scholarly journals Fine frequency tuning in monkey auditory cortex and thalamus

2011 ◽  
Vol 106 (2) ◽  
pp. 849-859 ◽  
Author(s):  
Edward L. Bartlett ◽  
Srivatsun Sadagopan ◽  
Xiaoqin Wang
Keyword(s):  
Auditory Cortex ◽  
Auditory Nerve ◽  
Animal Studies ◽  
De Novo ◽  
Frequency Tuning ◽  
Primary Auditory Cortex ◽  
Auditory Pathway ◽  
Nerve Fibers ◽  
Frequency Resolution ◽  
Human Auditory Cortex

The frequency resolution of neurons throughout the ascending auditory pathway is important for understanding how sounds are processed. In many animal studies, the frequency tuning widths are about 1/5th octave wide in auditory nerve fibers and much wider in auditory cortex neurons. Psychophysical studies show that humans are capable of discriminating far finer frequency differences. A recent study suggested that this is perhaps attributable to fine frequency tuning of neurons in human auditory cortex (Bitterman Y, Mukamel R, Malach R, Fried I, Nelken I. Nature 451: 197–201, 2008). We investigated whether such fine frequency tuning was restricted to human auditory cortex by examining the frequency tuning width in the awake common marmoset monkey. We show that 27% of neurons in the primary auditory cortex exhibit frequency tuning that is finer than the typical frequency tuning of the auditory nerve and substantially finer than previously reported cortical data obtained from anesthetized animals. Fine frequency tuning is also present in 76% of neurons of the auditory thalamus in awake marmosets. Frequency tuning was narrower during the sustained response compared to the onset response in auditory cortex neurons but not in thalamic neurons, suggesting that thalamocortical or intracortical dynamics shape time-dependent frequency tuning in cortex. These findings challenge the notion that the fine frequency tuning of auditory cortex is unique to human auditory cortex and that it is a de novo cortical property, suggesting that the broader tuning observed in previous animal studies may arise from the use of anesthesia during physiological recordings or from species differences.

Corticofugal Shaping of Frequency Tuning Curves in the Central Nucleus of the Inferior Colliculus of Mice

2005 ◽  
Vol 93 (1) ◽  
pp. 71-83 ◽  
Author(s):  
Jun Yan ◽  
Yunfeng Zhang ◽  
Günter Ehret
Keyword(s):  
Auditory Cortex ◽  
Inferior Colliculus ◽  
Cortical Neurons ◽  
Frequency Tuning ◽  
Tuning Curve ◽  
Primary Auditory Cortex ◽  
Nerve Fibers ◽  
Cortical Activation ◽  
Central Nucleus ◽  
Tuning Curves

Plasticity of the auditory cortex can be induced by conditioning or focal cortical stimulation. The latter was used here to measure how stimulation in the tonotopy of the mouse primary auditory cortex influences frequency tuning in the midbrain central nucleus of the inferior colliculus (ICC). Shapes of collicular frequency tuning curves (FTCs) were quantified before and after cortical activation by measuring best frequencies, FTC bandwidths at various sound levels, level tolerance, Q-values, steepness of low- and high-frequency slopes, and asymmetries. We show here that all of these measures were significantly changed by focal cortical activation. The changes were dependent not only on the relationship of physiological properties between the stimulated cortical neurons and recorded collicular neurons but also on the tuning curve class of the collicular neuron. Cortical activation assimilated collicular FTC shapes; sharp and broad FTCs were changed to the shapes comparable to those of auditory nerve fibers. Plasticity in the ICC was organized in a center (excitatory)-surround (inhibitory) way with regard to the stimulated location (i.e., the frequency) of cortical tonotopy. This ensures, together with the spatial gradients of distribution of collicular FTC shapes, a sharp spectral filtering at the core of collicular frequency-band laminae and an increase in frequency selectivity at the periphery of the laminae. Mechanisms of FTC plasticity were suggested to comprise both corticofugal and local ICC components of excitatory and inhibitory modulation leading to a temporary change of the balance between excitation and inhibition in the ICC.

