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Rogalla MM, Quass GL, Yardley H, Martinez-Voigt C, Ford AN, Wallace G, Dileepkumar D, Corfas G, Apostolides PF. Population coding of auditory space in the dorsal inferior colliculus persists with altered binaural cues. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.13.612867. [PMID: 39314270 PMCID: PMC11419156 DOI: 10.1101/2024.09.13.612867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 09/25/2024]
Abstract
Sound localization is critical for real-world hearing, such as segregating overlapping sound streams. For optimal flexibility, central representations of auditory space must adapt to peripheral changes in binaural cue availability, such as following asymmetric hearing loss in adulthood. However, whether the mature auditory system can reliably encode spatial auditory representations upon abrupt changes in binaural input is unclear. Here we use 2-photon Ca2+ imaging in awake head-fixed mice to determine how the higher-order "shell" layers of the inferior colliculus (IC) encode sound source location in the frontal azimuth, under binaural conditions and after acute monaural hearing loss induced by an ear plug ipsilateral to the imaged hemisphere. Spatial receptive fields were typically broad and not exclusively contralateral: Neurons responded reliably to multiple positions in the contra- and ipsi-lateral hemifields, with preferred positions tiling the entire frontal azimuth. Ear plugging broadened receptive fields and reduced spatial selectivity in a subset of neurons, in agreement with an inhibitory influence of ipsilateral sounds. However ear plugging also enhanced spatial tuning and/or unmasked receptive fields in other neurons, shifting the distribution of preferred angles ipsilaterally with minimal impact on the neuronal population's overall spatial resolution; these effects occurred within 2 hours of ear plugging. Consequently, linear classifiers trained on fluorescence data from control and ear-plugged conditions had similar classification accuracy when tested on held out data from within, but not across hearing conditions. Spatially informative neuronal population codes therefore arise rapidly following monaural hearing loss, in absence of overt experience.
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Affiliation(s)
- Meike M Rogalla
- Kresge Hearing Research Institute & Department of Otolaryngology - Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, United States
| | - Gunnar L Quass
- Kresge Hearing Research Institute & Department of Otolaryngology - Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, United States
| | - Harry Yardley
- Kresge Hearing Research Institute & Department of Otolaryngology - Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, United States
| | - Clara Martinez-Voigt
- Kresge Hearing Research Institute & Department of Otolaryngology - Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, United States
| | - Alexander N Ford
- Kresge Hearing Research Institute & Department of Otolaryngology - Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, United States
| | - Gunseli Wallace
- Kresge Hearing Research Institute & Department of Otolaryngology - Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, United States
| | - Deepak Dileepkumar
- Kresge Hearing Research Institute & Department of Otolaryngology - Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, United States
| | - Gabriel Corfas
- Kresge Hearing Research Institute & Department of Otolaryngology - Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, United States
| | - Pierre F Apostolides
- Kresge Hearing Research Institute & Department of Otolaryngology - Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, United States
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, United States
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Shi K, Quass GL, Rogalla MM, Ford AN, Czarny JE, Apostolides PF. Population coding of time-varying sounds in the nonlemniscal inferior colliculus. J Neurophysiol 2024; 131:842-864. [PMID: 38505907 PMCID: PMC11381119 DOI: 10.1152/jn.00013.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 02/29/2024] [Accepted: 03/15/2024] [Indexed: 03/21/2024] Open
Abstract
