Elizabeth A. Miesner

Bio: Elizabeth A. Miesner is an academic researcher from University of California, Los Angeles. The author has contributed to research in topics: Vocal learning & Song control system. The author has an hindex of 3, co-authored 3 publications receiving 1248 citations. Previous affiliations of Elizabeth A. Miesner include University of Southern California.

Forebrain lesions disrupt development but not maintenance of song in passerine birds

Abstract: The magnocellular nucleus of the anterior neostriatum is a forebrain nucleus of passerine birds that accumulates testosterone and makes monosynaptic connections with other telencephalic nuclei that control song production in adult birds. Lesions in the magnocellular nucleus disrupted song development in juvenile male zebra finches but did not affect maintenance of stable song patterns by adult birds. These results represent an instance in which lesions of a discrete brain region during only a restricted phase in the development of a learned behavior cause permanent impairment. Because cells of the magnocellular nucleus accumulate androgens these findings raise the possibility that this learning is mediated by hormones.

Axonal connections of a forebrain nucleus involved with vocal learning in zebra finches.

Abstract: Connections of a telencephalic vocal-control nucleus, the lateral magnocellular nucleus of the anterior neostriatum (lMAN), were studied in adult male zebra finches. Anterograde transport of horseradish peroxidase (alone or conjugated to wheat germ agglutinin) revealed that neurons in lMAN project to another forebrain song-control nucleus, the robust nucleus of the archistriatum (RA). RA is known to project onto the hypoglossal motor neurons that innervate the vocal organ. Retrograde transport of HRP from lMAN labeled a large thalamic nucleus, the medial portion of the dorsolateral nucleus of the thalamus (DLM). DLM in turn receives input from another nucleus of the song-control system, area X of the parolfactory lobe. We confirmed results of previous studies showing that area X receives a projection from the ventral area of Tsai (AVT) in the midbrain. In addition, we replicated results of previous experiments with canaries showing that the song-control nucleus HVc (caudal nucleus of the ventral hyperstriatum) receives input from three sources: the medial magnocellular nucleus of the anterior neostriatum (mMAN), the interfacial nucleus (NIf), and the uvae-form nucleus (Uva) of the thalamus. HVc neurons project to area X and to RA. In summary, there is a path from AVT in the midbrain, to area X, to DLM, and then to lMAN; HVc projects to X and hence indirectly to lMAN. We do not yet know the afferent connections of AVT. Thus, lMAN receives indirect input from a variety of other sources, including other regions known to be involved with vocal control.

A Neural Substrate of Prediction and Reward

Abstract: The capacity to predict future events permits a creature to detect, model, and manipulate the causal structure of its interactions with its environment. Behavioral experiments suggest that learning is driven by changes in the expectations about future salient events such as rewards and punishments. Physiological work has recently complemented these studies by identifying dopaminergic neurons in the primate whose fluctuating output apparently signals changes or errors in the predictions of future salient and rewarding events. Taken together, these findings can be understood through quantitative theories of adaptive optimizing control.

The new cognitive neurosciences

Abstract: Shows the many advances in the field of cognitive neurosciences. From the molecular level up to that of human consciousness, the contributions cover one of the most fascinating areas of science - the relationship between the structural and physiological mechanisms of the brain/nervous system.

BIRDSONG AND HUMAN SPEECH: Common Themes and Mechanisms

Abstract: Human speech and birdsong have numerous parallels. Both humans and songbirds learn their complex vocalizations early in life, exhibiting a strong dependence on hearing the adults they will imitate, as well as themselves as they practice, and a waning of this dependence as they mature. Innate predispositions for perceiving and learning the correct sounds exist in both groups, although more evidence of innate descriptions of species-specific signals exists in songbirds, where numerous species of vocal learners have been compared. Humans also share with songbirds an early phase of learning that is primarily perceptual, which then serves to guide later vocal production. Both humans and songbirds have evolved a complex hierarchy of specialized forebrain areas in which motor and auditory centers interact closely, and which control the lower vocal motor areas also found in nonlearners. In both these vocal learners, however, how auditory feedback of self is processed in these brain areas is surprisingly unclear. Finally, humans and songbirds have similar critical periods for vocal learning, with a much greater ability to learn early in life. In both groups, the capacity for late vocal learning may be decreased by the act of learning itself, as well as by biological factors such as the hormones of puberty. Although some features of birdsong and speech are clearly not analogous, such as the capacity of language for meaning, abstraction, and flexible associations, there are striking similarities in how sensory experience is internalized and used to shape vocal outputs, and how learning is enhanced during a critical period of development. Similar neural mechanisms may therefore be involved.

Sensitive Periods in the Development of the Brain and Behavior

Abstract: Experience exerts a profound influence on the brain and, therefore, on behavior. When the effect of experience on the brain is particularly strong during a limited period in development, this period is referred to as a sensitive period. Such periods allow experience to instruct neural circuits to process or represent information in a way that is adaptive for the individual. When experience provides information that is essential for normal development and alters performance permanently, such sensitive periods are referred to as critical periods. Although sensitive periods are reflected in behavior, they are actually a property of neural circuits. Mechanisms of plasticity at the circuit level are discussed that have been shown to operate during sensitive periods. A hypothesis is proposed that experience during a sensitive period modifies the architecture of a circuit in fundamental ways, causing certain patterns of connectivity to become highly stable and, therefore, energetically preferred. Plasticity that occurs beyond the end of a sensitive period, which is substantial in many circuits, alters connectivity patterns within the architectural constraints established during the sensitive period. Preferences in a circuit that result from experience during sensitive periods are illustrated graphically as changes in a ''stability landscape,'' a metaphor that represents the relative contributions of genetic and experiential influences in shaping the information processing capabilities of a neural circuit. By understanding sensitive periods at the circuit level, as well as understanding the relationship between circuit properties and behavior, we gain a deeper insight into the critical role that experience plays in shaping the development of the brain and behavior.