scholarly journals Broadened Population-Level Frequency Tuning in Human Auditory Cortex of Portable Music Player Users

PLoS ONE ◽  
2011 ◽  
Vol 6 (3) ◽  
pp. e17022 ◽  
Author(s):  
Hidehiko Okamoto ◽  
Henning Teismann ◽  
Ryusuke Kakigi ◽  
Christo Pantev
Keyword(s):  
Auditory Cortex ◽  
Frequency Tuning ◽  
Population Level ◽  
Human Auditory Cortex ◽  
Music Player

Frequency Tuning and Spontaneous Activity in the Auditory Nerve and Cochlear Nucleus Magnocellularis of the Barn Owl Tyto alba

1997 ◽  
Vol 77 (1) ◽  
pp. 364-377 ◽  
Author(s):  
Christine Köppl
Keyword(s):  
Response Latency ◽  
Cochlear Nucleus ◽  
Auditory Nerve ◽  
Frequency Tuning ◽  
Barn Owl ◽  
Nerve Fibers ◽  
Spontaneous Discharge ◽  
Tyto Alba ◽  
Nucleus Magnocellularis ◽  
Auditory Nerve Fibers

Köppl, Christine. Frequency tuning and spontaneous activity in the auditory nerve and cochlear nucleus magnocellularis of the barn owl Tyto alba. J. Neurophysiol. 77: 364–377, 1997. Single-unit recordings were obtained from the brain stem of the barn owl at the level of entrance of the auditory nerve. Auditory nerve and nucleus magnocellularis units were distinguished by physiological criteria, with the use of the response latency to clicks, the spontaneous discharge rate, and the pattern of characteristic frequencies encountered along an electrode track. The response latency to click stimulation decreased in a logarithmic fashion with increasing characteristic frequency for both auditory nerve and nucleus magnocellularis units. The average difference between these populations was 0.4–0.55 ms. The most sensitive thresholds were ∼0 dB SPL and varied little between 0.5 and 9 kHz. Frequency-threshold curves showed the simple V shape that is typical for birds, with no indication of a low-frequency tail. Frequency selectivity increased in a gradual, power-law fashion with increasing characteristic frequency. There was no reflection of the unusual and greatly expanded mapping of higher frequencies on the basilar papilla of the owl. This observation is contrary to the equal-distance hypothesis that relates frequency selectivity to the spatial respresentation in the cochlea. On the basis of spontaneous rates and/or sensitivity there was no evidence for distinct subpopulations of auditory nerve fibers, such as the well-known type I afferent response classes in mammals. On the whole, barn owl auditory nerve physiology conformed entirely to the typical patterns seen in other bird species. The only exception was a remarkably small spread of thresholds at any one frequency, this being only 10–15 dB in individual owls. Average spontaneous rate was 72.2 spikes/s in the auditory nerve and 219.4 spikes/s for nucleus magnocellularis. This large difference, together with the known properties of endbulb-of-Held synapses, suggests a convergence of ∼2–4 auditory nerve fibers onto one nucleus magnocellularis neuron. Some auditory nerve fibers as well as nucleus magnocellularis units showed a quasiperiodic spontaneous discharge with preferred intervals in the time-interval histogram. This phenomenon was observed at frequencies as high as 4.7 kHz.

scholarly journals Serotonin Transporter Defect Disturbs Structure and Function of the Auditory Cortex in Mice

2021 ◽  
Vol 15 ◽  
Author(s):  
Wenlu Pan ◽  
Jing Pan ◽  
Yan Zhao ◽  
Hongzheng Zhang ◽  
Jie Tang
Keyword(s):  
Auditory Cortex ◽  
Serotonin Transporter ◽  
Cortical Neurons ◽  
Pyramidal Neurons ◽  
Frequency Tuning ◽  
Primary Auditory Cortex ◽  
Neuronal Morphology ◽  
Neuronal Connections ◽  
The Central Nervous System ◽  
And Function

