scholarly journals Spectral and Temporal Modulation Tradeoff in the Inferior Colliculus

2010 ◽  
Vol 103 (2) ◽  
pp. 887-903 ◽  
Author(s):  
Francisco A. Rodríguez ◽  
Heather L. Read ◽  
Monty A. Escabí
Keyword(s):  
Inferior Colliculus ◽  
Spectral Characteristics ◽  
Receptive Fields ◽  
Nerve Fibers ◽  
Central Nucleus ◽  
Natural Sounds ◽  
Auditory Midbrain ◽  
Spectrotemporal Receptive Fields ◽  
Low Pass ◽  
Frequency Selective Channels

The cochlea encodes sounds through frequency-selective channels that exhibit low-pass modulation sensitivity. Unlike the cochlea, neurons in the auditory midbrain are tuned for spectral and temporal modulations found in natural sounds, yet the role of this transformation is not known. We report a distinct tradeoff in modulation sensitivity and tuning that is topographically ordered within the central nucleus of the inferior colliculus (CNIC). Spectrotemporal receptive fields (STRFs) were obtained with 16-channel electrodes inserted orthogonal to the isofrequency lamina. Surprisingly, temporal and spectral characteristics exhibited an opposing relationship along the tonotopic axis. For low best frequencies (BFs), units were selective for fast temporal and broad spectral modulations. A systematic progression was observed toward slower temporal and finer spectral modulation sensitivity at high BF. This tradeoff was strongly reflected in the arrangement of excitation and inhibition and, consequently, in the modulation tuning characteristics. Comparisons with auditory nerve fibers show that these trends oppose the pattern imposed by the peripheral filters. These results suggest that spectrotemporal preferences are reordered within the tonotopic axis of the CNIC. This topographic organization has profound implications for the coding of spectrotemporal features in natural sounds and could underlie a number of perceptual phenomena.

scholarly journals Role of the Zebra Finch Auditory Thalamus in Generating Complex Representations for Natural Sounds

2010 ◽  
Vol 104 (2) ◽  
pp. 784-798 ◽  
Author(s):  
Noopur Amin ◽  
Patrick Gill ◽  
Frédéric E. Theunissen
Keyword(s):  
Receptive Fields ◽  
Neural Representation ◽  
Natural Sounds ◽  
Auditory Midbrain ◽  
Complex Sounds ◽  
Auditory Thalamus ◽  
Spectrotemporal Receptive Fields ◽  
Primary Sensory Cortex ◽  
Relay Nucleus ◽  
Field L

We estimated the spectrotemporal receptive fields of neurons in the songbird auditory thalamus, nucleus ovoidalis, and compared the neural representation of complex sounds in the auditory thalamus to those found in the upstream auditory midbrain nucleus, mesencephalicus lateralis dorsalis (MLd), and the downstream auditory pallial region, field L. Our data refute the idea that the primary sensory thalamus acts as a simple, relay nucleus: we find that the auditory thalamic receptive fields obtained in response to song are more complex than the ones found in the midbrain. Moreover, we find that linear tuning diversity and complexity in ovoidalis (Ov) are closer to those found in field L than in MLd. We also find prevalent tuning to intermediate spectral and temporal modulations, a feature that is unique to Ov. Thus even a feed-forward model of the sensory processing chain, where neural responses in the sensory thalamus reveals intermediate response properties between those in the sensory periphery and those in the primary sensory cortex, is inadequate in describing the tuning found in Ov. Based on these results, we believe that the auditory thalamic circuitry plays an important role in generating novel complex representations for specific features found in natural sounds.

scholarly journals Receptive field dimensionality increases from the auditory midbrain to cortex

2012 ◽  
Vol 107 (10) ◽  
pp. 2594-2603 ◽  
Author(s):  
Craig A. Atencio ◽  
Tatyana O. Sharpee ◽  
Christoph E. Schreiner
Keyword(s):  
Inferior Colliculus ◽  
Receptive Fields ◽  
Primary Auditory Cortex ◽  
Single Stimulus ◽  
Response Patterns ◽  
Neural Responses ◽  
Temporal Response ◽  
Auditory Midbrain ◽  
Independent Components ◽  
Spectrotemporal Receptive Fields

