The role of lateral hypothalamic nucleus in mediating locomotive behaviors in pigeons (Columba livia).

The lateral hypothalamic nucleus (LHy) is located in the dorsolateral hypothalamus of birds, and it is essential to many life processes. However, limited information is available about the role of LHy in mediating locomotive behaviors. In this work, we investigated the structure and function of LHy in pigeons (Columba livia) by Nissl staining, immunohistochemical (IHC) staining, insituhybridization (ISH) staining and constant current stimulation methods. The results showed that LHy appears crescent in shape, and three-dimensional coordinate value range of LHy is: A: 5.0-8.0 mm, L: 0.7-1.2 mm, D: 9.5-10.3 mm. The dopaminergic neurons in LHy were distributed in small amount and concentrated manner, while the glutamatergic neurons were distributed in a large number and uniform manner. The distribution of the above two neurons at each coronal level showed a significant positive correlation (R2 = 0.7516, P < 0.001). Our work demonstrated that LHy mainly mediates forward movement (P < 0.01) and ipsilateral lateral movement (P < 0.001), and these movements were significantly effected by electrical stimulation intensity. Our results showed that LHy can mediate the generation of directional behavior and this will provide technical support for the study of locomotor behavior regulation in birds.

Spatial and single-nucleus transcriptomics decoding the molecular landscape and cellular organization of avian optic tectum.

The avian optic tectum (OT) has been studied for its diverse functions, yet a comprehensive molecular landscape at the cellular level has been lacking. In this study, we applied spatial transcriptome sequencing and single-nucleus RNA sequencing (snRNA-seq) to explore the cellular organization and molecular characteristics of the avian OT from two species: Columba livia and Taeniopygia guttata. We identified precise layer structures and provided comprehensive layer-specific signatures of avian OT. Furthermore, we elucidated diverse functions in different layers, with the stratum griseum periventriculare (SGP) potentially playing a key role in advanced functions of OT, like fear response and associative learning. We characterized detailed neuronal subtypes and identified a population of FOXG1+ excitatory neurons, resembling those found in the mouse neocortex, potentially involved in neocortex-related functions and expansion of avian OT. These findings could contribute to our understanding of the architecture of OT, shedding light on visual perception and multifunctional association.

The role of posterior pallial amygdala in mediating motor behaviors in pigeons.

The posterior pallial amygdala (PoA) is located on the basolateral caudal telencephalon, including the basal division of PoA (PoAb) and the compact division of PoA (PoAc). PoA plays a vital role in emotion regulation and is considered a part of the amygdala in birds. However, the regulatory functions responsible for motor behaviors and emotions between PoAb and PoAc are poorly understood. Therefore, we studied the structure and function of PoA by tract-tracing methods, constant current electrical stimulation, and different dopamine receptor drug injections in pigeons (Columba livia domestica). PoAb connects reciprocally with two nuclear groups in the cerebrum: 1) a continuum comprising the temporo-parieto-occipitalis, corticoidea dorsolateralis, hippocampus, and parahippocampalis areas and 2) rostral areas of the hemisphere, including the nucleus septalis lateralis and nucleus taeniae amygdalae. Extratelencephalic projections of PoAb terminate in the lateral hypothalamic nucleus and are scattered in many limbic midbrain regions. PoAb and PoAc mainly mediated the turning movement. In the 'open-field' test, D1 agonist and D2 antagonist could significantly reduce the latency period for entering into the central area and increase the residence time in the central area, whereas D1 antagonist and D2 agonist had the opposite effect. PoAb and PoAc are important brain areas that mediate turning behavior.