Tactile experience shapes prey-capture behavior in Etruscan shrews

Abstract

A crucial role of tactile experience for the maturation of neural response properties in the somatosensory system is well established, but little is known about the role of tactile experience in the development of tactile behaviors. Here we study how tactile experience affects prey capture behavior in Etruscan shrews, Suncus etruscus. Prey capture in adult shrews is a high-speed behavior that relies on precise attacks guided by tactile Gestalt cues. We studied the role of tactile experience by three different approaches. First, we analyzed the hunting skills of young shrews' right after weaning. We found that prey capture in young animals in most, but not all, aspects is similar to that of adults. Second, we performed whisker trimming for 3–4 weeks after birth. Such deprivation resulted in a lasting disruption of prey capture even after whisker re-growth: attacks lacked precise targeting and had a lower success rate. Third, we presented adult shrews with an entirely novel prey species, the giant cockroach. The shape of this roach is very different from the shrew's normal (cricket) prey and the thorax—the preferred point of attack in crickets—is protected by a heavy cuticle. Initially shrews attacked giant roaches the same way they attack crickets and targeted the thoracic region. With progressive experience, however, shrews adopted a new attack strategy targeting legs and underside of the roaches while avoiding other body parts. Speed and efficiency of attacks improved. These data suggest that tactile experience shapes prey capture behavior.

Biomimetic tactile target acquisition, tracking and capture

“…And of course, the hand-crafted models used here are unlikely to be optimal; an obvious route to improving performance, as well as increasing the number of stimuli that can be discriminated, is to use experience-driven learning [31]. In the same vein, such an approach could facilitate unsupervised identification of new classes of stimulus, a competence apparently displayed by the shrew when faced with a new class of prey [47]. On the physical side, the development of whiskers that are more robust to damage-without sacrificing sensory performance-would be a substantial leap forward in this area of robotics, and facilitate reproduction of aspects of biological active sensing which remain challenging (such as the very short timescale feedback exhibited by the shrew during a strike [23]).…”

“The Gaze Heuristic:” Biography of an Adaptively Rational Decision Process

“…It is these “whiskers” that are the source of information that represents the predator's gaze in the final milliseconds before impact (Sunquist & Sunquist, ). Vibrissae can detect air/water movements as small as 11 micrometers, and once in direct contact they can detect prey characteristics to an equal degree of precision (Adibi, Diamond, & Arabzadeh, ; Anjum & Brecht, ; Carvell & Simons, ).…”

Species-specific differences in synaptic transmission and plasticity

“…However, the investigation of the behavioural impact of mossy fiber synaptic transmission and LTP has not been conclusive, and has produced contradictory findings, with some studies finding that the lack or alterations of mossy fiber transmission results in impaired memory 17 – 19 , while others indicate there are no such effects 20 , 21 . However, even though shrews have comparatively lower mossy fiber LTP than mice, they can show spatial memory and hoard food stashes both close and away from their nests 22 and learn new strategies for hunting 3 . This seems to indicate that plasticity at the mossy fiber synapse might only play a limited role in spatial memory—however its involvement might vary in other forms of episodic-like memories such as contextual memory formation.…”

“…It is approximately 15 times smaller in body size and has a brain ~ 7 times smaller than a lab mouse. They hunt for their food, and prey on insects like crickets-consuming multiple times their body weight every day, primarily using somatosensory input from their whiskers 3 to guide hunting. Despite the minutely sized brain, the overall layout of the brain is rather similar to other mammalian brains, with a 6-layered cortex 1,2 and conserved genetic and architectural features in the neocortex and hippocampal formation 1,2,4 .…”

“…hoard food stashes both close and away from their nests 22 and learn new strategies for hunting 3 . This seems to indicate that plasticity at the mossy fiber synapse might only play a limited role in spatial memory-however its involvement might vary in other forms of episodic-like memories such as contextual memory formation.…”