Song competition changes the brain and behavior of a male songbird

Abstract

SUMMARY Males should adjust their behavior and its neural substrates according to the quality of competition that they assess by eavesdropping on other males'courtship signals. In European starlings (Sturnus vulgaris), females base mate choice, in part, on aspects of male song associated with its length,which positively correlates with the males' reproductive success,immunocompetence, age and ability to repel competing males. To determine how variation in the quality of male courtship song affects the brain and behavior of incidental male receivers, we exposed adult male starlings to either long or short songs periodically over 7 days, followed by 1 day of no song. We found no difference between groups in the length (i.e. quality) of songs that subjects produced during the experiment. However, compared with males exposed to short songs, those exposed to long songs sang more songs, exhibited more non-singing activity and, by the end of the experiment, weighed less and had a 30% larger robust nucleus of the arcopallium (RA), a forebrain nucleus that translates pre-motor signals into the appropriate combination of respiratory and syringeal activity. The change in RA volume was not entirely due to variation in song output, suggesting, for the first time, the possibility of acoustically driven plasticity in this motor nucleus. We hypothesize that such neuroplasticity helps prepare the individual for future song output tailored to the prevailing competitive environment.

Song Competition Affects Monoamine Levels in Sensory and Motor Forebrain Regions of Male Lincoln's Sparrows (Melospiza lincolnii)

“…Using previously described protocols [33], we fixed one hemisphere (alternating left and right between subjects within each treatment group) in 5% acrolein, saturated it with 30% sucrose for cryoprotection, froze it on dry ice and held it at −80°C for approximately two weeks until Nissl staining was conducted. The second hemisphere was fresh frozen on dry ice and held at −80°C until brain regions were micropunched and HPLC was conducted (ca.…”

“…Using micropunches (Fine Science Tools, Foster City, CA, USA), we took one tissue sample from each of four brain regions – the NCM and the CMM of the auditory telencephalon; the principal nucleus of the anterior forebrain pathway of the song control system, area X, and the principal nucleus of the motor pathway, RA. We chose brain sections containing each region based on boundaries defined by Nissl-staining ([33] for protocol) in sections from the alternate, fixed hemisphere and comparison with a zebra finch atlas [71]. Although inter-hemispheric differences in anatomy and plane of section could lead to errors when using one hemisphere (the Nissl stained one) to guide dissection in the other, we used punches with diameters well below the diameters of the brain regions of interest to ensure that we included only tissue that was within the targeted brain region.…”

“…1). The effects of exposure to songs of varying level of challenge persist after playbacks have ended, indicating that these behavioral differences reflect changes in the males' competitive states [16], [33], [34]. Given that socially-elicited changes in behavioral state can be mediated by monoamine-dependent neural plasticity, we examined the relationship between social challenge and the levels of particular monoamines in two forebrain networks implicated in song perception and the modulation of song motor output (Fig.…”

Variation in song system anatomy and androgen levels does not correspond to song characteristics in a tropical songbird

“…Small, Brenowitz, & Moore, 2007). Social context also influences male singing and song system anatomy (Sartor & Ball, 2005;Sockman, Salvante, Racke, Campbell, & Whitman, 2009;Strand, Ross, Weiss, & Deviche, 2008), and the volumes of male song nuclei vary with social status in species with complex social organization of breeding units. For example, dominant males of the white-browed sparrow weaver, Plocepasser mahali, have larger HVC and RA volumes and differ from subordinate males in the cellular machinery and gene expression patterns in these nuclei (Voigt & Gahr, 2011;Voigt, Leitner, & Gahr, 2007).…”

Environmental and Genetic Control of Brain and Song Structure in the Zebra Finch

“…We found a weak positive relationship between the number of male nest-mates and HVC volume, the inverse of the expected relationship if male nest-mates inhibit singing behavior. Sockman et al (2009) showed that European starlings exposed to playback of long songs developed larger RA than those exposed to short song, suggesting a stimulatory effect of listening to the song of others, which might explain the weak positive relationship between HVC and number of male nest-mates found here.…”