This research will investigate the mechanisms of synaptic integration in the lateral giant (LG) command neurons that trigger the escape tailflip of both developing and adult crayfish. Two questions will be addressed. The first asks how the LG's responses to mechanosensory inputs depend on the responses of tonic and phasic mechanosensory interneurons (MSIs) to tactile stimuli, the pattern of synaptic contact of individual MSIs on LG, the morphology of LG, and the passive and active membrane properties of LG. This question will be addressed by recording the responses of two identified MSIs, one phasic and one tonic, to mechanosensory stimuli that excite LG, by identifying possible MSI contact sites on LG and by recording LG's responses to them individually and in various patterns. The structural, biophysical and synaptic response data will be used to reconstruct the integrative properties of LG in a quantitative model that will acconut for the cell's responses to its normal patterns of input. The second question asks how the integrative properties of LG change during the animal's growth from post-natal fry to adult, and whether those changes and accompanying changes in synaptic inputs to LG can account for changes in tailflip behavior. We will analyse LG integrative properties in 2 cm, 6 cm and 12 cm animals in the manner described above, and develop quantitative models of them to determine how growth - related changes in cell shape, membrane properties and synaptic inputs should affect LG. We will also determine what changes occur in the number and pattern of inputs LG receives from identified MSIs and from the set of mechanosensory afferents. This study should identify the compensatory mechanisms that allow the labile disynaptic pathway to LG to remain viable during growth while the non- labile monosynaptic pathway fails. Since neuronal growth occurs in all nervous systems, both the changes in integrative properties during growth that we observe and the mechanisms that compensate for those changes may prove to be common features of developing nervous systems.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
Project #
Application #
Study Section
Neurology B Subcommittee 2 (NEUB)
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Georgia State University
Schools of Arts and Sciences
United States
Zip Code
Antonsen, Brian L; Edwards, Donald H (2007) Mechanisms of serotonergic facilitation of a command neuron. J Neurophysiol 98:3494-504
Antonsen, Brian L; Herberholz, Jens; Edwards, Donald H (2005) The retrograde spread of synaptic potentials and recruitment of presynaptic inputs. J Neurosci 25:3086-94
Herberholz, Jens; Sen, Marjorie M; Edwards, Donald H (2004) Escape behavior and escape circuit activation in juvenile crayfish during prey-predator interactions. J Exp Biol 207:1855-63
Herberholz, Jens; Mims, Christopher J; Zhang, Xiaodong et al. (2004) Anatomy of a live invertebrate revealed by manganese-enhanced Magnetic Resonance Imaging. J Exp Biol 207:4543-50
Antonsen, Brian L; Edwards, Donald H (2003) Differential dye coupling reveals lateral giant escape circuit in crayfish. J Comp Neurol 466:1-13
Herberholz, Jens; Antonsen, Brian L; Edwards, Donald H (2002) A lateral excitatory network in the escape circuit of crayfish. J Neurosci 22:9078-85
Herberholz, J; Schmitz, B (2001) Signaling via water currents in behavioral interactions of snapping shrimp (Alpheus heterochaelis). Biol Bull 201:6-16
Heitler, W J; Edwards, D H (1998) Effect of temperature on a voltage-sensitive electrical synapse in crayfish. J Exp Biol 201:503-13
Yeh, S R; Musolf, B E; Edwards, D H (1997) Neuronal adaptations to changes in the social dominance status of crayfish. J Neurosci 17:697-708
Yeh, S R; Fricke, R A; Edwards, D H (1996) The effect of social experience on serotonergic modulation of the escape circuit of crayfish. Science 271:366-9

Showing the most recent 10 out of 17 publications