Biology subjects

Roberts, T. F.

Publications and source records attributed to Roberts, T. F..

12 recordsLinked to original sources

bioRxiv2026

Stratified Palliobulbar and Midbrain Circuits Control the Timing and Acoustics of Learned Vocalizations

In mammals and birds, production of learned vocalizations depends on prominent projections from the pallium to the brainstem. Although pallial and cortical coding mechanisms for speech and birdsong are becoming increasingly clear, understanding how palliobulbar projections supervise brainstem circuits has remained challenging. Here we identify the functional organization of pallial and brainstem control of learned song in the zebra finch, a songbird in which genetic control of neuronal pathways is now feasible. We find that palliobulbar projections to the medulla and midbrain periaqueductal gray (PAG) arise from largely non-overlapping neuronal populations. Genetic silencing of these pathways reveals that projections to the medulla control the learned acoustic content defining individual song syllables, while projections to the PAG control the respiratory timing needed to sequence syllables. Using large-scale neuronal recordings, we find that song and innate calls are uniquely encoded within the PAG. Dual recordings from the palliobulbar neurons and the PAG suggest hierarchical encoding of expiratory and inspiratory events along this pathway. Lastly, genetic silencing reveals that PAG projections to the medulla are needed for birds to generate learned song and innate calls. Thus, stratified palliobulbar pathways control respiratory-timing and acoustics for song. Yet, without the PAG, they are insufficient to produce any vocalizations.

neuroscience↗

bioRxiv2026

Striatal Dopamine at Learned Sequence Boundaries Sustains Birdsong

Phasic striatal dopamine has been implicated in the initiation of well-trained action sequences in reward-guided tasks. Whether such signals also support natural skills learned without explicit cues or immediate rewards remains unknown. Using birdsong as a model of a naturally learned, skilled vocal behavior, we found that dopamine transients accompany the initiation of song sequences. These transients emerged during learning, shifting from later phases of the sequence toward sequence onset as song matured. Temporally targeted optogenetic inhibition of dopamine signaling at sequence onsets disrupted the maintenance of learned song, resulting in the gradual and severe deterioration of adult song. Thus, phasic dopamine signaling at sequence initiation develops during learning of a natural skilled behavior and is required for its long-term maintenance. One Sentence SummaryDopamine transients at song motif onset are required to maintain accurate adult zebra finch song, a naturally learned skilled behavior.

neuroscience↗

bioRxiv2026

Evolution of songbird vocal imitation involved multiple cellular innovations

A central goal of evolutionary neuroscience is to link behavioral adaptations to changes across the central nervous system. The dorsal telencephalon (i.e., pallium) varies widely in macrostructure across vertebrate clades and is thought to underlie the diversity of complex vertebrate behaviors. Yet, pallial cell types appear comparatively constrained in their evolutionary specializations relative to other parts of the nervous system, even across species with notable behavioral adaptations. Instead, differences among pallial neurons largely reflect their topographic organization. Here, we show that although transcriptomic identities of cell types in the songbird pallium largely follow this pattern, multiple cellular innovations exist within the vocal imitation brain regions distributed across the pallium. These include behavior-linked specializations to glutamatergic cell types in each region and the presence of PV- and SST-like GABAergic neurons unique to vocal imitation circuits. Additionally, we identify a concerted increase in glial composition that is accounted for by elevated proportions of astrocytes across vocal imitation circuits. These findings demonstrate that complex learned behaviors, such as vocal imitation, can be associated with the emergence of novel, behavior-associated cell types in the pallium; suggesting that selective pressures can, in some uncommon cases, favor functional specialization over conserved developmental constraints.

neuroscience↗

bioRxiv2025

Holistic Motor Control of Zebra Finch Song Syllable Sequences

How brain circuits are organized to skillfully produce learned sequences of behaviors is still poorly understood. Here, we functionally examine how the cortical song premotor region HVC, which is necessary for zebra finch song, controls the sequential production of learned song syllables. We find that HVC can generate the complete sequence of learned song syllables independently of its main synaptic input pathways. Thalamic input to HVC is permissive for song initiation but it is not required for transitions between syllables or completing song. We show that excitation of HVC neurons during song reliably causes vocalizations to skip back to the beginning of song, reminiscent of a skipping record. This restarting of syllable sequences can be induced at any moment in song and depends on local circuits within HVC. We identify and computationally model a synaptic network including intratelencephalic premotor and corticostriatal neurons within HVC that are essential for completing song syllable sequences. Together, our results show that the learned zebra finch song is controlled by a cortical sequence-generating network in HVC that, once started, can sustain production of all song syllables independent of major extrinsic input pathways. Thus, sequential neuronal activity can be organized to fuse well-learned vocal-motor sequences, ultimately achieving holistic control of this naturally learned behavior.

