Brain cells that command sexual behavior in the snail Helix aspersa

Area of Science:

• Neuroscience
• Animal Behavior
• Malacology

Background:

• The mesocerebrum's role in controlling complex behaviors is not fully understood.
• Sexual behavior in Helix aspersa is predominantly lateralized to the right side.

Purpose of the Study:

• To investigate the role of the mesocerebrum in the control of sexual behavior in Helix aspersa.
• To determine if the mesocerebrum exhibits lateralization consistent with the observed behavioral asymmetry.

Main Methods:

• Morphological analysis of mesocerebrum neuron number and size.
• Physiological tracing of neuronal pathways.
• Electrical stimulation (extracellular and intracellular) of the mesocerebrum.

Main Results:

• The right mesocerebrum lobe contains more and larger neurons than the left.
• Electrical stimulation of the right mesocerebrum, but not the left, elicited sexual organ movements.
• Neuronal pathways show a strong right-sided bias, projecting to the right pedal ganglion.

Conclusions:

• The mesocerebrum, particularly the right lobe, plays a critical role in commanding sexual behavior in Helix aspersa.
• A right-sided bias in mesocerebrum structure and function underlies the lateralization of sexual behavior.