Asymmetric temporal properties in the receptive field of retinal transient amacrine cells.

The speed of signal conduction is a factor determining the temporal properties of individual neurons and neuronal networks. We observed very different conduction velocities within the receptive field of fast-type On-Off transient amacrine cells in carp retina cells, which are tightly coupled to each other via gap junctions. The fastest speeds were found in the dorsal area of the receptive fields, on average five times faster than those detected within the ventral area.

Nitric oxide controls the light adaptive chromatic difference in receptive field size of H1 horizontal cell network in carp retina.

In carp retina, the receptive field size of the H1-type horizontal cell (HC) network is known to be chromatically selective, as electrophysiological signals are generated by short-wavelength (SW) light stimuli, which spread much less than those for long-wavelength (LW). We have shown previously that the signalling mechanism underlying this chromatic difference operates only in the light-adapted retina and that it involves cGMP as an intermediary messenger. In the present study, the possible role of nitric oxide (NO) as such a control mechanism was investigated.

Convergence Suppression and Divergence Facilitation: Minimum and Joint Use of Hidden Units by Multiple Outputs.

Pruning of multi-layer neural network structure is not a simple problem if two or more output units are present; unlike the single-output case, removing a hidden-output synaptic link does not necessarily mean elimination of a hidden unit. A new pruning algorithm called CSDF is presented. Its aim is to minimize the total number of active hidden units, thereby making some hidden units utilized jointly by more than one output unit.