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The Journal of Neuroscience : the... Aug 2021Hearing in noise is a problem often assumed to depend on encoding of energy level by channels tuned to target frequencies, but few studies have tested this hypothesis....
Hearing in noise is a problem often assumed to depend on encoding of energy level by channels tuned to target frequencies, but few studies have tested this hypothesis. The present study examined neural correlates of behavioral tone-in-noise (TIN) detection in budgerigars (, either sex), a parakeet species with human-like behavioral sensitivity to many simple and complex sounds. Behavioral sensitivity to tones in band-limited noise was assessed using operant-conditioning procedures. Neural recordings were made in awake animals from midbrain-level neurons in the inferior colliculus, the first processing stage of the ascending auditory pathway with pronounced rate-based encoding of stimulus amplitude modulation. Budgerigar TIN detection thresholds were similar to human thresholds across the full range of frequencies (0.5-4 kHz) and noise levels (45-85 dB SPL) tested. Also as in humans, thresholds were minimally affected by a challenging roving-level condition with random variation in background-noise level. Many midbrain neurons showed a decreasing response rate as TIN signal-to-noise ratio (SNR) was increased by elevating the tone level, a pattern attributable to amplitude-modulation tuning in these cells and the fact that higher SNR tone-plus-noise stimuli have flatter amplitude envelopes. TIN thresholds of individual neurons were as sensitive as behavioral thresholds under most conditions, perhaps surprisingly even when the unit's characteristic frequency was tuned an octave or more away from the test frequency. A model that combined responses of two cell types enhanced TIN sensitivity in the roving-level condition. These results highlight the importance of midbrain-level envelope encoding and off-frequency neural channels for hearing in noise. Detection of target sounds in noise is often assumed to depend on energy-level encoding by neural processing channels tuned to the target frequency. In contrast, we found that tone-in-noise sensitivity in budgerigars was often greatest in midbrain neurons not tuned to the test frequency, underscoring the potential importance of off-frequency channels for perception. Furthermore, the results highlight the importance of envelope processing for hearing in noise, especially under challenging conditions with random variation in background noise level over time.
Topics: Acoustic Stimulation; Animals; Auditory Pathways; Auditory Threshold; Brain Mapping; Conditioning, Operant; Cues; Electrodes, Implanted; Female; Inferior Colliculi; Male; Melopsittacus; Neurons; Noise; Pitch Perception; Signal-To-Noise Ratio
PubMed: 34266898
DOI: 10.1523/JNEUROSCI.3103-20.2021 -
Scientific Reports Aug 2015Infrared neural stimulation (INS) has been proposed as an alternative method to electrical stimulation because of its spatial selective stimulation. Independent of the...
Infrared neural stimulation (INS) has been proposed as an alternative method to electrical stimulation because of its spatial selective stimulation. Independent of the mechanism for INS, to translate the method into a device it is important to determine the energy for stimulation required at the target structure. Custom-designed, flat and angle polished fibers, were used to deliver the photons. By rotating the angle polished fibers, the orientation of the radiation beam in the cochlea could be changed. INS-evoked compound action potentials and single unit responses in the central nucleus of the inferior colliculus (ICC) were recorded. X-ray computed tomography was used to determine the orientation of the optical fiber. Maximum responses were observed when the radiation beam was directed towards the spiral ganglion neurons (SGNs), whereas little responses were seen when the beam was directed towards the basilar membrane. The radiant exposure required at the SGNs to evoke compound action potentials (CAPs) or ICC responses was on average 18.9 ± 12.2 or 10.3 ± 4.9 mJ/cm(2), respectively. For cochlear INS it has been debated whether the radiation directly stimulates the SGNs or evokes a photoacoustic effect. The results support the view that a direct interaction between neurons and radiation dominates the response to INS.
Topics: Animals; Cochlear Implants; Deep Brain Stimulation; Dose-Response Relationship, Radiation; Equipment Design; Equipment Failure Analysis; Evoked Potentials, Auditory, Brain Stem; Female; Fiber Optic Technology; Guinea Pigs; Inferior Colliculi; Infrared Rays; Lighting; Male; Neurons; Photic Stimulation; Radiation Dosage
PubMed: 26305106
DOI: 10.1038/srep13273 -
The Journal of Comparative Neurology Dec 2017The complex neuroanatomical connections of the inferior colliculus (IC) and its major subdivisions offer a juxtaposition of segregated processing streams with distinct...
