Hadley Horch

Associate Professor of Biology and Neuroscience Director of Neuroscience Program

Teaching this semester

BIOL 2135/NEUR 2135. Neurobiology

Examines fundamental concepts in neurobiology from the molecular to the systems level. Topics include neuronal communication, gene regulation, morphology, neuronal development, axon guidance, mechanisms of neuronal plasticity, sensory systems, and the molecular basis of behavior and disease. Weekly lab sessions introduce a wide range of methods used to examine neurons and neuronal systems.

BIOL 3329/NEUR 3329. Neuronal Regeneration

The consequences of neuronal damage in humans, especially in the brain and spinal cord, are frequently devastating and permanent. Invertebrates, on the other hand, are often capable of complete functional regeneration. Examines the varied responses to neuronal injury in a range of species. Topics include neuronal regeneration in planaria, insects, amphibians, and mammals. Students read and discuss original papers from the literature in an attempt to understand the basis of the radically different regenerative responses mounted by a variety of neuronal systems.

The Horch lab uses the cricket model system to examine the molecular neurobiological basis of a number of areas including regeneration, behavior, and development. Mainly, the lab will focus on the regeneration of interneurons in the auditory system of the cricket. Removing one ear induces auditory interneurons to sprout new dendrites, grow abnormally across the mid-line, and form synapses with intact auditory neurons from the opposite ear, both in developing as well as adult crickets. This is one of the most elegant and complex examples of neuronal regeneration known. Techniques such as dextran backfills, immunohistochemistry, and confocal microscopy will be used to understand the molecular cues involved in this phenomenon. Other projects include examining the role of octopamine on male cricket aggression and attempting to create transgenic crickets in order to examine the development of individual neurons.

Teaching Area: Molecular Neuroscience

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Education

  • B.A. Biology , Swarthmore College, 1993
  • PhD, Neurobiology, Duke University, 2001
  • Post-doctoral education, Department of Neurobiology and Behavior, Cornell University, 2001-2002

The Horch Lab

The Horch lab uses the cricket model system to examine the molecular neurobiological basis of a number of areas including neuronal regeneration and behavior.  Unlike many neuronal systems, the auditory system of the cricket demonstrates robust neuronal growth in response to denervation.  Removing one ear induces auditory interneurons to sprout new dendrites, grow abnormally across the mid-line, and form synapses with intact auditory neurons from the opposite ear.  Currently, students in my lab are using molecular biology to clone the genes for guidance cues from crickets.  We hope to examine the expression of these cues to assess if they might be involved in this regeneration.  We are also examining the 3-dimensional characteristics of these regenerated neurons.  The lab regularly uses techniques such as dye backfills, immunohistochemistry, in situ hybridization, PCR, and confocal microscopy.  We are also attempting to develop a method for transfecting living neurons in crickets.

The Horch lab is currently collaborating with Dr. Ron Hoy's lab at Cornell University. Dr. Hoy is an expert on the neurobiology of insects. Our lab groups meet several times a year, in Ithaca NY and at the annual Society for Neuroscience meeting. Learn more about work in Dr. Hoy's lab: http://www.nbb.cornell.edu/neurobio/hoy/webpage/hoyhome.html

In addition to the regeneration work, we are interested in how molecules influence behavior.  Specifically, we are examining how the neurohormone octopamine influences aggressive interactions between male crickets.  In our experiments, we are trying to turn "duds into studs" by giving the losing cricket octopamine prior to fighting the winning cricket.  

News


Sample Student Lab Research

The Neuroscience department awards its outstanding students with the opportunity to do serious lab research over the Summer. Stipends are available and projects are often co-authored for publication. This Summer has again yielded outstanding original research in the filed. Here are some sample projects:

John Hobbs '15
The effects of hormones on the sexual dimorphic auditory dendritic compensatory regeneration of the Cricket Gryllus bimaculatus
read a summary of the project »

Adam Zhang '14
Quantifying Changes in Semaphorin Expression after Deafferentation in Gryllus Bimaculatus
read a summary of the project »

Ketura Berry '13
Investigating Sema2a's Causative Role in Cricket Compensatory Growth
read a summary of the project »

Sarah Solomon
Molecular Characterization of Dendritic Regeneration in Gryllus bimaculatus
read a summary of the project »

Stephen Mallon
Molecular Characterization of Invertebrate Neural Regeneration
read a summary of the project »

Suen Wong
Compensatory Regeneration in the Auditory interneuron AN2 of the Cricket Gryllus Bimaculatus
read a summary of the project »

Laura Welsh
The Role of Octopamine in Male Cricket Aggression
read a summary of the project »

Recent Publications

Horch, H.W., Sheldon, E., Cutting, C.C., Williams, C.R., Riker, D.M., Peckler, H.R., and Sangal, R.B. 2011. Bilateral consequences of chronic unilateral denervation in the auditory system of the cricket Gryllus bimaculatus. Developmental Neuroscience, 33: 21-37.

Horch, H.W., McCarthy, S.S., Johansen, S.L., and Harris, J.M. 2009.  Differential gene expression during compensatory sprouting of dendrites in the auditory system of the cricket Gryllus bimaculatus. Insect Molecular Biology, 18: 483-496.

Maynard, K.M., McCarthy, S.S., Sheldon, E., Horch, H.W. 2007.  Developmental and adult expression of sempahorin 2a in the cricket Gryllus bimaculatus.  Journal of Comparative Neurology. 503: 169-181.

Horch, H.W.  2004.  Local effects of BDNF on dendritic growth.  Reviews in the Neurosciences, 15: 116-129.

Horch, H.W. and Katz, L.C. 2002.  BDNF release from single cells elicits local dendritic growth in nearby neurons. Nature Neuroscience, 5: 1177-1184.

Horch, H.W., Kruttgen, A., Portbury, S.D, and Katz, L.C. 1999. Destabilization of cortical dendrites and spines by BDNF. Neuron, 23: 353-364.

Horch, H.W., and Sargent, P.B. 1996. Effects of denervation on acetylcholine receptor clusters on frog cardiac ganglion neurons as revealed by quantitative laser scanning confocal microscopy. J. Neurosci. 16(5): 1720-1729.

Horch, H.W., and Sargent, P.B. 1996. Synaptic and extrasynaptic distribution of two distinct populations of nicotinic acetylcholine receptor clusters in the frog cardiac ganglion. J. Neurocytol. 25: 67-77.

Horch, H.W., and Sargent, P.B. 1995. Perisynaptic surface distribution of multiple classes of nicotinic acetylcholine receptors on neurons in the chicken ciliary ganglion. J. Neurosci. 15(12): 7778-7795.