Vijayan, S. | Search bioRxiv

bioRxiv2018

Look before you jump: jumping spiders discriminate different ants by visual cues

Ants, being ubiquitous, aggressive, and top predators, play a predominant role in terrestrial ecosystems. Jumping spiders are another prominent invertebrate predator that are present in similar habitats as that of ants. Most jumping spiders are thought to avoid ants, yet little is known if they discriminate among them. In this study we examined the response of jumping spider genus Plexippus towards three different ant species (Oecophylla smaragdina, the weaver ants; Camponotus sericeus the golden-back carpenter ants, and Leptogenys processionalis, the procession ants). In a behavioral assay that excluded tactile and chemical cues, we tested if spiders distinguish the three ants by visual cues alone. We recorded and analysed behaviors such as look, approach, stalk, attack, and avoidance by spiders towards ants. Our results show that the three ants differ in their color, movement and aggressive behavior. Spiders gave short looks to live ants, suggesting movement is important in detecting ants. Furthermore, spiders gave significantly more long looks to procession and golden-back ants compared to weaver ants. Spiders approached, stalked and attacked procession ants more compared to weaver ants. Numerous jumping spiders and ants overlap in their habitat, and it is advantageous to selectively avoid some ants over others. Our results suggests that jumping spiders can indeed distinguish ants that co-occur in their habitat by visual cues alone, however, the precise nature of visual cues warrants further studies.

animal behavior and cognition↗

bioRxiv2017

Cortical circuit based lossless neural integrator for perceptual decision-making

The intrinsic uncertainty of sensory information (i.e., evidence) does not necessarily deter an observer from making a reliable decision. Indeed, uncertainty can be reduced by integrating (accumulating) incoming sensory evidence. It is widely thought that this accumulation is instantiated via recurrent rate-code neural networks. Yet, these networks do not fully explain important aspects of perceptual decision-making, such as a subjects ability to retain accumulated evidence during temporal gaps in the sensory evidence. Here, we utilized computational models to show that cortical circuits can switch flexibly between retention and integration modes during perceptual decision-making. Further, we found that, depending on how the sensory evidence was readout, we could simulate stepping and ramping activity patterns, which may be analogous to those seen in different studies of decision-making in the primate parietal cortex. This finding may reconcile these previous empirical studies because it suggests these two activity patterns emerge from the same mechanism.

neuroscience↗