The inferior colliculus (IC) of the midbrain is important for complex sound processing, such as discriminating conspecific vocalizations and human speech. The IC's nonlemniscal, dorsal "shell" region is likely important for this process, as neurons in these layers project to higher-order thalamic nuclei that subsequently funnel acoustic signals to the amygdala and nonprimary auditory cortices, forebrain circuits important for vocalization coding in a variety of mammals, including humans. However, the extent to which shell IC neurons transmit acoustic features necessary to discern vocalizations is less clear, owing to the technical difficulty of recording from neurons in the IC's superficial layers via traditional approaches. Here, we use two-photon Ca2+ imaging in mice of either sex to test how shell IC neuron populations encode the rate and depth of amplitude modulation, important sound cues for speech perception. Most shell IC neurons were broadly tuned, with a low neurometric discrimination of amplitude modulation rate; only a subset was highly selective to specific modulation rates. Nevertheless, neural network classifier trained on fluorescence data from shell IC neuron populations accurately classified amplitude modulation rate, and decoding accuracy was only marginally reduced when highly tuned neurons were omitted from training data. Rather, classifier accuracy increased monotonically with the modulation depth of the training data, such that classifiers trained on full-depth modulated sounds had median decoding errors of ∼0.2 octaves. Thus, shell IC neurons may transmit time-varying signals via a population code, with perhaps limited reliance on the discriminative capacity of any individual neuron.NEW & NOTEWORTHY The IC's shell layers originate a "nonlemniscal" pathway important for perceiving vocalization sounds. However, prior studies suggest that individual shell IC neurons are broadly tuned and have high response thresholds, implying a limited reliability of efferent signals. Using Ca2+ imaging, we show that amplitude modulation is accurately represented in the population activity of shell IC neurons. Thus, downstream targets can read out sounds' temporal envelopes from distributed rate codes transmitted by populations of broadly tuned neurons.
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Affiliation(s)
- Kaiwen Shi
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Gunnar L Quass
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Meike M Rogalla
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Alexander N Ford
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Jordyn E Czarny
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States
| | - Pierre F Apostolides
- Department of Otolaryngology-Head & Neck Surgery, Kresge Hearing Research Institute, University of Michigan Medical School, Ann Arbor, Michigan, United States
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, United States
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3
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Shi K, Quass GL, Rogalla MM, Ford AN, Czarny JE, Apostolides PF. Population coding of time-varying sounds in the non-lemniscal Inferior Colliculus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.14.553263. [PMID: 37645904 PMCID: PMC10461978 DOI: 10.1101/2023.08.14.553263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
The inferior colliculus (IC) of the midbrain is important for complex sound processing, such as discriminating conspecific vocalizations and human speech. The IC's non-lemniscal, dorsal "shell" region is likely important for this process, as neurons in these layers project to higher-order thalamic nuclei that subsequently funnel acoustic signals to the amygdala and non-primary auditory cortices; forebrain circuits important for vocalization coding in a variety of mammals, including humans. However, the extent to which shell IC neurons transmit acoustic features necessary to discern vocalizations is less clear, owing to the technical difficulty of recording from neurons in the IC's superficial layers via traditional approaches. Here we use 2-photon Ca2+ imaging in mice of either sex to test how shell IC neuron populations encode the rate and depth of amplitude modulation, important sound cues for speech perception. Most shell IC neurons were broadly tuned, with a low neurometric discrimination of amplitude modulation rate; only a subset were highly selective to specific modulation rates. Nevertheless, neural network classifier trained on fluorescence data from shell IC neuron populations accurately classified amplitude modulation rate, and decoding accuracy was only marginally reduced when highly tuned neurons were omitted from training data. Rather, classifier accuracy increased monotonically with the modulation depth of the training data, such that classifiers trained on full-depth modulated sounds had median decoding errors of ~0.2 octaves. Thus, shell IC neurons may transmit time-varying signals via a population code, with perhaps limited reliance on the discriminative capacity of any individual neuron.
