Predator Cat Odors Activate Sexual Arousal Pathways in Brains of Toxoplasma gondii Infected Rats
(A) General schematic model of limbic brain activity in a male rat after exposure to an emotionally salient odor. (B) Exposure to an inaccessible estrous female activates the ‘reproductive’ pathway, producing robust MEApd activity and evoking approach behavior. (C) Exposure to cat urine activates the ‘defensive’ pathway, producing robust activation of excitatory (+) VMHdm neurons and evoking defensive, aversion behavior. Excitatory (pointed arrow) projections from the MEApv activate inhibitory (−) VMHvl neurons, countering inhibitory (blunted arrow) projections from the MEApd and suppressing any approach behavior. (D) Proposed model for Toxoplasma rats during exposure to cat urine. Robust MEApd activity biases toward approach behavior. Aversion behavior remains, but is lessened. Raw density of c-Fos (large print) ±SEM (small print) activity is given for each region during relevant odor exposure. Model adapted from Choi 2005. AOB, accessory olfactory bulb; MEA, medial amygdala; VMH, ventromedial hypothalamus.