A Discontinuous Tonotopic Organization in the Inferior Colliculus of the Rat

Malmierca, Manuel S.; Izquierdo, Marco A.; Cristaudo, Salvatore; Hernández, Ó.; Pérez-González, David; Covey, Ellen; Oliver, Douglas L.

doi:10.1523/jneurosci.0238-08.2008

Cited by 143 publications

(147 citation statements)

References 47 publications

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“…rat (Malmierca et al 2008). For all of the stimuli, our bandwidths of 0.15 octave SD for 10 kHz and 0.11 octave SD for 20 kHz were much smaller than the expected bandwidths of each isofrequency lamina (i.e., 0.28 or 0.29 octave) and support the conclusion that the BFmatched sites were within a given 10-or 20-kHz lamina.…”

Section: Acoustic Stimulisupporting

confidence: 68%

Response features across the auditory midbrain reveal an organization consistent with a dual lemniscal pathway

Straka

Schmitz

Lim

2014

Journal of Neurophysiology

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Straka MM, Schmitz S, Lim HH. Response features across the auditory midbrain reveal an organization consistent with a dual lemniscal pathway. J Neurophysiol 112: 981-998, 2014. First published May 14, 2014 doi:10.1152/jn.00008.2014.-The central auditory system has traditionally been divided into lemniscal and nonlemniscal pathways leading from the midbrain through the thalamus to the cortex. This view has served as an organizing principle for studying, modeling, and understanding the encoding of sound within the brain. However, there is evidence that the lemniscal pathway could be further divided into at least two subpathways, each potentially coding for sound in different ways. We investigated whether such an interpretation is supported by the spatial distribution of response features in the central nucleus of the inferior colliculus (ICC), the part of the auditory midbrain assigned to the lemniscal pathway. We recorded responses to pure tone stimuli in the ICC of ketamine-xylazineanesthetized guinea pigs and used three-dimensional brain reconstruction techniques to map the location of the recording sites. Compared with neurons in caudal-and-medial regions within an isofrequency lamina of the ICC, neurons in rostral-and-lateral regions responded with shorter first-spike latencies with less spiking jitter, shorter durations of spiking responses, a higher proportion of spikes occurring near the onset of the stimulus, lower thresholds, and larger local field potentials with shorter latencies. Further analysis revealed two distinct clusters of response features located in either the caudal-and-medial or the rostral-and-lateral parts of the isofrequency laminae of the ICC. Thus we report substantial differences in coding properties in two regions of the ICC that are consistent with the hypothesis that the lemniscal pathway is made up of at least two distinct subpathways from the midbrain up to the cortex. functional organization; inferior colliculus; lemniscal; medial geniculate; auditory cortex THE ASCENDING AUDITORY PATHWAY has traditionally been separated into two pathways, the lemniscal "core" pathway and the nonlemniscal pathway (Andersen et al. 1980;Ehret and Romand 1997;Rauschecker and Romanski 2011;Rouiller 1997). The lemniscal pathway includes neurons in the central nucleus of the inferior colliculus (ICC), the ventral division of the medial geniculate body (MGV), and core auditory cortex regions (ACC). Neurons within the lemniscal pathway are tonotopically organized and primarily code for auditory information. Within the ICC and MGV, the tonotopicity derives from an arrangement of isofrequency laminae, where each lamina is a two-dimensional sheet formed by the dendritic arbors of neurons that respond optimally to similar "best frequencies" (Cetas et al. 2001;Imig and Morel 1985;Malmierca et al. 1993;Winer and Schreiner 2005). In contrast, neurons within the nonlemniscal pathway include regions outside of ICC, MGV, and ACC, have poor or no tonotopic organization, code for multimodal information, and are tho...

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Section: Acoustic Stimulisupporting

confidence: 68%

Response features across the auditory midbrain reveal an organization consistent with a dual lemniscal pathway

Straka

Schmitz

Lim

2014

Journal of Neurophysiology

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“…A tungsten electrode (1-2 M⍀) (Merrill and Ainsworth, 1972) was used to record extracellular single-unit responses. Stimuli were delivered through a sealed acoustic system (Rees, 1990;Malmierca et al, 2005Malmierca et al, , 2008 using two electrostatic loudspeakers (EC1, Tucker-Davis Technologies) driven by two ED1 (Tucker-Davis Technologies) modules. All stimuli were generated and delivered to the contralateral ear using TDT System 2 (Tucker-Davis Technologies) hardware and custom software (Malmierca et al, 2009).…”

