Individual differences in the motivation to communicate relate to levels of midbrain and striatal catecholamine markers in male European starlings

Abstract

Individuals display dramatic differences in social communication even within similar social contexts. Across vertebrates dopaminergic projections from the ventral tegmental area (VTA) and midbrain central gray (GCt) strongly influence motivated, reward-directed behaviors. Norepinephrine is also rich in these areas and may alter dopamine neuronal activity. The present study was designed to provide insight into the roles of dopamine and norepinephrine in VTA and GCt and their efferent striatal target, song control region area X, in the regulation of individual differences in the motivation to sing. We used high pressure liquid chromatography with electrochemical detection to measure dopamine, norepinephrine and their metabolites in micropunched samples from VTA, GCt, and area X in male European starlings (Sturnus vulgaris). We categorized males as sexually motivated or non-sexually motivated based on individual differences in song produced in response to a female. Dopamine markers and norepinephrine in VTA and dopamine in area X correlated positively with sexually-motivated song. Norepinephrine in area X correlated negatively with non-sexually-motivated song. Dopamine in GCt correlated negatively with sexually-motivated song, and the metabolite DOPAC correlated positively with non-sexually-motivated song. Results highlight a role for evolutionarily conserved dopaminergic projections from VTA to striatum in the motivation to communicate and highlight novel patterns of catecholamine activity in area X, VTA, and GCt associated with individual differences in sexually-motivated and non-sexually-motivated communication. Correlations between dopamine and norepinephrine markers also suggest that norepinephrine may contribute to individual differences in communication by modifying dopamine neuronal activity in VTA and GCt.

Song in an Affiliative Context Relates to the Neural Expression of Dopamine- and Neurotensin-Related Genes in Male European Starlings

“…This is the first instance in which NTR1 has been associated with singing behavior, although LS has previously been implicated in undirected song production [Heimovics and Riters, 2006, 2007]. In male starlings, concentrations of the DA metabolite DOPAC and D1 receptor densities in LS positively correlate with undirected song [Heimovics et al, 2009; Heimovics et al, 2011], suggesting that DA activity in LS may stimulate this type of vocalization. NT neurons in VTA project to LS [Binder et al, 2001], and NTR1 activation in septum could depolarize DA neurons or reduce dopaminergic inhibition, as reported in other brain regions [Binder et al, 2001; Lu et al, 2009; Mercuri et al, 1993], and thereby facilitate song.…”

Rapid Effects of an Aggressive Interaction on Dehydroepiandrosterone, Testosterone and Oestradiol Levels in the Male Song Sparrow Brain: a Seasonal Comparison

“…Plasma was collected and stored at À20°C until radioimmunoassay. The Palkovits punch technique was used to microdissect brain tissue from six brain areas: the MSt, POA, AH, TnA, NCM and midbrain (17)(18)(19). Brains were sectioned in the coronal plane at 300 lm on a cryostat (À10°C) using a plane of sectioning that closely matched a zebra finch atlas (20).…”

Neurotensin immunolabeling relates to sexually-motivated song and other social behaviors in male European starlings (Sturnus vulgaris)

“…Dopamine, its metabolites, or enzymes involved in dopamine synthesis in VTA are tightly linked to sexually-motivated song [8-11], suggesting that dopaminergic projections from VTA may be crucial for controlling this type of communication. Neurotensin (NT) is a neuropeptide that strongly modulates activity in the mesolimbic dopamine system (reviewed in [12]).…”