Conditional dendritic oscillators in a lobster mechanoreceptor neurone

Area of Science:

• Neuroscience
• Sensory Physiology
• Crustacean Nervous System

Background:

• The anterior gastric receptor (AGR) is a primary mechanoreceptor in the lobster stomatogastric nervous system.
• AGR is known for autoactivity, but its precise firing patterns and origins require further investigation.

Purpose of the Study:

• To investigate the nature and origin of pacemaker-like activity in the lobster AGR.
• To determine the mechanisms underlying spontaneous bursting and tonic firing patterns in AGR.
• To explore the modulatory effects of neuropeptides on AGR activity.

Main Methods:

• Intra- and extracellular recordings from in vitro lobster stomatogastric nervous system preparations.
• Voltage-sensitive membrane potential recordings and electrical stimulation of AGR dendrites and cell body.
• Application of neuropeptide F1 and other neuroactive substances to study modulation of firing patterns.

Main Results:

• 20% of AGR preparations exhibited spontaneous rhythmic bursting (0.5-2.5 Hz) without mechanical stimulation, driven by dendritic oscillations.
• Dendritic origin of bursting was confirmed by dendritic action potentials preceding somatic spikes, sustained bursting after dendritic isolation, and phase resetting by dendritic stimulation.
• Neuropeptide F1 rapidly and reversibly induced bursting from tonic firing when applied to the dendritic membrane, while other tested substances had no effect.

Conclusions:

• The AGR possesses an endogenous oscillatory mechanism in its dendrites, enabling spontaneous bursting.
• Extrinsic modulatory influences, such as neuropeptide F1, can dynamically alter the AGR's activity pattern from tonic firing to bursting.
• The AGR's ability to burst enhances sensory coding complexity through modulation of burst duration and spike frequency within bursts.