Individual fMRI maps of all phalanges and digit bases of all fingers in human primary somatosensory cortex.

This study determined the individual maps of all fingers in Brodmann area 3b of the human primary somatosensory cortex in a single fMRI session by tactile stimulation at 19 sites across all phalanges and digit bases of the 5 right-hand digits. To quantify basic features of the digit maps within and across subjects, we applied standard descriptive measures, but also implemented a novel quantitative analysis. This so-called Direction/Order (DiOr) method tested whether subjects exhibited an ordering of peak fMRI representations along their individual direction of alignment through the set of analyzed phalanges and whether these individual directions were similar across subjects. Across-digit analysis demonstrated that for each set of homologous phalanges, the D5-to-D1 representations were successively represented along a common direction of alignment. Hence, the wellknown mediolateral D5-to-D1 somatotopy was not only confirmed for the distal phalanges (pi), but could also be shown for the medial (p2) and proximal phalanges (p3). In contrast, the peak activation for the digit bases (p4) only partly elicited that digit succession. Complementary, intra-digit analysis revealed a divergent picture of map topography for the different digits. Within D5 (and in a trend: D4), an ordered pl-to-p3 succession was found across subjects, pointing to a consistent intra-digit somatotopy for D5, with p3 generally found medial-posterior to pl. In contrast, for D1, D2, and D3, most subjects did not present with ordered pl-to-p3 maps nor were directions of alignment similarly oriented between subjects. These digits therefore exhibited highly diverse representation patterns across subjects

Cost saving with ultrasonography in a developing country district hospital

Objective: To estimate the potential monetary reduction induced by the introduction of an ultrasound unit in a major district hospital in a developing country. Design: Propective study. Subjects: Patients referred with abnominal diseases and pregnancy. Setting: 'Wad Medani Teaching Hospital, Central Sudan. Results: Local specialists referring the patients stated that an estimated 792 radiologic procedures would have been carried out to obtain the same amount of information as achieved by ultrasound. Such procedures budgeted approximately 8100 US dollars, in terms of equipment, material and personnel by 1987 rates. Such savings have benefited all departments of the hospital. Conclusion: The authors consider this as evidence for the fact that despite its initial high investment (15000 US dollars), availability of ultrasound virtually reduced expenditure on other radiological diagnostic procedures. This is of special benefit for the limited budgets of hospitals in non-industrialiied countries.East African Medical Journal, May 1999, 272-27

Somatotopic map and inter- and intra-digit distance in Brodmann area 2 by pressure stimulation

The somatotopic representation of the tactile stimulation on the finger in the brain is an essential part of understanding the human somatosensory system as well as rehabilitation and other clinical therapies. Many studies have used vibrotactile stimulations and reported finger somatotopic representations in the Brodmann area 3 (BA 3). On the contrary, few studies investigated finger somatotopic representation using pressure stimulations. Therefore, the present study aimed to find a comprehensive somatotopic representation (somatotopic map and inter- and intra-digit distance) within BA 2 of humans that could describe tactile stimulations on different joints across the fingers by applying pressure stimulation to three joints-the first (p1), second (p2), and third (p3) joints-of four fingers (index, middle, ring, and little finger). Significant differences were observed in the inter-digit distance between the first joints (p1) of the index and little fingers, and between the third joints (p3) of the index and little fingers. In addition, a significant difference was observed in the intra-digit distance between p1 and p3 of the little finger. This study suggests that a somatotopic map and inter- and intra-digit distance could be found in BA 2 in response to pressure stimulation on finger joints.ope

Learner autonomy in developing countries

Learner autonomy may have special relevance now in developing countries, where a dissonance often exists between what formal education offers and what many learners want or need. Globalization and its technologies are providing new means of accessing knowledge, but school language lessons remain largely unchanged. Almost by default, successful language learners in developing country contexts are autonomous learners who can exploit out-of-school resources, while some of the most effective pedagogy involves promoting autonomy as a means of confronting low-resource challenges. This chapter argues for more research into both these phenomena, in order to increase understanding of them and to enable identification of principles for practice. It also emphasizes the need for such research to be conducted with and by local teachers and learners

Individual left-hand and right-hand intra-digit representations in human primary somatosensory cortex.

Individual intra-digit somatotopy of all phalanges of the middle and little finger of the right and left hand was studied by functional magnetic resonance imaging in 12 healthy subjects. Phalanges were tactilely stimulated and activation in BA 3b of the human primary somatosensory cortex could be observed for each individual phalanx. Activation peaks were further analysed using the Direction/Order (DiOr) method, which identifies somatotopy, if a significantly high number of subjects exhibit ordered distal-to-proximal phalanx representions along a similar direction. Based on DiOr, ordered and similar-direction-aligned intra-digit maps across subjects were found at the left hand for the little and middle finger and at the right hand for the little finger. In these digits the proximal phalanges were represented more medially along the course of the central sulcus than the distal phalanges. This is contrasted by the intra-digit maps for the middle finger of the right hand, which showed larger inter-subject variations of phalanx alignments without a similar within-digit representation across subjects. As all subjects were right-handed and as the middle finger of the dominant hand probably plays a more individual role in everyday tactile performance than the little finger of the right hand and all left-hand digits, the observed variation might reflect a functional somatotopy based on individual use of that particular digit at the dominant hand

Feature-based attentional modulation of orientation perception in somatosensation.

In a reaction time study of human tactile orientation detection the effects of spatial attention and feature-based attention were investigated. Subjects had to give speeded responses to target orientations (parallel and orthogonal to the finger axis) in a random stream of oblique tactile distractor orientations presented to their index and ring fingers. Before each block of trials, subjects received a tactile cue at one finger. By manipulating the validity of this cue with respect to its location and orientation (feature), we provided an incentive to subjects to attend spatially to the cued location and only there to the cued orientation. Subjects showed quicker responses to parallel compared to orthogonal targets, pointing to an orientation anisotropy in sensory processing. Also, faster reaction times (RTs) were observed in location-matched trials, i.e., when targets appeared on the cued finger, representing a perceptual benefit of spatial attention. Most importantly, RTs were shorter to orientations matching the cue, both at the cued and at the uncued location, documenting a global enhancement of tactile sensation by feature-based attention. This is the first report of a perceptual benefit of feature-based attention outside the spatial focus of attention in somatosensory perception. The similarity to effects of feature-based attention in visual perception supports the notion of matching attentional mechanisms across sensory domains