Two-dimensional receptive fields of midbrain lateral line units in the goldfish, Carassius auratus

The incomparable fascination of comparative physiology: 40 years with animals in the field and laboratory

This paper is not meant to be a review article. Instead, it gives an overview of the major research projects that the author, together with his students, colleagues and collaborators, has worked on. Although the main focus of the author's work has always been the fish lateral line, this paper is mainly about all the other research projects he did or that were done in his laboratory. These include studies on fishing spiders, weakly electric fish, seals, water rats, bottom dwelling sharks, freshwater rays, venomous snakes, birds of prey, fire loving beetles and backswimmers. The reasons for this diversity of research projects? Simple. The authors's lifelong enthusiasm for animals, and nature's ingenuity in inventing new biological solutions. Indeed, this most certainly was a principal reason why Karl von Frisch and Alfred Kühn founded the Zeitschrift für vergleichende Physiologie (now Journal of Comparative Physiology A) 100 years ago.

Developmental and architectural principles of the lateral-line neural map

The transmission and central representation of sensory cues through the accurate construction of neural maps is essential for animals to react to environmental stimuli. Structural diversity of sensorineural maps along a continuum between discrete- and continuous-map architectures can influence behavior. The mechanosensory lateral line of fishes and amphibians, for example, detects complex hydrodynamics occurring around the animal body. It triggers innate fast escape reactions but also modulates complex navigation behaviors that require constant knowledge about the environment. The aim of this article is to summarize recent work in the zebrafish that has shed light on the development and structure of the lateralis neural map, which is helping to understand how individual sensory modalities generate appropriate behavioral responses to the sensory context.

Central representation of spatial and temporal surface wave parameters in the African clawed frog

Xenopus laevis employs mechano-sensory lateral lines to, for instance, capture arthropods on the surface of turbid waters with poor visibility based on incoming wave signals. To characterise central representations of surface waves emitted from different locations, responses to several wave parameters were extracellularly recorded across brainstem, midbrain and thalamic areas. Overall, 339 of 411 statistically analysed responses showed significantly altered spike rates during the presentation of surface waves. Of these units, 45.1% were obtained in the torus semicircularis including its laminar subnucleus (23.3%) that is known to process auditory cues. Wave parameters contributing to central object representations were indicated by response rates that systematically varied with amplitude (76.3% of 160 tested units), frequency (74.4% of 270 tested units), source angle (93.7% of 79 tested units), or source distance (63.8% of 218 tested units). Map-like parameter representations were rather diffuse, yet an increased fraction of units tuned to frontal source angles was observed at deeper tissue layers (>180 μm), and an increased fraction of best neuronal responses to low wave frequencies (≤25 Hz) at rostral midbrain sections. Responses to wave frequencies remained largely robust across tested unit samples independent of source angles, and distances (N = 62). In comparison, spatial response characteristics seemed fragile across different wave frequencies in 68.3% of 41 recordings.