Medial amygdala, posterior

Martinez-Marcos A. and Halpem M. (1999b). Differential projections from the anterior and posterior divisions of the accessory olfactory bulb to the medial amygdala in the opossum, Monodelphis domestica. Europ J Neurosci 11, 3789-3799. 

Fig. 35.1 Simplified diagram of chemosensory circuit in amygdala. Vomeronasal input via accessory olfactory bulb (VNO/ AOB) is analyzed in anterior and posterior medial amygdala (MeA, MeP). MeP appears to be inhibited by intercalated nucleus (ICNc) for heterospecific and artificial stimuli. MOE/ MOB Main olfactory epithelium/Main olfactory bulb. ACN Anterior Cortical Nucleus. PC Piriform Cortex. BLA Basolateral amygdala. ICNr rostral part of medial intercalated nucleus. ICNc caudal part of ICN. MPOA Medial Preoptic Area. VMH Ventro-medial hypothalamus...

The AOB has direct projections to the amygdala, specifically to the medial and posterior cortical nuclei, the bed nucleus of the stria terminalis and the nucleus of the accessory olfactory tract. These pathways may be involved in the processing of pheromonal information. Neurons in the AOB targets express gonadal steroid receptors and thus may be modulated directly by circulating hormones. The efferent connections of the accessory olfactory system are summarized in Fig. 22. 

Aggressiveness results from the failure of inhibitory neurochemical processes or exaggeration of stimulatory processes in brain regions, such as the orbito-ffontal cortex, the septal area, hippocampus, amygdala, caudate nucleus, thalamus, ventro-medial and posterior hypothalamus, midbrain tegmentum, pons, and the fastigial nuclei and anterior lobe of the cerebellum. 

Studies of c-fos expression in the accessory olfactory system have been performed almost exclusively in the context of sexual behavior of animals (Fiber, Adames Swann, 1993 Schellinck, Smyth, Brown Wilkinson, 1993 Baum, Brown, Kica, Rubin, Johnson Papaioannou, 1994 Femandez-Fewell and Meredith, 1994 Rajendren and Moss, 1994 Bressler and Baum, 1996). Many studies show that c-fos is expressed in the vomeronasal projection circuit (i.e. the anterior olfactory bulb, the medial amygdala, the posterior medial bed nucleus of the stria terminalis, or the medial preoptic area) after mating behavior. Importantly, there have been no reports of specific c-fos expression in the VNO. 

Fig. 3 Vomeronasal system. Schematic representation of a rodent nasal cavity and brain (lateral view). Accessory olfactory bulb (AOB) mitral cells project to vomeronasal and extended amygdala. Inset The VNO is a bilateral tubular structure located at the base of the nasal septum. VSNs that express the same V1R or V2R converge on a small number of glomeruli in the AOB. Sensory neurons located in the apical layer of the epithelium project to the anterior part of the AOB, whereas those present in the basal layer project to the posterior part. MOE main olfactory epithelium, MOB main olfactory bulb, BSTMPM posteromedial bed nucleus of the stria terminalis, MEA medial amygdaloid nucleus, BACfF bed nucleus of the accessory olfactory tract, PMCO posteromedial cortical amygdaloid area...

Schematic diagram of the gustatory pathway in rodents. Taste receptor cells are innervated by one of three cranial nerves (VII, IX, or X), which project topographically into the rostral portion of nucleus of the solitary tract (NST). Cells within the NST send projections into the reticular formation (RF), through which connections are made to oral motor nuclei V, VII, and XII and the nucleus ambiguous (NA). Ascending fibers connect to the parabrachial nuclei (PbN) of the pons, from which two parallel pathways emerge. One pathway carries taste information to the insular cortex (IC) via the ventral posterior medial nucleus, parvicellularis (VPMpc), of the thalamus. The other pathway projects into areas of the limbic forebrain involved in food and water regulation, reinforcement, reward, and stress, including the lateral hypothalamus (LH), the central nucleus ofthe amygdala (CeA), and the bed nucleus of the stria terminalis (BST). These areas and the IC are interconnected and send descending projections back to both the PbN and NST...

FIGURE 12.3 (See color insert.) Control of activation processes. OFC, orbitofrontal cortex AM, amygdala MDT, medial dorsal thalamus AH, anterior hypothalamus RF, reticular formation SC, spinal cord HI, hippocampus CC, cingulate cortex S, septum ADT, anterior dorsal thalamus PH, posterior hypothalamus SMP, sensory-motor projections CS, corpus striatum LDT, lateral dorsal thalamus SR, subthalamic regions T, tectum. Orange, structures of the arousal network green, structures of the effort network blue, structures of the activation network. (Adapted from Pribram, K.H. and McGuinness, D., Psychol. Rev., 82(2), 116, 1975.)... 

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