PT - JOURNAL ARTICLE AU - Michael Meredith AU - Jenne M. Westberry TI - Distinctive Responses in the Medial Amygdala to Same-Species and Different-Species Pheromones AID - 10.1523/JNEUROSCI.1139-04.2004 DP - 2004 Jun 23 TA - The Journal of Neuroscience PG - 5719--5725 VI - 24 IP - 25 4099 - http://www.jneurosci.org/content/24/25/5719.short 4100 - http://www.jneurosci.org/content/24/25/5719.full SO - J. Neurosci.2004 Jun 23; 24 AB - Chemosignals related to reproductive and social status (pheromones) carry messages between opposite-sex and same-sex individuals in many species. Each individual must distinguish signals relevant to its own social behavior with conspecifics from signals used by other (heterospecific) species relevant to their social behavior. In male hamsters, the medial amygdala responded in a categorically different way to conspecific stimuli (socially relevant) and heterospecific stimuli (not socially relevant but serving similar purposes for other species), and may play an important role in this decision. Immediate-early gene responses to conspecific chemosignals and heterospecific chemosignals were characteristically different. The categorical responses, generated by chemosensory input from the vomeronasal organ and (probably) GABA inhibition within the amygdala, were not apparent at more peripheral sensory levels. This is the first evidence for an important role of the amygdala, a limbic structure known to be involved in social and emotional behavior, in discrimination of species specificity in chemosignals. Figure 2. Artificial stimuli, resulting in abnormal spatiotemporal patterns of input to the amygdala, failed to activate the MeP and are categorized with heterospecific stimuli. a, FRAs expression was significantly greater (*p < 0.01) in the MeA ipsilateral to electrical stimulation of one vomeronasal organ than on the unstimulated side, or in electrode-implanted, unstimulated controls [two-way RM ANOVA with the following factors: side (ipsilateral, contralateral) and treatment (stimulated, unstimulated) with Tukey post hoc tests; n.s., nonsignificant]. The MeP was not activated; in fact, FRAs expression was significantly less (*p < 0.01) on the stimulated side (ANOVA, as above). b, The mGluR2 agonist LCCG-I disinhibited (increased) AOB output when infused unilaterally into the AOB, initiating significantly greater infusion-side Fos expression in the MeA (*p < 0.01) than on the control side or on either side of saline-infused animals. LCCG-I infusion produced no significant activation in the MeP or in the ACN of the olfactory amygdala (ANOVA, as above for each area).