As diffusion tractography is increasingly used to generate quantitative measures to address clinical questions, it is important to characterise the inter-session reproducibility and inter-subject variability of these measures. Here, we assess the reproducibility and variability of diffusion tractography measures using diffusion data from 8 subjects scanned 3 times. We used probabilistic tractog...

A 53-year-old woman complained about a 2-year-history of progressive tetraparesia with global brisk reflexes, global amyotrophy and fasciculations. As her clinical picture suggested a motor neuron disease, she performed electroneuromyography (ENMG) unvealing anterior horn compromise and brain MRI study with the so-called “bright tongue sign” (Figure), in this context suggestive of amyotrophic l...

A 45-year-old man presented with 2-month-history of progressive gait disturbances and behavioral changes. Examination showed vibration sense compromise and pyramidal signs of release. Blood test revealed low serum vitamin B12 (120 pg/mL; normal range>200 pg/mL). Brain MRI disclosed hyperintense signal in corticospinal tracts, a similar pattern observed in motor neuron disease (MND) (Figure). Re...

Genetic mosaics offer an excellent opportunity to analyze complex gene functions. Chimeras consisting of mutant and wild-type cells provide not only the avenue for lineage-specific gene rescue but can also distinguish cell-autonomous from non-cell-autonomous gene functions. Using an independent genetic marker for wild-type cells, we constructed Dab1(+/+) <--> Dab1(-/-) chimeras with the aim of ...

It has been hypothesized that the magnocellular red nucleus (RNm) contributes to compensation for motor impairments associated with lesions of the pyramidal tract. To test this hypothesis, we used stimulus triggered averaging (StTA) of electromyographic (EMG) activity to characterize changes in motor output from the red nucleus after lesions of the pyramidal tract. Three monkeys were trained to...

Slow finger movements in man are not smooth, but are characterized by 8- to 12-Hz discontinuities in finger acceleration thought to have a central source. We trained two macaque monkeys to track a moving target by performing index finger flexion/extension movements and recorded local field potentials (LFPs) and spike activity from the primary motor cortex (M1); some cells were identified as pyr...

Hemiparesis may be the result of lesions in the contralateral pyramidal tract in the brain or, less frequently, in the ipsilateral pyramidal tract in the upper cervical spinal cord. However, although rare, multiple lesions that simultaneously occur in both of these regions may be the cause of acute hemiparesis, and the clinical symptoms can often be misdiagnosed as a stroke. In addition, the co...

BACKGROUND AND PURPOSE Early evaluation of the pyramidal tract is a prerequisite in patients with intracerebral hemorrhage (ICH) in order to decide the optimal treatment or to assess appropriate rehabilitation. The aim of this study was to evaluate and predict the neuromotor and functional outcome of an ICH by using diffusion tensor imaging (DTI) in the acute phase. MATERIALS AND METHODS Eigh...

Beta2 frequency (20-30 Hz) oscillations appear over somatosensory and motor cortices in vivo during motor preparation and can be coherent with muscle electrical activity. We describe a beta2 frequency oscillation occurring in vitro in networks of layer V pyramidal cells, the cells of origin of the corticospinal tract. This beta2 oscillation depends on gap junctional coupling, but it survives a ...