Dataset Information

Topography and physiology of ascending streams in the auditory tectothalamic pathway.

ABSTRACT: Auditory information is relayed from the cochlea along parallel pathways and reaches the inferior colliculus (IC) and the medial geniculate body (MGB) en route to the cortex. Although the ascending tectothalamic pathway to the ventral division of the MGB is regarded as a high-fidelity information-bearing channel, the roles of the pathways to the dorsal and medial divisions are more opaque. Here, we show fundamental differences between these ascending pathways using an in vitro slice preparation. Using photostimulation, we found three main patterns of input (excitatory, inhibitory, and mixed) that differed in each pathway. Furthermore, electrical stimulation of the central nucleus of the IC evoked a depressing response in the MGB with no metabotropic glutamate (mGlu) receptor component, whereas stimulation of the lateral cortex of the IC evoked a facilitating response with an mGlu receptor component. These data suggest that the ascending tectothalamic pathways are functionally distinct from one another.

SUBMITTER: Lee CC

PROVIDER: S-EPMC2806784 | biostudies-literature | 2010 Jan

REPOSITORIES: biostudies-literature

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Topography and physiology of ascending streams in the auditory tectothalamic pathway.

Lee Charles C CC Sherman S Murray SM

Proceedings of the National Academy of Sciences of the United States of America 20091215 1

Auditory information is relayed from the cochlea along parallel pathways and reaches the inferior colliculus (IC) and the medial geniculate body (MGB) en route to the cortex. Although the ascending tectothalamic pathway to the ventral division of the MGB is regarded as a high-fidelity information-bearing channel, the roles of the pathways to the dorsal and medial divisions are more opaque. Here, we show fundamental differences between these ascending pathways using an in vitro slice preparation. ...[more]

PMID: 20018757

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Project description:It is increasingly recognized that brain-derived estrogens (neuroestrogens) can regulate brain physiology and behavior much faster than what was previously known from the transcriptional action of estrogens on nuclear receptors. One of the best examples of such neuromodulation by neuroestrogens concerns the acute regulation of sensory coding by the auditory cortex as demonstrated by electrophysiological studies of selected neurons in zebra finches. Yet, the spatial extent of such modulation by neuroestrogens is not known. Using functional magnetic resonance imaging, we demonstrate here that acute estrogen depletion alters within minutes auditory processing in male European starlings. These effects are confined to very specific but large areas of the auditory cortex. They are also specifically lateralized to the left hemisphere. Interestingly, the modulation of auditory responses by estrogens was much larger (both in amplitude and in topography) in March than in December or May/June. This effect was presumably independent from changes in circulating testosterone concentrations since levels of the steroid were controlled by subcutaneous implants, thus suggesting actions related to other aspects of the seasonal cycle or photoperiodic manipulations. Finally, we also show that estrogen production specifically modulates selectivity for behaviorally relevant vocalizations in a specific part of the caudomedial nidopallium. These findings confirm and extend previous conclusions that had been obtained by electrophysiological techniques. This approach provides a new very powerful tool to investigate auditory responsiveness in songbirds and its fast modulation by sex steroids.SIGNIFICANCE STATEMENT Neuroestrogens can acutely modulate sensory processing in a manner similar to neuromodulators. We report that acute estrogen depletion rapidly disrupts auditory processing in large areas of the male starling brain. Effects were larger in March than in December or May/June, lateralized to the left hemisphere and specific to behaviorally relevant stimuli. These findings confirm and extend previous data that identified an acute regulation of auditory neurons in zebra finches by (1) delineating the extent of the brain region affected, (2) confirming its lateralization, and (3) demonstrating that a large part of the auditory brain regions are acutely affected by estrogens. These findings provide a very powerful tool to investigate auditory responsiveness in songbirds and its fast modulation by sex steroids.

Dataset Information

Topography and physiology of ascending streams in the auditory tectothalamic pathway.

Publications

Topography and physiology of ascending streams in the auditory tectothalamic pathway.

Similar Datasets

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