The Head-fixed Behaving Rat—Procedures and Pitfalls

This paper describes experimental techniques with head-fixed, operantly conditioned rodents that allow the control of stimulus presentation and tracking of motor output at hitherto unprecedented levels of spatio-temporal precision. Experimental procedures for the surgery and behavioral training are presented. We place particular emphasis on potential pitfalls using these procedures in order to assist investigators who intend to engage in this type of experiment. We argue that head-fixed rodent models, by allowing the combination of methodologies from molecular manipulations, intracellular electrophysiology, and imaging to behavioral measurements, will be instrumental in combining insights into the functional neuronal organization at different levels of observation. Provided viable behavioral methods are implemented, model systems based on rodents will be complementary to current primate models—the latter providing highest comparability with the human brain, while the former offer hugely advanced methodologies on the lower levels of organization, for example, genetic alterations, intracellular electrophysiology, and imaging

Neuronal precision and the limits for acoustic signal recognition in a small neuronal network

Recognition of acoustic signals may be impeded by two factors: extrinsic noise, which degrades sounds before they arrive at the receiver’s ears, and intrinsic neuronal noise, which reveals itself in the trial-to-trial variability of the responses to identical sounds. Here we analyzed how these two noise sources affect the recognition of acoustic signals from potential mates in grasshoppers. By progressively corrupting the envelope of a female song, we determined the critical degradation level at which males failed to recognize a courtship call in behavioral experiments. Using the same stimuli, we recorded intracellularly from auditory neurons at three different processing levels, and quantified the corresponding changes in spike train patterns by a spike train metric, which assigns a distance between spike trains. Unexpectedly, for most neurons, intrinsic variability accounted for the main part of the metric distance between spike trains, even at the strongest degradation levels. At consecutive levels of processing, intrinsic variability increased, while the sensitivity to external noise decreased. We followed two approaches to determine critical degradation levels from spike train dissimilarities, and compared the results with the limits of signal recognition measured in behaving animals

Statusseminar Wirkungen von Luftverunreinigungen auf Waldbäume und Waldböden

During the 2 - 4th December 1985 the "Project Management for Ecotoxicological Research" in the Nuclear Research Centre, Jülich (PTU) and the "Landesanstalt für Immissionsschutz" des Landes Nordrhein-Westfalen (LIS) organized a joint seminar concerning the topics a) effects of air pollutions on obove parts of forest trees(LIS) b) effects of air pollutions on soil and below parts of forest trees (PTU). The presentations to topic a) were focused on air pollutants as possible factors for direct damage of obove parts of forest trees. In order to answer this question both morphological, cytological and physiological aspects were considered. Topic b) emphasized investigations concerning - changes of soil conditions by depositions of pollutants - nitrogen impact and the effects on forest ecosystems - turnover of fine-roots and the importance/function of mycorrhiza within the ecosystem forest/soil. The report contains the presentations and results of the mentioned topics