Nitric Oxide-Mediated Modulation of Central Network Dynamics during Olfactory Perception.

Area of Science:

• Neuroscience
• Olfactory System Research
• Molluscan Neurobiology

Background:

• Nitric oxide (NO) is known to modulate central olfactory networks and is involved in olfactory learning.
• Land mollusks possess a specialized olfactory brain region, the procerebral (PC) lobe, which exhibits local field potential (LFP) oscillations influenced by olfactory input.

Purpose of the Study:

• To investigate the release of NO in the PC lobe of the land slug Limax in response to olfactory stimulation.
• To determine the role of NO in modulating PC lobe network dynamics, including LFP oscillations and neural synchronicity, during olfactory processing.

Main Methods:

• An NO-selective electrode was used to measure NO concentration in the PC lobe of an isolated tentacle-brain preparation of Limax.
• Olfactory stimulation and electrical stimulation of the superior tentacle nerve (STN) were applied.
• The effects of the NO synthase inhibitor L-NAME on NO release, LFP oscillations, and neural synchronicity were examined.

Main Results:

• Olfactory stimulation led to a transient increase in NO concentration in the PC lobe, which was inhibited by L-NAME.
• L-NAME blocked the frequency increase and enhanced spatial synchronicity of LFP oscillations induced by olfactory stimulation or STN stimulation.
• L-NAME did not inhibit synaptic transmission to nonbursting (NB)-type PC lobe neurons, suggesting NO is produced in an activity-dependent manner by these neurons.

Conclusions:

• NO is released in the PC lobe during olfactory stimulation and plays a significant role in modulating olfactory network dynamics.
• NO signaling, potentially via NB neuron activity, is essential for precise odor representation and memory formation.
• These findings provide insights into the neurobiological mechanisms underlying olfactory perception and learning in mollusks.