Oculomotor behavior as an """"""""ideal system"""""""" for the study of the neurophysiologic mechanisms of voluntary and reflex behavior. As an overt and measurable behavior, motor systems are ideal for study of the fundamental mechanisms for how the brain transforms sensory inputs and volitional commands into outputs. Among the motor systems, eye movements have the advantage of being relatively simple. In order to study volitional behavior in vivo, we use chronic recording techniques in trained primates. In one set of experiments, we are studying the fundamental cellular and circuit mechanism for generating saccadic eye movements, the high-velocity eye flicks that one uses to scan the surrounding environment. The brain circuit that generates saccadic behavior is essentially a biologic machine that acts like a central pattern generator, a closed-loop neural circuit that creates a stereotyped motor output in response to inputs from higher centers. Like any machine, one can attempt to understand how it works by """"""""reverse engineering."""""""" That is, given the machine's output, how do the internal circuits function to produce that output? One systems engineering approach is to inject characteristic input signals at critical points within the circuit and compare the output to quantitative predictions based on assumptions about the biological mechanisms. Using this approach, we have addressed several fundamental issues in oculomotor physiology, which in turn reveals brain mechanisms that are general to all behavior. By studying the brain in live and behaving subjects, we obtain fundamental insight into how it computes, plans movements and represents information. We come to understand the brain's wiring diagrams and how networks of interconnected neurons function together as an effective biologic machine. Such basic biology research is essential as the fundamental underpinning for understanding brain function when compromised by disease or injury. The health relatedness of this research is that the understanding of how the normal, healthy brain works is a sine qua non for understanding the human condition in health and in illness.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY008217-11
Application #
6609668
Study Section
Visual Sciences B Study Section (VISB)
Program Officer
Hunter, Chyren
Project Start
1996-12-01
Project End
2005-06-30
Budget Start
2003-07-01
Budget End
2004-06-30
Support Year
11
Fiscal Year
2003
Total Cost
$338,625
Indirect Cost
Name
State University New York Stony Brook
Department
Other Basic Sciences
Type
Schools of Arts and Sciences
DUNS #
804878247
City
Stony Brook
State
NY
Country
United States
Zip Code
11794
Noto, Christopher T; Gnadt, James W (2009) Saccade trajectories evoked by sequential and colliding stimulation of the monkey superior colliculus. Brain Res 1295:99-118
Paul, Kush; Gnadt, James W (2006) Activity of omnipause neurons during ""staircase saccades"" elicited by persistent microstimulation of the superior colliculus. Vision Res 46:3430-42
Carasig, Dana; Paul, Kush; Fucito, Michele et al. (2006) Irrepressible saccades from a tectal lesion in a Rhesus monkey. Vision Res 46:1161-9
Ramcharan, E J; Gnadt, J W; Sherman, S M (2005) Higher-order thalamic relays burst more than first-order relays. Proc Natl Acad Sci U S A 102:12236-41
Gnadt, James W; Echols, Stanley D; Yildirim, Abidin et al. (2003) Spectral cancellation of microstimulation artifact for simultaneous neural recording in situ. IEEE Trans Biomed Eng 50:1129-35
Paul, Kush; Gnadt, James W (2003) Reliable real-time spike discrimination during microstimulation. J Neurosci Methods 128:191-5
Gnadt, J W; Jackson, M E; Litvak, O (2001) Analysis of the frequency response of the saccadic circuit: system behavior. J Neurophysiol 86:724-40
Jackson, M E; Litvak, O; Gnadt, J W (2001) Analysis of the frequency response of the saccadic circuit: numerical simulations. Neural Netw 14:1357-76
Jackson, M E; Gnadt, J W (1999) Numerical simulation of nonlinear feedback model of saccade generation circuit implemented in the LabView graphical programming language. J Neurosci Methods 87:137-45
Gnadt, J W; Beyer, J (1998) Eye movements in depth: What does the monkey's parietal cortex tell the superior colliculus? Neuroreport 9:233-8

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