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Affiliation(s)
- Kaiwen Shi
- Kresge Hearing Research Institute, Department of Otolaryngology — Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, MI, 48109
| | - Gunnar L. Quass
- Kresge Hearing Research Institute, Department of Otolaryngology — Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, MI, 48109
| | - Meike M. Rogalla
- Kresge Hearing Research Institute, Department of Otolaryngology — Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, MI, 48109
| | - Alexander N. Ford
- Kresge Hearing Research Institute, Department of Otolaryngology — Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, MI, 48109
| | - Jordyn E. Czarny
- Kresge Hearing Research Institute, Department of Otolaryngology — Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, MI, 48109
| | - Pierre F. Apostolides
- Kresge Hearing Research Institute, Department of Otolaryngology — Head & Neck Surgery, University of Michigan Medical School, Ann Arbor, MI, 48109
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, 48109
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Eftekharian K, Sharifi G, Eftekharian A, Bidari-Zerehpoosh F. Contralateral tinnitus and hearing loss due to a tumor at the region of inferior colliculus: illustrative case. JOURNAL OF NEUROSURGERY: CASE LESSONS 2022; 3:CASE21624. [PMID: 36130546 PMCID: PMC9379620 DOI: 10.3171/case21624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 12/06/2021] [Indexed: 11/06/2022]
Abstract
BACKGROUND
Subjective hearing loss resulting from unilateral lesions of the quadrigeminal cistern region or inferior colliculus is a rare entity.
OBSERVATIONS
The authors presented the case of a 32-year-old man with a history of 4 months of nonpulsatile tinnitus and 1 month of unilateral sensorineural hearing loss. He was otherwise healthy with no significant previous medical history. Intravenous gadolinium contrast magnetic resonance imaging of the head revealed a lesion at the region of the left inferior colliculus suggestive of a lipoma. The tumor was removed, and the patient had no significant hearing change afterward, with an improvement in tinnitus. The histological examination demonstrated the tumor as a fibrolipoma.
LESSONS
Contralateral subjective hearing loss is an uncommon presentation for a lesion in the region of the inferior colliculus.
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Oberle HM, Ford AN, Dileepkumar D, Czarny J, Apostolides PF. Synaptic mechanisms of top-down control in the non-lemniscal inferior colliculus. eLife 2022; 10:e72730. [PMID: 34989674 PMCID: PMC8735864 DOI: 10.7554/elife.72730] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 12/19/2021] [Indexed: 01/05/2023] Open
Abstract
Corticofugal projections to evolutionarily ancient, subcortical structures are ubiquitous across mammalian sensory systems. These 'descending' pathways enable the neocortex to control ascending sensory representations in a predictive or feedback manner, but the underlying cellular mechanisms are poorly understood. Here, we combine optogenetic approaches with in vivo and in vitro patch-clamp electrophysiology to study the projection from mouse auditory cortex to the inferior colliculus (IC), a major descending auditory pathway that controls IC neuron feature selectivity, plasticity, and auditory perceptual learning. Although individual auditory cortico-collicular synapses were generally weak, IC neurons often integrated inputs from multiple corticofugal axons that generated reliable, tonic depolarizations even during prolonged presynaptic activity. Latency measurements in vivo showed that descending signals reach the IC within 30 ms of sound onset, which in IC neurons corresponded to the peak of synaptic depolarizations evoked by short sounds. Activating ascending and descending pathways at latencies expected in vivo caused a NMDA receptor-dependent, supralinear excitatory postsynaptic potential summation, indicating that descending signals can nonlinearly amplify IC neurons' moment-to-moment acoustic responses. Our results shed light upon the synaptic bases of descending sensory control and imply that heterosynaptic cooperativity contributes to the auditory cortico-collicular pathway's role in plasticity and perceptual learning.
