Involvement of the avian song system in reproductive behaviour

Female songbirds use male song as an indicator of fitness and use that information to select their mate. Investigations of the female auditory system have provided evidence that the neurons within the caudal mesopallium (CM) are involved in the processing of songs that a female finds attractive, however, it is not clear how CM may exert its influence on behavioral indicators of mate choice. In the present study, anterograde tracing revealed the efferent connections of the female songbird CM. The results demonstrate connections to other auditory regions previously described in males, as well as novel connections to brain regions implicated in motor control. As in males, CM neurons in females project robustly to the lateral and medial extents of the caudal nidopallium, and to the ventral intermediate arcopallium. In a novel finding that is not present in males, CM neurons also project to the robust nucleus of the arcopallium and to the caudal striatum. Calling behavior and the expression of copulation solicitation displays are key indicators of female mate choice, and the projections found here bridge critical gaps necessary to understand how auditory perception can influence circuits related to the expression of those affiliative behaviors in female songbirds.

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Caudal mesopallial neurons in female songbirds bridge sensory and motor brain regions

Dunning

Maze

Atwood

et al. 2018

“…A well‐studied example is nucleus robustus arcopallialis (RA), a prominent vocal arcopallial nucleus in songbirds. RA receives projections from other pallial vocal areas, projects to vocal and respiratory centers in the midbrain and medulla, and plays key roles in the encoding and expression of learned vocalizations (Hahnloser, Kozhevnikov, & Fee, ; Long & Fee, ; Nottebohm et al, ; Nottebohm, Kelley, & Paton, ; Spiro, Dalva, & Mooney, ; Vicario, ; Wild, ; Wild & Botelho, ; Wild, Williams, & Suthers, ). Analogous nuclei are present in the other bird groups that evolved vocal learning (caudal part of the anterior arcopallium [AAc] in parrots and VA in hummingbirds; Brauth, Heaton, Shea, Durand, & Hall, ; Durand, Heaton, Amateau, & Brauth, ; Gahr, ; Jarvis & Mello, ; Jarvis et al, ), but seem absent in birds that lack this behavioral trait (Kroodsma & Konishi, ; Saldanha, Schultz, London, & Schlinger, , but also see Liu, Wada, Jarvis, & Nottebohm, ; de Lima et al, ).…”

Section: Introductionmentioning

confidence: 99%

Molecular architecture of the zebra finch arcopallium

Mello¹,

Kaser²,

Buckner³

et al. 2019

The arcopallium, a key avian forebrain region, receives inputs from numerous brain areas and is a major source of descending sensory and motor projections. While there is evidence of arcopallial subdivisions, the internal organization or the arcopallium is not well understood. The arcopallium is also considered the avian homologue of mammalian deep cortical layers and/or amygdalar subdivisions, but one‐to‐one correspondences are controversial. Here we present a molecular characterization of the arcopallium in the zebra finch, a passerine songbird species and a major model organism for vocal learning studies. Based on in situ hybridization for arcopallial‐expressed transcripts (AQP1, C1QL3, CBLN2, CNTN4, CYP19A1, ESR1/2, FEZF2, MGP, NECAB2, PCP4, PVALB, SCN3B, SCUBE1, ZBTB20, and others) in comparison with cytoarchitectonic features, we have defined 20 distinct regions that can be grouped into six major domains (anterior, posterior, dorsal, ventral, medial, and intermediate arcopallium, respectively; AA, AP, AD, AV, AM, and AI). The data also help to establish the arcopallium as primarily pallial, support a unique topography of the arcopallium in passerines, highlight similarities between the vocal robust nucleus of the arcopallium (RA) and AI, and provide insights into the similarities and differences of cortical and amygdalar regions between birds and mammals. We also propose the use of AMV (instead of nucleus taenia/TnA), AMD, AD, and AI as initial steps toward a universal arcopallial nomenclature. Besides clarifying the internal organization of the arcopallium, the data provide a coherent basis for further functional and comparative studies of this complex avian brain region.

“…Consistent with a role for female RA in the control of vocalizations, retrograde labeling experiments in female zebra finches demonstrate descending connectivity from RA to the vocal hindbrain (Johnson & Sellix, ). Interestingly, experiments in a related species (canary) suggest the descending connectivity of RA may also influence female copulatory solicitation displays (CSDs) via disynaptic control of spinal motoneuron pools (Wild & Botelho, ). These data lead to the view that HVC and RA may be a part of a more general network that controls courtship and reproductive behavior (including learned song and CSDs) in both sexes (reviewed by Perkes et al, ).…”

Section: Discussionmentioning

confidence: 99%

Female zebra finches do not sing yet share neural pathways necessary for singing in males

Shaughnessy

Hyson

Bertram

et al. 2018

Adult female zebra finches (Taeniopygia guttata), which do not produce learned songs, have long been thought to possess only vestiges of the forebrain network that supports learned song in males. This view ostensibly explains why females do not sing—many of the neural populations and pathways that make up the male song control network appear rudimentary or even missing in females. For example, classic studies of vocal‐premotor cortex (HVC, acronym is name) in male zebra finches identified prominent efferent pathways from HVC to vocal‐motor cortex (RA, robust nucleus of the arcopallium) and from HVC to the avian basal ganglia (Area X). In females, by comparison, the efferent targets of HVC were thought to be only partially innervated by HVC axons (RA) or absent (Area X). Here, using a novel visually guided surgical approach to target tracer injections with precision, we mapped the extrinsic connectivity of the adult female HVC. We find that female HVC shows a mostly male‐typical pattern of afferent and efferent connectivity, including robust HVC innervation of RA and Area X. As noted by earlier investigators, we find large sex differences in the volume of many regions that control male singing (male > female). However, sex differences in volume were diminished in regions that convey ascending afferent input to HVC. Our findings do not support a vestigial interpretation of the song control network in females. Instead, our findings support the emerging view that the song control network may have an altogether different function in nonsinging females.