Response properties of neurons in cat dorsal lateral suprasylvian cortex to optic flow fields.

Single neurons in the dorsal lateral suprasylvian cortex (DLS) of the cat were tested with large field optic flow stimuli simulating translation and spiral motion (including radiation and rotation) in different directions. Most cells were responsive to both kinds of movement with fairly good direction selectivity. Generally, the responses were better to spiral motion than to translation, and better to radiation than to rotation. Moreover, the direction tuning for spiral was broader than that for planar motion. The dot size in the stimulus patterns had no certain influence on the responses and direction preference. These results suggest that DLS might be substantially involved in the detection and analysis of complex optic flow information, and to some extent, in favor of the radiation component inside.

Postnatal development of nicotinamide adenine dinucleotide phosphate-diaphorase-positive neurons in the retina of the golden hamster.

The histochemical method was used to investigate the postnatal development of nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) -positive neurons in retinas of the golden hamster. NADPH-d-positive neurons were discernible in the retina at postnatal day (P)1. From P4 onward to adulthood, when the retina acquired its laminated characteristics, NADPH-d- positive neurons were observed in the inner nuclear layer (INL) and the ganglion cell layer (GCL). Results showed that NADPH-d-positive neurons in INL and GCL followed different time courses and patterns in their development. NADPH-d-positive neurons in INL underwent a sharp increase from P4 to P8 (3.6-fold), followed by a decrease to 46% of the maximum at P12. This value was maintained relatively constant to the adult level. The mean diameters of NADPH-d-positive neurons in INL, which were smaller than those in the GCL for all ages, increased from P8 to P12 and from P20 to adulthood. As for neurons in the GCL, the increase in cell number was not so apparent for the earlier postnatal days until P20; thereafter, an obvious increase to the adult level was observed. The mean diameters of the NADPH-d-positive cell bodies in the GCL increased with age, except for P16-P20, during which time there was a slight and insignificant decrease. The tendency of changes in cell density was basically similar to that of the total number for both the INL and the GCL. Between P12 and P20, the density distribution map of the NADPH-d-positive neurons underwent dramatic changes: The highest density shifted from the upper central retina at the earlier postnatal days to the lower central retina in the adult. The two waves of increase in NADPH-d-positive neurons coincide with the process of axonal elongation and synaptogenesis and the acquisition of visual function and experience. It is suggested that these NADPH-d-positive neurons are related to these two developmental events.

[Processing of optic flow information during self-motion].

For human beings and animals, the observer encounters the so-called optic flow during locomotion, the image motion pattern of the environment on the retina, which includes three basic modes of motion: rotation, expansion/contraction and translation. The analysis of optic flow information is vital for determining the direction and velocity of locomotion and has been a hotspot of the studies on visual information processing in recent years. In this article, some progresses in psychophysics and electrophysiology studies on optic flow are introduced and the neural mechanism of optic flow processing in mammalian brain is discussed.