Showing papers on "Summation published in 1972"
TL;DR: It is suggested that enhanced photosensitivity of post Synaptic activity is a result of summation of many receptors onto the postsynaptic elements, and that transients in the post synaptic responses are related to the complex synaptic arrangements in the ocellar plexus to be described in the following paper.
Abstract: Intracellular responses from receptors and postsynaptic units have been recorded in the median ocellus of the dragonfly. The receptors respond to light with a graded, depolarizing potential and a single, tetrodotoxin-sensitive impulse at "on." The postsynaptic units (ocellar nerve dendrites) hyperpolarize during illumination and show a transient, depolarizing response at "off." The light-evoked slow potential responses of the postsynaptic units are not altered by the application of tetrodotoxin to the ocellus. It appears, therefore, that the graded receptor potential, which survives the application of tetrodotoxin, is responsible for mediating synaptic transmission in the ocellus. Comparison of pre- and postsynaptic slow potential activity shows (a) longer latencies in postsynaptic units by 5–20 msec, (b) enhanced photosensitivity in postsynaptic units by 1–2 log units, and (c) more transient responses in postsynaptic units. It is suggested that enhanced photosensitivity of postsynaptic activity is a result of summation of many receptors onto the postsynaptic elements, and that transients in the postsynaptic responses are related to the complex synaptic arrangements in the ocellar plexus to be described in the following paper.
114 citations
TL;DR: It was concluded that a normal neuron could be recruited into a high-frequency bursting firing pattern if about 1% of its inputs possessed such firing patterns.
62 citations
01 Jan 1972
TL;DR: In this article, the authors show that between the energy flux of electromagnetic radiation of a given bandwidth, called the stimulus, and the light sensation, there are physical, chemical, physiological and psychological events.
Abstract: There is no light, but we may see light. Light is a sensation and thus has no physical existence. Between the energy flux of electromagnetic radiation of a given bandwidth, called the stimulus, and the light sensation, there are physical, chemical, physiological and psychological events.
40 citations
TL;DR: This threshold energy relation was found to be capable of describing the results of Graham and Margaria (1935) which had hitherto been considered aberrant.
36 citations
TL;DR: The results show that when halving the stimulus duration the sound pressure must be increased 3 dB to maintain the threshold, thus keeping the acoustic energy constant, and a clear frequency dependence in temporal integration is demonstrated.
Abstract: The relation between stimulus duration and stimulus intensity in perception of acoustic energy generally referred to as the temporal integration, i.e. temporal summation is investigated. In previous studies a wide variety of methods has been used, and accordingly, different results have been obtained. To establish a normal material for later comparison of temporal integration in hearing impaired ears 30 normal persons were investigated. Temporal integration was measured as monoaural threshold determinations for the frequencies 500, 1 kHz, 2 kHz, 4 kHz, and 8 kHz using stimulus durations varying from 1 to 1 000 msec. The results show that when halving the stimulus duration the sound pressure must be increased 3 dB to maintain the threshold, thus keeping the acoustic energy constant. A clear frequency dependence in temporal integration is demonstrated. We hope that the method of calculating temporal integration in this trial will facilitate the comparison of results of different investigators and thereby ex...
34 citations
TL;DR: It is concluded that temporal summation does not occur in the goldfish and that enhanced sensitivity for long sounds, found in mammals, is unnecessary for fish since most fish sounds consist of short pulses.
Abstract: Auditory thresholds were determined in the goldfish (Carassius auratus) for sound pulses with duty cycles from 1%–90% of 100‐ and 1000‐msec periods. Thresholds were also determined for pulses from 10 to 500 msec in duration with at least 490 msec between pulses. Results indicate that there are no differences in threshold between short pulses and continuous tones and that thresholds are the same whether there is a long or short signal off‐time between pulses. It is concluded that temporal summation does not occur in the goldfish and that enhanced sensitivity for long sounds, found in mammals, is unnecessary for fish since most fish sounds consist of short pulses. It is suggested that temporal summation most probably occurs in higher auditory centers in the brain of mammals and the lack of these centers is the reason for no temporal summation in goldfish.
30 citations
TL;DR: Self- Stimulation mapping studies of the rat diencephalon, the anatomy of the MFB, and previous double pulse self-stimulation studies reveal evidence for latent addition, neural refractoriness and temporal summation.
21 citations
TL;DR: The change of critical duration and of the form of the function relating threshold energy to stimulus duration was determined during the first 22 s of dark adaptation following light adaptation to several luminances.
Abstract: The change of critical duration and of the form of the function relating threshold energy to stimulus duration was determined during the first 22 s of dark adaptation following light adaptation to several luminances. For all adapting luminances tested, the critical duration increased during dark adaptation from the value obtained for the increment threshold. As adapting luminance decreased or time in the dark increased, the form of the summation function changed, so that the transition from complete temporal summation to no summation became less abrupt. The data show departures from the equivalent-background analysis of dark adaptation. A filter model relating threshold energy and time constant under varying adaptation conditions provides a general, but not precise, description of the data. The change of temporal summation during dark adaptation is similar to that found for decreased size of test field, decreased wavelength of test field, and decreased background luminance.
20 citations
TL;DR: The investigation was concerned with temporal summation for supraliminal electrocutaneous stimuli to the tongue and pulse duration and one experiment dealt with pulse duration.
Abstract: The investigation was concerned with temporal summation for supraliminal electrocutaneous stimuli to the tongue. One experiment (N = 5) dealt with pulse duration and a second experiment (N = 5) was...
1 citations