The ventromedial hypothalamic nucleus in the zebra finch (Taeniopygia guttata): Afferent and efferent projections in relation to the control of reproductive behavior

Abstract

Sex-specific mating behaviors occur in a variety of mammals, with the medial preoptic nucleus (POM) and the ventromedial hypothalamic nucleus (VMH) mediating control of male and female sexual behavior, respectively. In birds, likewise, POM is predominantly involved in the control of male reproductive behavior, but the degree to which VMH is involved in female reproductive behavior is unclear. Here, in male and female zebra finches, a combination of aromatase immunohistochemistry and conventional tract tracing facilitated the definition of two separate but adjacent nuclei in the basal hypothalamus: an oblique band of aromatase-positive (AR+) neurons, and ventromedial to this, an ovoid, aromatase-negative (AR-) nucleus. The AR- nucleus, but not the AR+ nucleus, was here shown to receive a projection from rostral parts of the thalamic auditory nucleus ovoidalis and from the nucleus of the tractus ovoidalis. The AR- nucleus also receives an overlapping, major projection from previously uncharted regions of the medial arcopallium and a minor projection from the caudomedial nidopallium. Both the AR- and the AR+ nuclei project to the intercollicular nucleus of the midbrain. No obvious sex differences in either the pattern of AR immunoreactivity or of the afferent projections to the AR- nucleus were observed. The significance of these results in terms of the acoustic control of avian reproductive behavior is discussed, and a comparison with the organization of VMH afferents in lizards suggests a homologous similarity of the caudal telencephalon in sauropsids.

As above, so below: Whole transcriptome profiling demonstrates strong molecular similarities between avian dorsal and ventral pallial subdivisions

“…However, other genes showing sparse expression in the hyperpallium, like SATB2 , are not enriched in the arcopallium and challenge this idea. Alternatively, a recent study reported a sparse population of nidopallium projection neurons with extratelencephalic targets (Wild, 2017), further highlighting the potential cell type similarities between the hyperpallium and nidopallium subdivisions. Further molecular profiling using single cell/nuclei RNA sequencing technology is necessary to test these hypotheses and aid in our understanding of the evolutionary relationships of these cell types across vertebrates.…”

Acoustic developmental programming: a mechanistic and evolutionary framework

“…However, Box 3. Neurophysiological pathways for acoustic developmental programming Some non-auditory brain regions are responsive to sound Neurophysiological responses to sound can be observed in several brain regions that are not thought to be primarily auditory in their functions [109][110][111]. In particular, the hippocampus is known to respond to some particular acoustic features of music and songs in both humans [111] and birds [112], including during development [113].…”

Parallel organization of the avian sensorimotor arcopallium: Tectofugal visual pathway in the pigeon (Columba livia)

“…The arcopallium generates two prominent projections. The viscerolimbic zone is the origin of the hypothalamic part of the occipitomesencephalic tract (HOM), a prominent descending projection to subpallial structures, including the medial and lateral hypothalamus and the limbic areas of the striatum (Atoji et al, 2006;Davies, Csillag, Szekely, & Kabai, 1997;Wild, 2017;Zeier & Karten, 1971). Whereas the sensorimotor arcopallium, along with a minor contribution from the PoA, is the origin of the OM, which reaches several thalamic, mesencephalic, and brain stem areas (Zeier & Karten, 1971).…”