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The purpose of the study was to determine whether amblyopes show detection loss for second-order spatial information, and if present, whether the loss is explained by the loss of first-order spatial input. We psychophysically determined detection thresholds for the amblyopic and non-amblyopic eyes of five adult amblyopes and the dominant eyes of three(More)
Humans with amblyopia have a well-documented loss of sensitivity for first-order, or luminance defined, visual information. Recent studies show that they also display a specific loss of sensitivity for second-order, or contrast defined, visual information; a type of image structure encoded by neurons found predominantly in visual area A18/V2. In the present(More)
Amblyopes show bilateral loss of sensitivity for second-order (contrast defined) stimuli that can be further suppressed by flanking second-order stimuli (whereas flanks facilitate sensitivity in normal observers). The suppressive flank effect in amblyopes might be explained by abnormal pooling of second-order contrast across visual space. In this study, we(More)
Activation of the 5-HT4 receptor mediates widespread effects in central and peripheral nervous systems. Recent developments, such as the identification of novel, selective agonists and antagonists, as well the cloning of the receptor, have provided insights into the physiological role of the receptor. In this article, Richard Eglen and colleagues assess the(More)
1. A series of isoquinolines have been identified as 5-HT3 receptor antagonists. One of these, RS 25259-197 [(3aS)-2-[(S)-1-azabicyclo[2.2.2]oct-3-yl]-2,3,3a,4,5,6-hexahydro- 1- oxo-1H-benzo[de]isoquinoline-hydrochloride], has two chiral centres. The remaining three enantiomers are denoted as RS 25259-198 (R,R), RS 25233-197 (S,R) and RS 25233-198 (R,S). 2.(More)
In the present studies we investigated the actions of ondansetron, a prototypic 5-hydroxytryptamine3 (5-HT3) receptor antagonist, on performance in a complex spatial navigation/memory task in rats. Specifically, we compared the activity of ondansetron to that of the cholinesterase inhibitor physostigmine in attenuating two distinct cognitive deficits in the(More)
The objective of this study was to explore the role of 5-HT3 receptors in modulating potassium (K+)-evoked release of [3H]-acetylcholine ([3H]-ACh) from superfused slices of rat entorhinal cortex previously loaded with [3H]-choline. Rat entorhinal cortices were cross-chopped into 300 microns slices, superfused with oxygenated Krebs buffer containing 2.5(More)
In the present studies we investigated the actions of (R)- and (S)-zacopride, potent 5-HT3 receptor antagonists with 5-HT4 receptor agonists properties, on performance in a spatial learning and memory task in rats, the Morris water maze. A significant cognitive/performance deficit, as indicated by the increased escape latency across several trials, was(More)
1. The distribution, pharmacology and effects of neurodegenerative diseases on 5-HT4 receptors in human brain have been characterized in vitro. 2. The 5-HT4 receptor in post mortem human brain tissue was specifically labelled with [3H]-GR 113808. In human putamen, this ligand labelled a homogeneous population of sites, with an apparent affinity (-log Kd) of(More)
The novel N-methyl-D-aspartate receptor channel ligand (+)-[3H]5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5, 10-imine maleate ([3H]MK-801) has been utilized to label this receptor in human brain tissue. Characteristics of [3H]MK-801 binding to well-washed membranes from 17 control subjects and 16 patients with Alzheimer's disease were determined in(More)