The infrared sense of rattlesnakes: Neuronal processing of a low-resolution image
Pitvipers, such as rattlesnakes, have a specialized sensory system in the upper jaw to detect infrared (IR) radiation. This extra sense is used for behavioural thermoregulation, predator avoidance and particularly to detect and strike at endothermic prey.
The infrared system consists of bilateral pit organs that resemble simple pinhole cameras and map IR objects onto the sensory epithelium as blurred representations of the environment. Although the image is of low resolution, rattlesnakes can strike precisely at potential prey even in complete darkness.
To gather a first understanding of how spatial and directional information is extracted from the blurred IR-images, we recorded neurons in isolated rattlesnake brains intracellularly. Our data from two unique infrared sensitive nuclei (LTTD, RC), indicates that synaptic processing related to contrast enhancement and IR object motion already takes place at the level of the hindbrain.