Hearing Impairment Induces Frequency-Specific Adjustments in Auditory Spatial Tuning in the Optic Tectum of Young Owls

1999 ◽  
Vol 82 (5) ◽  
pp. 2197-2209 ◽  
Author(s):  
Joshua I. Gold ◽  
Eric I. Knudsen
Keyword(s):  
Optic Tectum ◽  
Frequency Tuning ◽  
Receptive Fields ◽  
Dependent Manner ◽  
Frequency Dependent ◽  
Auditory Space ◽  
Spatial Tuning ◽  
Auditory Experience ◽  
Tectal Neurons ◽  
Interaural Level Differences

Bimodal, auditory-visual neurons in the optic tectum of the barn owl are sharply tuned for sound source location. The auditory receptive fields (RFs) of these neurons are restricted in space primarily as a consequence of their tuning for interaural time differences and interaural level differences across broad ranges of frequencies. In this study, we examined the extent to which frequency-specific features of early auditory experience shape the auditory spatial tuning of these neurons. We manipulated auditory experience by implanting in one ear canal an acoustic filtering device that altered the timing and level of sound reaching the eardrum in a frequency-dependent fashion. We assessed the auditory spatial tuning at individual tectal sites in normal owls and in owls raised with the filtering device. At each site, we measured a family of auditory RFs using broadband sound and narrowband sounds with different center frequencies both with and without the device in place. In normal owls, the narrowband RFs for a given site all included a common region of space that corresponded with the broadband RF and aligned with the site's visual RF. Acute insertion of the filtering device in normal owls shifted the locations of the narrowband RFs away from the visual RF, the magnitude and direction of the shifts depending on the frequency of the stimulus. In contrast, in owls that were raised wearing the device, narrowband and broadband RFs were aligned with visual RFs so long as the device was in the ear but not after it was removed, indicating that auditory spatial tuning had been adaptively altered by experience with the device. The frequency tuning of tectal neurons in device-reared owls was also altered from normal. The results demonstrate that experience during development adaptively modifies the representation of auditory space in the barn owl's optic tectum in a frequency-dependent manner.

scholarly journals Early Auditory Experience Induces Frequency-Specific, Adaptive Plasticity in the Forebrain Gaze Fields of the Barn Owl

2001 ◽  
Vol 85 (5) ◽  
pp. 2184-2194 ◽  
Author(s):  
Greg L. Miller ◽  
Eric I. Knudsen
Keyword(s):  
Barn Owl ◽  
Adaptive Plasticity ◽  
Dependent Manner ◽  
Sound Sources ◽  
Frequency Dependent ◽  
Auditory Space ◽  
Binaural Cues ◽  
Normal Representation ◽  
Output Structure ◽  
Auditory Experience

Binaural acoustic cues such as interaural time and level differences (ITDs and ILDs) are used by many species to determine the locations of sound sources. The relationship between cue values and locations in space is frequency dependent and varies from individual to individual. In the current study, we tested the capacity of neurons in the forebrain localization pathway of the barn owl to adjust their tuning for binaural cues in a frequency-dependent manner in response to auditory experience. Auditory experience was altered by raising young owls with a passive acoustic filtering device that caused frequency-dependent changes in ITD and ILD. Extracellular recordings were made in normal and device-reared owls to characterize frequency-specific ITD and ILD tuning in the auditory archistriatum (AAr), an output structure of the forebrain localization pathway. In device-reared owls, individual sites in the AAr exhibited highly abnormal, frequency-dependent variations in ITD tuning, and across the population of sampled sites, there were frequency-dependent shifts in the representation of ITD. These changes were in a direction that compensated for the acoustic effects of the device on ITD and therefore tended to restore a normal representation of auditory space. Although ILD tuning was degraded relative to normal at many sites in the AAr of device-reared owls, the representation of frequency-specific ILDs across the population of sampled sites was shifted in the adaptive direction. These results demonstrate that early auditory experience shapes the representation of binaural cues in the forebrain localization pathway in an adaptive, frequency-dependent manner.

