Afferent Connectivity of the Zebrafish Habenulae

Abstract

The habenulae are bilateral nuclei located in the dorsal diencephalon that are conserved across vertebrates. Here we describe the main afferents to the habenulae in larval and adult zebrafish. We observe afferents from the subpallium, nucleus rostrolateralis, posterior tuberculum, posterior hypothalamic lobe, median raphe; we also see asymmetric afferents from olfactory bulb to the right habenula, and from the parapineal to the left habenula. In addition, we find afferents from a ventrolateral telencephalic nucleus that neurochemical and hodological data identify as the ventral entopeduncular nucleus (vENT), confirming and extending observations of Amo et al. (2014). Fate map and marker studies suggest that vENT originates from the diencephalic prethalamic eminence and extends into the lateral telencephalon from 48 to 120 hour post-fertilization (hpf). No afferents to the habenula were observed from the dorsal entopeduncular nucleus (dENT). Consequently, we confirm that the vENT (and not the dENT) should be considered as the entopeduncular nucleus “proper” in zebrafish. Furthermore, comparison with data in other vertebrates suggests that the vENT is a conserved basal ganglia nucleus, being homologous to the entopeduncular nucleus of mammals (internal segment of the globus pallidus of primates) by both embryonic origin and projections, as previously suggested by Amo et al. (2014).

Identification of accessory olfactory system and medial amygdala in the zebrafish

“…Arrowheads indicate where a projection terminates. Olfactory bulb projections shown as dashed lines to telencephalic targets are selective for mediodorsal olfactory bulb (present paper and additional data from9101314151644). Abbreviations: Cr: crypt cells; Dp: posterior zone of dorsal telencephalon; Ha: habenula; Had: dorsal part of Ha; Hav: ventral part of Ha; OB: olfactory bulb; OE: olfactory epithelium; oc: optic chiasma; on: olfactory nerve; Po: preoptic region; Tel: telencephalon; TeO: optic tectum; TH: tuberal hypothalamus; Vd, Vp, Vs, Vv: dorsal, postcommissural, supracommissural, ventral nucleus of ventral telencephalon.…”

“…10; Vp, Vs, Had;101644). Our tracing data presented here demonstrate that the adult zebrafish mediodorsal olfactory bulb area not only projects to the posterior zone of the dorsal telencephalon, as well as to the dorsal, ventral, supracommissural and postcommissural nuclei of the ventral telencephalon, but in addition also to the intermediate nucleus of the ventral telencephalon.…”

Masking of a circadian behavior in larval zebrafish involves the thalamo-habenula pathway

“…Connectivity from this nucleus to the habenula has been shown by several groups 24, 28, 29 . The neuropil of the nucleus rostrolateralis may include the arborization field AF4 24, 30 .…”

The Brain of the Archerfish Toxotes chatareus: A Nissl-Based Neuroanatomical Atlas and Catecholaminergic/Cholinergic Systems

“…However, there is substantial evidence that this ventral EN in zebrafish corresponds to the bed nucleus of the stria medullaris (Mueller and Guo, 2009). Alternatively, it might be part of basal ganglia as suggested for zebrafish (Turner et al, 2016). At more caudal levels, where habenula (Ha) and postoptic commissure emerge ( Figure 3H ), this stalk still includes the PPp.…”