Olfactory bulbectomy impairs the rat's radial-maze behavior

Area of Science:

• Neuroscience
• Behavioral Neuroscience
• Olfactory System

Background:

• Previous research indicated that damage to the lateral olfactory tracts and septo-hippocampal system caused similar deficits in hamster behaviors like nest building and food hoarding.
• The role of the olfactory system in complex spatial tasks, particularly in relation to the septo-hippocampal system, remained less understood.

Purpose of the Study:

• To investigate whether olfactory system lesions, specifically olfactory bulbectomy, induce deficits in radial-maze behavior comparable to those caused by septo-hippocampal lesions.
• To explore the functional relationship between the olfactory system and the septo-hippocampal system in spatial navigation.

Main Methods:

• Hamsters trained on an 8-arm radial maze task.
• Radical olfactory bulbectomy was performed on trained hamsters.
• Behavioral performance in the radial maze was assessed post-surgery, focusing on arm choice patterns and accuracy.

Main Results:

• Olfactory bulbectomy resulted in a significant decline in previously learned radial-maze behavior.
• The observed behavioral deficits included increased choices of adjacent arms and decreased choices of distant arms.
• Choice accuracy decreased more rapidly across successive choices within a trial, and the probability of repeating arm choice sequences was abnormally high.

Conclusions:

• Olfactory bulbectomy disrupts spatial memory and navigation in a manner similar to septo-hippocampal lesions.
• These findings suggest that the observed deficits are likely due to the disruption of interconnections between the olfactory and septo-hippocampal systems.
• The study highlights the importance of olfactory-related neural pathways, beyond direct olfactory sensitivity, for efficient performance in spatial tasks like radial-maze navigation.