Electrophysiological and activity-dependent gene expression studies of birdsong have contributed to the understanding of the neural representation of natural sounds. However, we have limited knowledge about the overall spatial topography of song representation in the avian brain. Here, we adapt the noninvasive functional MRI method in mildly sedated zebra finches (Taeniopygia guttata) to localize and characterize song driven brain activation. Based on the blood oxygenation level-dependent signal, we observed a differential topographic responsiveness to playback of bird's own song, tutor song, conspecific song, and a pure tone as a nonsong stimulus. The bird's own song caused a stronger response than the tutor song or tone in higher auditory areas. This effect was more pronounced in the medial parts of the forebrain. We found left-right hemispheric asymmetry in sensory responses to songs, with significant discrimination between stimuli observed only in the right hemisphere. This finding suggests that perceptual responses might be lateralized in zebra finches. In addition to establishing the feasibility of functional MRI in sedated songbirds, our results demonstrate spatial coding of song in the zebra finch forebrain, based on developmental familiarity and experience.imaging ͉ learning ͉ memory B irdsong is studied as a model of vocal learning, perception, production, and motor abnormalities of speech (1, 2). There are interesting parallels between song development and speech development (3) and between auditory and vocal pathways in the songbird and human brain (4). Therefore, insights from experiments on songbirds may contribute to the understanding of auditory and vocal function in humans. For example, minimal models of speech dyspraxia (5) and dysfluencies such as stuttering are being developed in zebra finches (6). Zebra finches are capable of learning, producing, perceiving, and discriminating complex sound patterns. Birdsong in zebra finches consists of a sequence of distinctive sounds produced by males and is characterized by a consistent and reproducible acoustic profile. Song is learned by imitating the song of an adult conspecific tutor during a sensitive period of development (7-10). Recently, it has been shown that songbirds are able to learn recursive syntactic patterns, presumably a simple form of grammar (11), thus extending the potential applicability of the birdsong model to our understanding of the biological basis of languages. Several brain structures are required for learning, production, and perception of birdsong. It is known from electrophysiological studies that song learning nuclei, such as the lateral magnocellular nucleus of the anterior nidopallium (LMAN) and X (12), play an important role in song development. In parallel with song motor learning, auditory song selectivity gradually emerges during development (13-17). Robust sensory responses to auditory stimuli have been recorded in the primary auditory area in the caudal telencephalic region (field L), the caudomedial nidopallium (N...
We examined the relative proficiency of four languages (Spanish, German, French, English) of a multilingual speaker with aphasia, JM. JM’s self-rated proficiency was consistent with his naming accuracy for nouns and verbs (The Object and Action Naming Battery, Druks & Masterson, 2000) and with his performance on selected subtests of the Bilingual Aphasia Test (Paradis & Libben, 1987). Within and between-language changes were measured following two periods of language treatment, one in a highly-proficient language (Spanish) and one in a less-proficient language (English). The various outcome measures differed in their sensitivity to treatment-associated changes. Cross-language treatment effects were linked to the language of the environment at the time of testing and to relative language proficiency.
Juvenile male zebra finches develop their song by imitation. Females do not sing but are attracted to males' songs. With functional Magnetic Resonance Imaging (fMRI) and Event Related Potentials (ERPs) we tested how early auditory experience shapes responses in the auditory forebrain of the adult bird. Adult male birds kept in isolation over the sensitive period for song learning showed no consistency in auditory responses to conspecific songs, calls, and syllables. Thirty seconds of song playback each day over development, which is sufficient to induce song imitation, was also sufficient to shape stimulus-specific responses. Strikingly, adult females kept in isolation over development showed responses similar to those of males that were exposed to songs. We suggest that early auditory experience with songs may be required to tune perception towards conspecific songs in males, whereas in females song selectivity develops even without prior exposure to song.
Song development provides an opportunity to study the mechanisms of vocal learning dynamically at molecular, cellular and systems levels, and across time scales ranging from minutes to months. To exploit these opportunities one needs to identify appropriate units, types and time scales of vocal change in nearly real time. The previous chapter by Tchernikovski et al. in this volume described techniques that make this research strategy feasible by allowing us to observe the song learning process through a "temporal microscope" with variable degrees of resolution. In this chapter we summarize some of the new observations and raise hypotheses about the learning strategy of the bird. We focus on inferences that can be drawn from behavioral observations to the nature and complexity of the instructive signal that guides the vocal change (error-signal). We examine two effects: i) the emergence of syllable types and ii) changes in features within a syllable type. We found that different features of the same syllable change during different and sometimes disjointed developmental windows. We discuss the possibility that song imitation is achieved by correcting partial errors, and that features of those partial errors change adaptively during development, perhaps concurrently with changes in perception and in motor proficiency. Those hypotheses can be best examined by across levels investigation, starting from identifying critical moments in song development and recording of articulatory dynamics and neural patterns when only a few features of specific syllables undergo rapid changes. Such investigation could relate behavioral events to brain mechanisms that guide song learning from moment-to-moment and across extended periods.
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