Magnetic magic: How stimulation alters feeding patterns in Aplysia californica

Repetitive transcranial magnetic stimulation (rTMS) is emerging as a groundbreaking treatment for eating disorders, such as anorexia and bulimia nervosa, though its underlying neurological mechanisms remain elusive. To shed light on the effects of rTMS on neural control of feeding behavior, we investigated the feeding responses in the marine mollusk Aplysia californica. Using in vitro preparations, we elicited feeding responses and performed dual nerve recordings to identify motor programs associated with rejection and ingestion. We applied rTMS to the cerebral ganglion, the neural center responsible for switching between ingestion and rejection behaviors. At a clinically relevant frequency of 10 Hz, rTMS terminated rejection responses and promoted ingestion responses in the buccal ganglion, which directly executes feeding behaviors. Direct stimulation of the buccal ganglion or lesioning the connection between the cerebral and buccal ganglia prevented the rTMS-mediated transition from rejection to ingestion. These findings establish Aplysia as a pivotal model for studying the cellular and molecular basis of rTMS in the treatment of eating disorders, underscoring the remarkable adaptability of neural circuits and paving the way for transformative advancements in therapeutic applications.