The complex neuroanatomical connections of the inferior colliculus (IC) and its major subdivisions offer a juxtaposition of segregated processing streams with distinct organizational features. While the tonotopically layered central nucleus is well-documented, less is known about functional compartments in the neighboring lateral cortex (LCIC). In addition to a laminar framework, LCIC afferent-efferent patterns suggest a multimodal mosaic, consisting of a patchy modular network with surrounding extramodular domains. This study utilizes several neurochemical markers that reveal an emerging LCIC modular-extramodular microarchitecture. In newborn and post-hearing C57BL/6J and CBA/CaJ mice, histochemical and immunocytochemical stains were performed for acetylcholinesterase (AChE), nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d), glutamic acid decarboxylase (GAD), cytochrome oxidase (CO), and calretinin (CR). Discontinuous layer 2 modules are positive for AChE, NADPH-d, GAD, and CO throughout the rostrocaudal LCIC. While not readily apparent at birth, discrete cell clusters emerge over the first postnatal week, yielding an identifiable modular network prior to hearing onset. Modular boundaries continue to become increasingly distinct with age, as surrounding extramodular fields remain largely negative for each marker. Alignment of modular markers in serial sections suggests each highlight the same periodic patchy network throughout the nascent LCIC. In contrast, CR patterns appear complementary, preferentially staining extramodular LCIC zones. Double-labeling experiments confirm that NADPH-d, the most consistent developmental modular marker, and CR label separate, nonoverlapping LCIC compartments. Determining how this emerging modularity may align with similar LCIC patch-matrix-like Eph/ephrin guidance patterns, and how each interface with, and potentially influence developing multimodal LCIC projection configurations is discussed.
Topics: Acetylcholinesterase; Animals; Animals, Newborn; Auditory Pathways; Calbindin 2; Electron Transport Complex IV; Female; Glutamate Decarboxylase; Inferior Colliculi; Male; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; NADPH Dehydrogenase
PubMed: 28786102
DOI: 10.1002/cne.24300 -
Neurobiology of Aging Sep 2021The age-related loss of GABA in the inferior colliculus (IC) likely plays a role in the development of age-related hearing loss. Perineuronal nets (PNs), specialized...
The age-related loss of GABA in the inferior colliculus (IC) likely plays a role in the development of age-related hearing loss. Perineuronal nets (PNs), specialized aggregates of extracellular matrix, increase with age in the IC. PNs, associated with GABAergic neurotransmission, can stabilize synapses and inhibit structural plasticity. We sought to determine whether PN expression increased on GABAergic and non-GABAergic IC cells that project to the medial geniculate body (MG). We used retrograde tract-tracing in combination with immunohistochemistry for glutamic acid decarboxylase and Wisteria floribunda agglutinin across three age groups of Fischer Brown Norway rats. Results demonstrate that PNs increase with age on lemniscal and non-lemniscal IC-MG cells, however two key differences exist. First, PNs increased on non-lemniscal IC-MG cells during middle-age, but not until old age on lemniscal IC-MG cells. Second, increases of PNs on lemniscal IC-MG cells occurred on non-GABAergic cells rather than on GABAergic cells. These results suggest that synaptic stabilization and reduced plasticity likely occur at different ages on a subset of the IC-MG pathway.
Topics: Aging; Animals; Auditory Pathways; GABAergic Neurons; Geniculate Bodies; Glutamate Decarboxylase; Hearing Loss; Inferior Colliculi; Male; Nerve Net; Plant Lectins; Rats; Receptors, N-Acetylglucosamine; Thalamus
PubMed: 34004491
DOI: 10.1016/j.neurobiolaging.2021.04.001 -
ELife Jan 2020The inferior colliculus (IC) is the major midbrain auditory integration center, where virtually all ascending auditory inputs converge. Although the IC has been...