In the primary auditory cortex, spectrotemporal receptive fields (STRFs) are composed of multiple independent components that capture the processing of disparate stimulus aspects by any given neuron. The origin of these multidimensional stimulus filters in the central auditory system is unknown. To determine whether multicomponent STRFs emerge prior to the forebrain, we recorded from single neurons in the main obligatory station of the auditory midbrain, the inferior colliculus. By comparing results of different spike-triggered techniques, we found that the neural responses in the inferior colliculus can be accounted for by a single stimulus filter. This was observed for all temporal response patterns, from strongly phasic to tonic. Our results reveal that spectrotemporal stimulus encoding undergoes a fundamental transformation along the auditory neuraxis, with the emergence of multidimensional receptive fields beyond the auditory midbrain.

scholarly journals Anesthetic state modulates excitability but not spectral tuning or neural discrimination in single auditory midbrain neurons

2011 ◽  
Vol 106 (2) ◽  
pp. 500-514 ◽  
Author(s):  
Joseph W. Schumacher ◽  
David M. Schneider ◽  
Sarah M. N. Woolley
Keyword(s):  
Receptive Fields ◽  
Population Level ◽  
Sensory Function ◽  
Spectral Tuning ◽  
Auditory Midbrain ◽  
Sensory Physiology ◽  
Neural Excitability ◽  
Midbrain Neurons ◽  
Spectrotemporal Receptive Fields

The majority of sensory physiology experiments have used anesthesia to facilitate the recording of neural activity. Current techniques allow researchers to study sensory function in the context of varying behavioral states. To reconcile results across multiple behavioral and anesthetic states, it is important to consider how and to what extent anesthesia plays a role in shaping neural response properties. The role of anesthesia has been the subject of much debate, but the extent to which sensory coding properties are altered by anesthesia has yet to be fully defined. In this study we asked how urethane, an anesthetic commonly used for avian and mammalian sensory physiology, affects the coding of complex communication vocalizations (songs) and simple artificial stimuli in the songbird auditory midbrain. We measured spontaneous and song-driven spike rates, spectrotemporal receptive fields, and neural discriminability from responses to songs in single auditory midbrain neurons. In the same neurons, we recorded responses to pure tone stimuli ranging in frequency and intensity. Finally, we assessed the effect of urethane on population-level representations of birdsong. Results showed that intrinsic neural excitability is significantly depressed by urethane but that spectral tuning, single neuron discriminability, and population representations of song do not differ significantly between unanesthetized and anesthetized animals.

scholarly journals A Generalized Linear Model for Estimating Spectrotemporal Receptive Fields from Responses to Natural Sounds

PLoS ONE ◽  
2011 ◽  
Vol 6 (1) ◽  
pp. e16104 ◽  
Author(s):  
Ana Calabrese ◽  
Joseph W. Schumacher ◽  
David M. Schneider ◽  
Liam Paninski ◽  
Sarah M. N. Woolley
Keyword(s):  
Linear Model ◽  
Generalized Linear Model ◽  
Receptive Fields ◽  
Natural Sounds ◽  
Spectrotemporal Receptive Fields

scholarly journals Laminar Diversity of Dynamic Sound Processing in Cat Primary Auditory Cortex

2010 ◽  
Vol 103 (1) ◽  
pp. 192-205 ◽  
Author(s):  
Craig A. Atencio ◽  
Christoph E. Schreiner
Keyword(s):  
Auditory Cortex ◽  
Transfer Functions ◽  
Receptive Fields ◽  
Primary Auditory Cortex ◽  
Functional Characteristic ◽  
Modulation Transfer ◽  
Spectral Modulation ◽  
Spectrotemporal Receptive Fields ◽  
Low Pass ◽  
Acoustic Modulation

