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Hysteresis reduction in proprioception using presynaptic shunting inhibition
N G Hatsopoulos1, M Burrows, G Laurent
1Computation and Neural Systems Program, California Institute of Technology, Pasadena 91125, USA.
Journal of Neurophysiology
|March 1, 1995
Summary
Presynaptic inhibition in locust leg afferents reduces neural hysteresis, acting as an automatic gain control. This mechanism allows interneurons to accurately code joint angles despite large input variations.
Area of Science:
- Neuroscience
- Biophysics
- Insect Physiology
Background:
- Angular-position-sensitive afferents in locust legs display significant hysteresis in their tonic responses.
- Spiking local interneurons receiving input from these afferents show considerably less hysteresis.
Purpose of the Study:
- To test the hypothesis that presynaptic inhibitory interactions between afferent axons reduce interneuron hysteresis.
- To investigate if these interactions function as an automatic gain control mechanism.
Main Methods:
- Utilized two neural models: an abstract nonspiking model with shunting inhibition and a compartmental model with presynaptic shunting inhibition.
- Analyzed how lateral inhibition in afferent networks affects postsynaptic unit coding and how presynaptic inhibition impacts synaptic conductance.
Main Results:
- The abstract model showed that lateral inhibition enabled a postsynaptic unit to code joint angle without saturation over a wide input range.
- The compartmental model demonstrated that presynaptic shunting inhibition counterbalanced high afferent firing rates, stabilizing postsynaptic input.
Conclusions:
- Presynaptic inhibitory interactions between afferent axons effectively reduce neural hysteresis in locust leg interneurons.
- This inhibitory mechanism acts as an automatic gain control, ensuring reliable coding of joint position.