Based on a wide variety of data, it is now clear that the brains of birds and teleost (bony) fish possess a core "social behavior network" within the basal forebrain and midbrain that is homologous to the social behavior network of mammals. The nodes of this network are reciprocally connected, contain receptors for sex steroid hormones, and are involved in multiple forms of social behavior. Other hodological features and neuropeptide distributions are likewise very similar across taxa. This evolutionary conservation represents a boon for experiments on phenotypic behavioral variation, as the extraordinary social diversity of teleost fish and songbirds can now be used to generate broadly relevant insights into issues of brain function that are not particularly tractable in other vertebrate groups. Two such lines of research are presented here, each of which addresses functional variation within the network as it relates to divergent patterns of social behavior. In the first set of experiments, we have used a sexually polymorphic fish to demonstrate that natural selection can operate independently on hypothalamic neuroendocrine functions that are relevant for 1) gonadal regulation and 2) sex-typical behavioral modulation. In the second set of experiments, we have exploited the diversity of avian social organizations and ecologies to isolate species-typical group size as a quasiindependent variable. These experiments have shown that specific areas and peptidergic components of the social behavior network possess functional properties that evolve in parallel with divergence and convergence in sociality. Keywords sociality; aggression; sexual behavior; communication; vocalization; arginine vasopressin; arginine vasotocin; isotocin; mesotocin; oxytocin; fish; bird; bed nucleus of the stria terminalis; amygdala; lateral septum; anterior hypothalamus; ventromedial hypothalamus; preoptic area; periaqueductal gray; nucleus intercollicularis; c-fos; egr-1; ZenkThe research program described below is designed to address two major goals. The first of these goals is to elucidate evolutionary themes in the neuroendocrine, functional, and connectional organization of brain circuits that regulate social behavior. This will provide a phylogenetically broad framework for examining the neural and neuroendocrine mechanisms of behavior, and will allow detailed and meaningful comparisons to be made across the major vertebrate classes. Building upon this foundation, the second primary goal is to capitalize on the extraordinary behavioral diversity of birds and teleost (bony) fish to elucidate the ways that neural and neuroendocrine mechanisms are adjusted over evolutionary time to produce intraspecific and interspecific variation in behavior. If conducted within a well-characterized, comparative framework, these findings obtained in birds and fish should yield solid predictions for other vertebrates as well. Thus, our work addresses evolutionary themes, as described in the first section below, and variations on those themes, as...

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Vocal behavior is multifaceted and requires that vocal-motor patterning be integrated at multiple brain levels with auditory, neuroendocrine, and other social behavior processes (e.g., courtship and aggression). We now provide anatomical evidence for an extensive vocal network in teleost fishes (Batrachoididae: Porichthys notatus; Opsanus beta) that is strongly integrated with neuroendocrine and auditory pathways and that exhibits striking similarities to the vocal-acoustic circuitry known for mammals. Biotin compound injections into neurophysiologically identified vocal regions of the forebrain (preoptic area and anterior hypothalamus) and of the midbrain (periaqueductal gray and paralemniscal tegmentum) reveal extensive connectivity within and between these regions, as well as reciprocal relationships with the auditory thalamus and/or auditory midbrain (torus semicircularis). Thus, specific components of the basal forebrain and midbrain are here designated as the forebrain vocal-acoustic complex (fVAC) and midbrain vocal-acoustic complex (mVAC), respectively. Biotin injections into the mVAC and a previously identified hindbrain vocal pattern generator likewise provide anatomical evidence for a distributed network of descending projections to the vocal pacemaker-motoneuron circuitry. Together, the present experiments establish a vocal-auditory-neuroendocrine network in teleost fish that links the forebrain and midbrain to the hindbrain vocal pattern generator (i.e., fVAC --> mVAC --> pattern generator) and provides an anatomical framework for the previously identified neuropeptide modulation of vocal activity elicited from the forebrain and midbrain, which contributes to the expression of sex- and male morph-specific behavior. We conclude with a broad comparison of these findings with those for other vertebrate taxa and suggest that the present findings provide novel insights into the structure of conserved behavioral regulatory circuits that have led to evolutionary convergence in vocal-acoustic systems.

The peptide arginine-vasopressin (mammals) and its evolutionary precursor arginine-vasotocin (non-mammals) modulate reproductive physiology and numerous related social behaviours, as do oxytocin (mammals) and its homologues mesotocin and isotocin (fish). The distributions in the brain and/or the behavioural functions of these peptides often differ between the sexes, and between species with divergent social structures. Here we present neurophysiological evidence that males with vocal characteristics typical of females share a pattern of neuropeptide function with females rather than conspecific males. The plainfin midshipman fish (Porichthys notatus) has two male morphs with different reproductive tactics and vocalizations (a key species-typical behaviour which varies in its physical attributes and contextual usage, depending on the morph's social strategy). Forebrain-evoked, rhythmic vocal-motor activity that precisely mimics natural vocalizations was modulated by arginine-vasotocin, isotocin and their antagonists delivered to the preoptic area-anterior hypothalamus, a primary site for behavioural integration in all vertebrates. Peptides had different effects in males that acoustically court females (arginine-vasotocin-sensitive) than in females and sneak-spawning males (isotocin-sensitive), showing that the neuromodulatory mechanisms that establish reproduction-related behaviour can be dissociated from gonadal sex.

Measles is an infectious disease in humans caused by the measles virus (MeV). Before the introduction of an effective measles vaccine, virtually everyone experienced measles during childhood. Symptoms of measles include fever and maculopapular skin rash accompanied by cough, coryza and/or conjunctivitis. MeV causes immunosuppression, and severe sequelae of measles include pneumonia, gastroenteritis, blindness, measles inclusion body encephalitis and subacute sclerosing panencephalitis. Case confirmation depends on clinical presentation and results of laboratory tests, including the detection of anti-MeV IgM antibodies and/or viral RNA. All current measles vaccines contain a live attenuated strain of MeV, and great progress has been made to increase global vaccination coverage to drive down the incidence of measles. However, endemic transmission continues in many parts of the world. Measles remains a considerable cause of childhood mortality worldwide, with estimates that >100,000 fatal cases occur each year. Case fatality ratio estimates vary from <0.01% in industrialized countries to >5% in developing countries. All six WHO regions have set goals to eliminate endemic transmission of MeV by achieving and maintaining high levels of vaccination coverage accompanied by a sensitive surveillance system. Because of the availability of a highly effective and relatively inexpensive vaccine, the monotypic nature of the virus and the lack of an animal reservoir, measles is considered a candidate for eradication.