Gerald S. Wasserman

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Mental timing studies may be influenced by powerful cognitive illusions that can produce an asymmetry in their rate of progress relative to neuronal timing studies. Both types of timing research are also governed by a temporal asymmetry, expressed by the fact that the direction of causation must follow time's arrow. Here we refresh our earlier suggestion(More)
Efferent nerves coursing from the brain to the lateral eye of the horseshoe crab, Limulus polyphemus, increase its nighttime sensitivity to light. They release octopamine, which produces a categorical increase of photoreceptor response duration in vitro. Analogous in vivo timing effects on the electroretinogram (ERG) were demonstrated when octopamine was(More)
Action potentials (APs) were intracellularly recorded from eccentric cells (which give rise to optic nerve fibers) in Limulus lateral eyes and their neural coding efficacies were determined over a wide range of light adaptation states and relative stimulus intensities. Extremely stringent data quality procedures were followed to ensure that the results are(More)
Evaluates 2 theoretical models suggested to explain studies of the effect of stimulus intensity on the perceived duration of brief light flashes. Some studies found a direct relationship between the 2 variables; others found an indirect relationship. Each model suggests that an additional variable interacts with stimulus intensity. Proposed variables have(More)
The methods of Fechner and Stevens for assessing sensation quantity usually yield different psychophysical functions even when all other factors are controlled. In this experiment, corresponding differences occurred when different features of the same sensory receptor signals were analyzed. In the visual system, the receptor potential saturated if the peak(More)
Octopamine, a major efferent neurotransmitter in the lateral eye of the horseshoe crab (Limulus polyphemus), has previously been shown to modulate photoreceptor responses evoked by long flashes. Quantification of these data indicates that this modulation produced a genuine increase in sensitivity to light which cannot be entirely due to an increase in(More)
The neural coding problem is defined and several possible answers to it are reviewed. A widely accepted answer descends from early suggestions that neural activity, in general, is isomorphic with sensation and that the biological signals resident in the axons of neurons, in particular, are given by their frequency of firing. More recent data are reviewed(More)
Efferents from the brain of Limulus course toward its lateral eye and release octopamine and substance P into it. These neurotransmitters have previously been found to act as neuromodulators in this visual system by altering the size of its responses to light. We report here that both also modulate the timing of the receptor potentials (RPs) evoked by brief(More)