Fiber connections of the compact division of the posterior pallial amygdala and lateral part of the bed nucleus of the stria terminalis in the pigeon (Columba livia)

Abstract

The compact division of the posterior pallial amygdala (PoAc) and lateral part of the bed nucleus of the stria terminalis (BSTL) are components of the limbic system in the pigeon brain. In this study, we examined the position and fiber connections of these two nuclei by using Nissl staining and tract-tracing methods. PoAc occupies a central division in the posterior pallial amygdala. BSTL faces the ventral horn of the lateral ventricle and extends between A 7.25 and A 10.50. PoAc and BSTL connect bidirectionally by the stria terminalis. PoAc connects reciprocally with two nuclear groups in the cerebrum: 1) a continuum consisting of the caudoventral nidopallium, lateral part of the caudoventral nidopallium (NCVl), subnidopallium beneath NCVl, and piriform cortex and 2) rostral areas of the hemisphere, including the frontolateral and frontomedial nidopallium and the densocellular part of the hyperpallium. Extratelencephalic projections of PoAc terminate in the dorsomedial thalamic nuclei and reach the lateral hypothalamic area via the hypothalamic part of the occipito-mesencephalic tract. BSTL also connects reciprocally with two main regions: 1) the same continuum as for PoAc projections, except the piriform cortex and 2) rostral areas of the hemisphere, including the olfactory tubercle and nucleus accumbens. Extratelencephalic reciprocal connections are with the substantia nigra, nucleus subceruleus dorsalis, parabrachial nucleus, locus coeruleus, and nucleus of the solitary tract. The dorsomedial subdivision of the hippocampal formation projects massively to PoAc and BSTL. These findings indicate that PoAc and BSTL are important components of an interconnected neural circuit involving widespread regions of the neuraxis and mediating limbic-visceral functions.

Telencephalic organization of the olfactory system in homing pigeons (Columba livia)

“…The assumption that not CPi but PoAc receives input from HF is further supported by anterograde BDA tracings into the DM of the HF that demonstrate only very few fibers in the CPi (Atoji and Wild, 2004). Comparing the labeling pattern of injections limited to the CPi and the larger ones of our study with that of Bingman et al (1994), it seems very likely that the projections from CDL, TPO, NC, PoAb, PoAc, DM, TuO, and the NDB terminate within the PoAc (Atoji et al, 2006) and not within the CPi. Moreover, in contrast to the study by Bingman et al (1994), no projection from the ipsilateral TnA was detected in the present study.…”

“…A likely candidate represents the PoAc since it shares several connections with the CPi (Atoji et al, 2006). PoAc afferents from HD, NFL, HF, and contralateral CPi and PoAb have been described, as well as input from the HF and from the septum but not from the OB and CPP (Atoji et al, 2006). The assumption that not CPi but PoAc receives input from HF is further supported by anterograde BDA tracings into the DM of the HF that demonstrate only very few fibers in the CPi (Atoji and Wild, 2004).…”

“…It is more likely that the afferents from the HF that were observed by Bingman et al (1994) resulted from tracer spread into areas adjoining the CPi. A likely candidate represents the PoAc since it shares several connections with the CPi (Atoji et al, 2006). PoAc afferents from HD, NFL, HF, and contralateral CPi and PoAb have been described, as well as input from the HF and from the septum but not from the OB and CPP (Atoji et al, 2006).…”

Embryonic Origin of the Islet1 and Pax6 Neurons of the Chicken Central Extended Amygdala Using Cell Migration Assays and Relation to Different Neuropeptide-Containing Cells

“…This has also been suggested for the ENK neurons of mouse CeC [Bupesh et al, 2011a]. Like the mammalian CeC [Jolkkonen and Pitkänen, 1998;Cassell et al, 1999;Csáki et al, 2000], the region identified by us as the chicken CeC likely receives pallial amygdalar input (data on pigeon: Kröner and Güntürkün [1999]) and projects to the BSTL [Atoji et al, 2006] and the paraventricular hypothalamic domain . However, it is unknown whether the cells projecting to the hypothalamus are ENK neurons (all of which are GABAergic; i.e.…”

“…The avian pINP shows connections similar to those of the mammalian CeL/CeM, including input from the pallial amygdala and output to the BSTL [Atoji et al, 2006], paraventricular hypothalamic domain and dorsal vagal complex [Berk, 1987], and may be involved in fear behavior [reviewed by Vicario et al, 2014]. However, connectivity and behavioral studies focusing on the avian pINP, including its different neuronal subpopulations, are urgently needed.…”