Scott

SCOTT N. CURRIE, PH.D.

Associate Professor of Cell Biology & Neuroscience
Go to Currie Neuroscience Faculty page

EDUCATION:
BA, 1978, Biology, University of California, San Diego; La Jolla, CA.
M.S., 1983, Biology, Northeastern University Marine Science Center, Nahant, MA.
Ph. D, 1986, Animal Physiology, University of California, Davis; Davis, CA.
Postdoctoral training, (1986-1992), Washington University; St. Louis, MO.

RESEARCH SUMMARY:
Coordinated rhythmic movements (e.g., breathing, walking, swimming, scratching) are characterized by precise temporal sequences of muscle activation referred to as motor patterns or motor programs. Motor pattern sequences are produced by rhythmically active networks of nerve cells called central pattern generators (CPGs) in the brain and spinal cord. Most of my work, funded by an NSF grant, examines cellular- and circuit-level mechanisms used by spinal cord CPG networks to generate rhythmic swimming and scratching movements in the turtle hindlimb. Both whole-animal (in situ)and isolated spinal cord (in vitro) preparations are used in these studies. The understanding of CPG mechanisms in biological neural networks is relevant to the understanding of human movement disorders and the design of biologically based ("biomimetic") control systems in robotics.

Turbo-turtle

We recorded the first fictive swimming motor patterns in turtles that were immobilized by a neuromuscular blocking agent (Juranek and Currie, 2000). "Fictive" motor patterns are recorded directly from muscle nerves, without actual movement. We elicit fictive swim activity by electrically stimulating descending fiber tracts in a specific region of the spinal cord. Brief stimulation of a scratch reflex during ongoing fictive swimming can interrupt and permanently reset the rhythm of the swim. This shows that there are strong central interactions between swim and scratch neural networks, and suggests that they may share key timing elements. I have begun investigating pre-motor command systems in the turtle brainstem that activate locomotor CPGs in the spinal cord.

Urashima Taro

I recently collaborated with Dr. Joseph Ayers and several engineers on a project to design and build biomimetic underwater robots for use in mine detection. The ultimate goal of this work, funded by DARPA-CBS, is to use finite-state-machine controllers, organized into command, coordinating and CPG systems, to control (1) an 8-legged ambulatory robot based on the lobster, and (2) an undulatory swimming robot based on the lamprey (an eel-like lower vertebrate). My part in this project was to assist in the "reverse engineering" of lamprey swimming, turning, and orientation behaviors from the animal to the robot. Shape-memory-alloy (nitinol, or Flexinol™) wires, which shorten by about 5% in response to a train of current pulses, are used as "artificial muscle" to produce robotic movement. This work is described in the new book "Neurotechnology for Biomimetic Robots", published by MIT Press. It also appeared in a UCR News article.

Click on image to download movie (avi format, ~4MB)
Soft rubber lamprey model swims via passively conducted undulatory waves
while suspended beneath a frictionless air track. Undulatory oscillations were
generated by a DC motor via a thin rod, inserted into the model just behind the "head"
and driven by a sine wave from a function generator. By manually adjusting the sine wave's
DC offset, the model could be made to turn right or left.

Selected Publications

Samara, R.F. and Currie, S.N. (2008) Electrically evoked locomotor activity in the turtle spinal cord hemi-enlargement preparation. Submitted to the Journal of Neuroscience.
Samara, R.F. and Currie, S.N. (2008) Location of spinal cord pathways that control hindlimb movement amplitude and interlimb coordination during voluntary swimming in turtles. Journal of Neurophysiology 99: 1953-1968. [download pdf]
Samara, R.F. and Currie, S.N. (2007) Crossed commissural pathways in the spinal hindlimb enlargement are not necessary for right-left hindlimb alternation during turtle swimming. Journal of Neurophysiology 98: 2223-2231. [download pdf]
Currie, S.N. (In preparation) Interaction between right and left hindlimb swim networks in the turtle spinal cord. To be submitted to the Journal of Neuroscience.
Currie, S.N. (In preparation) Activity of multifunctional abdominal muscles during breathing and swimming in freshwater turtles. To be submitted to the Journal of Experimental Biology.
Wilbur, C., Vorus, W., Cao, Y. and Currie, S. (2002) A lamprey-based undulatory vehicle. In: Neurotechnology for Biomimetic Robots (J. Ayers, J. Davis, A. Rudolph, eds.). MIT Press, Cambridge, MA. [download pdf chapter] [buy book]
Juranek, J. and Currie, S.N. (2000) Electrically evoked fictive swimming in the low-spinal immobilized turtle. Journal of Neurophysiology 83: 146-155. [download pdf]
Currie, S.N. (1999) Fictive hindlimb motor patterns evoked by AMPA and NMDA in turtle spinal cord-hindlimb nerve preparations. Journal of Physiology (Paris) 93: 199-211. [download pdf]
Currie, S.N. and Gonsalves, G.G. (1999) Reciprocal interactions in the turtle hindlimb enlargement contribute to scratch rhythmogenesis. Journal of Neurophysiology 81: 2977-2987. [download pdf]
Currie, S.N. and Gonsalves, G.G. (1998) Crossed reciprocal inhibition and scratch rhythmogenesis in the turtle spinal cord. Ann. NY Acad. Sci. 860: 458-460. [download pdf]
Stein, P.S.G., McCullough, M.L. and Currie, S.N. (1998) Spinal motor patterns in the turtle. Ann. NY Acad. Sci. 860: 142-154. [download pdf]
Ayers, J., Zavracky, P., McGruer, N., Massa, D.P., Vorus, W.S., Mukherjee, R. and Currie, S.N. (1998) A modular behavioral-based architecture for biomimetic autonomous underwater robots. Proceedings of the Autonomous Vehicles in Mine Countermeasures Symposium. Naval Postgraduate School. (Published on CD). [html version]
Stein, P.S.G., McCullough, M.L., Currie, S.N. (1998) Reconstruction of flexor/extensor alternation during fictive rostral scratching by two-site stimulation in the spinal turtle with a transverse spinal hemisection. Journal of Neuroscience 18: 467-479. [download pdf]
Currie, S.N. and Gonsalves, G.G. (1997) Right-left interactions between rostral scratch networks generate rhythmicity in the pre-enlargement spinal cord of the turtle. Journal of Neurophysiology 78: 3479-3483. [download pdf]
Currie, S.N. and Lee, S. (1997) Glycinergic inhibition contributes to the generation rostral scratch motor patterns in the turtle spinal cord. Journal of Neuroscience 17: 3322-3333. [download pdf]
Currie, S.N. and Lee, S. (1996) Sensory-evoked pocket scratch motor patterns in the in vitro turtle spinal cord: reduction of excitability by an N-methyl-D-aspartate antagonist. Journal of Neurophysiology 76: 81-92. [abstract]
Currie, S.N. and Lee, S. (1996) Glycinergic inhibition in the turtle spinal cord regulates the intensity and pattern of fictive flexion reflex motor output. Neuroscience Letters 205: 75-78. [download pdf]
Stein, P.S.G., Victor, J.C., Field, E.C. and Currie, S.N. (1995) Bilateral control of hindlimb scratching in the spinal turtle: contralateral spinal circuitry contributes to the normal ipsilateral motor pattern of fictive rostral scratching. Journal of Neuroscience 15: 4343-4355. [abstract]