Deep tectal cells in pigeons respond to kinematograms

Abstract

Deep tectal neurons in pigeons respond selectively to moving visual stimuli, and are inhibited by large background patterns moved in-phase with these stimuli. In this investigation we demonstrate that these same deep tectal neurons respond equally well to kinematograms as they do to traditional luminance contrast stimuli typically employed in visual experiments. Computer generated kinematograms, the motion domain equivalents of random dot stereograms, were used as stimuli in these experiments. These kinematograms, where a small centrally located set of random dots is moved coherently in one direction while the remaining dots are moved in a different direction, thus constitute a pure motion stimulus where the stimulus form is only visible in the dynamic pattern, but does not exist on any single frame. Both 'object' configured and 'hole' configured kinematograms were employed; the former appearing as regions of texture moving over, or in front of, the background texture, while the latter appear as windows through which a more distant textured surface is revealed. Extracellular recordings from isolated deep tectal cells showed that all units responded in a very similar manner whether the stimulus was an 'object' configured kinematogram or the more traditional luminance contrast variety. This similarity included directional selectivity, the in-phase inhibition anti-phase facilitation effect, and sensitivity to opposed motion independent of direction. However, when the kinematograms were configured as 'holes' none of the units tested responded to these stimuli. The significance of these observations for tectal functioning, image segmentation through motion and animal camouflage is discussed.

Object detection in the fly during simulated translatory flight

“…In this respect, FD cells have similar characteristics to cells found in the cat (Sterling and Wickelgren 1969), in the privet hawkmoth (Collett 1971;Collett and King 1975), in the pigeon (Frost and Nakayama 1983;Frost et al 1988) and in primates (Allman et al 1985;Tanaka et al 1986). Only two of the set of four FD cells are relevant in the present context: The FD1 and the FD4 cell are selective for front-to-back motion in front of the ipsilateral eye, i.e.…”

“…Landing occurred frequently when bees approached the edge facing the elevated side but hardly ever when they approached the edge facing the lower side, indicating that the landings on the edges are triggered by a local increase rather than by a decrease in motion speed perceived at the edge (Lehrer and Srinivasan 1993). Frost et al (1988) demonstrated that tectal cells in pigeons do not respond to random dot kinematograms in which an object solely de®ned by relative motion appeared as a``hole'' in the background, whereas they strongly respond to an object that appeared as elevated above the background. However, in the case of the kinematograms the depth impression was determined by the direction of motion of the border of a group of coherently moving dots making up the object, whereas in our case relative depth was de®ned on the basis of the relative velocities of object and background.…”

Neuronal Motion After-Response Induced in the Tectal Neurons of Toads by Moving Textured Background

“…Of course, the area of the moving background must also be large enough to stimulate a large portion of the vi sual field [Kass and Kass,I960]. Previous investiga tions [Frost, 1978;Frost et al, 1981Frost et al, , 1988Tanaka et al, 1986] were not successful in eliciting this effect, perhaps due to the absence of one or more of these crit ical factors in the experimental conditions. In the present study, however, 29 out of 66 neurons (44%) exhibited motion after-responses, and it is not known why this phenomenon did not occur in the other neu rons (more than 56%).…”

A Taxonomy of Different Forms of Visual Motion Detection and Their Underlying Neural Mechanisms

“…These same neurons also fire well to kinematograms (which are the motion domain equivalents of random dot stereograms), when the configuration presented is equivalent to an object moving over the top of, or in front of, a background, thus breaking camouflage in cryptically patterned animals that are moving. These neurons, first found in pigeons, do not respond when kinemato-grams configured as holes or windows are presented to the same cells [Frost et al, 1988].…”