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Affiliation(s)
- Hannah M Oberle
- Kresge Hearing Research Institute & Department of Otolaryngology, University of MichiganAnn ArborUnited States
- Neuroscience Graduate Program, University of MichiganAnn ArborUnited States
| | - Alexander N Ford
- Kresge Hearing Research Institute & Department of Otolaryngology, University of MichiganAnn ArborUnited States
| | - Deepak Dileepkumar
- Kresge Hearing Research Institute & Department of Otolaryngology, University of MichiganAnn ArborUnited States
| | - Jordyn Czarny
- Kresge Hearing Research Institute & Department of Otolaryngology, University of MichiganAnn ArborUnited States
| | - Pierre F Apostolides
- Kresge Hearing Research Institute & Department of Otolaryngology, University of MichiganAnn ArborUnited States
- Molecular and Integrative Physiology, University of Michigan Medical SchoolAnn ArborUnited States
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6
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Joris PX, van der Heijden M. Early Binaural Hearing: The Comparison of Temporal Differences at the Two Ears. Annu Rev Neurosci 2019; 42:433-457. [DOI: 10.1146/annurev-neuro-080317-061925] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Many mammals, including humans, are exquisitely sensitive to tiny time differences between sounds at the two ears. These interaural time differences are an important source of information for sound detection, for sound localization in space, and for environmental awareness. Two brainstem circuits are involved in the initial temporal comparisons between the ears, centered on the medial and lateral superior olive. Cells in these nuclei, as well as their afferents, display a large number of striking physiological and anatomical specializations to enable submillisecond sensitivity. As such, they provide an important model system to study temporal processing in the central nervous system. We review the progress that has been made in characterizing these primary binaural circuits as well as the variety of mechanisms that have been proposed to underlie their function.
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Affiliation(s)
- Philip X. Joris
- Department of Neurosciences, KU Leuven, 3000 Leuven, Belgium
| | - Marcel van der Heijden
- Department of Neuroscience, Erasmus University Medical Center, 3000 CA Rotterdam, Netherlands
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Agarwal M, Ulmer JL, Klein AP, Mark LP. Cortical and Subcortical Substrates of Cranial Nerve Function. Semin Ultrasound CT MR 2015; 36:275-90. [PMID: 26233861 DOI: 10.1053/j.sult.2015.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The pivotal role of cranial nerves in a wholesome life experience cannot be overemphasized. Research has opened new avenues to understand cranial nerve function. Classical concept of strict bilateral cortical control of cranial nerves has given way to concepts of hemispheric dominance and hemispheric lateralization. An astute Neuroradiologist should keep abreast of these concepts and help patients and referring physicians by applying this knowledge in reading images. This chapter provides an overview of cranial nerve function and latest concepts pertaining to their cortical and subcortical control.
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Affiliation(s)
- Mohit Agarwal
- Department of Radiology, Medical College of Wisconsin, Milwaukee, WI.
| | - John L Ulmer
- Department of Radiology, Medical College of Wisconsin, Milwaukee, WI
| | - Andrew P Klein
- Department of Radiology, Medical College of Wisconsin, Milwaukee, WI
| | - Leighton P Mark
- Department of Radiology, Medical College of Wisconsin, Milwaukee, WI
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Abstract
Auditory processing can be disrupted by brainstem lesions. It is estimated that approximately 57% of brainstem lesions are associated with auditory disorders. However diseases of the brainstem usually involve many structures, producing a plethora of other neurologic deficits, often relegating "auditory symptoms in the background." Lesions below or within the cochlear nuclei result in ipsilateral auditory-processing abnormalities detected in routine testing; disorders rostral to the cochlear nuclei may result in bilateral abnormalities or may be silent. Lesions in the superior olivary complex and trapezoid body show a mixture of ipsilateral, contralateral, and bilateral abnormalities, whereas lesions of the lateral lemniscus, inferior colliculus, and medial geniculate body do not affect peripheral auditory processing and result in predominantly subtle contralateral abnormalities that may be missed by routine auditory testing. In these cases psychophysical methods developed for the evaluation of central auditory function should be employed (e.g., dichotic listening, interaural time perception, sound localization). The extensive connections of the auditory brainstem nuclei not only are responsible for binaural interaction but also assure redundancy in the system. This redundancy may explain why small brainstem lesions are sometimes clinically silent. Any disorder of the brainstem (e.g., neoplasms, vascular disorders, infections, trauma, demyelinating disorders, neurodegenerative diseases, malformations) that involves the auditory pathways and/or centers may produce hearing abnormalities.