The inferior colliculus (IC) is the major midbrain auditory integration center, where virtually all ascending auditory inputs converge. Although the IC has been extensively studied for sound processing, little is known about the neural activity of the IC in moving subjects, as frequently happens in natural hearing conditions. Here, by recording neural activity in walking mice, we show that the activity of IC neurons is strongly modulated by locomotion, even in the absence of sound stimuli. Similar modulation was also found in hearing-impaired mice, demonstrating that IC neurons receive non-auditory, locomotion-related neural signals. Sound-evoked activity was attenuated during locomotion, and this attenuation increased frequency selectivity across the neuronal population, while maintaining preferred frequencies. Our results suggest that during behavior, integrating movement-related and auditory information is an essential aspect of sound processing in the IC.
Topics: Animals; Auditory Pathways; Auditory Perception; Disease Models, Animal; Hearing Loss; Inferior Colliculi; Locomotion; Mice
PubMed: 31987070
DOI: 10.7554/eLife.52228 -
Hearing Research Oct 2015The inferior colliculus (IC) receives ascending and descending information from several convergent neural sources. As such, exploring the neural pathways that converge...
The inferior colliculus (IC) receives ascending and descending information from several convergent neural sources. As such, exploring the neural pathways that converge in the IC is crucial to uncovering their multi-varied roles in the integration of auditory and other sensory information. Among these convergent pathways, the IC commissural connections represent an important route for the integration of bilateral information in the auditory system. Here, we describe the preparation and validation of a novel in vitro slice preparation for examining the functional topography and synaptic properties of the commissural and intrinsic projections in the IC of the mouse. This preparation, in combination with modern genetic approaches in the mouse, enables the specific examination of these pathways, which potentially can reveal cell-type specific processing channels in the auditory midbrain.
Topics: Animals; Auditory Cortex; Auditory Pathways; Brain Mapping; Electrophysiology; Hearing; Immunohistochemistry; In Vitro Techniques; Inferior Colliculi; Lasers; Light; Mesencephalon; Mice; Mice, Transgenic; Neurons; Patch-Clamp Techniques; gamma-Aminobutyric Acid
PubMed: 26319767
DOI: 10.1016/j.heares.2015.08.011 -
Neuroscience Jun 2008The inferior colliculus is a major relay nucleus in the ascending auditory pathways that receives multiple glutamatergic inputs. Vesicular glutamate transporters 1 and 2...
The inferior colliculus is a major relay nucleus in the ascending auditory pathways that receives multiple glutamatergic inputs. Vesicular glutamate transporters 1 and 2 (VGLUT1, VGLUT2) most often have complementary non-overlapping distributions and can be used to differentiate glutamatergic inputs. The present study therefore examined co-immunolabeling of VGLUT1 and VGLUT2 in three divisions of the rat inferior colliculus. Additional co-immunolabeling of microtubule-associated protein 2 and neuronal class III beta-tubulin provided visualization of neuronal soma and processes and allowed identification of axo-somatic versus axo-dendritic contacts. Results showed numerous VGLUT1 and 2 immunolabeled terminals in the central nucleus, lateral cortex and dorsal cortex. In all three divisions there was little to no co-containment of the two vesicular glutamate transporters indicating a complementary distribution. VGLUT1 made predominantly axo-dendritic connections in the neuropil, while VGLUT2 had many axo-somatic contacts in addition to axo-dendritic contacts. VGLUT2 immunolabeled terminals were numerous on the soma and proximal dendrites of many medium-to-large and large neurons in the central nucleus and medium to large neurons in the dorsal cortex. There were more VGLUT2 terminals than VGLUT1 in all divisions and more VGLUT2 terminals in dorsal and lateral cortices than in the central nucleus. This study shows that VGLUT1 and VGLUT2 differentiate complementary patterns of glutamatergic inputs into the central nucleus, lateral and dorsal cortex of the inferior colliculus with VGLUT1 endings predominantly on the dendrites and VGLUT2 on both dendrites and somas.
Topics: Animals; Auditory Pathways; Inferior Colliculi; Microtubule-Associated Proteins; Neurons; Rats; Rats, Sprague-Dawley; Tubulin; Vesicular Glutamate Transport Protein 1; Vesicular Glutamate Transport Protein 2
PubMed: 18436385
DOI: 10.1016/j.neuroscience.2008.03.036 -
PeerJ 2022Three new species of are described from the continental shelf of the Campos Basin, southwest Atlantic, Brazil. differs from all other species in the presence of two...