neuroscience↗

bioRxiv2025

Evolution of the cellular landscape in mammalian striatum

The dorsal striatum is important for highly specialized functions including movement, learning, and habit formation. However, it is not known if species-specialized behaviors are associated with cellular specializations in the striatum. Here, we compared single-nucleus RNA sequencing (snRNA-seq) data from human, chimpanzee, rhesus macaque, common marmoset, and pale spear-nosed bat caudate (CN) and putamen (Pu) separately as well as mouse caudoputamen (C-Pu), which represents divergence among species spanning approximately 94 million years of evolution. We observed a lower neuron-to-glia ratio in primate striata compared to non-primates, reflecting the allometric scaling of neuron density and relative glia density invariance in larger brains. Among neurons, eccentric spiny projection neurons (eSPNs) - an SPN of unknown function - showed significantly lower proportions in non-primate striata for both CN and Pu. Focusing on the heterogeneity within interneurons, we identified two bat striatal interneuron cell types that are nearly absent in other species: which express LMO3, and co-express FOXP2 and TSHZ2. Other striatal interneurons also showed significantly differential abundance between primates and non-primates. In summary, we provide a comprehensive snRNA- seq dataset of dorsal striatum, identify novel interneuron innovations in bat, and uncover fundamental cellular composition differences between primate and non-primate striata.

genomics↗

bioRxiv2024

AVN: A Deep Learning Approach for the Analysis of Birdsong

Deep learning tools for behavior analysis have enabled important new insights and discoveries in neuroscience. Yet, they often compromise interpretability and generalizability for performance, making it difficult to quantitively compare phenotypes across datasets and research groups. We developed a novel deep learning-based behavior analysis pipeline, Avian Vocalization Network (AVN), for the learned vocalizations of the most extensively studied vocal learning model species - the zebra finch. AVN annotates songs with high accuracy across multiple animal colonies without the need for any additional training data and generates a comprehensive set of interpretable features to describe the syntax, timing, and acoustic properties of song. We use this feature set to compare song phenotypes across multiple research groups and experiments, and to predict a birds stage in song development. Additionally, we have developed a novel method to measure song imitation that requires no additional training data for new comparisons or recording environments and outperforms existing similarity scoring methods in its sensitivity and agreement with expert human judgements of song similarity. These tools are available through the open-source AVN Python package and graphical application, which makes them accessible to researchers without any prior coding experience. Altogether, this behavior analysis toolkit stands to facilitate and accelerate the study of vocal behavior by enabling a standardized mapping of phenotypes and learning outcomes, thus helping scientists better link behavior to the underlying neural processes.

neuroscience↗

bioRxiv2022

Synaptic Connectivity of Afferent Inputs onto Projection Neurons in the Songbird HVC

Sensorimotor computations for learning and behavior rely on precise patterns of synaptic connectivity. Yet, we typically lack the synaptic wiring diagrams for long-range connections between sensory and motor circuits in the brain. Here we provide the synaptic wiring diagram for sensorimotor circuits involved in learning and production of male zebra finch song, a natural and ethologically relevant behavior. We examined the functional synaptic connectivity from the 4 main sensory afferent pathways onto the 3 known classes of projection neurons of the song premotor cortical region HVC. Recordings from hundreds of identified projection neurons reveal rules for monosynaptic connectivity and the existence of polysynaptic ensembles of excitatory and inhibitory neuronal populations in HVC. Circuit tracing further identifies novel connections between HVCs presynaptic partners. Our results indicate a modular organization of ensemble-like networks for integrating long-range input with local circuits, providing important context for information flow and computations for learned vocal behavior.

neuroscience↗

bioRxiv2022

Bidirectional synaptic changes in deep and superficial hippocampal neurons following in vivo activity

Neuronal activity during experience is thought to induce plastic changes within the hippocampal network which underlie memory formation, although the extent and details of such changes in vivo remain unclear. Here, we employed a temporally precise marker of neuronal activity, CaMPARI2, to label active CA1 hippocampal neurons in vivo, followed by immediate acute slice preparation and electrophysiological quantification of synaptic properties. Recently active neurons in the superficial sublayer of stratum pyramidale displayed larger post-synaptic responses at excitatory synapses from area CA3, with no change in pre-synaptic release probability. In contrast, in vivo activity weakened both pre- and post-synaptic excitatory weights onto pyramidal cells in the deep sublayer. In vivo activity of deep and superficial neurons within sharp-wave ripples was bidirectionally changed across experience, consistent with the observed changes in synaptic weights. These findings reveal novel, fundamental mechanisms through which the hippocampal network is modified by experience to store information.

