorsal column nuclei path use glutamate and/or aspartate as neurotransmitter(s). D-[3H]Asp injections focused on the dorsal horn at cervical segments label a fraction of perikarya of the substantia gelatinosa and a sparser population of larger neurons in laminae IV to VI for a distance of 3-5 segments above and below the injection point. No brain stem neuronal perikarya appear labeled following spinal injections of D-[3H]asp although autoradiographic grains overlie pyramidal tract fibers on the side contralateral to the injection. This labeling however has not been observed rostral to lower pontine levels nor over cortical neurons at any of the survival times used in the present experiments (6-72 h). As in cases with cuneate injections this pattern of labeling contracts with that obtained after spinal injections of either [3H]GABA or HRP. Although labeling of neocortical neurons has not been observed after spinal injections of D [3H]asp, possibly as a result of the length of corticospinal axons, retrograde labeling of these elements for at least some distance may be taken as suggestive of a special affinity of their terminals for glutamate and/or aspartate.

Animals↗

PubMed1977

Spike-wave rhythms in cat cortex induced by parenteral penicillin. II. Cellular features.

Epileptiform potentials, consisting of spontaneous, generalized bursts frequently assuming a 3/sec spike-wave form and tonic clonic electrographic seizures were produced in 32 lightly anesthetized cats by parenteral injections of penicillin. The activity of 83 identified pyramidal tract cells and 207 cortical non-pyramidal tract cells was correlated with the surface EEG. The majority of both cell types generated depolarizations and action potentials with the EEG spike. Hyperpolarizations, during which cells were inhibited, followed the depolarizations. The depolarizations responded to injected current as if they were generated by excitatory synapses; and hyperpolarizations to injected current and chloride ions as if generated by proximal inhibitory synapses. Attempts to identify a class of neurons firing during the surface-negative wave (presumed inhibitory interneurons) were unsuccessful. Forty-two units were recorded during tonic-clonic seizures. Intracellular records disclosed tonic oscillations of membrane potential, phased bursting with "depolarization shifts", abortive action potentials and post-ictal hyperpolarizations. Cell somata often depolarized to the point of inactivation, but axons continued to fire at high rates. These results emphasize the role of EPSP-IPSP sequences in the generation of spike-wave rhythms.

Action Potentials↗

PubMed1998

Three-dimensional anisotropy contrast (3DAC) magnetic resonance imaging of the human brain: application to assess Wallerian degeneration.

Three-dimensional anisotropy contrast (3DAC) magnetic resonance imaging is a new algorithm for the treatment of apparent diffusion tensor using the three primary colors. To determine if 3DAC has a clinical application for human brain, six normal volunteers and twenty patients with supratentorial cerebrovascular accidents were examined using clinical magnetic resonance imaging (MRI), and the changes in the 3DAC images associated with Wallerian degeneration of the pyramidal tract were evaluated. The 3DAC images exhibited impressive anatomical resolution. In all chronic stage patients with hemiparesis, the colors in the pyramidal tract were faded. Patients examined during the acute stage who later recovered from hemiparesis had no visible changes of the 3DAC image, whereas patients who recovered poorly showed distinct color fading in the pyramidal tract within 14 days following stroke. In conclusion, very fine anatomical structures are visible on 3DAC images, and it can be used as a diagnostic tool for the human brain.

Aged↗

PubMed1983

Transient cerebrocerebellar projections in kittens: postnatal development and topography.

Orthograde and retrograde labeling techniques were used to study the ontogenesis of transient cerebrocerebellar projections in kittens. Tritiated amino-acid or horseradish peroxidase injections were made into the coronal gyrus of the primary somatosensory cortex of kittens 1-70 postnatal days old. Orthogradely labeled axons were observed bilaterally in the superior and inferior cerebellar peduncles in kittens between 6 and 49 postnatal days of age. Most cerebrocerebellar axons labeled on the ipsilateral side arise from the pyramidal tract as it courses through the pontine nuclei. These axons descend through the pontine tegmentum as a diffusely organized corticotegmental tract and enter the ipsilateral superior cerebellar peduncle. Fewer cerebrocerebellar axons leave the pyramidal tract caudal to the pontine nuclei and project into the contralateral superior cerebellar peduncle. Cerebrocerebellar projections through the superior cerebellar peduncles terminate primarily in the cerebellar nuclei, where they are localized in the interpositus nuclei and in immediately adjacent areas of the dentate and fastigial nuclei. More caudally, labeled axons exit from the pyramidal tract and take a superficial route around the ventrolateral brainstem into the inferior cerebellar peduncles bilaterally. These projections are more numerous contralaterally and are directed primarily to the internal granule cell layer of the posterolateral folia of the anterior lobe, the posteromedial simplex lobule, and the dorsal paramedian lobule. Horseradish peroxidase injections were made into the cerebellar posterior lobe and deep nuclei and the results from these cases showed that the cerebrocerebellar pathway originates from pyramidal neurons in layer V primarily in the coronal, the precoronal, and the anterior and posterior sigmoid gyri on both sides. In these gyri, many of the HRP-positive neurons were found in clusters of two to five neurons, aligned in anterior-posterior strips. The results from all experiments provide evidence about the ontogeny of cerebrocerebellar projections. Projections through the superior cerebellar peduncles generally develop at 6-8 postnatal days of age, whereas projections through the inferior cerebellar peduncles first are seen at 8-10 days postnatally. Cerebrocerebellar projections reach their maximum development in the second postnatal week but sharply decrease in density during the third postnatal week. No cerebrocerebellar projections were observed after the seventh postnatal week of development. Possible functional implications for this transient projection are discussed.

Animals↗

PubMed2005

Diffusion tensor tractography in patients with cerebral tumors: a helpful technique for neurosurgical planning and postoperative assessment.

OBJECTIVE: To demonstrate the role of diffusion tensor tractography (DTT) in preoperative mapping of eloquent tracts in relation to cerebral tumors and to determine whether it is helpful for neurosurgical planning and postoperative assessment. METHODS AND MATERIALS: Sixteen patients with brain tumors underwent diffusion tensor imaging (DTI). The pyramidal tract, corpus callosum and optic radiation were reconstructed and the exact location of a lesion with respect to these tracts was observed to design a reasonable surgical plan for preserving vital tracts while maximizing tumor resection. After surgery, DTI was performed again and these tracts were evaluated to investigate the surgical outcomes. Twenty-four patients with suspicion of pyramidal tract involvement were also evaluated as a control group. RESULTS: The relationship between tracts and tumors was classified as three types: type I is simple displacement, type II is displacement with disruption and type III is simple disruption. Twelve cases involved in pyramidal tract (DTT group), one was type I with reduction of displacement after surgery, nine were type II with reduction of displacement and other two were type III without any improvement. The extent of tumor resection (p = 0.045) and postoperative improvement of locomotive function (p = 0.015) of DTT group were significantly higher than those of control group. Corpus callosum was involved in seven cases, three were type II with reduction of displacement and four were type III without any improvement. Optic radiation was involved in three cases, all were type I with reduction of displacement. CONCLUSION: DTT allowed for visualization of the exact location of tumors relevant to eloquent tracts and was found to be beneficial in the neurosurgical planning and postoperative assessment.

Adult↗