Binaural mechanisms of spatial tuning in the cat's superior colliculus distinguished using monaural occlusion

1987 ◽  
Vol 57 (3) ◽  
pp. 688-701 ◽  
Author(s):  
J. C. Middlebrooks
Keyword(s):  
Superior Colliculus ◽  
Frequency Tuning ◽  
Free Field ◽  
Broad Band ◽  
Receptive Fields ◽  
Sound Field ◽  
Recording Site ◽  
Binaural Interaction ◽  
Spatial Tuning ◽  
Contralateral Ear

This study explores the mechanisms of auditory spatial tuning in the superior colliculus of the anesthetized cat by correlating spatial tuning within specific regions of space with particular types of binaural interaction. The auditory spatial tuning of units was measured using a movable, broad-band stimulus presented in a free sound field. The contribution of each ear to the response of a unit was identified by acutely plugging one or the other ear. Every unit became largely or entirely unresponsive when a foam-rubber earplug was placed in the ear contralateral to the recording site. Thus, every unit exhibited an excitatory or facilitatory influence from the contralateral ear. A plug placed in the ipsilateral ear had different effects on different units. For half of the units (16/32), an ipsilateral earplug produced increases in the sizes of the units' receptive fields and increases in the magnitudes of their responses to stimuli presented from most locations. Thus, these units exhibited inhibition from the ipsilateral ear. Another class of units (9/32) exhibited ipsilateral facilitation, in that an ipsilateral earplug caused decreases in the sizes of the units' receptive fields and prominent decreases in their response magnitudes. For the remaining units (7/32), an ipsilateral earplug resulted in decreases in the sizes of the units' receptive fields, but produced both decreases in the responses of units to stimuli presented in their best areas and increases in the responses to stimuli presented away from the best areas. Thus these units exhibited mixed facilitatory and inhibitory ipsilateral influences. The influence of an ipsilateral earplug on a unit's response tended to correlate with its spatial tuning. The region of space within which a sound source was most effective in activating a unit was its “best area”. The best areas of units exhibiting ipsilateral inhibition were located furthest peripherally, those of units showing ipsilateral facilitation were located furthest frontally, and the best areas of units showing mixed ipsilateral influences were located in an intermediate area. The frequency tuning of units measured using a free-field tone source also tended to correlate with the locations of their best areas. Half of the units tested (27/54) responded to tones of the sound pressure levels (SPLs) that were used (up to 50 dB SPL).(ABSTRACT TRUNCATED AT 400 WORDS)

Auditory properties of space-tuned units in owl's optic tectum

1984 ◽  
Vol 52 (4) ◽  
pp. 709-723 ◽  
Author(s):  
E. I. Knudsen
Keyword(s):  
Sound Source ◽  
Optic Tectum ◽  
High Frequency ◽  
Frequency Tuning ◽  
Free Field ◽  
Sound Intensity ◽  
Tyto Alba ◽  
Visual Axis ◽  
Response Latencies ◽  
Spatial Tuning

Auditory units in the optic tectum of the barn owl (Tyto alba) were studied under free-field conditions with a movable sound source. These units are selective for sound location and their spatial tuning varies systematically across the tectum, forming a map of space (8). I found that frequency tuning, response latencies, and thresholds of units changed in parallel with their spatial tuning, suggesting that as a consequence these properties also are topographically distributed in the optic tectum. Response rates were determined primarily by the location of the sound source. Regardless of sound intensity, only stimuli delivered from a restricted “best area” elicited vigorous responses. Minimum response latencies were shortest for units with frontal best areas and increased systematically for units with best areas located more peripherally. The response latencies of units with best areas centered within 25 degrees of the owl's visual axis were virtually independent of sound intensity and speaker position. The latencies of units with more peripheral best areas varied with speaker position and were shortest when the speaker was in the best area. Thresholds to noise stimuli were lowest for units with best areas directly in front of the owl and increased systematically for units with best areas located more peripherally. Thus, in the representation of frontal space, where units have the smallest receptive fields and the magnification of space is the greatest (8), units also respond to the weakest sound fields. Many units (20%) could not be driven with tonal stimuli; of those that could, most were broadly tuned for frequency. Characteristic frequencies and high-frequency cutoffs shifted lower as best areas moved peripherally. High-frequency tones, which excited units with frontal best areas, either inhibited or failed to drive units with peripheral best areas. These systematic changes in unit response properties influence how sounds from different locations are represented in the tectum and reflect integrative strategies used by the owl's auditory system in deriving a representation of auditory space.

scholarly journals Topographically localised modulation of tectal cell spatial tuning by natural scenes

2021 ◽  
Author(s):  
Thomas Trevelyan James Sainsbury ◽  
Giovanni Diana ◽  
Martin Patrick Meyer
Keyword(s):  
Receptive Fields ◽  
Visual Space ◽  
Spatial Arrangement ◽  
Natural Scenes ◽  
Visual Neurons ◽  
Contextual Modulation ◽  
Hunting Behaviour ◽  
Spatial Tuning ◽  
Restricted Region ◽  
Tectal Neurons

