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Cranial visceral afferents activate central pathways that mediate systemic homeostatic processes. Afferent information arrives in the brainstem nucleus of the solitary tract (NTS) and is relayed to other CNS sites for integration into autonomic responses and complex behaviors. Little is known about the organization or nature of processing within NTS. We injected fluorescent retrograde tracers into two nuclei to identify neurons that project to sites involved in autonomic regulation: the caudal ventrolateral medulla (CVLM) or paraventricular nucleus of the hypothalamus (PVN). We found distinct differences in synaptic connections and performance in the afferent path through NTS to these neurons. Anatomical studies using confocal and electron microscopy found prominent, primary afferent synapses directly on somata and dendrites of CVLM-projecting NTS neurons identifying them as second-order neurons. In …