Serotonin transporter (SERT) modulates the level of 5-HT and significantly affects the activity of serotonergic neurons in the central nervous system. The manipulation of SERT has lasting neurobiological and behavioral consequences, including developmental dysfunction, depression, and anxiety. Auditory disorders have been widely reported as the adverse events of these mental diseases. It is unclear how SERT impacts neuronal connections/interactions and what mechanism(s) may elicit the disruption of normal neural network functions in auditory cortex. In the present study, we report on the neuronal morphology and function of auditory cortex in SERT knockout (KO) mice. We show that the dendritic length of the fourth layer (L-IV) pyramidal neurons and the second-to-third layer (L-II/III) interneurons were reduced in the auditory cortex of the SERT KO mice. The number and density of dendritic spines of these neurons were significantly less than those of wild-type neurons. Also, the frequency-tonotopic organization of primary auditory cortex was disrupted in SERT KO mice. The auditory neurons of SERT KO mice exhibited border frequency tuning with high-intensity thresholds. These findings indicate that SERT plays a key role in development and functional maintenance of auditory cortical neurons. Auditory function should be examined when SERT is selected as a target in the treatment for psychiatric disorders.

scholarly journals Facilitatory and Inhibitory Frequency Tuning of Combination-Sensitive Neurons in the Primary Auditory Cortex of Mustached Bats

1999 ◽  
Vol 82 (5) ◽  
pp. 2327-2345 ◽  
Author(s):  
Jagmeet S. Kanwal ◽  
Douglas C. Fitzpatrick ◽  
Nobuo Suga
Keyword(s):  
Auditory Cortex ◽  
Frequency Tuning ◽  
Temporal Structure ◽  
Primary Auditory Cortex ◽  
Frequency Discrimination ◽  
Inhibitory Response ◽  
Center Frequency ◽  
Constant Frequency ◽  
Single Tone ◽  
Threshold Response

Mustached bats, Pteronotus parnellii parnellii,emit echolocation pulses that consist of four harmonics with a fundamental consisting of a constant frequency (CF1-4) component followed by a short, frequency-modulated (FM1-4) component. During flight, the pulse fundamental frequency is systematically lowered by an amount proportional to the velocity of the bat relative to the background so that the Doppler-shifted echo CF2 is maintained within a narrowband centered at ∼61 kHz. In the primary auditory cortex, there is an expanded representation of 60.6- to 63.0-kHz frequencies in the “Doppler-shifted CF processing” (DSCF) area where neurons show sharp, level-tolerant frequency tuning. More than 80% of DSCF neurons are facilitated by specific frequency combinations of ∼25 kHz (BFlow) and ∼61 kHz (BFhigh). To examine the role of these neurons for fine frequency discrimination during echolocation, we measured the basic response parameters for facilitation to synthesized echolocation signals varied in frequency, intensity, and in their temporal structure. Excitatory response areas were determined by presenting single CF tones, facilitative curves were obtained by presenting paired CF tones. All neurons showing facilitation exhibit at least two facilitative response areas, one of broad spectral tuning to frequencies centered at BFlowcorresponding to a frequency in the lower half of the echolocation pulse FM1 sweep and another of sharp tuning to frequencies centered at BFhigh corresponding to the CF2 in the echo. Facilitative response areas for BFhigh are broadened by ∼0.38 kHz at both the best amplitude and 50 dB above threshold response and show lower thresholds compared with the single-tone excitatory BFhigh response areas. An increase in the sensitivity of DSCF neurons would lead to target detection from farther away and/or for smaller targets than previously estimated on the basis of single-tone responses to BFhigh. About 15% of DSCF neurons show oblique excitatory and facilitatory response areas at BFhigh so that the center frequency of the frequency-response function at any amplitude decreases with increasing stimulus amplitudes. DSCF neurons also have inhibitory response areas that either skirt or overlap both the excitatory and facilitatory response areas for BFhigh and sometimes for BFlow. Inhibition by a broad range of frequencies contributes to the observed sharpness of frequency tuning in these neurons. Recordings from orthogonal penetrations show that the best frequencies for facilitation as well as excitation do not change within a cortical column. There does not appear to be any systematic representation of facilitation ratios across the cortical surface of the DSCF area.

