Song practice as a rewarding form of play in songbirds

Abstract

In adult songbirds, the primary functions of song are mate attraction and territory defense; yet, many songbirds sing at high rates as juveniles and outside these primary contexts as adults. Singing outside primary contexts is critical for song learning and maintenance, and ultimately necessary for breeding success. However, this type of singing (i.e., song "practice") occurs even in the absence of immediate or obvious extrinsic reinforcement; that is, it does not attract mates or repel competitors. Here we review studies that support the hypothesis that song practice is stimulated and maintained by intrinsic reward mechanisms (i.e., that it is associated with a positive affective state). Additionally, we propose that song practice can be considered a rewarding form of play behavior similar to forms of play observed in multiple young animals as they practice sequences of motor events that are used later in primary adult reproductive contexts. This review highlights research suggesting at least partially overlapping roles for neural reward systems in birdsong and mammalian play and evidence that steroid hormones modify these systems to shift animals from periods of intrinsically rewarded motor exploration (i.e., singing in birds and play in mammals) to the use of similar motor patterns in primary reproductive contexts.

Mu opioid receptors in the medial preoptic area govern social play behavior in adolescent male rats

“…[1][2][3] Specifically, studies demonstrate a crucial role for opioids that bind to mu opioid receptors (MORs, gene name Oprm1) in the medial preoptic area (MPOA) in affiliative communication and reward that differs from that observed from mate-directed communication. 1,2,4,5 In rodent models, the MPOA is well-known for its role in sexual and maternal reward [6][7][8] ; however, the role of MPOA in reward beyond these contexts has not been well studied.…”

Birdsong as a window into language origins and evolutionary neuroscience

“…of the reward-related memories) and associated dopaminergic neuromodulation, and the other regarding pleasure (i.e. elicited positive affective states), associated with opioid and endocannabinoid neuromodulation [32]. The role of cannabinoids in song variability and learning is substantiated by the reduction in stereotypy and number of learned notes in the songs of young birds exposed to an endocannabinoid agonist relative to songs of non-exposed juveniles [33].…”

“…Moreover, the plastic period of juvenile song learning closes when zebra finches mature and testosterone levels rise [49,50]. These endogenous hormones have long been recognized to modulate DA in mammalian and songbird brains [51,52], and have more recently been investigated in endocannabinoid-associated reward systems in both animal groups [32,[53][54][55]. Therefore, context-dependent surges in testosterone levels and changes in the timing of sexual maturation impact the function of intrinsic reward systems in both songbird and mammalian brains.…”

Undirected singing rate as a non-invasive tool for welfare monitoring in isolated male zebra finches

“…Songbirds, such as the zebra finch (Taeniopygia guttata), serve as the main animal model to study vocal learning-the ability to learn vocalization by imitation [1]. Despite a wide range of research [2][3][4][5][6][7][8][9][10][11][12][13][14][15], little is known about the impact of typical experimental manipulations on the songbird's welfare [16][17][18].…”