For primary auditory cortex (AI) laminae, there is little evidence of functional specificity despite clearly expressed cellular and connectional differences. Natural sounds are dominated by dynamic temporal and spectral modulations and we used these properties to evaluate local functional differences or constancies across laminae. To examine the layer-specific processing of acoustic modulation information, we simultaneously recorded from multiple AI laminae in the anesthetized cat. Neurons were challenged with dynamic moving ripple stimuli and we subsequently computed spectrotemporal receptive fields (STRFs). From the STRFs, temporal and spectral modulation transfer functions (tMTFs, sMTFs) were calculated and compared across layers. Temporal and spectral modulation properties often differed between layers. On average, layer II/III and VI neurons responded to lower temporal modulations than those in layer IV. tMTFs were mainly band-pass in granular layer IV and became more low-pass in infragranular layers. Compared with layer IV, spectral MTFs were broader and their upper cutoff frequencies higher in layers V and VI. In individual penetrations, temporal modulation preference was similar across layers for roughly 70% of the penetrations, suggesting a common, columnar functional characteristic. By contrast, only about 30% of penetrations showed consistent spectral modulation preferences across layers, indicative of functional laminar diversity or specialization. Since local laminar differences in stimulus preference do not always parallel the main flow of information in the columnar cortical microcircuit, this indicates the influence of additional horizontal or thalamocortical inputs. AI layers that express differing modulation properties may serve distinct roles in the extraction of dynamic sound information, with the differing information specific to the targeted stations of each layer.

External nucleus of inferior colliculus: auditory and spinal somatosensory afferents and their interactions

1978 ◽  
Vol 41 (4) ◽  
pp. 837-847 ◽  
Author(s):  
L. M. Aitkin ◽  
H. Dickhaus ◽  
W. Schult ◽  
M. Zimmermann
Keyword(s):  
Inferior Colliculus ◽  
Pure Tone ◽  
Tactile Stimulation ◽  
Receptive Fields ◽  
The Body ◽  
Central Nucleus ◽  
Auditory Input ◽  
Somatosensory Information ◽  
Somatic Receptive Fields ◽  
Stimulation Of

1. The discharges of 129 units were studied in the external nucleus of the inferior colliculus of 11 anesthetised and paralyzed cats. This region is known to receive fibers from auditory nuclei and the dorsal column nuclei. 2. Stimuli used were pure tone bursts, monaural or binaural, tactile stimulation of the body surface, and electrical stimulation of the dorsal columns (DC) at a low cervical level and of the contralateral and ipsilateral tibial nerves. 3. Forty-six percent of units were only influenced by one type of stimulation (26% auditory, 20% DC). Of the remaining bimodally influenced units, the majority was excited by pure tone stimuli and inhibited by DC stimulation. 4. A small proportion of the total population (18%) was excited by both DC and auditory input, and units sensitive to both tones and tactile stimulation of the skin were rare (4%). 5. Auditory tuning curves were generally very broad compared with those of units in the central nucleus of the inferior colliculus. Similarly, somatic receptive fields were large and usually extended over a whole limb. 6. The majority of tone-responsive units were influenced binaurally (70%); most somatic receptive fields were located on the contralateral fore- or hindlimb (16/18). 7. The results indicate that both auditory and somatosensory information is contained in the discharges of units in the external nucleus of the inferior colliculus. 8. Speculations are made about the role of this nucleus in descending auditory input to the spinal cord and in the comparison of auditory and cutaneous information during sound-evoked coordinated body movements.

Effects of interaural time delays of noise stimuli on low-frequency cells in the cat's inferior colliculus. III. Evidence for cross-correlation

1987 ◽  
Vol 58 (3) ◽  
pp. 562-583 ◽  
Author(s):  
T. C. Yin ◽  
J. C. Chan ◽  
L. H. Carney
Keyword(s):  
Inferior Colliculus ◽  
Acoustic Signal ◽  
Cross Correlation ◽  
Low Frequency ◽  
Nerve Fibers ◽  
Broadband Noise ◽  
The Other ◽  
Central Nucleus ◽  
Interaural Phase ◽  
Phase Relationships

