PDF(Pubmed)
Abstract：
BACKGROUND: Most vocal learning species exhibit an early critical period during which their vocal control neural circuitry facilitates the acquisition of new vocalizations. Some taxa, most notably humans and parrots, retain some degree of neurobehavioral plasticity throughout adulthood, but both the extent of this plasticity and the neurogenetic mechanisms underlying it remain unclear. Differential expression of the transcription factor FoxP2 in both songbird and parrot vocal control nuclei has been identified previously as a key pattern facilitating vocal learning. We hypothesize that the resilience of vocal learning to cognitive decline in open-ended learners will be reflected in an absence of age-related changes in neural FoxP2 expression. We tested this hypothesis in the budgerigar (Melopsittacus undulatus), a small gregarious parrot in which adults converge on shared call types in response to shifts in group membership. We formed novel flocks of 4 previously unfamiliar males belonging to the same age class, either \"young adult\" (6 mo - 1 year) or \"older adult\" (≥ 3 year), and then collected audio-recordings over a 20-day learning period to assess vocal learning ability. Following behavioral recording, immunohistochemistry was performed on collected neural tissue to measure FoxP2 protein expression in a parrot vocal learning center, the magnocellular nucleus of the medial striatum (MMSt), and its adjacent striatum.
RESULTS: Although older adults show lower vocal diversity (i.e. repertoire size) and higher absolute levels of FoxP2 in the MMSt than young adults, we find similarly persistent downregulation of FoxP2 and equivalent vocal plasticity and vocal convergence in the two age cohorts. No relationship between individual variation in vocal learning measures and FoxP2 expression was detected.
CONCLUSIONS: We find neural evidence to support persistent vocal learning in the budgerigar, suggesting resilience to aging in the open-ended learning program of this species. The lack of a significant relationship between FoxP2 expression and individual variability in vocal learning performance suggests that other neurogenetic mechanisms could also regulate this complex behavior.
RESULTS: Although older adults show lower vocal diversity (i.e. repertoire size) and higher absolute levels of FoxP2 in the MMSt than young adults, we find similarly persistent downregulation of FoxP2 and equivalent vocal plasticity and vocal convergence in the two age cohorts. No relationship between individual variation in vocal learning measures and FoxP2 expression was detected.
CONCLUSIONS: We find neural evidence to support persistent vocal learning in the budgerigar, suggesting resilience to aging in the open-ended learning program of this species. The lack of a significant relationship between FoxP2 expression and individual variability in vocal learning performance suggests that other neurogenetic mechanisms could also regulate this complex behavior.
摘要：
背景：大多数声乐学习物种表现出早期的关键时期，在此期间，它们的声乐控制神经回路有助于获得新的发声。一些分类单元，最著名的是人类和鹦鹉，在整个成年期保留一定程度的神经行为可塑性，但是这种可塑性的程度和潜在的神经遗传学机制仍不清楚。转录因子FoxP2在鸣鸟和鹦鹉声音控制核中的差异表达先前已被确定为促进声音学习的关键模式。我们假设，开放式学习者的声乐学习对认知能力下降的韧性将反映在神经FoxP2表达中没有与年龄相关的变化。我们在鹦鹉（Melopsittacusundulatus）中检验了这一假设，一种群居的小型鹦鹉，成年人在响应组成员的变化时聚集在共享呼叫类型上。我们形成了4个以前不熟悉的男性属于同一年龄段的新群体，“年轻成年人”(6个月-1年)或“年长成年人”(≥3年)，然后在20天的学习期内收集录音以评估声乐学习能力。在行为记录之后，对收集的神经组织进行免疫组织化学，以测量鹦鹉发声学习中心的FoxP2蛋白表达，内侧纹状体的大细胞核（MMSt），和它相邻的纹状体。
结果：尽管与年轻人相比，老年人在MMST中表现出较低的声音多样性（即曲目大小）和较高的FoxP2绝对水平，我们发现在这两个年龄组中FoxP2的持续下调和等效的声带可塑性和声带趋同.未检测到声乐学习措施的个体差异与FoxP2表达之间的关系。
结论：我们发现神经证据支持鹦鹉持续的声乐学习，在该物种的开放式学习计划中表明对衰老的抵抗力。FoxP2表达与声乐学习表现的个体差异之间缺乏显着关系，这表明其他神经遗传学机制也可以调节这种复杂的行为。
结果：尽管与年轻人相比，老年人在MMST中表现出较低的声音多样性（即曲目大小）和较高的FoxP2绝对水平，我们发现在这两个年龄组中FoxP2的持续下调和等效的声带可塑性和声带趋同.未检测到声乐学习措施的个体差异与FoxP2表达之间的关系。
结论：我们发现神经证据支持鹦鹉持续的声乐学习，在该物种的开放式学习计划中表明对衰老的抵抗力。FoxP2表达与声乐学习表现的个体差异之间缺乏显着关系，这表明其他神经遗传学机制也可以调节这种复杂的行为。
