[Functional topography of the human corpus callosum].

The concept of a topographical map of the corpus callosum (CC) has emerged from lesion studies in humans and from anatomical tracing investigations in other mammals. We conducted the first in vivo study aimed at outlining the topographical organization of the normal human CC, using non-invasive functional magnetic resonance imaging (fMRI). We tested cortical and callosal activation by the BOLD effect during simple sensory stimulation (tactile, gustatory and visual) and simple motor tasks in 38 volunteers.

Topographical organization of human corpus callosum: an fMRI mapping study.

The concept of a topographical map of the corpus callosum (CC) has emerged from human lesion studies and from anatomical tracing investigations in other mammals. Over the last few years, a rising number of researchers have been reporting functional magnetic resonance imaging (fMRI) activation in white matter, particularly the CC. In this study, the scope for describing CC topography with fMRI was explored by evoking activation through simple sensory stimulation and motor tasks.

Mirror-image discrimination and reversal in the disconnected hemispheres.

Two callosotomized patients and 24 neurologically normal subjects performed simple binary discriminations between upright letters flashed in one or other visual field. Where discrimination of the letters F and R by name either showed a left-hemisphere advantage or no hemispheric effect, discrimination of whether the same letters were normal or backward showed a right-hemisphere advantage. These results suggest that discrimination of mirror-image letters depends on matching to an exemplar, for which the right-hemisphere is dominant, while letter naming depends on abstract category recognition.

Now you see it, now you don't: variable hemineglect in a commissurotomized man.

We describe the case of a callosotomized man, D.D.V.

Contribution of posterior corpus callosum to the interhemispheric transfer of tactile information.

Three total and three partial callosotomy patients underwent neuropsychological testing to evaluate interhemispheric transfer of tactile information. Tactile transfer is required to name objects presented to the left hand, to compare objects held in either hand, and to transfer topological information between hands. Tactile Naming, Same-Different Recognition, and Tactile Finger Localization Tests (intra- and intermanual tasks) were administered as specific tools.

Bilateral cortical representation of the trunk midline in human first somatic sensory area.

The cortical representation of the trunk zone in the human first somatosensory area was studied with functional magnetic resonance imaging (fMRI) to establish whether the cutaneous regions close to the midline are represented in this area of both hemispheres. Cortical activation foci evoked by unilateral tactile stimulation of ventral trunk regions were detected in the postcentral gyrus of the contralateral hemisphere slightly medial to or just behind the omega-shaped region of the central sulcus and in the anterior bank of the postcentral sulcus. These regions probably correspond to the trunk ventral midline representation zones of areas 3a-3b and 1-2, respectively.

Direct synaptic connections between corticothalamic axon terminals and interneurons in the cat ventrobasal complex.

Lesion-induced degeneration was combined with immunocytochemistry to study, with electron microscopy, the synaptic connectivity between corticothalamic axon terminals from the first and second somatosensory areas and local circuit neurons of the ipsilateral ventrobasal complex (VB), selectively labelled with an antibody raised against gamma-aminobutyric acid (GABA). Four days from the cortical ablation many degenerating axon terminals, forming asymmetric synapses, were found on dendritic trees of both labelled and unlabelled neurons of VB and occasionally on presynaptic dendrites. The main finding of the present paper is that 64.

Postnatal development of the glutamate vesicular transporter VGLUT1 in rat cerebral cortex.

The expression of the vesicular glutamate transporter VGLUT1 in the rat neocortex was studied during postnatal development using immunocytochemistry and Western blotting. At all ages, VGLUT immunoreactivity is localized to puncta that coexpress the presynaptic marker synaptophysin. VGLUT1 immunoreactivity is faint at birth, increases in the subplate during the first postnatal week, invades the supragranular layers in the second week and reaches the adult pattern at P20-P30.