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Hughes LE, Rowe JB, Ghosh BCP, Carlyon RP, Plack CJ, Gockel HE. The binaural masking level difference: cortical correlates persist despite severe brain stem atrophy in progressive supranuclear palsy. J Neurophysiol 2014; 112:3086-94. [PMID: 25231610 PMCID: PMC4269715 DOI: 10.1152/jn.00062.2014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 09/13/2014] [Indexed: 11/22/2022] Open
Abstract
Under binaural listening conditions, the detection of target signals within background masking noise is substantially improved when the interaural phase of the target differs from that of the masker. Neural correlates of this binaural masking level difference (BMLD) have been observed in the inferior colliculus and temporal cortex, but it is not known whether degeneration of the inferior colliculus would result in a reduction of the BMLD in humans. We used magnetoencephalography to examine the BMLD in 13 healthy adults and 13 patients with progressive supranuclear palsy (PSP). PSP is associated with severe atrophy of the upper brain stem, including the inferior colliculus, confirmed by voxel-based morphometry of structural MRI. Stimuli comprised in-phase sinusoidal tones presented to both ears at three levels (high, medium, and low) masked by in-phase noise, which rendered the low-level tone inaudible. Critically, the BMLD was measured using a low-level tone presented in opposite phase across ears, making it audible against the noise. The cortical waveforms from bilateral auditory sources revealed significantly larger N1m peaks for the out-of-phase low-level tone compared with the in-phase low-level tone, for both groups, indicating preservation of early cortical correlates of the BMLD in PSP. In PSP a significant delay was observed in the onset of the N1m deflection and the amplitude of the P2m was reduced, but these differences were not restricted to the BMLD condition. The results demonstrate that although PSP causes subtle auditory deficits, binaural processing can survive the presence of significant damage to the upper brain stem.
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Affiliation(s)
- Laura E Hughes
- Department of Clinical Neurosciences,University of Cambridge, Cambridge, United Kingdom; Cognition and Brain Sciences Unit, Medical Research Council, Cambridge, United Kingdom;
| | - James B Rowe
- Department of Clinical Neurosciences,University of Cambridge, Cambridge, United Kingdom; Cognition and Brain Sciences Unit, Medical Research Council, Cambridge, United Kingdom; Behavioural and Clinical Neuroscience Institute, Cambridge University, Cambridge, United Kingdom
| | - Boyd C P Ghosh
- Wessex Neuroscience Centre, Southampton, United Kingdom; and
| | - Robert P Carlyon
- Cognition and Brain Sciences Unit, Medical Research Council, Cambridge, United Kingdom
| | - Christopher J Plack
- School of Psychological Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | - Hedwig E Gockel
- Cognition and Brain Sciences Unit, Medical Research Council, Cambridge, United Kingdom
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Abstract
The ability to synchronize movement to a steady beat is a fundamental skill underlying musical performance and has been studied for decades as a model of sensorimotor synchronization. Nevertheless, little is known about the neural correlates of individual differences in the ability to synchronize to a beat. In particular, links between auditory-motor synchronization ability and characteristics of the brain's response to sound have not yet been explored. Given direct connections between the inferior colliculus (IC) and subcortical motor structures, we hypothesized that consistency of the neural response to sound within the IC is linked to the ability to tap consistently to a beat. Here, we show that adolescent humans who demonstrate less variability when tapping to a beat have auditory brainstem responses that are less variable as well. One of the sources of this enhanced consistency in subjects who can steadily tap to a beat may be decreased variability in the timing of the response, as these subjects also show greater between-trial phase-locking in the auditory brainstem response. Thus, musical training with a heavy emphasis on synchronization of movement to musical beats may improve auditory neural synchrony, potentially benefiting children with auditory-based language impairments characterized by excessively variable neural responses.
