Position  Post-doc @ McGill University, Montreal
 e-mail  volker.hofmann[@]mail.mcgill.ca
   

 

Volker's Research while in the lab

Side View
Side view of Gnathonemus petersii´s head.
Electroreceptors in the skin can be seen as bright dots.

How does the central nervous system extract information from the environment? What are active behavioral strategies to optimize this information extraction? How does the central nervous system represent, process and analyze such sensory signals?

Along this line of research I am currently working on the active electrolocation system of the elephant nose fish, Gnathonemus petersii. This weakly electric fish emits short electric pulses (electric organ discharge = EOD) that built up an electric field around the body of the animal. Objects nearby the fish distort this field and thus modulate the voltage distribution (electric image) on the skin of the animal that holds an array of electroreceptors (see picture). These alterations are used by the animal for active electrolocation.

By moving relative to an object during sampling, spatial and temporal changes in the sensory input (= electric flow) are generated that comprise potential perceptual cues. My current research investigates if and how fish exploit these sensory possibilities during unrestrained and task related behavioral experiments.

Furthermore I am interested in information encoding of medullary electrosensory units (ELL). How ELL units respond to stationary and dynamic stimulation with physical objects is investigated with electrophyiological methods (see picture below).

Side View

Original recording of a ELL-unit response to stimulation with a metal cube at different distances
(red arrwos = EOD artefact, black vertical = spike activity)

 

Publications

Hollmann V, Hofmann V, Engelmann J (2016) A somatotopic map of the active electrosensory sense in the midbrain of the mormyrid Gnathonemus petersii | Journal of Comparative Neurology (accepted)

Hofmann V, Geurten BRH, Sanguinetti-Scheck JI,  Gómez-Sena L, Engelmann J (2014) Motor patterns during active electrosensory acquisition.; Front Behav Neuorsci, 8(186): 1-14, doi:10.3389/fnbeh.2014.00186 | LINK

Hofmann V, Sanguinetti-Scheck JI, Künzel S, Geurten B, Gómez-Sena L, Engelmann J (2013) Sensory flow shaped by active sensing: sensorimotor strategies in electric fish.; J Exp Biol 213: 2487-2500, doi:10.1242/jeb.082420, | LINK

Hofmann V, Sanguinetti-Scheck JI, Gómez-Sena L, Engelmann J (2013) From static electric images to electric flow: Towards dynamic perceptual cues in active electroreception; J Phys-Paris 107: 95-106, | LINK

Conference Proceedings | Talks

Hofmann V, Sanguinetti JI, Geurten B, Gómez-Sena L, Engelmann J (2013) Sensorimotor patterns during electrolocation behavior of mormyrid fish. Satellite Symposium "Neuroethology" of the 106th annual meeting of the German Zoological Society, Munich, Germany.

Hofmann V, Sanguinetti JI, Geurten B, Gómez-Sena L, Engelmann J (2012) Towards an alphabet of motor patterns in active electrolocation behavior of Gnathonemus petersii. Satellite Symposium "Weakly electric fishes: Neural systems, behavior and evolution" of the ICN 2012, College Park, MD, USA.

Hofmann V, Sanguinetti J, Gómez-Sena L, Engelmann J (2011) Analysing sensory related behavior in active electrolocation: Linking motor patterns to electric flow information. 104th Annual Meeting of the German Zoological Society, Saarbrücken.

Conference Proceedings | Posters

Hofmann V, Pedraja FE, Engelmann J (2014) Estimation of object distance based on electrosensory input dynamics. 107th annual meeting of the DZG 2014, Goettingen, Germany.

Hofmann V, Künzel S, Sanguinetti JI, Engelmann J (2013) Object detection and distance discrimination by mormyrid ELL neurons. Satellite Symposium "Neuroethology" & main meeting of the DZG 106th annual meeting 2013, Munich, Germany.

Hofmann V, Sanguinetti JI, Geurten B, Gómez-Sena L, Engelmann J (2013) Sensorimotor patterns during electrolocation behavior of mormyrid fish. DZG 106th annual meeting 2013, Munich, Germany.

Kassing V, Hofmann V, Engelmann J (2013) Functional connectivity between ELL and the torus semicircularis of the weakly electric fish Gnathonemus petersii. Sattelite Symposium "Neuroethology" of the 106th annual meeting of the German Zoological Society, Konstanz, Germany.

Hofmann V, Sanguinetti JI, Gómez-Sena L, Engelmann J (2012) Spatiotemporal analysis of static electric images: A tool to investigate electric flow? 105th Annual Meeting of the German Zoological Society, Konstanz & 10th International Congress of Neuroethology, College Park, MD, USA.

Hofmann V, Sanguinetti JI, Geurten B, Gómez-Sena L, Engelmann J (2012) Towards an alphabeth of motor patterns in active electrolocation behavior of Gnathonemus petersii. 10th International Congress of Neuroethology, College Park, MD, USA.

Künzel S, Hofmann V, Sanguinetti JI, Engelmann J (2012) Linking behavior and sensory processing: Analysis of distance estimation capability in neurons of the Mormyrid ELL. 10th International Congress of Neuroethology, College Park, MD, USA.

Sanguinetti JI, Hofmann V, Engelmann J, Gómez-Sena L (2012) Towards dynamic perceptual cues in active electroreception: Modelling of electric image flow based on sensory related behaviour. 10th International Congress of Neuroethology, College Park, MD, USA.

Hofmann V, Zelick RD, Bleckmann H (2011) Responses of midbrain lateral line units in goldfish, Carassius auratus, may be used to determine flow velocity. International Congress Flow Sensing in Air and Water, Bonn.

Hofmann V, Zelick RD, Bleckmann H (2009) Responses of midbrain lateral line units in the goldfish, Carassius auratus, to bulk water flow. NBM - Natural and Biomimetic Mechanosensing, International Conference, Dresden.

Hofmann V, Zelick RD, Bleckmann H (2009) Neuronal encoding of bulk water flow in the midbrain of the goldfish (Carassius auratus). 32nd Göttingen Neurobiology Conference, Eighth Meeting of the German Neuroscience Society, Göttingen.

PhD Thesis

Sensorimotor interactions in an active sensory system. Universität Bielefeld

Diploma Thesis

Responses of midbrain lateral line units in the torus semicircularis of the goldfish, Carassus auratus, to bulk water flow. Rheinische Friedrich-Wilhelms-Universität Bonn

 

News

In the News

Süddeutsche Zeitung - Picture published (2013-06-13) | LINK
Süddeutsche Zeitung - Review of JEB special issue on electric fish (2013-06-13) | LINK

Awards

Best poster contribution in the section "Neurobiology" at the 106th annual meeting of the German Zoological Society, Munich, Germany:
Hofmann V, Sanguinetti JI, Geurten B, Gómez-Sena L, Engelmann J (2013) Sensorimotor patterns during electrolocation behavior of mormyrid fish.