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R B Pinter

Publications and source records attributed to R B Pinter.

5 recordsLinked to original sources
PubMed1991

An identifiable molluscan neuron responds to changes in earth-strength magnetic fields.

Diverse animals can orient using geomagnetic cues, but little is known about the neurophysiological mechanisms that underlie magnetic field detection. The marine mollusc Tritonia diomedea (Bergh) has a magnetic sense and its nervous system is amenable to cellular-level electrophysiological analysis. In a semi-intact whole-animal preparation, intracellular recordings from the large, visually identifiable neurons left pedal 5 (LPe5) and right pedal 5 (RPe5) in the brain of Tritonia revealed enhanced electrical activity in response to changes in ambient earth-strength magnetic fields. No such changes in activity were observed in approximately 50 other neurons subjected to identical magnetic stimuli. The responses of LPe5 were characterized by increases in spiking frequency occurring about 6-16 min after the ambient magnetic field had been rotated to a new position. The response was abolished when the brain had been isolated from the periphery of the animal by severing nerves, a procedure that also transected prominent neurites of LPe5. We hypothesize that LPe5 is one component of a neural circuit mediating detection of the earth's magnetic field or orientation to it.

Animals↗
PubMed1990

Shift of edge-taxis to scototaxis depends on mean luminance and is predicted by a matched filter theory on the responses of fly lamina LMC cells.

The strength of the flanking inhibitory regions of the receptive fields of fly lamina cells (LMC) decreases as the mean luminance is lowered. Simultaneously, the biphasic temporal flash (impulse) response of the lamina cells becomes monophasic on lowering luminance. For a moving-edge stimulus at high mean luminance, this implies that the spatial integration by the lamina cell yields a temporal waveform which is congruent to the waveform of the temporal impulse response of the lamina cell. In other words, the temporal waveform generated by the moving edge is matched to the temporal waveform most preferred by the lamina cell. The edge is the stimulus causing the largest amplitude response at high (above 1 cd/m2) levels of luminance. On lowering luminance, the now monophasic nature of the spatial and temporal impulse responses of the lamina gives a preference not for the edges but for the center of a uniform region. We describe this theory and its behavioral corroboration in walking flies (Lucilia cuprina).

Animals↗
PubMed1990

What causes edge fixation in walking flies?

The orientation of freely walking flies (female Lucilia cuprina) to lines and stripes in a circular arena is described. The following observations were made. 1. The flies walked straight towards a dark line using the frontal eye region, but a pale line on a dark background was only weakly attractive. 2. In bright conditions flies walked in a curved line towards a black-white edge, the path being convex towards the dark side of the border. The curves indicated that the flies were heading for a point about 5-10 degrees to the dark side of the edge. 3. In dim conditions the edge of a dark region was not especially attractive and flies headed towards any point in the dark area. These observations can be accounted for by assuming that the fly walks towards the darkest region in its visual field (scototaxis). In bright conditions the edges of a dark region become more attractive than its centre. This change could be explained if lateral inhibition creates a 'Mach-band' effect, making the edges appear darker than the centre. Thus, fixation behaviour in walking Lucilia females seems to be a simple taxis.

Animals↗