AbstractVisual neurons can have their tuning properties contextually modulated by the presence of visual stimuli in the area surrounding their receptive field, especially when that stimuli contains natural features. However, stimuli presented in specific egocentric locations may have greater behavioural relevance, raising the possibility that the extent of contextual modulation may vary with position in visual space. To explore this possibility we utilised the small size and optical transparency of the larval zebrafish to describe the form and spatial arrangement of contextually modulated cells throughout an entire tectal hemisphere. We found that the spatial tuning of tectal neurons to a prey-like stimulus sharpens when the stimulus is presented in the context of a naturalistic visual scene. These neurons are confined to a spatially restricted region of the tectum and have receptive fields centred within a region of visual space in which the presence of prey preferentially triggers hunting behaviour. Our results demonstrate that circuits that support behaviourally relevant modulation of tectal neurons are not uniformly distributed. These findings add to the growing body of evidence that the tectum shows regional adaptations for behaviour.

scholarly journals Auditory Spatial Tuning at the Crossroads of the Midbrain and Forebrain

2009 ◽  
Vol 102 (3) ◽  
pp. 1472-1482 ◽  
Author(s):  
M. Lucía Pérez ◽  
Sharad J. Shanbhag ◽  
José Luis Peña
Keyword(s):  
Sound Localization ◽  
Thalamic Nucleus ◽  
Receptive Fields ◽  
Frequency Range ◽  
Auditory Space ◽  
Coding Schemes ◽  
Sound Direction ◽  
Spatial Tuning ◽  
The Difference ◽  
Similar Combination

The barn owl's midbrain and forebrain contain neurons tuned to sound direction. The spatial receptive fields of these neurons result from sensitivity to combinations of interaural time (ITD) and level (ILD) differences over a broad frequency range. While a map of auditory space has been described in the midbrain, no similar topographic representation has been found in the forebrain. The first nuclei that belong exclusively to the forebrain and midbrain pathways are the thalamic nucleus ovoidalis (Ov) and the external nucleus of the inferior colliculus (ICx), respectively. The midbrain projects to the auditory thalamus before sharp spatial receptive fields emerge; although Ov and ICx receive projections from the same midbrain nuclei, they are not directly connected. We compared the spatial tuning in Ov and ICx. Thalamic neurons respond to a broader frequency range and their ITD and ILD tuning varied more across frequency. However, neurons in Ov showed spatial receptive fields as selective as neurons in ICx. Thalamic spatial receptive fields were tuned to frontal and contralateral space and correlated with their tuning to ITD and ILD. Our results indicate that spatial tuning emerges in both pathways by similar combination selectivity to ITD and ILD. However, the midbrain and the thalamus do not appear to repeat exactly the same processing, as indicated by the difference in frequency range and the broader tuning to binaural cues. The differences observed at the initial stages of these sound-localization pathways may reflect diverse functions and coding schemes of midbrain and forebrain.

Neurotransmitter Involvement in Development and Maintenance of the Auditory Space Map in the Guinea Pig Superior Colliculus

1998 ◽  
Vol 80 (6) ◽  
pp. 2941-2953 ◽  
Author(s):  
Neil J. Ingham ◽  
Sally K. Thornton ◽  
Damian McCrossan ◽  
Deborah J. Withington
Keyword(s):  
Guinea Pig ◽  
Superior Colliculus ◽  
Glutamate Receptors ◽  
Guinea Pigs ◽  
Receptive Fields ◽  
Fine Tuning ◽  
Auditory Space ◽  
Spatial Tuning ◽  
Nmda Glutamate Receptors ◽  
Auditory Space Map