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11
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Gruters KG, Groh JM. Sounds and beyond: multisensory and other non-auditory signals in the inferior colliculus. Front Neural Circuits 2012; 6:96. [PMID: 23248584 PMCID: PMC3518932 DOI: 10.3389/fncir.2012.00096] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 11/15/2012] [Indexed: 11/20/2022] Open
Abstract
The inferior colliculus (IC) is a major processing center situated mid-way along both the ascending and descending auditory pathways of the brain stem. Although it is fundamentally an auditory area, the IC also receives anatomical input from non-auditory sources. Neurophysiological studies corroborate that non-auditory stimuli can modulate auditory processing in the IC and even elicit responses independent of coincident auditory stimulation. In this article, we review anatomical and physiological evidence for multisensory and other non-auditory processing in the IC. Specifically, the contributions of signals related to vision, eye movements and position, somatosensation, and behavioral context to neural activity in the IC will be described. These signals are potentially important for localizing sound sources, attending to salient stimuli, distinguishing environmental from self-generated sounds, and perceiving and generating communication sounds. They suggest that the IC should be thought of as a node in a highly interconnected sensory, motor, and cognitive network dedicated to synthesizing a higher-order auditory percept rather than simply reporting patterns of air pressure detected by the cochlea. We highlight some of the potential pitfalls that can arise from experimental manipulations that may disrupt the normal function of this network, such as the use of anesthesia or the severing of connections from cortical structures that project to the IC. Finally, we note that the presence of these signals in the IC has implications for our understanding not just of the IC but also of the multitude of other regions within and beyond the auditory system that are dependent on signals that pass through the IC. Whatever the IC “hears” would seem to be passed both “upward” to thalamus and thence to auditory cortex and beyond, as well as “downward” via centrifugal connections to earlier areas of the auditory pathway such as the cochlear nucleus.
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Affiliation(s)
- Kurtis G Gruters
- Department of Psychology and Neuroscience, Duke University Durham, NC, USA
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12
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Burke AJ, Hatano M, Kelly JB. Behavioral consequences of unilateral inferior colliculus lesions in the rat. Hear Res 2012; 294:10-20. [PMID: 23010333 DOI: 10.1016/j.heares.2012.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Revised: 08/03/2012] [Accepted: 09/10/2012] [Indexed: 10/27/2022]
Abstract
This study was carried out to determine the behavioral sensitivity to sound of rats with unilateral lesions of inferior colliculus (IC) located ipsilateral or contralateral to the projection pathway from one ear. Absolute thresholds for the detection of a broad-band noise burst were compared for rats with a profound conductive hearing loss in one ear and a lesion placed either ipsilateral or contralateral to the normally functioning ear. The rats were trained to make withdrawal responses to avoid a shock when they detected the presence of a noise burst. Sound pressure level was systematically lowered to obtain psychophysical curves from which absolute thresholds could be determined. Complete lesions of the contralateral IC resulted in substantial elevations in absolute threshold relative to normal whereas equivalent lesions of the ipsilateral IC produced relatively little elevation. In neither case did unilateral destruction of the IC produce a total inability to respond to sound. Contralateral IC lesions that included the dorsal nucleus of the lateral lemniscus (DNLL) produced a significantly greater elevation in behavioral thresholds than complete lesions limited to the IC. The results indicate a predominance of the contralateral over the ipsilateral pathway to IC for maintaining normal thresholds. They also indicate that other pathways that bypass the IC are likely involved in detecting the presence of a sound.
