The representation of three-dimensional visual space in the cat's striate cortex

1. Binocularly driven single units were recorded in the cat's striate cortex. For each neurone the two monocular receptive fields were stimulated simultaneously in order to assess the optimal positioning of the image in both eyes to give the best binocular response.2. The electrode was driven perpendicular to the surface of the brain to explore cortical columns, all the cells of which are known to have the same preferred target orientation.3. All orientation columns were found to fit into one of two classes according to their binocular organization.4. In a constant depth column the receptive fields of binocular neurones cover a small retinal area and they are laid out in almost identical arrays in the two eyes. Consequently, the horizontal disparity is practically the same for all the units. The depth column as a whole is viewing a thin sheet of visual space, a few degrees wide, floating at some distance from the cat. There may be about 0.6 degrees disparity difference between neighbouring depth columns.5. In a constant direction column the binocular units' fields are all super-imposed on the retina contralateral to the hemisphere containing the column. In the ipsilateral eye they are more scattered horizontally. Therefore the horizontal disparity varies enormously from cell to cell and the column as a whole is viewing a cylinder of visual space directed towards the contralateral eye. Neighbouring direction columns may vary by about 4 degrees in their oculocentric visual direction.6. This columnar arrangement is probably important for space perception in the cat. Activity in only one depth and one direction column would specify the orientation and the three-dimensional locus of an object in space.7. The two types of column may be involved in the control of disjunctive and conjugate eye movements.     

EPSPs in rat neocortical pyramidal neurones in vitro are prolonged by NMDA receptor-mediated currents.

We investigated the influence of 2-amino-5-phosphonovalerate (APV), a selective antagonist of the N-methyl-D-aspartate (NMDA) receptor, on the time course of small excitatory postsynaptic potentials (EPSPs) in pyramidal neurones in layer 2/3 of adult rat visual cortex in vitro. Time constants of the voltage decay following the EPSPs (T(s)) and after brief (2 ms) pulses of current injected at the soma (T(p)) were determined from semilogarithmic plots of averages of 100-250 trials. The mean T(s)/T(p) ratio decreased from 1.53 +/- 0.29 (S.D.) to 1.10 +/- 0.08 on addition of 50 microM APV to the bathing medium (P less than 0.001; n = 23), but there was no significant change in EPSP peak amplitude or rise-time. These results suggest that the time course of many small EPSPs, even at negative membrane potentials and in the presence of Mg2+, can be prolonged by NMDA receptor-mediated currents.     

Sexual discordance in monozygotic twins

We report on monozygotic (MZ) twins who were discordant for phenotypic sex and Ullrich-Turner syndrome (UTS). The nonviable female was hydropic with cystic hygromas, ventricular septal defect, bicuspid aortic valve, polysplenia, intestinal malrotation, and small ovaries. The male was phenotypically normal. The monochorionic, diamniotic placenta had hydropic changes limited to the UTS infant's side. Skin samples from the infants and blood from their parents were obtained for cytogenetic and molecular analysis. Karyotypes of the twins were 45,X and 46,XY. Quinacrine polymorphisms on 7 chromosomes and RFLP analysis at 8 loci showed complete identity. MZ twins discordant for phenotypic sex have been described previously. Most of these show evidence of mosaicism in a 45,X patient with a normal 46,XY cell line, and a normal 46,XY male. While the issue of mosaicism in our case cannot be fully resolved, no mosaicism was found in 50 cells analyzed cytogenetically from each culture or by PCR analysis of a Y-specific sequence. The twins probably originated from either postzygotic nondisjunction or anaphase lag, followed or accompanied by twinning. The discordant placental morphology suggests an embryonic origin of at least part of the placental mesenchymal core.     

Universal Mindfulness Training in Schools for Adolescents: a Scoping Review and Conceptual Model of Moderators,Mediators, and Implementation Factors

Prevention Science - There is evidence that universal school-based mindfulness training (SBMT) can have positive effects for young people. However, it is unknown who benefits most from such...     

Helical CT amniography of congenital diaphragmatic hernia

OBJECTIVE: Accurate prenatal diagnosis of congenital diaphragmatic hernia is important for perinatal planning and potential fetal surgery. We describe the application and usefulness of helical CT amniography in the evaluation of suspected congenital diaphragmatic hernia in three fetuses. CONCLUSION: Helical CT amniography is an efficient means for evaluation of congenital diaphragmatic hernia. Accurate diagnosis was made in all three patients.     

Health and illness among the elderly of minority ethnic groups living in Birmingham: some new findings

The number of people over pensionable age who are of ethnic minority (New Commonwealth) origin is increasing rapidly. A limited survey of 348 Afro-Caribbean and Asian elderly people and 52 elderly Europeans living in Birmingham was recently carried out to investigate, among other things, their health and use of health services. The main survey findings on the proportions of the elderly needing to visit their doctors or go to hospital for treatment, the proportions suffering problems of sight, hearing and walking or having dental problems, and other indicators of health and illness are briefly discussed in this paper.