Section: Methodsmentioning

confidence: 99%

“…The highest frequency produced by this system was limited to 40 kHz. The second and third harmonic components in the signal were Ն40 dB below the level of the fundamental at the highest output level (Malmierca et al, 2008(Malmierca et al, , 2009. Action potentials were recorded with a BIOAMP amplifier (Tucker-Davis Technologies), the 10ϫ output of which was further amplified and bandpass filtered (PC1, Tucker-Davis Technologies; between 0.5 and 3 kHz) before passing through a spike discriminator (SD1, Tucker-Davis Technologies).…”

Section: Methodsmentioning

confidence: 99%

“…Stimuli to measure FRAs in single units were 75 ms duration pure tones (5 ms rise/fall time). Frequency and intensity of the stimulus were varied randomly (0 -100 dB attenuation in 5 or 10 dB levels and in 25 frequency steps from 0.1 to 40 kHz, to cover approximately two to three octaves above and below the best frequency Malmierca et al, 2008).…”

Section: Methodsmentioning

confidence: 99%

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Effect of Auditory Cortex Deactivation on Stimulus-Specific Adaptation in the Medial Geniculate Body

Antunes¹,

Malmierca²

2011

J. Neurosci.

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An animal's survival may depend on detecting new events or objects in its environment, and it is likely that the brain has evolved specific mechanisms to detect such changes. In sensory systems, neurons often exhibit stimulus-specific adaptation (SSA) whereby they adapt to frequently occurring stimuli, but resume firing when "surprised" by rare or new ones. In the auditory system, SSA has been identified in the midbrain, thalamus, and auditory cortex (AC). It has been proposed that the SSA observed subcortically originates in the AC as a higher-order property that is transmitted to the subcortical nuclei via corticofugal pathways. Here we report that SSA in the auditory thalamus of the rat remains intact when the AC is deactivated by cooling, thus demonstrating that the AC is not necessary for the generation of SSA in the thalamus. The AC does, however, modulate the responses of thalamic neurons in a way that strongly indicates a gain modulation mechanism. The changes imposed by the AC in thalamic neurons depend on the level of SSA that they exhibit.

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“…The different types of cells represented within the central nucleus (each characterised by distinct electrophysiological properties and discharge patterns) enable highly precise representation of complex auditory signals (Peruzzi et al, 2000). Animal studies have shown that the central nucleus receives ascending (bottomeup) projections from various brainstem nuclei (summarised in Baumann et al, 2011) e including the dorsal and posterior ventral cochlear nucleus (Warr, 1969;Oliver, 1984) e and is tonotopically organised along the dorsoeventral axis (Schreiner and Langner, 1997;Malmierca et al, 2008;Baumann et al, 2011;Cheung et al, 2012). Evidence for a tonotopic organisation within the central nucleus has been found in humans as well, where high-resolution functional magnetic resonance imaging has identified a dorsolateral-to-ventromedial gradient preferentially responding to low-to-high frequencies (De Martino et al, 2013).…”

Section: Inferior Colliculusmentioning

confidence: 99%

Subcortical processing in auditory communication

2015

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a b s t r a c tThe voice is a rich source of information, which the human brain has evolved to decode and interpret. Empirical observations have shown that the human auditory system is especially sensitive to the human voice, and that activity within the voice-sensitive regions of the primary and secondary auditory cortex is modulated by the emotional quality of the vocal signal, and may therefore subserve, with frontal regions, the cognitive ability to correctly identify the speaker's affective state. So far, the network involved in the processing of vocal affect has been mainly characterised at the cortical level. However, anatomical and functional evidence suggests that acoustic information relevant to the affective quality of the auditory signal might be processed prior to the auditory cortex.Here we review the animal and human literature on the main subcortical structures along the auditory pathway, and propose a model whereby the distinction between different types of vocal affect in auditory communication begins at very early stages of auditory processing, and relies on the analysis of individual acoustic features of the sound signal. We further suggest that this early feature-based decoding occurs at a subcortical level along the ascending auditory pathway, and provides a preliminary coarse (but fast) characterisation of the affective quality of the auditory signal before the more refined (but slower) cortical processing is completed.

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A Discontinuous Tonotopic Organization in the Inferior Colliculus of the Rat

Cited by 143 publications

References 47 publications

Response features across the auditory midbrain reveal an organization consistent with a dual lemniscal pathway

Response features across the auditory midbrain reveal an organization consistent with a dual lemniscal pathway

Effect of Auditory Cortex Deactivation on Stimulus-Specific Adaptation in the Medial Geniculate Body

Subcortical processing in auditory communication

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