Ingham, Neil J., Sally K. Thornton, Damian McCrossan, and Deborah J. Withington. Neurotransmitter involvement in development and maintenance of the auditory space map in the guinea pig superior colliculus. J. Neurophysiol. 80: 2941–2953, 1998. The mammalian superior colliculus (SC) is a complex area of the midbrain in terms of anatomy, physiology, and neurochemistry. The SC bears representations of the major sensory modalites integrated with a motor output system. It is implicated with saccade generation, in behavioral responses to novel sensory stimuli and receives innervation from diverse regions of the brain using many neurotransmitter classes. Ethylene-vinyl acetate copolymer (Elvax-40W polymer) was used here to deliver chronically neurotransmitter receptor antagonists to the SC of the guinea pig to investigate the potential role played by the major neurotransmitter systems in the collicular representation of auditory space. Slices of polymer containing different drugs were implanted onto the SC of guinea pigs before the development of the SC azimuthal auditory space map, at ∼20 days after birth (DAB). A further group of animals was exposed to aminophosphonopentanoic acid (AP5) at ∼250 DAB. Azimuthal spatial tuning properties of deep layer multiunits of anesthetized guinea pigs were examined ∼20 days after implantation of the Elvax polymer. Broadband noise bursts were presented to the animals under anechoic, free-field conditions. Neuronal responses were used to construct polar plots representative of the auditory spatial multiunit receptive fields (MURFs). Animals exposed to control polymer could develop a map of auditory space in the SC comparable with that seen in unimplanted normal animals. Exposure of the SC of young animals to AP5, 6-cyano-7-nitroquinoxaline-2,3-dione, or atropine, resulted in a reduction in the proportion of spatially tuned responses with an increase in the proportion of broadly tuned responses and a degradation in topographic order. Thus N-methyl-d-aspartate (NMDA) and non-NMDA glutamate receptors and muscarinic acetylcholine receptors appear to play vital roles in the development of the SC auditory space map. A group of animals exposed to AP5 beginning at ∼250 DAB produced results very similar to those obtained in the young group exposed to AP5. Thus NMDA glutamate receptors also seem to be involved in the maintenance of the SC representation of auditory space in the adult guinea pig. Exposure of the SC of young guinea pigs to γ-aminobutyric acid (GABA) receptor blocking agents produced some but not total disruption of the spatial tuning of auditory MURFs. Receptive fields were large compared with controls, but a significant degree of topographical organization was maintained. GABA receptors may play a role in the development of fine tuning and sharpening of auditory spatial responses in the SC but not necessarily in the generation of topographical order of the these responses.

scholarly journals Spectral cues are necessary to encode azimuthal auditory space in the mouse superior colliculus

2019 ◽  
Author(s):  
Shinya Ito ◽  
Yufei Si ◽  
David A. Feldheim ◽  
Alan M. Litke
Keyword(s):  
Superior Colliculus ◽  
Critical Role ◽  
Receptive Fields ◽  
Spectral Structure ◽  
Topographic Map ◽  
Neural Encoding ◽  
Spectral Filtering ◽  
Auditory Space ◽  
Spectral Cues ◽  
Interaural Level Differences

AbstractSound localization plays a critical role in animal survival. Three cues can be used to compute sound direction: interaural timing differences (ITDs), interaural level differences (ILDs) and the direction-dependent spectral filtering by the head and pinnae (spectral cues). Little is known about how spectral cues contribute to the neural encoding of auditory space. Here we report on auditory space encoding in the mouse superior colliculus (SC). We show that the mouse SC contains neurons with spatially-restricted receptive fields (RFs) that form an azimuthal topographic map. We found that frontal RFs require spectral cues and lateral RFs require ILDs. The neurons with frontal RFs have frequency tunings that match the spectral structure of the specific head and pinna filter for sound coming from the front. These results demonstrate that patterned spectral cues in combination with ILDs give rise to the topographic map of azimuthal auditory space.

Dynamics of visually guided auditory plasticity in the optic tectum of the barn owl

1995 ◽  
Vol 73 (2) ◽  
pp. 595-614 ◽  
Author(s):  
M. S. Brainard ◽  
E. I. Knudsen
Keyword(s):  
Visual Field ◽  
Optic Tectum ◽  
Visual Experience ◽  
Normal Values ◽  
Interaural Time Difference ◽  
Receptive Fields ◽  
Visually Guided ◽  
Barn Owls ◽  
Tectal Neurons ◽  
The Right

1. In the optic tectum of normal barn owls, bimodal (auditory-visual) neurons are tuned to the values of interaural time difference (ITD) that are produced by sounds at the locations of their visual receptive fields (VRFs). The auditory tuning of tectal neurons is actively guided by visual experience during development: in the tectum of adult owls reared with an optically displaced visual field, neurons are tuned to abnormal values of ITD that are close to the values produced by sounds at the locations of their optically displaced VRFs. In this study we investigated the dynamics of this experience-dependent plasticity. 2. Owls were raised from shortly after eye-opening (14-22 days of age) with prismatic spectacles that displaced the visual field to the right or left. Starting at approximately 60 days of age, multiunit recordings were made to assess the tuning of tectal neurons to ITD presented via earphones. In the earliest recording sessions (ages 60-80 days), ITD tuning was often close to normal, even though the majority of the owls' previous experience was with an altered correspondence between ITD values and VRF locations. Subsequently, over a period of weeks, responses to the normal range of ITDs were gradually eliminated while responses to values of ITD corresponding with the optically displaced VRF were acquired. 3. At intermediate stages in this process, the ITD tuning at many sites became abnormally broad, so that responses were simultaneously present to both normal values of ITD and to values corresponding with the optically displaced VRF. At this stage the latencies and durations of newly acquired responses systematically exceeded the latencies and durations of the responses to normal values of ITD. 4. Dynamic changes in ITD tuning similar to those recorded in the optic tectum also occurred in the external nucleus of the inferior colliculus (ICX), which provides the major source of ascending auditory input to the tectum. 5. These results suggest the hypothesis that the neural selectivity for ITD in the barn owl's tectum is first established by vision-independent mechanisms and only subsequently calibrated by visual experience. This calibration involves both the elimination of responses to normal values of ITD and the visually guided acquisition of responses to novel values and can be accounted for by plasticity at the level of the ICX.