1. We tested the coincidence, or cross-correlation, model of Jeffress, which proposes a neuronal mechanism for sensitivity to interaural time differences (ITDs) in low-frequency cells in the central nucleus of the inferior colliculus (ICC) of the cat. Different tokens of Gaussian noise stimuli were delivered to the two ears. We studied the neural responses to changes in ITDs of these stimuli and examined the manner in which the binaural cells responded to them. All of our results support the idea that the central binaural neurons perform an operation very similar to cross-correlation on the inputs arriving from each side. These inputs are transformed from the actual acoustic signal by the peripheral auditory system, and these transformations are reflected in the properties of the cross-correlations. 2. The responses to ITDs of identical broadband noise stimuli to the two ears varies cyclically as a function of ITD at a frequency close to the best frequency of the neuron. This cyclic response is a consequence of the narrowband filtering of the wideband acoustic signal by the auditory nerve fibers. To examine the effects of using stimuli to the two ears that were correlated to each other to different degrees, we generated pairs of noises. Each pair consisted of one standard noise, which was delivered to one ear, and a linear sum of two standard uncorrelated noises, which was delivered to the other ear. The responses of 34 neurons in the ICC to ITDs of noises with variable interaural coherence were examined. When partially correlated noises were delivered, there was a positive and approximately linear relationship between the degree of modulation of the response as a function of ITD and interaural coherence. The degree of modulation was measured by the synchronization coefficient, or vector strength, over one period of the ITD curve. 3. We examined the effects of altering the interaural phase relationships of the input noise stimuli. The phase of the noise stimuli was changed by digitally filtering the standard noise so that only a phase delay was imposed. The responses to ITDs with differing interaural phase relationships were then studied by delivering a phase-shifted noise to one ear and the standard noise to the other. The ITD curves in response to phase-shifted noise were shifted by about the same amount as the shift of the stimulus; the shift of the response was measured with respect to the case with identical noises to the two ears.(ABSTRACT TRUNCATED AT 400 WORDS)

Coactivation of different neurons within an isofrequency lamina of the inferior colliculus elicits enhanced auditory cortical activation

2012 ◽  
Vol 108 (4) ◽  
pp. 1199-1210 ◽  
Author(s):  
Roger Calixto ◽  
Minoo Lenarz ◽  
Anke Neuheiser ◽  
Verena Scheper ◽  
Thomas Lenarz ◽  
...  
Keyword(s):  
Inferior Colliculus ◽  
Temporal Integration ◽  
Three Dimensional ◽  
Primary Auditory Cortex ◽  
Cortical Activation ◽  
Central Nucleus ◽  
Speech Understanding ◽  
Auditory Midbrain ◽  
Temporal Cues ◽  
Multiple Regions

The phenomenal success of the cochlear implant (CI) is attributed to its ability to provide sufficient temporal and spectral cues for speech understanding. Unfortunately, the CI is ineffective for those without a functional auditory nerve or an implantable cochlea required for CI implementation. As an alternative, our group developed and implanted in deaf patients a new auditory midbrain implant (AMI) to stimulate the central nucleus of the inferior colliculus (ICC). Although the AMI can provide frequency cues, it appears to insufficiently transmit temporal cues for speech understanding. The three-dimensional ICC consists of two-dimensional isofrequency laminae. The single-shank AMI only stimulates one site in any given ICC lamina and does not exhibit enhanced activity (i.e., louder percepts or lower thresholds) for repeated pulses on the same site with intervals <2–5 ms, as occurs for CI pulse or acoustic click stimulation. This enhanced activation, related to short-term temporal integration, is important for tracking the rapid temporal fluctuations of a speech signal. Therefore, we investigated the effects of coactivation of different regions within an ICC lamina on primary auditory cortex activity in ketamine-anesthetized guinea pigs. Interestingly, our findings reveal an enhancement mechanism for integrating converging inputs from an ICC lamina on a fast scale (<6-ms window) that is compromised when stimulating just a single ICC location. Coactivation of two ICC regions also reduces the strong and long-term (>100 ms) suppressive effects induced by repeated stimulation of just a single location. Improving AMI performance may require at least two shanks implanted along the tonotopic gradient of the ICC that enables coactivation of multiple regions along an ICC lamina with the appropriate interstimulus delays.

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