Sasha N. Zill, PhD

Sasha Zill, Ph.D.Professor
Department: Anatomy and Pathology
Office: CEB 216
Phone: (304) 696-7384 | Fax: (304) 696-7290
Personal webpage:

Research Interests

Our research is a labor of love that has as its context understanding how the nervous system generates motor behaviors.  It can be argued that nervous systems evolved in animals to allow for sensible decisions to be made in generating and adapting motor actions.  Sense organs provide the information needed for making these modifications. The animals we have studied are arthropod invertebrates, and most work in the lab is done on sense organs of insects that detect mechanical forces (mechanoreceptors).

Cogent reasons for studying insects are that their nervous systems have fewer neurons and their sense organs are individually identifiable. Experiments can be performed on these animals that are difficult or impossible to do in vertebrates. Our results are relevant to problems in motor control and Biorobotics. We have also studied these questions using engineering methods. However, the actual impetus for our studies is that insect behaviors are fascinating and richly complex. They are also constructed with an economy of design that reflects their remarkable adaptive success and longevity. Our research is further described on our webpages (see The specific projects we are currently pursuing are described in Projects and our Publications are listed and some are available for download. We also have a number of video sequences available for study or perusal, many of which have audio channels with recordings of sensory or motor activities during the behaviors. We have also posted a page related to Issues in Medical Education and teaching Basic Science/Neurobiology as a forum for ideas and discussion.

Zill Fig (1)

Mechanoreceptors in stick insects (Zill Lab) Campaniform sensilla of the stick insect are echanoreceptors that monitor force acting on a leg. Many groups of sensilla are found in the trochanteral segment of the leg. Strains in the exoskeleton are detected by processes of sensory neurons that attach to the caps (right). The information provided by the sense organs has been modeled in simulations and emulated in robotic legs (Micrographs: Middle, Josef Schmitz and Annelie Exter; Right. Sumaiya Chaudhry and David Neff)

Selected Publications

Positive force feedback in development of substrate grip in the stick insect tarsus.
Zill SN, Chaudhry S, Exter A, Büschges A, Schmitz J. Arthropod Struct Dev. 2014 Jun 18. pii: S1467-8039(14)00048-6. doi: 10.1016/j.asd.2014.06.002. [Epub ahead of print] PMID: 24951882 [PubMed – as supplied by publisher]

Directional specificity and encoding of muscle forces and loads by stick insect tibial campaniform sensilla, including receptors with round cuticular caps.
Zill SN, Chaudhry S, Büschges A, Schmitz J. Arthropod Struct Dev. 2013 Nov;42(6):455-67. doi: 10.1016/j.asd.2013.10.001. Epub 2013 Oct 11. PMID: 24126203 [PubMed – indexed for MEDLINE]

Force encoding in stick insect legs delineates a reference frame for motor control.
Zill SN, Schmitz J, Chaudhry S, Büschges A. J Neurophysiol. 2012 Sep;108(5):1453-72. doi: 10.1152/jn.00274.2012. Epub 2012 Jun 6. PMID: 22673329 [PubMed – indexed for MEDLINE] Free PMC Article

Zill, S, Büschges, A, Schmitz, J (2011) Encoding of force increases and decreases by tibial campaniform sensilla in the stick insect, Carausius morosus. J Comp Physiol A  197:851-867.

Zill SN (2010) Invertebrate neurobiology: role of the insect brain in walking. Current Biology 2-: 438-440.

Zill SN, Keller BR, Chaudhry S, Duke ER, Neff D, Quinn R, Flannigan C (2010) Detecting substrate engagement: responses of tarsal campaniform sensilla in cockroaches. J Comp Physiol A 196:407-420.

Zill SN, Keller BR, Duke ER (2009) Sensory signals of unloading in one leg follow stance onset in another leg: Transfer of load and emergent coordination in cockroach walking. J Neurophysiol 101:2297-2304.

Zill SN, Keller BR (2009) Neurobiology: Reconstructing the neural control of leg coordination. Current Biology 19: 371-373.

Zill SN, Keller BR (2008) Neurobiology: Venom of wasps and initiation of movements. Current Biology 18: 525-527.

Zill SN (2007) Invertebrate neurobiology: sensory processing in reverse for backward walking. Current Biology 17: R462-464.

Keller BR, Duke EF, Amer AS, Zill SN (2007) Tuning posture to body load: decreases in load produce discrete sensory signals in the legs of freely standing cockroaches.  J Comp Physiol A 193:881-891

Quimby L, Amer A and Zill, SN (2006) Common motor mechanisms support body weight in serially homologous legs of cockroaches in posture and locomotion.  J Comp Physiol A 192:247-266

Kaliyamoorthy S, Zill SN, Quinn RD (2005) Force sensors in hexapod locomotion.  Int J Robotics Res 24: 563-574

Zill S, Schmitz J, Büschges A (2004) Load sensing and control of posture and locomotion.  Arthropod Struct and Dev 33:273-286 (Special Issue: Arthropod Locomotion Systems: from Biological Materials and Systems to Robotics, RE Ritzmann, SN Gorb and RD Quinn, eds.)

Laboratory Personnel

Sumaiya Chaudhry