Facilitation of synchronized spike discharges by oscillations in frog retinal ganglion cells

s177 FIRING PATTERNS

335

OF ISOLATED

AND THEIR REGULATION

TOSHIHIDE

TABATA

AND MASANOBU

GOLDFISH

RETINAL GANGLION

BY A Ba2+-SENSITIVE

In some vertebrates,

Brain Sci. Inst., RIKEN, Wako, Saitama 351-0198,

Univ. Schl. of Med., 13-1 Takara, Kanazawa,

An important property to distinguish discharge.

K+ CURRENT

KANO

CREST, Japan Sci. and Tech. Corp.; Lab. for Cellular Neurophysiol., Japan; Dept. of Physiol., Kanazawa

the subtypes of vertebrate

of synaptic inputs which reflect the visual responses

discharge

tonicity also depends on intrinsic mechanisms

Ishikawa 920-8640, Japan.

retinal ganglion cells (RGCs) is the tonicity of spike

it has been thought that the discharge

dynamics

tonicity of a RGC is primarily determined by the cells. However, it is unclear whether the

of presynaptic

of RGCs.

To address this question,

discharge of RGCs in the absence of synaptic inputs, using isolated cell preparations patch whole-cell

current-clamp

maintain their repetitive

technique.

discharge

When depolarized

throughout

of the RGCs are limited in discharge

application

of millimolar

concentrations

contribution

the early termination

This suggests that a certain Moreover, an extracellular

of the repetitive

of Ba*+ blocked a non-inactivating

voltage-gated

FACILITATION RETINAL

HIROSHI ISHIKANE Department Bunkyo-ku,

OF SYNCHRONIZED

GANGLION

SPIKE

based on the kinetic analysis.

BY OSCILLATIONS

IN FROG

and MASAO TACHIBANA

Using a planar multi-electrode

array, we recorded

ganglion cells (the dimming detectors) series of checkerboard

and Sociology,

light-evoked

The University

spike discharges

of the retina isolated from the dark-adapted

patterns to map the receptive

analysis was performed

under temporally modulated

fields of dimming detectors

of Tokyo, 7-3-l Hongo,

from multiple OFF-sustained frog.

with reverse correlation

technique.

to evaluate the temporal relation between the discharge patterns of dimming

diffuse illumination.

The synchronized

activity was detected

activities, which were peaked at the frequency

even in cell pairs a

with the oscillatory

Hz. When GABA, antagonists

were applied to the retina, the oscillatory activities were almost completely

activity became weak in adjacent cell pairs and disappeared

that the oscillatory activities facilitate the establishment

NEURONAL

337 HIROYUKI

in remote cell pairs

of synchrony between dimming detectors

FOR DIRECTIONAL EVIDENCES

SELECTIVITY

and Computer

Many vertebrates

for directionally

30

abolished, and

These results suggest in the frog retina,

IN THE RETINA:

AGAINST THE BARLOW-LEVICK

Science, Fat. of Engineering,

MODEL

Kagoshima

Univ., Kagoshima

selectivity in the retina, receptive and suppressive

selective retinal ganglion cells with single and paired stationary fit well both the receptive fields and suppressive

about I-3 deg. toward the preferred fields by a stationary

direction

light spot maximally

responses

field, and, thus suppresses

Levick (1965).

suppressive

the responses.

Directional

mapped

spots of light in the Japanese quail.

Two-

fields and reveal that the suppressive

fields

of the cell, relative to the receptive

suppresses

To clarify

fields were quantitatively

of the receptive

fields.

Stimulation

of the

fields with a delay of 100 ms.

An object moving in the direction opposite to the preferred direction stimulates the suppressive

exerted by the displaced

890-0065, Japan.

are known to have retinal ganglion cells that prefer object motion in a particular direction.

for the directional

Gaussian functions

are displaced

the receptive

of approximately

UCHIYAMA

a neuronal mechanism

suppressive

MECHANISM

ELECTROPHYSIOLOGICAL

Dept. of Information

dimensional

type

The retina was illuminated with a

few mm apart and accompanied

the synchronized

in some RGCs. Possible

CELLS

of Psychology, Graduate School of Humanities Tokyo 113-0033

Cross-correlation

DISCHARGES

discharge

K+ current.

of this Ba’+-sensitive K’ current to limiting discharge tonicity will be discussed

336

detectors

with a I-set current stimulus, many RGCs could not

tonicity by their intrinsic mechanisms.

of Ba*+ abolished

we measured the spike

from adult goldfish and a perforated-

the stimulus while some others could.

population

Under voltage clamp, similar concentration

CELLS

field first, before stimulating

selectivity thus results from delayed transient suppression

fields, and not by asymmetrical

inhibitory conduction

as hypothesized

by Barlow and