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Affiliation(s)
- Aaron J Burke
- Laboratory of Sensory Neuroscience, Department of Psychology, Carleton University, Ottawa, Canada
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Binaural electric-acoustic interactions recorded from the inferior colliculus of Guinea pigs: the effect of masking observed in the central nucleus of the inferior colliculus. Clin Exp Otorhinolaryngol 2012; 5:122-31. [PMID: 22977708 PMCID: PMC3437412 DOI: 10.3342/ceo.2012.5.3.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 12/12/2011] [Accepted: 01/09/2012] [Indexed: 11/17/2022] Open
Abstract
Objectives To investigate the electric-acoustic interactions within the inferior colliculus of guinea pigs and to observe how central masking appears in invasive neural recordings of the inferior colliculus (IC). Methods A platinum-iridium wire was inserted to scala tympani through cochleostomy with a depth no greater than 1 mm for intracochlear stimulation of electric pulse train. A 5 mm 100 µm, single-shank, thin-film, penetrating recording probe was inserted perpendicularly to the surface of the IC in the coronal plane at an angle of 30-40° off the parasagittal plane with a depth of 2.0-2.5 mm. The peripheral and central masking effects were compared using electric pulse trains to the left ear and acoustic noise to the left ear (ipsilateral) and to the right ear (contralateral). Binaural acoustic stimuli were presented with different time delays and compared with combined electric and acoustic stimuli. The averaged evoked potentials and total spike numbers were measured using thin-film electrodes inserted into the central nucleus of the IC. Results Ipsilateral noise had more obvious effects on the electric response than did contralateral noise. Contralateral noise decreased slightly the response amplitude to the electric pulse train stimuli. Immediately after the onset of acoustic noise, the response pattern changed transiently with shorter response intervals. The effects of contralateral noise were evident at the beginning of the continuous noise. The total spike number decreased when the binaural stimuli reached the IC most simultaneously. Conclusion These results suggest that central masking is quite different from peripheral masking and occurs within the binaural auditory system, and this study showed that the effect of masking could be observed in the IC recording. These effects are more evident and consistent with the psychophysical data from spike number analyses than with the previously reported gross potential data.
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Jutras B, Mayer D, Joannette E, Carrier ME, Chénard G. Assessing the Development of Binaural Integration Ability With the French Dichotic Digit Test: Écoute Dichotique de Chiffres. Am J Audiol 2012; 21:51-9. [DOI: 10.1044/1059-0889(2012/10-0040)] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Purpose
Binaural integration is assessed by dichotic listening tests. This study aimed to assess the development of binaural integration ability using a newly developed dichotic digit test in French.
Method
Twenty-eight children with normal hearing sensitivity and binaural integration capacity, assessed with a dichotic listening word test, participated in the study. The children were divided into 3 groups: nine 6-year-olds, nine 9-year-olds, and ten 12-year-olds. They completed 4 subtests with earphones at normal conversational level. Three subtests consisted of 1, 2, and 3 different digit pairs, respectively, between 1 and 9 that were sent dichotically to the ears. The fourth subtest consisted of 4 digits, but only the 2 middle digits were sent dichotically.
Results
Performance improved significantly as a function of age and decreased with increasing number of digits to be repeated. All groups performed significantly better on digits presented in the right ear than the left ear, and on the digit rather than the word test.
Conclusion
The new French dichotic digit test would be useful in assessing binaural integration in children. The 4 subtests make it suitable for inclusion in a test battery to assess central auditory processing in children and are an alternative, especially the fourth subtest, to the French version of the Staggered Spondaic Word Test (Rudmin & Normandin, 1983).
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Affiliation(s)
- Benoît Jutras
- Université de Montréal and Research Center, CHU Sainte-Justine, Quebec, Canada
| | - David Mayer
- Université de Montréal and Research Center, CHU Sainte-Justine, Quebec, Canada
| | - Élyse Joannette
- Université de Montréal and Research Center, CHU Sainte-Justine, Quebec, Canada
| | - Marie-Eve Carrier
- Université de Montréal and Research Center, CHU Sainte-Justine, Quebec, Canada
| | - Gwendoline Chénard
- Université de Montréal and Research Center, CHU Sainte-Justine, Quebec, Canada
