Antidromic Activation Reveals Tonotopically Organized Projections From Primary Auditory Cortex to the Central Nucleus of the Inferior Colliculus in Guinea Pig

Lim, Hubert H.; Anderson, David J.

doi:10.1152/jn.00384.2006

Cited by 53 publications

(75 citation statements)

References 137 publications

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“…The point-to-point tonotopy is a predominant feature of the colliculothalamic and thalamocortical projections as well as of the corticothalamic and cortiocollicular projections (Redies et al, 1989;Saldana et al, 1996;Winer et al, 1999Winer et al, , 2001Bajo and Moore, 2005;Takayanagi and Ojima, 2006;Bajo et al, 2007;Lim and Anderson, 2007). The colliculothalamic, thalamocortical, and corticofugal projections constitute reciprocal connections that link the inferior colliculus, the medial geniculate body, and the auditory cortex in a tonotopic loop [colliculo-thalamo-corticocollicular loop (CTCC loop)].…”

Section: Discussionmentioning

confidence: 99%

“…Both the ascending and descending (corticofugal) pathways are apparently involved in learning-induced or experience-dependent neural plasticity in the auditory system (Suga et al, 2002;Suga and Ma, 2003;Yan, 2003). Anatomical and physiological studies indicate that the ascending and descending projections form multiple feedback loops that are tonotopically organized (Redies et al, 1989;Winer et al, 1999;Winer et al, 2001;Takayanagi and Ojima, 2006;Lim and Anderson, 2007). Do the tonotopic loops allow RF plasticity to be achieved and coordinated at different levels of the auditory system?…”

Section: Introductionmentioning

confidence: 99%

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

Yan²

2007

J. Neurosci.

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The ascending and descending projections of the central auditory system form multiple tonotopic loops. This study specifically examines the tonotopic pathway from the auditory thalamus to the auditory cortex and then to the auditory midbrain in mice. We observed the changes of receptive fields in the central nucleus of the inferior colliculus of the midbrain evoked by focal electrical stimulation of the ventral division of the medial geniculate body of the thalamus. The receptive field of an auditory neuron was characterized by five parameters: the best frequency, minimum threshold, bandwidth, size of receptive field, and average spike number. We found that focal thalamic stimulation changed the parametric values characterizing the recorded collicular receptive fields toward those characterizing the stimulated thalamic receptive fields. Cortical inactivation with muscimol prevented the development of the collicular plasticity induced by focal thalamic stimulation. Our data suggest that the intact colliculo-thalamo-cortico-collicular loops are important for the coordination of sound-guided plasticity in the central auditory system.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Yan²

2007

J. Neurosci.

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“…The main input layer of A1, which approximately corresponds to layer III/IV (Huang and Winer, 2000;Smith and Populin, 2001), was taken as the site with the shortest latency current sink and PSTH response. Details on and results using this method have been presented previously (Lim and Anderson, 2007).…”

Section: Placement Of Probesmentioning

confidence: 99%

Spatially Distinct Functional Output Regions within the Central Nucleus of the Inferior Colliculus: Implications for an Auditory Midbrain Implant

Lim¹,

Anderson²

2007

J. Neurosci.

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The inferior colliculus central nucleus (ICC) has potential as a new site for an auditory prosthesis [i.e., auditory midbrain implant (AMI)]for deaf patients who cannot benefit from cochlear implants (CIs). We have previously shown that ICC stimulation achieves lower thresholds, greater dynamic ranges, and more localized, frequency-specific primary auditory cortex (A1) activation than CI stimulation. However, we also observed that stimulation location along the caudorostral (isofrequency) dimension of the ICC affects thresholds and frequency specificity in A1, suggesting possible differences in functional (output) organization within the ICC. In this study, we electrically stimulated different regions along the isofrequency laminas of the ICC and recorded the corresponding A1 activity in ketamineanesthetized guinea pigs using multisite probes to systematically assess ICC stimulation location effects. Our results indicate that stimulation of more rostral and somewhat ventral regions within an ICC lamina achieves lower thresholds, smaller discriminable level steps, and larger evoked potentials in A1. We also observed longer first spike latencies, which correlated with reduced spiking precision, when stimulating in more caudal and dorsal ICC regions. These findings suggest that at least two spatially distinct functional output regions exist along an ICC lamina: a caudal-dorsal region and a rostral-ventral region. The AMI will be implanted along the tonotopic axis of the ICC to achieve frequency-specific activation. However, stimulation location along the ICC laminas affects response properties that have shown to be important for speech perception performance, and needs to be considered when implanting future AMI patients.

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“…Some IC neurons also display intrinsic conductances that lead to adaptive responses in vitro (Sivaramakrishnan and Oliver, 2001;Bal et al, 2002). Finally, the IC, and its inputs, are subject to centrifugal influences (Zhang et al, 1997;Winer, 2006;Bajo et al, 2007;Lim and Anderson, 2007). Such processes operate over widely varying timescales; it remains unclear which of them contribute to adaptation observed in the IC in vivo, and at what stage in the auditory pathway the adaptation first arises.…”

Section: Introductionmentioning

confidence: 99%

Rapid Neural Adaptation to Sound Level Statistics

Dean

Robinson

Harper

et al. 2008

Journal of Neuroscience

177

168

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Auditory neurons must represent accurately a wide range of sound levels using firing rates that vary over a far narrower range of levels. Recently, we demonstrated that this "dynamic range problem" is lessened by neural adaptation, whereby neurons adjust their inputoutput functions for sound level according to the prevailing distribution of levels. These adjustments in input-output functions increase the accuracy with which levels around those occurring most commonly are coded by the neural population. Here, we examine how quickly this adaptation occurs. We recorded from single neurons in the auditory midbrain during a stimulus that switched repeatedly between two distributions of sound levels differing in mean level. The high-resolution analysis afforded by this stimulus showed that a prominent component of the adaptation occurs rapidly, with an average time constant across neurons of 160 ms after an increase in mean level, much faster than our previous experiments were able to assess. This time course appears to be independent of both the timescale over which sound levels varied and that over which sound level distributions varied, but is related to neural characteristic frequency. We find that adaptation to an increase in mean level occurs more rapidly than to a decrease. Finally, we observe an additional, slow adaptation in some neurons, which occurs over a timescale of tens of seconds. Our findings provide constraints in the search for mechanisms underlying adaptation to sound level. They also have functional implications for the role of adaptation in the representation of natural sounds.

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Antidromic Activation Reveals Tonotopically Organized Projections From Primary Auditory Cortex to the Central Nucleus of the Inferior Colliculus in Guinea Pig

Cited by 53 publications

References 137 publications

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

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

Spatially Distinct Functional Output Regions within the Central Nucleus of the Inferior Colliculus: Implications for an Auditory Midbrain Implant

Rapid Neural Adaptation to Sound Level Statistics

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