Related Experiment Videos
Theoretical analysis of gradient detection by growth cones
1Georgetown Institute for Cognitive and Computational Sciences, Georgetown University Medical Center, 3970 Reservoir Road, Washington, DC 20007, USA.
Journal of Neurobiology
|October 8, 1999
Summary
Growth cones navigate developing nervous systems by sensing molecular gradients. A biophysical model predicts that growth cones likely use spatial sensing and their sensitivity depends on ligand concentration, diffusion speed, and size.
Area of Science:
- Neuroscience
- Biophysics
- Developmental Biology
Background:
- Axon guidance relies on molecular gradients in the developing nervous system.
- The physical mechanisms of gradient sensing by growth cones remain poorly understood.
Purpose of the Study:
- To apply the Berg and Purcell (1977) model to estimate the physical limits of growth cone gradient sensing.
- To predict how physiological parameters influence growth cone sensitivity to molecular gradients.
Main Methods:
- Utilized the Berg and Purcell (1977) model for gradient sensing.
- Modeled gradient detection as a comparison of concentrations at spatially or temporally separated points.
- Estimated the minimum detectable gradient steepness as a function of physiological parameters.
Main Results:
- Growth cones likely employ spatial rather than temporal sensing strategies.
- Sensitivity increases with ligand concentration, diffusion speed, growth cone size, and averaging time.
- Minimum detectable gradient steepness is estimated to be 1-10%, varying with ligand type and dimensionality.
- The model provides insights into the role of filopodia in gradient detection.
Conclusions:
- The biophysical model provides quantitative predictions for growth cone gradient sensing.
- Understanding these physical constraints is crucial for comprehending axon guidance mechanisms.
- Further research can experimentally test these model predictions regarding growth cone sensing strategies and sensitivity.