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Slow current changes underlying square shaped potential waves in warmed Aplysia neurones
Experientia
|May 15, 1976
Summary
Warming transforms Aplysia L11 neurons from regular firing to bursting. This change is caused by slow square waves, which result from negative slope current-voltage characteristics and slow current variations observed during voltage clamp experiments.
Area of Science:
- Neuroscience
- Cellular Electrophysiology
Background:
- The L11 neuron in Aplysia exhibits regular firing patterns under normal conditions.
- Neuronal bursting is a crucial pattern for various physiological processes.
Purpose of the Study:
- To investigate the mechanisms underlying the transition of the Aplysia L11 neuron from regular firing to bursting upon warming.
- To elucidate the ionic basis of temperature-induced bursting in this model system.
Main Methods:
- Utilizing voltage clamp techniques with slow voltage ramps to analyze the current-voltage (I-V) characteristics of the L11 neuron.
- Recording neuronal activity at different temperatures and in the presence of specific ion channel blockers (TTX, Co++).
Main Results:
- Warming induces a negative slope region (negative resistance) in the L11 neuron's I-V curve.
- Temperature increase leads to very slow current variations (time constants of 10-50 seconds) in response to voltage changes.
- Slow square waves, responsible for bursting, were observed and replicated at room temperature using TTX or Co++.
Conclusions:
- The observed negative slope and slow current variations are the primary biophysical mechanisms responsible for temperature-induced bursting in Aplysia L11 neurons.
- These findings provide a detailed explanation for the generation of slow square waves that underlie bursting activity.