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Dugger BN, Tu M, Murray ME, Dickson DW. Disease specificity and pathologic progression of tau pathology in brainstem nuclei of Alzheimer's disease and progressive supranuclear palsy. Neurosci Lett 2011; 491:122-6. [PMID: 21236314 DOI: 10.1016/j.neulet.2011.01.020] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2010] [Revised: 01/04/2011] [Accepted: 01/06/2011] [Indexed: 10/18/2022]
Abstract
Previous studies have shown tau pathology in the inferior colliculus (IC) and superior colliculus (SC) in Alzheimer's disease (AD); however, it has not been compared to other tauopathies, such as progressive supranuclear palsy (PSP), or characterized with respect to progression of tau pathology in AD. The main purpose of this study was to investigate frequency, neuroanatomical selectivity and disease specificity of tau pathology in visual and auditory nuclei (SC and lateral geniculate body (LGB); IC and medial geniculate body (MGB), respectively). We measured phospho-tau burden with immunohistochemistry and image analysis in 26 cases of AD, 37 PSP and 11 normal controls. Tau burden was also assessed in two unrelated brainstem nuclei (substantia nigra (SN) and pedunculopontine nucleus (PPN)) of the same cases. We found tau burden to be greater in the SC of PSP compared to AD and controls. Conversely, tau burden was greater in the IC of AD compared to PSP and controls. The MGB and LGB had sparse tau pathology in both AD and PSP. This disease selectivity parallels known deficits in visual reflexes in PSP and auditory reflexes in AD. Tau burden was greater in the SC, IC, and PPN in both PSP and AD compared to controls, and greater in the SN in PSP compared to AD and controls. Although present at early Braak neurofibrillary tangle stages, the SC, IC, PPN and SN did not accumulate tau consistently until later stages. These findings support a concept of tau pathology affecting the brainstem at mid-to-late stage AD.
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Montibeller GR, Stan AC, Krauss JK, Nakamura M. Calcifying pseudoneoplasm of the inferior colliculus: an unusual location for a rare tumor: case report. Neurosurgery 2009; 65:E1005-6; discussion E1006. [PMID: 19834389 DOI: 10.1227/01.neu.0000351770.69874.15] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Quadrigeminal plate lesions are rare and usually present with a silent clinical course. Tumors, vascular lesions, inflammatory and infectious processes have been described in this region. Calcifying pseudoneoplasms, also reported as fibro-osseous lesions, cerebral calculi, and brain stones, are unusual lesions in the central nervous system. They can be revealed by cranial radiography, computed tomography, and magnetic resonance imaging as calcified masses and should be differentiated from neoplastic, inflammatory, and vascular lesions. To the best of our knowledge, the occurrence of a calcifying pseudoneoplasm located at the quadrigeminal plate has not yet been reported. CLINICAL PRESENTATION A 67-year-old woman with a 6-month history of several daily attacks of dizziness presented to our service. Magnetic resonance imaging studies revealed a tumor in the right inferior colliculus. This lesion was isointense on T1-weighted imaging, hypointense on T2-weighted imaging, and homogeneously enhanced with contrast. INTERVENTION The lesion at the quadrigeminal plate was completely removed, and the patient was successfully treated without any new neurological deficit. At the time of follow-up, all preoperative symptoms had resolved. CONCLUSION We report the first case of a calcifying pseudoneoplasm of the inferior colliculus. Complete surgical removal of this type of tumor is feasible. We propose surgical treatment in this location when this tumor becomes symptomatic.
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Paiement P, Champoux F, Bacon BA, Mercier C, Gagné JP, Lassonde M, Lepore F. Auditory pathways fail to re-establish normal cortical activation patterns in response to binaural stimulation following a unilateral lesion of the inferior colliculus. Neurocase 2009; 15:89-96. [PMID: 19153871 DOI: 10.1080/13554790802620566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The aim of this study was to investigate cortical activation in response to binaural stimulus presentations in an individual (FX) with a circumscribed traumatic hemorrhagic lesion of the right inferior colliculus. FX and control subjects were exposed to complex sounds while undergoing a functional magnetic resonance imaging assessment. Whereas normally-hearing individuals show well-balanced bilateral activation patterns in response to binaural auditory stimulation, the same stimuli produced stronger activation in the left hemisphere in FX. Combined with previous data, these findings reinforce the notion that the inferior colliculus is an essential auditory relay and that its loss cannot be significantly compensated.
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Affiliation(s)
- Philippe Paiement
- Department of Psychology, University of Montreal, Montreal, Quebec, Canada
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