DOI: 10.5061/dryad.gb5mkkwvj
title: Neural FoxP2 expression in an aging open-ended vocal learner

description: Most vocal learning species exhibit an early critical period during which
 their vocal control neural circuity can facilitate the acquisition of new
 vocalizations. Some taxa, most notably humans and parrots, retain this
 neurobehavioral plasticity throughout adulthood. Downregulation of the
 transcription factor FoxP2 in both songbird and parrot vocal control
 nuclei has been identified as a key expression pattern facilitating vocal
 learning. We hypothesize that open-ended vocal learning is vulnerable to
 cognitive decline, and that this deterioration will be reflected in
 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 yr) or
 “older adult” (≥ 3 yr), and then collected audio-recordings over a 20-day
 learning period to assess vocal learning ability. Following behavioral
 recording, whole brains were extracted and immunohistochemistry was
 performed to measure FoxP2 protein expression in a parrot vocal learning
 center, the magnocellular nucleus of the medial striatum (MMSt), and its
 adjacent striatum. We find similarly downregulated FoxP2 expression and
 equivalent vocal plasticity and vocal convergence in young and older
 adults suggesting the maintenance of two components of open-ended learning
 into old age in the budgerigar. No relationship between individual
 variation in vocal learning measures and FoxP2 expression was detected.
description: # Neural FoxP2 expression in an aging open-ended vocal learner Most vocal
 learning species exhibit an early critical period during which their vocal
 control neural circuity can facilitate the acquisition of new
 vocalizations. Some taxa, most notably humans and parrots, retain this
 neurobehavioral plasticity throughout adulthood. Downregulation of the
 transcription factor FoxP2 in both songbird and parrot vocal control
 nuclei has been identified as a key expression pattern facilitating vocal
 learning. We hypothesize that open-ended vocal learning is vulnerable to
 cognitive decline and that this deterioration will be reflected in
 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 yr) or older
 adult ( 3 yr), and then collected audio recordings over a 20-day learning
 period to assess vocal learning ability. Following behavioral recording,
 whole brains were extracted and immunohistochemistry was performed to
 measure FoxP2 protein expression in a parrot vocal learning center, the
 magnocellular nucleus of the medial striatum (MMSt), and its adjacent
 striatum. We find similarly downregulated FoxP2 expression and equivalent
 vocal plasticity and vocal convergence in young and older adults
 suggesting the maintenance of two components of open-ended learning into
 old age in the budgerigar. No relationship between individual variation in
 vocal learning measures and FoxP2 expression was detected. ## Underlying
 data: This dataset contains dataframes (.csv) of both vocal and neural
 data and the corresponding code used in analyzing this data in the form of
 an R script (.R): 1. **Vocal_Brain_Correlation_03_09_2023_Final.r** (R
 script consisting of code used for data analysis and statistics for
 age-related differences in FoxP2 expression.) 2.
 **AgeLearn_Treatments_Master.csv** (Dataframe containing experiment
 metadata such as bird identities and corresponding age class treatment.
 NAs in 'Hatch date' column indicate unknown hatch dates of birds
 obtained from a breeder who provided us with approximate ages.) 3.
 **agg_dat.csv** (Dataframe containing vocal learning measures for each
 bird and each recording block. Column names acoustic.area,
 acoustic.overlap, and acoustic.overlap.to.group correspond to vocal
 diversity, vocal plasticity, and vocal convergence, respectively. NAs in
 acoustic measurement columns indicate birds that produced too few calls
 for quantification purposes.) 4. **Vocal_Brain_Corr_03_09_2023_Final.csv**
 (Dataframe of FoxP2 MMSt/VSP expression ratios and vocal learning measures
 taken during the 5th recording block. NAs in acoustic measurement columns
 indicate birds that produced too few calls for quantification purposes.)
 5. **Vocal_Brain_Corr_03_09_2023_Final_WithAdditionalMMSTVSP.csv**
 (Dataframe of FoxP2 % expression in MMSt, FoxP2 % expression in VSP, FoxP2
 MMSt/VSP expression ratio, and vocal learning measures taken during the
 5th recording block. NAs in acoustic measurement columns indicate birds
 that produced too few calls for quantification purposes.) 6.
 **data_analysis.html** (R code for data analysis & statistics for
 Bayesian models testing relationship between FoxP2 expression and vocal
 learning).