PhD Project 7
Neurogenomics of vocal learning: decoding the functions of FoxPs in vocal perception and production learning
(last update 2019-06-27)
The discovery that the FOXP2 gene is implicated in speech and language provided the first molecular windows into this trait. One way to decipher the roles of genes like FOXP2 is through comparative research using songbirds - birds that acquire their songs by auditory-guided vocal learning. Using FOXP knockdown technology, functions of zebra finch FOXP genes will be assessed for a novel subject - the perception, discrimination and processing of vocalizations, such as natural songs, along with strings of song elements organized according to artificial grammar algorithms. This promises unique insights into evolutionary precursors of linguistic function in non-speaking species.
Listening motivation for song playbacks depends on local FoxP1 expression in HVC of adult female zebra finches
Team members: Heim, Fisher, Scharff (FUB), Ten Cate, and Riebel (LU)
Female songbirds select their mates often based on their display of learned song. Female zebra finches don’t produce song, but establish a preference for their fathers’ song early in life. Although they don’t sing, female expression of FoxP1 is similar to that of singing males. Thus, the hypothesis was that FoxP1 is necessary for auditory perception of song. To test this, FoxP1 expression in female zebra finches was reduced and assessed their song preference.
Female zebra finches which received a viral construct to reduce FoxP1 expression as adults into HVC showed lower pecking activity than their respective controls during preference tests with playbacks of zebra finch song (see Figure a). Furthermore, the same group also showed a weaker preference for familiar song than matched controls (see Figure b) while they still showed a preference for familiar song above chance (Figure b, dotted line) and did not display decreased activity levels or fine motor deficits. No differences in pecking activity or preference strength were detected in females which received a FoxP1 knockdown as juveniles and in both age groups with injections into CMM. This suggests that a local knockdown of FoxP1 in HVC of adult females does not affect discriminative abilities but leads to lower interest in auditory stimuli.
This project for the first time unites experts and pioneers on Forkhead box proteins, transcriptomics, songbird genetics and cognitive abilities of birds with a focus female zebra finches. Thereby, this project benefits from the best of all worlds and provides a novel and comparative approach to the function of transcription factors implicated in human speech and language. This project sets a path for potential future collaborations and exchanges among the involved labs to further polish their methods and approach behavioural paradigms studying vocal learning from a different perspective.
All treatment groups (N= 12) during 4 day long song preference tests. Blue = Controls, Red = FoxP1-knockdowns. X-axis: different brain areas where viral particles where injected at different developmental stages. (Adult = >90 days, Juvenile = at the onset of the sensory phase (23 days of age), HVC (used as a proper name), Caudomedial Mesopallium (CMM)).
a) Total number (log scale) of requested playbacks by pecking any of the two pecking keys provided.
b) preference strength for familiar song over unfamiliar song (percentage of playback requests for familiar song when given the choice between familiar and unfamiliar song playbacks.
All behavioural experiments, RNA extractions and sequencing analyses have been completed. In total, 96 birds of 4 different treatment groups were treated, tested and analysed. Specifically, birds which received a local knockdown of FoxP1 in HVC as adults showed a weaker preference for their fathers’ song in comparison to matched controls and also requested fewer playbacks during preference tests while their participating rate was not different from controls in go/no-go tasks. Additional behavioural differences were not detected within the used paradigms.
Currently, four manuscripts are in preparation. One review on the potential role in perception of forkhead box transcription factors, two data chapters on the preference tests and the go/no-go tests, respectively, and one manuscript on the transcriptional differences across all treatment groups.
This project uniquely brings together behavioural work and molecular genomics experiments. It not only involves collaboration inside, but also outside our consortium (Constance Scharff; Freie Universität Berlin) and combines expertise in neurogenomic techniques and behavioural test essays. Thus far, no study has examined the role of FoxP genes for vocal perceptual learning in any animal model. This may also provide a new window on their role in human speech and language processing, where the effects of these genes on vocal perception are hard to disentangle from other effects and not experimentally accessible.