Signal transmission in the catfish retina. III. Transmission to type-C cell.

Current injected into horizontal-cell somas and axons produced transient (on-off) depolarizations from type-C cells (commonly known as transient amacrine cells) similar to those produced by light. Both the light- and current-induced responses had very small linear components and nonlinear components as represented by the second-order kernels, which reproduced the cell's response with a reasonable degree of accuracy. The second-order kernels were well defined and stereotyped.

Signal transmission in the catfish retina. II. Transmission to type-N cell.

Responses from channel catfish type-N (sustained amacrine) cells were evoked either by step changes in illuminance, i.e. brightening or dimming from a mean illuminance, or by a white-noise modulated light stimulus.

Signal transmission in the catfish retina. I. Transmission in the outer retina.

Extrinsic current, either pulsatile or white-noise modulated, was injected into the (cone) horizontal-cell soma and axon, and resulting responses were recorded from nearby points. In the case of white-noise inputs, signal transmission between the two points was characterized by Wiener kernels. The signal transmission within the lamina, the S-space, formed by the (cone) horizontal-cell somas and axons is quasi-linear and very fast, indicating that the laminae are purely resistive networks within the frequency range of the light-evoked response.

Yuta (shaman) and community mental health on Okinawa.

This study reports on the relations between the yuta (shaman) and the community mental health activities on Okinawa, Japan. Focus is on the process of initiation of the yuta and its meanings from the mental health viewpoints, the functions of the yuta in the particular cultural background of the island, and the importance of admitting the existence of the yuta in its relations to the psychiatric treatment in a mental hospital. The discussion is based on the authors' research findings which were obtained mostly through their therapeutic activities and their field studies.

Spontaneous membrane fluctuation in catfish type-N cells.

Type-N (sustained) amacrine cells in catfish retina produce spontaneous membrane fluctuation of about 35 Hz. Fluctuations were seen either in dark or with a steady illumination. As all the distal cells and type-C (transient) amacrine cell did not produce any spontaneous fluctuation, type-N cells were the source of the oscillatory potentials.

Effects of dopamine on photopic L-type S-potentials in the catfish retina.

Photopic L-type responses were recorded from the soma and the axon terminal of horizontal cells of the catfish (Ictalurus punctatus) retina in eye-cup preparations. The responses were produced by a spot of light with 100-micron diameter (intensity, 10 microW/cm2), which was flashed or steadily illuminated and swept along a 6-mm length over the retinal surface at a speed of 0.95 mm/sec.

Turtle and catfish horizontal cells show different dynamic response.

Horizontal cell responses of catfish and turtle have been found to differ in a characteristic way. These characteristics established by white-noise analysis show that the impulse response (first order Wiener kernel) of the catfish horizontal cell has a substantially shorter latency as well as peak response time than that of the turtle. The turtle horizontal cell, on the other hand, has a dynamic gain which is twice that of the catfish.

Effects of background and spatial pattern on incremental sensitivity of catfish horizontal cells.

Incremental sensitivity of cones and horizontal cells was examined in the retina of the channel catfish (Ictalurus punctatus). In horizontal cells, steady full-field background illumination made the spot-evoked dynamic response larger and faster. The "enhancement" of incremental sensitivity was maximal at background levels of 20-50 microW/cm2.

Decreased sensitivity of platelets to prostacyclin in patients with diabetes mellitus.

In order to ascertain the platelet sensitivity to prostacyclin (PGI2) in patients with diabetes mellitus, we determined the percentage inhibition of platelet aggregation and platelet ATP secretion following PGI2 addition in an in vitro system. The percentage inhibition of platelet aggregation caused by PGI2 in final concentration of 1.25, 2.

Salivary urea nitrogen as an index to renal function: a test-strip method.

To investigate the feasibility of using salivary urea nitrogen as an index of renal glomerular filtration rate, we developed and applied a new analytical system consisting of a urease-containing test strip and an automatic reflectance spectrometer. The concentrations of urea nitrogen so determined correlate well (r = 0.93) with concentrations in serum.

A new photographic method for mapping spatio-temporal receptive field using television snow stimulation.

A means was devised to measure simultaneously spatial as well as temporal characteristics of visual receptive fields by stimulating the retina with the noise obtained on an unused television channel. The input, television snow, and the output, neural response, were recorded on a video tape. The tape was played back to obtain the (linear) spatio-temporal Wiener kernel by cross-correlating the input with the output.

Synaptic organization involving receptor, horizontal and on- and off-center bipolar cells in the catfish retina.

HRP-injected bipolar cells were analyzed electron microscopically in catfish retina. The dendrites of the two types of bipolar cells (on-center and off-center) invaginated into the photoreceptor terminals in distinct patterns. Those from off-center bipolars ended as the central element of triads in such a way that every synaptic ridge examined was contacted by a single process along its apex.

Regional difference in density of monoamine-accumulating cells of carp and catfish retinas.

By means of a histofluorescence technique, a comparative study was conducted on the regional density of dopaminergic (DA) and indoleamine-accumulating (IA) cells in carp (Cyprinus carpio) and catfish (Ictalurus punctatus) retinas. In order to enhance detection of fluorescent cells, noradrenaline (NA; 5.0 micrograms) or a mixture of NA (2.

A comparison of spatio-temporal receptive fields of ganglion cells in the retinas of the tadpole and adult frog.

Receptive fields formed by ganglion cells were measured simultaneously in time and space in the adult and tadpole retinas. The spatio-temporal receptive-fields (STRFs) were measured by cross-correlating the spatio-temporal white-noise stimulus with the cells' spike discharges. Crosscorrelation was made photographically to extract the first order STRF kernel (approximately linear component of the STRFs).

Spatio-temporal visual receptive fields as revealed by spatio-temporal random noise.

A means was devised to visualize the retinal receptive fields in time and space using the noise on unused television channels as spatio-temporal inputs and performing correlation between the input and output photographically. The method was applied to characterize the receptive fields of catfish retinal ganglion cells. The results were 1) there were two major types of receptive fields, circular and elliptical, 2) shapes and sizes of the field components changed with time (latency), and 3) a field's surround was often localized as hot spots.

Direct electrical connections between transient amacrine cells in the catfish retina.

Transient amacrine cells were identified by their intracellularly recorded response to flashes of light. These cells typically respond with a transient depolarization, often followed by a steady-state response during the stimulus. When two electrodes were placed in different transient amacrine cells, current of either polarity passed through one electrode produced a steady-state voltage change that was recorded by the electrode in the nearby cell.

Spatial organizations of catfish retinal neurons. II. Circular stimulus.

1. Temporal dynamics of receptive-field components were identified by use of circular stimuli whose diameter was modulated in white-noise fashion. 2.