Modulation of the Receptive Fields of Midbrain Neurons Elicited by Thalamic Electrical Stimulation through Corticofugal Feedback

Wu, Yamin; Yan, Jun

doi:10.1523/jneurosci.1320-07.2007

Cited by 48 publications

(38 citation statements)

References 62 publications

(76 reference statements)

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“…Indeed, studies using iontophoresis to block inhibition within the IC have shown that the removal of either GABAergic or glycinergic inhibition can change the spectral (Vater et al, 1992;Yang et al, 1992;Palombi and Caspary, 1996;LeBeau et al, 2001) and temporal response properties of individual neurons (Koch and Grothe, 1998;Caspary et al, 2002), and can also result in the weakening of inhibitory regions in the STRF (Andoni et al, 2007). A previous study has shown that similar changes in the response properties of IC neurons can also be observed after manipulation of activity in the thalamus and cortex, suggesting that some of the intensity-dependent changes in STRFs that we observe in the IC may also reflect changes in other brain regions (Wu and Yan, 2007).…”

Section: Relation To Previous Studies Of Intensity-dependent Nonlineasupporting

confidence: 66%

Dynamic Spectrotemporal Feature Selectivity in the Auditory Midbrain

Lesica

Grothe²

2008

J. Neurosci.

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The transformation of auditory information from the cochlea to the cortex is a highly nonlinear process. Studies using tone stimuli have revealed that changes in even the most basic parameters of the auditory stimulus can alter neural response properties; for example, a change in stimulus intensity can cause a shift in a neuron's preferred frequency. However, it is not yet clear how such nonlinearities contribute to the processing of spectrotemporal features in complex sounds. Here, we use spectrotemporal receptive fields (STRFs) to characterize the effects of stimulus intensity on feature selectivity in the mammalian inferior colliculus (IC). At low intensities, we find that STRFs are relatively simple, typically consisting of a single excitatory region, indicating that the neural response is simply a reflection of the stimulus amplitude at the preferred frequency. In contrast, we find that STRFs at high intensities typically consist of a combination of an excitatory region and one or more inhibitory regions, often in a spectrotemporally inseparable arrangement, indicating selectivity for complex auditory features. We show that a linear-nonlinear model with the appropriate STRF can predict neural responses to stimuli with a fixed intensity, and we demonstrate that a simple extension of the model with an intensity-dependent STRF can predict responses to stimuli with varying intensity. These results illustrate the complexity of auditory feature selectivity in the IC, but also provide encouraging evidence that the prediction of nonlinear responses to complex stimuli is a tractable problem.

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Section: Relation To Previous Studies Of Intensity-dependent Nonlineasupporting

confidence: 66%

Dynamic Spectrotemporal Feature Selectivity in the Auditory Midbrain

Lesica

Grothe²

2008

J. Neurosci.

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“…Thus, for this class, the excitatory IC inputs to MGB neurons are inhibited by convergent inputs from neighboring channels, perhaps enabling a sharpening of the receptive field (27). Bartlett and Smith (11,12) found a similar class of mixed inputs, which were further segregated based on the temporal sequence of excitation and inhibition.…”

Section: Discussionmentioning

confidence: 95%

Topography and physiology of ascending streams in the auditory tectothalamic pathway

Lee

Sherman

2009

Proc. Natl. Acad. Sci. U.S.A.

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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.A uditory information ascends from the sensory periphery along parallel pathways, synapsing in the inferior colliculus (IC) and then the medial geniculate body (MGB) en route to the cortex. At the tectothalamic synapse, the IC central nucleus (ICc) reliably transmits excitatory and inhibitory information to the ventral division of the MGB (MGBv) (1, 2). However, the role of the tectothalamic projections from the lateral (ICl), dorsal (ICd), and caudal cortices of the IC [collectively referred to here as the shell region (ICs)] to the dorsal (MGBd) and medial (MGBm) divisions of the MGB are less well understood and may serve either a driving or modulatory role, or both (3, 4). Based on the presence or absence of a cortical layer 5 input, these MGB divisions have been termed first order (MGBv; no layer 5 input) or higher order (MGBd and MGBm; having a layer 5 input), and it is thought that the higher order nuclei play an important role as part of corticothalamocortical circuits (5-7). Previous work in the somatosensory thalamus suggests that the principal driving input to higher order thalamic nuclei arises from this layer 5 input (8). In the auditory system, the anatomical substrates supporting such a driving corticothalamic pathway from layer 5 are also present (6, 7). However, if the cortex provides the principal driving input to the higher order nuclei of the MGB, what is the role of the ascending tectal inputs?Another issue of interest is the observation that auditory tectothalamic inputs are composed of both excitatory and inhibitory pathways. Anatomical studies suggest that the inhibitory feedforward projections to the MGB arise throughout the IC (9, 10), and physiological investigations find several distinct classes of excitatory and inhibitory inputs (11-13). However, the topographic organization of excitatory and inhibitory inputs in the tectothalamic pathways is largely undefined. Are these pathways organized similarly across collicular and thalamic nuclei? Do they align topographically with the anisotropi...

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“…Forty-one female C57 mice (Charles River Laboratories) aged 4 -7 weeks and weighing 14.6 -24.0 g were used in this study. Animal preparation, acoustic stimulation, electrical stimulation of the auditory cortex, recording of action potentials and data processing were mostly the same as those described previously (Yan and Ehret, 2002;Jafari et al, 2007;Wu and Yan, 2007). All protocols and procedures were in accordance with the Canadian Council on Animal Care and approved by the Animal Care Committee of the University of Calgary (protocol number: M04044).…”

Section: Methodsmentioning

confidence: 99%

Corticofugal Modulation of Initial Sound Processing in the Brain

Luo¹,

Wang²,

Kashani³

et al. 2008

J. Neurosci.

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121

116

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The brain selectively extracts the most relevant information in top-down processing manner. Does the corticofugal system, a "back projection system," constitute the neural basis of such top-down selection? Here, we show how focal activation of the auditory cortex with 500 nA electrical pulses influences the auditory information processing in the cochlear nucleus (CN) that receives almost unprocessed information directly from the ear. We found that cortical activation increased the response magnitudes and shortened response latencies of physiologically matched CN neurons, whereas decreased response magnitudes and lengthened response latencies of unmatched CN neurons. In addition, cortical activation shifted the frequency tunings of unmatched CN neurons toward those of the activated cortical neurons. Our data suggest that cortical activation selectively enhances the neural processing of particular auditory information and attenuates others at the first processing level in the brain based on sound frequencies encoded in the auditory cortex. The auditory cortex apparently implements a long-range feedback mechanism to select or filter incoming signals from the ear.

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Modulation of the Receptive Fields of Midbrain Neurons Elicited by Thalamic Electrical Stimulation through Corticofugal Feedback

Cited by 48 publications

References 62 publications

Dynamic Spectrotemporal Feature Selectivity in the Auditory Midbrain

Dynamic Spectrotemporal Feature Selectivity in the Auditory Midbrain

Topography and physiology of ascending streams in the auditory tectothalamic pathway

Corticofugal Modulation of Initial Sound Processing in the Brain

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