Research

Texas-Rattlesnake (Crotalus atrox)

I'm mainly interested in sensory systems of reptiles, especially snakes. During the evolution sensory systems of snakes underwent several unique modifications, which e.g. resulted in the development of a sophisticated infrared system. This system is integrated into the visual system in higher brain areas. We use an in vitro whole-brain preparation of a rattlesnake to investigate the infrared system from the signal transduction in the periphery up to the multimodal integration into the visual system in the optic tectum.

Recently, I started two new research projects on the neuronal activation of motor systems. These projects investigate the neuronal control of the predatory strike in arboreal snakes and the activation of the superfast rattlesnake shaker muscle.

Projects

Coding of spatial information in the primary infrared nucleus of rattlesnakes

Pitvipers (e.g. Rattlesnakes) possess a specialized sensory system to detect infrared (IR) radiation. The infrared system provides these snakes with a presumably precise IR-image of the surrounding environment, which allows them to strike towards warm-blooded prey even in complete darkness. Considering the optical properties of the peripheral infrared organ (pit-organ), which resemble those of a simple pinhole camera, this is not self-evident.

Infrared information of the snakes' environment is topographically aligned in a spatial map in the optic tectum and integrated into the spatial map of the visual system. It is hypothesized that the extraction of spatial information from the sensory input already takes place in the primary infrared nucleus (LTTD), which projects to the optic tectum via a second exclusive infrared sensitive nucleus (RC). To investigate the reconstruction of an precise IR-image and the formation of the infrared-map in the CNS, the functions and properties of the primary and secondary infrared nuclei in the hindbrain need to be investigated in detail.

Thus the aim of this project is to unveil anatomy, histochemistry and physiology of the LTTD and RC, to understand the mechanisms by which the spatial component of sensory input is encoded in the infrared system.The principles by which this extraction of spatial information is realized are further investigated in comparative studies with boid snakes also capable to sense in infrared radiation.

In prospective studies the results will be used by computational neuroscientists to check the applicability of found principles into algorithms which might be used in novel, miniaturized infrared cameras that achieve similar spatial performance as today’s expensive systems.

Organotopic organization of the LTTD (Kohl et al., 2014)

Neuronal activation of striking patterns in arboreal snakes

Boid snakes (Boidae) are capable of performing fast and precise predatory strikes. During the pre-strike phase, arboreal snakes visually inspect their potential target with up to 2/3 of the body freely extended into space. After strike initiation this static position is changed into a highly dynamic strike performance. This computational/experimental study will investigate the static/dynamic switch and the coordination of axial muscle activity during the pre-strike-strike transition.

Amazon tree boa (Corallus hortulanus)

Methods

  • In-vitro single-cell and multiarray recordings
  • Intracellular tracer injection
  • anterograde and retrograde neuronal tracing
  • Immunohistochemistry
  • High-speed motion analysis
  • µCT-scans
  • Behavioural experiments
Anterograde labeld neurons in the trigeminal ganglion
Axonal terminations of primary infrared fibers in the LTTD