Olfactory Projections to Locomotor Control Centers in the Sea Lamprey

Area of Science:

• Neuroscience
• Comparative Biology
• Olfactory System Research

Background:

• Olfaction guides animal behavior, but the neural basis of olfactory-elicited motor responses remains unclear.
• The sea lamprey's posterior tuberculum (PT) contains dopaminergic neurons homologous to mammalian structures involved in motor control.
• Olfactory inputs reach the PT via the medial olfactory bulb (medOB) or lateral pallium (LPal).

Purpose of the Study:

• To characterize olfactory input transmission to the PT in the sea lamprey (Petromyzon marinus).
• To elucidate the neural pathway linking olfactory stimuli to locomotion initiation.

Main Methods:

• Anatomical tracing to identify projections from the medOB to the PT.
• Electrophysiology to record PT neuron activity in response to medOB and LPal stimulation.
• Calcium imaging to track olfactory signal propagation.
• Semi-intact preparations to observe locomotion induced by stimulation.

Main Results:

• Abundant medOB projections were found near PT dopaminergic neurons.
• PT neurons were activated by both medOB and LPal inputs.
• Olfactory stimulation of medOB and LPal induced locomotion, correlated with PT neural activity.
• PT neurons were active during spontaneous locomotion.

Conclusions:

• The medOB and LPal convey olfactory information to PT dopaminergic neurons.
• The PT acts as a crucial relay, activating the brainstem motor system to initiate locomotion.
• This study reveals a key neural circuit for olfactory-driven motor behavior in a primitive vertebrate.