scholarly journals Coding of Amplitude Modulation in Primary Auditory Cortex

2011 ◽  
Vol 105 (2) ◽  
pp. 582-600 ◽  
Author(s):  
Pingbo Yin ◽  
Jeffrey S. Johnson ◽  
Kevin N. O'Connor ◽  
Mitchell L. Sutter
Keyword(s):  
Auditory Cortex ◽  
Mixed Mode ◽  
Modulation Frequency ◽  
Primary Auditory Cortex ◽  
Auditory Pathway ◽  
Temporal Modulation ◽  
Temporal Synchrony ◽  
Trial Analysis ◽  
A1 Neurons ◽  
Vector Strength

Conflicting results have led to different views about how temporal modulation is encoded in primary auditory cortex (A1). Some studies find a substantial population of neurons that change firing rate without synchronizing to temporal modulation, whereas other studies fail to see these nonsynchronized neurons. As a result, the role and scope of synchronized temporal and nonsynchronized rate codes in AM processing in A1 remains unresolved. We recorded A1 neurons' responses in awake macaques to sinusoidal AM noise. We find most (37–78%) neurons synchronize to at least one modulation frequency (MF) without exhibiting nonsynchronized responses. However, we find both exclusively nonsynchronized neurons (7–29%) and “mixed-mode” neurons (13–40%) that synchronize to at least one MF and fire nonsynchronously to at least one other. We introduce new measures for modulation encoding and temporal synchrony that can improve the analysis of how neurons encode temporal modulation. These include comparing AM responses to the responses to unmodulated sounds, and a vector strength measure that is suitable for single-trial analysis. Our data support a transformation from a temporally based population code of AM to a rate-based code as information ascends the auditory pathway. The number of mixed-mode neurons found in A1 indicates this transformation is not yet complete, and A1 neurons may carry multiplexed temporal and rate codes.

Evidence of sharp frequency tuning in the human auditory cortex

1994 ◽  
Vol 75 (1-2) ◽  
pp. 67-74 ◽  
Author(s):  
Mikko Sams ◽  
Riitta Salmelin
Keyword(s):  
Auditory Cortex ◽  
Frequency Tuning ◽  
Human Auditory Cortex

Current Source Density Profiles of Stimulus-Specific Adaptation in Rat Auditory Cortex

2009 ◽  
Vol 102 (3) ◽  
pp. 1483-1490 ◽  
Author(s):  
Francois D. Szymanski ◽  
Jose A. Garcia-Lazaro ◽  
Jan W. H. Schnupp
Keyword(s):  
Auditory Cortex ◽  
Current Source ◽  
Primary Auditory Cortex ◽  
Auditory Pathway ◽  
Afferent Input ◽  
Current Source Density ◽  
Specific Adaptation ◽  
Source Density ◽  
Density Analysis ◽  
Layer V

Neurons in primary auditory cortex (A1) are known to exhibit a phenomenon known as stimulus-specific adaptation (SSA), which means that, when tested with pure tones, they will respond more strongly to a particular frequency if it is presented as a rare, unexpected “oddball” stimulus than when the same stimulus forms part of a series of common, “standard” stimuli. Although SSA has occasionally been observed in midbrain neurons that form part of the paraleminscal auditory pathway, it is thought to be weak, rare, or nonexistent among neurons of the leminscal pathway that provide the main afferent input to A1, so that SSA seen in A1 is likely generated within A1 by local mechanisms. To study the contributions that neural processing within the different cytoarchitectonic layers of A1 may make to SSA, we recorded local field potentials in A1 of the rat in response to standard and oddball tones and subjected these to current source density analysis. Although our results show that SSA can be observed throughout all layers of A1, right from the earliest part of the response, there are nevertheless significant differences between layers, with SSA becoming significantly stronger as stimulus-related activity passes from the main thalamorecipient layers III and IV to layer V.

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