Inhibitory interactions among rodent taste axons.

Area of Science:

• Neuroscience
• Sensory Biology
• Gustatory System

Background:

• The chorda tympani nerve is crucial for taste sensation in rodents.
• Understanding neural plasticity and cross-innervation in taste pathways is important for sensory research.

Purpose of the Study:

• To investigate the effects of dual chorda tympani nerve innervation on taste bud morphology and neural responses in Mongolian gerbils.
• To determine if dual innervation alters taste bud number or volume and to examine the impact on neural signal processing, particularly inhibition.

Main Methods:

• Experimental dual innervation of the left Mongolian gerbil tongue with both chorda tympani nerves.
• Assessment of fungiform taste bud number and volume.
• Recording of impulse discharges in both native and foreign chorda tympani nerves during taste stimulation.
• Electrical stimulation of the native nerve to assess its effect on foreign nerve responses.

Main Results:

• Dual innervation did not increase taste bud number or volume.
• Approximately half of the taste buds were dually innervated and neurotrophically maintained.
• Simultaneous impulse discharges occurred in both nerves when stimulating the left tongue side.
• Dual innervation enhanced neural inhibition, significantly reducing responses to NaCl and sucrose in the foreign nerve.
• Electrical stimulation of the native nerve reduced foreign nerve responses by 52% (NaCl) and 41% (sucrose).
• Inhibition onset was rapid and persisted with a 11.5-minute half-life, independent of brain connection.

Conclusions:

• Dual chorda tympani innervation accentuates lateral inhibitory connections within the gustatory system.
• These enhanced inhibitory pathways may play a physiological role in filtering extraneous sensory information.
• The findings provide insights into neural mechanisms underlying taste perception and sensory integration.