scholarly journals The effects of the NMDAR co-agonist D-serine on the structure and function of the optic tectum

2021 ◽  
Author(s):  
Zahraa Chorghay ◽  
Vanessa J. Li ◽  
Arna Ghosh ◽  
Anne Schohl ◽  
Edward S. Ruthazer
Keyword(s):  
Optic Tectum ◽  
Receptive Fields ◽  
Chronic Administration ◽  
Dendritic Morphology ◽  
Glutamatergic Synapses ◽  
Functional Changes ◽  
Synapse Density ◽  
Mature Neurons ◽  
Tectal Neurons ◽  
And Function

The N-methyl-D-aspartate type glutamate receptor (NMDAR) is a molecular coincidence detector which converts correlated patterns of neuronal activity into cues for the structural and functional refinement of developing circuits in the brain. D-serine is an endogenous co-agonist of the NMDAR. In this study, we investigated the effects of potent enhancement of NMDAR-mediated currents by chronic administration of saturating levels of D-serine on the developing Xenopus retinotectal circuit. Chronic exposure to the NMDAR co-agonist D-serine resulted in structural and functional changes to the optic tectum. D-serine administration affected synaptogenesis and dendritic morphology in recently differentiated tectal neurons, resulting in increased arbor compaction, reduced branch dynamics, and higher synapse density. These effects were not observed in more mature neurons. Calcium imaging to examine retinotopic map organization revealed that tectal neurons of animals raised in D-serine had sharper visual receptive fields . These findings suggest that the availability of endogenous NMDAR co-agonists like D-serine at glutamatergic synapses may regulate the refinement of circuits in the developing brain.

scholarly journals Adaptation-induced modification of motion selectivity tuning in visual tectal neurons of adult zebrafish

2015 ◽  
Vol 114 (5) ◽  
pp. 2893-2902 ◽  
Author(s):  
Vanessa Hollmann ◽  
Valerie Lucks ◽  
Rafael Kurtz ◽  
Jacob Engelmann
Keyword(s):  
Optic Tectum ◽  
Brain Area ◽  
Direction Selectivity ◽  
Adult Brain ◽  
Orientation Tuning ◽  
Adult Zebrafish ◽  
Short Term ◽  
Short Term Plasticity ◽  
The Difference ◽  
Tectal Neurons

In the developing brain, training-induced emergence of direction selectivity and plasticity of orientation tuning appear to be widespread phenomena. These are found in the visual pathway across different classes of vertebrates. Moreover, short-term plasticity of orientation tuning in the adult brain has been demonstrated in several species of mammals. However, it is unclear whether neuronal orientation and direction selectivity in nonmammalian species remains modifiable through short-term plasticity in the fully developed brain. To address this question, we analyzed motion tuning of neurons in the optic tectum of adult zebrafish by calcium imaging. In total, orientation and direction selectivity was enhanced by adaptation, responses of previously orientation-selective neurons were sharpened, and even adaptation-induced emergence of selectivity in previously nonselective neurons was observed in some cases. The different observed effects are mainly based on the relative distance between the previously preferred and the adaptation direction. In those neurons in which a shift of the preferred orientation or direction was induced by adaptation, repulsive shifts (i.e., away from the adapter) were more prevalent than attractive shifts. A further novel finding for visually induced adaptation that emerged from our study was that repulsive and attractive shifts can occur within one brain area, even with uniform stimuli. The type of shift being induced also depends on the difference between the adapting and the initially preferred stimulus direction. Our data indicate that, even within the fully developed optic tectum, short-term plasticity might have an important role in adjusting neuronal tuning functions to current stimulus conditions.

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