Forschung / Research

 

As functional and evolutionary morphologist the fundamental interest of my research is to understand evolutionary transformations in biological systems. The particular focus of my research is directed to the motion system of mammals. I want to understand how adaptive changes in form-function relationships arose against the background of phylogenetic heritage and evolutionary constraints. Examples are the reconstruction of plesiomorphic and derived characters of primate locomotion (e.g. Schmidt, 2008; Schmidt, Habilitation thesis 2010) or the comparison of functional and developmental determinants in mammalian limb proportions (Schmidt and Fischer, 2009). The motion system has multiple biological roles in the life of an animal and current research activities are directed to non-locomotory activities related to the care of the body surface. Grooming plays a predominant role for an individual’s health and fitness, and I want to know how functional demands on grooming could have influenced the evolution of the mammalian motion system.

The transfer of biological solutions into engineering has a long tradition in Jena. Together with our colleagues from the Technical University Ilmenau we extracted common principles of self-stability in the locomotion of small mammals or of climbing kinematics in rats, primates and chameleons. The latter were implemented in the engineering of Ratnic, a small climbing robot (Tetra GmbH Ilmenau). A current collaborative project explores the technical solution of short-distance mechanoreceptors according to the sinus hairs of mammals. Beside the application in engineering, locomotor studies become of increasing importance as diagnostic tool in preclinical and genetic research projects. Here, we demonstrate the potential of high-resolution kinematic analyses based on X-ray fluoroscopy.

 

 Research overview

 

Current Research Projects

 The Biological Role of Carpal Vibrissae during Locomotion. 

   
 

Many small-sized mammals have three or more sinus hairs near the wrist joint of the forelimb, called “carpal vibrissae”. Though these hairs do not “vibrate” like the well-known whiskers of the face. Rats typically have at least three of these hairs whose tips form a triangle. Sandra Niederschuh in her PhD. project investigates the function of these hairs as feedback sensors during locomotion. She analysed the effect of removal of these hairs (they regenerate within two weeks) on limb kinematics and body posture. It appears that carpal sinus hairs are not only useful in detecting substrate properties, but also play a role as feedback sensors for locomotor speed, presumably by measuring the contact phase duration. Another aspect of this research topic is the investigation of the microstructure of the follicle-sinus complex using Micro-CT and histological examinations.

Our biological perspective on carpal vibrissae is embedded in a collaborative project with engineers and scientists of the Technical University Ilmenau (Project: „Technical, non-visual characterization of substrate contacts using carpal vibrissae as a biological model“, supported by the German Research Foundation). Together, we explore how technical solutions for lever-based mechanosensors can be realized according to the function of vibrissae. We investigate, for example, the texture and material properties of the hairs, their flexural properties at substrate contact or how contact and bending of artificial vibrissae can be transformed into signals that inform about surface texture and other substrate properties.
 
 Carpal vibrissae Anat    A. Location of three carpal sinus hairs on the rat's forepaw (Niederschuh et al. 2017). B. Longitudinal section of the follicle-sinus complex of a carpal sinus hair. Paraffin-embedded tissue, Goldner staining (Müller-Langer 2015).
 Project partners:    
  Hartmut Witte, Thomas Helbig, Danja Voges (DEPT of Biomechatronics, TU Ilmenau)  
 Vibrissen Biol Role   Adjustment of body posture on continuous and discontinuous substrate. Red arrows indicate changes observed in the absence of sensory feedback from carpal sinus hairs (Niederschuh et al. 2017).
 
  Klaus Zimmermann, Tatiana Becker, Carsten Behn and others (DEPT of Mechanical Engineering, TU Ilmenau)  
     
Publications:  
  Helbig, T.; Voges, D.; Niederschuh, S.; Schmidt, M.; Witte, H. (2014): Characterizing the substrate contact of carpal vibrissae of   rats during locomotion. In: Biomimetic and Biohybrid Systems. Lecture Notes in Computer Science Volume 8608, pp 399-401.  
  Niederschuh, S.; Helbig, T.; Zimmermann, K.; Witte, H.; Schmidt, M. (2017): Kinematic response in limb and body posture depending on sensory feedback from carpal sinus hairs in the rat (Rattus norvegicus). Zoology.  
  Niederschuh, S.; Witte, H.; Schmidt, M. (2015): The role of vibrissal sensing in forelimb position control during travelling locomotion in the rat (Rattus norvegicus, Rodentia). Zoology 118, 51-62.  
  Volkova, T.; Zeidis, I.; Witte, H.; Schmidt, M.; Zimmermann, K. (2016): Analysis of the vibrissa parametric resonance causing a signal amplification during whisking behaviour. Journal of Bionic Engineering 13, 312-323.  
     