Three new species of are described from the continental shelf of the Campos Basin, southwest Atlantic, Brazil. differs from all other species in the presence of two anterior testes, slender spicules with enlarged proximal ends, 7-11 pre-cloacal papilliform supplements, and females with a pair of constriction structures, one on each branch of the ovary. shows sexual dimorphism in the size of the amphidial fovea, which occupies 100% of the diameter of the corresponding area in the male; the buccal cavity provided with five teeth and a slightly cuticularized cuticular ring. has four longitudinal-lateral rows of glands associated with small pores, one seta and three pores small pre-cloacal, and the gubernaculum has a triangular base. An amendment to the diagnosis of the genus is proposed, where the number of teeth was modified.
Topics: Animals; Female; Male; Nematoda; Chromadorea; Brazil; Dietary Supplements; Inferior Colliculi
PubMed: 35287342
DOI: 10.7717/peerj.12734 -
Human Brain Mapping Feb 2021Auditory steady-state responses (ASSRs) are evoked brain responses to modulated or repetitive acoustic stimuli. Investigating the underlying neural generators of ASSRs...
Auditory steady-state responses (ASSRs) are evoked brain responses to modulated or repetitive acoustic stimuli. Investigating the underlying neural generators of ASSRs is important to gain in-depth insight into the mechanisms of auditory temporal processing. The aim of this study is to reconstruct an extensive range of neural generators, that is, cortical and subcortical, as well as primary and non-primary ones. This extensive overview of neural generators provides an appropriate basis for studying functional connectivity. To this end, a minimum-norm imaging (MNI) technique is employed. We also present a novel extension to MNI which facilitates source analysis by quantifying the ASSR for each dipole. Results demonstrate that the proposed MNI approach is successful in reconstructing sources located both within (primary) and outside (non-primary) of the auditory cortex (AC). Primary sources are detected in different stimulation conditions (four modulation frequencies and two sides of stimulation), thereby demonstrating the robustness of the approach. This study is one of the first investigations to identify non-primary sources. Moreover, we show that the MNI approach is also capable of reconstructing the subcortical activities of ASSRs. Finally, the results obtained using the MNI approach outperform the group-independent component analysis method on the same data, in terms of detection of sources in the AC, reconstructing the subcortical activities and reducing computational load.
Topics: Adult; Auditory Cortex; Brain Mapping; Cochlear Nucleus; Electroencephalography; Evoked Potentials, Auditory; Female; Geniculate Bodies; Humans; Inferior Colliculi; Male; Young Adult
PubMed: 33166050
DOI: 10.1002/hbm.25262 -
PloS One 2015We present a theory by which idealized models of auditory receptive fields can be derived in a principled axiomatic manner, from a set of structural properties to (i)...
We present a theory by which idealized models of auditory receptive fields can be derived in a principled axiomatic manner, from a set of structural properties to (i) enable invariance of receptive field responses under natural sound transformations and (ii) ensure internal consistency between spectro-temporal receptive fields at different temporal and spectral scales. For defining a time-frequency transformation of a purely temporal sound signal, it is shown that the framework allows for a new way of deriving the Gabor and Gammatone filters as well as a novel family of generalized Gammatone filters, with additional degrees of freedom to obtain different trade-offs between the spectral selectivity and the temporal delay of time-causal temporal window functions. When applied to the definition of a second-layer of receptive fields from a spectrogram, it is shown that the framework leads to two canonical families of spectro-temporal receptive fields, in terms of spectro-temporal derivatives of either spectro-temporal Gaussian kernels for non-causal time or a cascade of time-causal first-order integrators over the temporal domain and a Gaussian filter over the logspectral domain. For each filter family, the spectro-temporal receptive fields can be either separable over the time-frequency domain or be adapted to local glissando transformations that represent variations in logarithmic frequencies over time. Within each domain of either non-causal or time-causal time, these receptive field families are derived by uniqueness from the assumptions. It is demonstrated how the presented framework allows for computation of basic auditory features for audio processing and that it leads to predictions about auditory receptive fields with good qualitative similarity to biological receptive fields measured in the inferior colliculus (ICC) and primary auditory cortex (A1) of mammals.
Topics: Acoustic Stimulation; Algorithms; Animals; Auditory Cortex; Auditory Pathways; Auditory Perception; Humans; Inferior Colliculi; Models, Neurological
PubMed: 25822973
DOI: 10.1371/journal.pone.0119032