Auditory-visual speech integration by prelinguistic infants: Perception of an emergent consonant in the McGurk effect

The McGurk effect, in which auditory [ba] dubbed onto [go] lip movements is perceived as da or tha, was employed in a real-time task to investigate auditory-visual speech perception in prelingual infants. Experiments 1A and 1B established the validity of real-time dubbing for producing the effect. In Experiment 2, 4(1)/(2)-month-olds were tested in a habituation-test paradigm, in which 2 an auditory-visual stimulus was presented contingent upon visual fixation of a live face. The experimental group was habituated to a McGurk stimulus (auditory [ba] visual [ga]), and the control group to matching auditory-visual [ba]. Each group was then presented with three auditory-only test trials, [ba], [da], and [deltaa] (as in then). Visual-fixation durations in test trials showed that the experimental group treated the emergent percept in the McGurk effect, [da] or [deltaa], as familiar (even though they had not heard these sounds previously) and [ba] as novel. For control group infants [da] and [deltaa] were no more familiar than [ba]. These results are consistent with infants'perception of the McGurk effect, and support the conclusion that prelinguistic infants integrate auditory and visual speech information. (C) 2004 Wiley Periodicals, Inc.

Regional specialization in pyramidal cell structure in the visual cortex of the galago: An intracellular injection study of striate and extrastriate areas with comparative notes on New World and Old World monkeys

Recent studies have revealed marked differences in the basal dendritic structure of layer III pyramidal cells in the cerebral cortex of adult simian primates. In particular, there is a consistent trend for pyramidal cells of increasing complexity with anterior progression through occipitotemporal cortical visual areas. These differences in pyramidal cell structure, and their systematic nature, are believed to be important for specialized aspects of visual processing within, and between, cortical areas. However, it remains unknown whether this regional specialization in the pyramidal cell phenotype is unique to simians, is unique to primates in general or is widespread amongst mammalian species. In the present study we investigated pyramidal cell structure in the prosimian galago (Otolemur garnetti). We found, as in simians, that the basal dendritic arbors of pyramidal cells differed between cortical areas. More specifically, pyramidal cells became progressively more spinous through the primary (V1), second (V2), dorsolateral (DL) and inferotemporal ( IT) visual areas. Moreover, pyramidal neurons in V1 of the galago are remarkably similar to those in other primate species, in spite of large differences in the sizes of this area. In contrast, pyramidal cells in inferotemporal cortex are quite variable among primate species. These data suggest that regional specialization in pyramidal cell phenotype was a likely feature of cortex in a common ancestor of simian and prosimian primates, but the degree of specialization varies between species. Copyright (C) 2005 S. Karger AG, Basel.

Development of an oligonucleotide-based SNP detection method on lateral flow strips using hexapet tages

Detection of point mutations or single nucleotide polymorphisms (SNPs) is important in relation to disease susceptibility or detection in pathogens of mutations determining drug resistance or host range. There is an emergent need for rapid detection methods amenable to point-of-care applications. The purpose of this study was to reduce to practice a novel method for SNP detection and to demonstrate that this technology can be used downstream of nucleic acid amplification. The authors used a model system to develop an oligonucleotide-based SNP detection system on nitrocellulose lateral flow strips. To optimize the assay they used cloned sequences of the herpes simplex virus-1 (HSV-1) DNA polymerase gene into which they introduced a point mutation. The assay system uses chimeric polymerase chain reaction (PCR) primers that incorporate hexameric repeat tags ("hexapet tags"). The chimeric sequences allow capture of amplified products to predefined positions on a lateral flow strip. These "hexapet" sequences have minimal cross-reactivity and allow specific hybridization-based capture of the PCR products at room temperature onto lateral flow strips that have been striped with complementary hexapet tags. The allele-specific amplification was carried out with both mutant and wild-type primer sets present in the PCR mix ("competitive" format). The resulting PCR products carried a hexapet tag that corresponded with either a wild-type or mutant sequence. The lateral flow strips are dropped into the PCR reaction tube, and mutant sequence and wild-type sequences diffuse along the strip and are captured at the corresponding position on the strip. A red line indicative of a positive reaction is visible after 1 minute. Unlike other systems that require separate reactions and strips for each target sequence, this system allows multiplex PCR reactions and multiplex detection on a single strip or other suitable substrates. Unambiguous visual discrimination of a point mutation under room temperature hybridization conditions was achieved with this model system in 10 minutes after PCR. The authors have developed a capture-based hybridization method for the detection and discrimination of HSV-1 DNA polymerase genes that contain a single nucleotide change. It has been demonstrated that the hexapet oligonucleotides can be adapted for hybridization on the lateral flow strip platform for discrimination of SNPs. This is the first step in demonstrating SNP detection on lateral flow using the hexapet oligonucleotide capture system. It is anticipated that this novel system can be widely used in point-of-care settings.

Should an oral glucose tolerance test be performed routinely in all renal transplant recipients?

Posttransplantation diabetes (PTD) contributes to cardiovascular disease and graft loss in renal transplant recipients (RTR). Current recommendations advise fasting blood glucose (FBG) as the screening and diagnostic test of choice for PTD. This study sought to determine (1) the predictive power of FBG with respect to 2-h blood glucose (2HBG) and (2) the prevalence of PTD using FBG and 2HBG compared with that using FBG alone, in prevalent RTR. A total of 200 RTR (mean age 52 yr; 59% male; median transplant duration 6.6 yr) who were >6 mo posttransplantation and had no known history of diabetes were studied. Patients with FBG