Bachelor- and Mastertheses:    
  Dargel, Lisa (2011): The role of vibrissae in detecting obstacles (at the example of Rattus norvegicus): Step-up.    
  Müller-Langer, Katharina (2015): Relationship between structure and function in the follicle-sinus complex of the carpal vibrissae of the rat (Rattus norvegicus, Rodentia).    
  Niederschuh, Sandra (2011): The role of vibrissae in detecting obstacles (at the example of Rattus norvegicus): Openings in the floor.     
  Niederschuh, Sandra (2013): The importance of sensory feedback from the mystacial vibrissae for the locomotion on discontinuous substrates in rats (Rattus norvegicus, Rodentia).    
  Stampe, Jana (2011): The role of vibrissae in detecting obstacles at the example of narrow passages.    
       

The Functional Morphology of Body Care.

   
 

Among the repertoire of idiomotion (= non-locomotory activities, directed to the animal itself), grooming plays a predominant role with respect to the amount of time that mammals dedicate to this behaviour. Its ecological importance has been investigated in a vast number of species. Also, the neural control of head washing and scratching has been studied intensively. But, scant attention has been payed to its adaptive significance for the function and morphology of the mammalian motion system. To fill the gap between behavioural and neurological research perspectives, we aim to develop research approaches which make grooming activities accessible to questions regarding its functional morphology. Currently, we study small-sized mammals such as rodents.

Our studies involve two aspects. First, we explore the overall performance and its intraspecific and interspecific variation to find out how mammals groom their fur, in particular, what are the most frequent targets of grooming, which areas of the body surface receive less attention and how is the relative contribution of oral grooming, forelimb and hind limb utilization. The second aspect comprises the analysis of limb and body kinematics of selected grooming movements. With the aid of X-ray fluoroscopy and XROMM, we are able to decompose even such complex activities like head washing into basic and comparable units.
   Grooming Rattus THGrooming RattusGrooming movements in the Norway rat. XROMM animation of head washing by Julia van Beesel (click images to play the movies).
       
Publications:    
  coming soon.    
       
Bachelor- and Mastertheses:    
  Heidemann, Juliane (2013): Forelimb movements during grooming and other non-locomotory activities of the rabbit (Oryctolagus cuniculus, Leporidae, Lagomorpha).    
  Oettel, Nina (2013): The repertoire of non-locomotory movements of the Mongolian gerbil (Meriones unguiculatus, Rodentia).    
  Pretzsch, Tina (2016): Locomotion and idiomotion of the rabbit (Oryctolagus cuniculus, Leporidae, Lagomorpha).    
  Schnappat, Britta (2016): Spatio-temporal pattern of grooming episodes in mammals of different size and body proportions.    
  Weber, Janina (2016): Grooming behaviour of the Sibirian chipmunk, Tamias sibiricus (Mammalia: Rodentia, Sciuridae).    
  van Beesel, Julia (2013): Forelimb kinematics of grooming movements in the Norway rat (Rattus norvegicus, Rodentia).    
  van Beesel, Julia (2016): Grooming movements of the Norway rat (Rattus norvegicus, Muridae, Rodentia) – a kinematic analysis using the XROMM method..    
       

Diagnostic Potential of Motion Analyses.

   
  Behavioural and performance analyses become of increasing importance as diagnostic tools in preclinical medical research and genetics. But, linking anatomy and physiology with behaviour and performance is difficult because of individual variation and flexibility in the latter. Functional morphologists, therefore, implement an intermediate descriptive level: the motion principles which underlie performance, e.g. the footfall patterns of gaits, the measures of speed changes, limb and body kinematics or substrate reaction forces. The analysis of such motion principles in animal models for diseases or in mutants has the potential to explain observed differences in performance and behaviour between treated and control individuals. But, evolutionary morphology also profit from such studies by learning much about intraspecific physiological and functional plasticity of the motion system and about the ability to compensate for a lesion in the central nervous system, for a dysfunction of a certain joint or for an genetic aberration.    
       
Current collaborative project:    
 

The Role of the Wilms Tumor Suppressor Gene Wt1 in the Neural Control of Locomotion in Mice (2014 - ).

Partners: Christoph Englert, Danny Schnerwitzki (Research Group Molecular Genetics, Leibniz Institute for Age Research - Fritz Lipmann Institute)