neuroscience↗

bioRxiv2020

Functional Identification of Specialized Basal Ganglia Circuits that Regulate Vocal Motor Sequences

Disruption of the transcription factor FoxP2, which is enriched in the basal ganglia, impair vocal development in humans and songbirds. The basal ganglia are essential for the selection and sequencing of motor actions, but the circuit mechanisms governing accurate sequencing of learned vocalizations are unknown. Here, we show expression of FoxP2 in the basal ganglia is vital for the fluent initiation and termination of birdsong, and the maintenance of song syllable sequencing in adulthood. Knockdown of FoxP2 imbalances dopamine receptor expression across striatal direct-like and indirect-like pathways, suggesting a role of dopaminergic signaling in regulating vocal-motor sequencing. Confirming this prediction, we show that phasic dopamine activation, and not inhibition, during singing drives repetition of song syllables, thus also impairing fluent initiation and termination of birdsong. These findings demonstrate discrete circuit origins for the dysfluent repetition of vocal elements, a phenotype commonly observed in speech disorders.

neuroscience↗

bioRxiv2020

Autism-linked gene FoxP1 selectively regulates the cultural transmission of learned vocalizations

Autism spectrum disorders (ASD) are characterized by impaired learning of culturally transmitted behaviors like social skills, speech, and language1-3. These behaviors are learned by copying parents and other social models during development, a two-stage process that involves forming memories of appropriate behaviors during social experiences and then using those memories to guide imitation. How ASD-linked genes impair these often-intertwined aspects of learning is not known, thereby limiting our understanding of the developmental progression of ASD and the targeting of therapeutic interventions. Here we show that these aspects of learning are dissociable and that the ASD-linked gene FoxP1 selectively impairs learning from social experience, but not behavioral imitation. Haploinsufficiency of FOXP1 in humans causes FOXP1 syndrome, a neurodevelopmental disorder typified by severe disruptions in speech and language development, and other ASD-associated symptoms4,5. We tested how knockdown of FoxP1 (FP1-KD) affects the cultural transmission of vocal behaviors in zebra finches, a songbird that learns by memorizing and vocally copying the song of an adult song-tutor. We find that FP1-KD blocks song learning in juvenile birds by selectively impairing their ability to encode a memory during social experiences with a songtutor. These learning deficits are linked to disruptions in experience-driven structural and functional plasticity. However, if birds are exposed to tutor-song prior to FP1-KD, their ability to imitate that song during development is unaffected. Thus, FP1-KD impairs cultural transmission of vocalizations by disrupting the ability to form appropriate vocal memories, yet spares the ability to use previously acquired memories to guide vocal learning. This indicates that learning from social experience may be particularly vulnerable in FOXP1 syndrome.

neuroscience↗

bioRxiv2018

Transitioning between preparatory and precisely sequenced neuronal activity in production of a skilled behavior

Precise neural sequences are associated with the production of well-learned skilled behaviors. Yet, how neural sequences arise in the brain remains unclear. In songbirds, premotor projection neurons in the cortical song nucleus HVC are necessary for producing learned song and exhibit precise sequential activity during singing. Using cell-type specific calcium imaging we identify populations of HVC premotor neurons associated with the beginning and ending of singing-related neural sequences. We discovered neurons that bookend singing-related sequences and neuronal populations that transition from sparse preparatory activity prior to song to precise neural sequences during singing. Recordings from downstream premotor neurons or the respiratory system suggest that pre-song activity may be involved in motor preparation to sing. These findings reveal population mechanisms associated with moving from non-vocal to vocal behavioral states and suggest that precise neural sequences begin and end as part of orchestrated activity across functionally diverse populations of cortical premotor neurons.

neuroscience↗

bioRxiv2017

A Basal Ganglia Circuit Sufficient to Guide Birdsong Learning

Learning complex vocal behaviors, like speech and birdsong, is thought to rely on continued performance evaluation. Whether candidate performance evaluation circuits in the brain are sufficient to guide vocal learning is not known. Here, we test the sufficiency of VTA projections to the vocal basal ganglia (Area X) in singing zebra finches, a songbird species that learns to produce a complex and stereotyped multi-syllabic courtship song during development. We optogenetically manipulate VTA axon terminals in singing birds contingent on how the pitch of individual song syllables are naturally performed. We find that optical excitation and inhibition of VTA terminals have opponent effects on future performances of targeted song syllables and are each sufficient to reliably guide learned changes in song, consistent with positive and negative reinforcement of performance outcomes. These findings define a central role for reinforcement mechanisms in learning vocalizations and provide the first demonstration of minimal circuit elements for learning vocal behaviors.

neuroscience↗