Responses in area hMT+ reflect tuning for both auditory frequency and motion after blindness early in life

Previous studies report that human middle temporal complex (hMT+) is sensitive to auditory motion in early-blind individuals. Here, we show that hMT+ also develops selectivity for auditory frequency after early blindness, and that this selectivity is maintained after sight recovery in adulthood. Frequency selectivity was assessed using both moving band-pass and stationary pure-tone stimuli. As expected, within primary auditory cortex, both moving and stationary stimuli successfully elicited frequency-selective responses, organized in a tonotopic map, for all subjects. In early-blind and sight-recovery subjects, we saw evidence for frequency selectivity within hMT+ for the auditory stimulus that contained motion. We did not find frequency-tuned responses within hMT+ when using the stationary stimulus in either early-blind or sight-recovery subjects. We saw no evidence for auditory frequency selectivity in hMT+ in sighted subjects using either stimulus. Thus, after early blindness, hMT+ can exhibit selectivity for auditory frequency. Remarkably, this auditory frequency tuning persists in two adult sight-recovery subjects, showing that, in these subjects, auditory frequency-tuned responses can coexist with visually driven responses in hMT+.

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The effects of contrast on visual orientation and spatial frequency discrimination: a comparison of single cells and behavior

Journal of Neurophysiology ◽

10.1152/jn.1987.57.3.773 ◽

1987 ◽

Vol 57 (3) ◽

pp. 773-786 ◽

Cited By ~ 186

Author(s):

B. C. Skottun ◽

A. Bradley ◽

G. Sclar ◽

I. Ohzawa ◽

R. D. Freeman

Keyword(s):

Spatial Frequency ◽

Striate Cortex ◽

Frequency Tuning ◽

Single Cells ◽

Frequency Discrimination ◽

Frequency Selectivity ◽

Response Amplitude ◽

Visual Orientation ◽

Characteristic Analysis ◽

Response Variance

We have compared the effects of contrast on human psychophysical orientation and spatial frequency discrimination thresholds and on the responses of individual neurons in the cat's striate cortex. Contrast has similar effects on orientation and spatial frequency discrimination: as contrast is increased above detection threshold, orientation and spatial frequency discrimination performance improves but reaches maximum levels at quite low contrasts. Further increases in contrast produce no further improvements in discrimination. We measured the effects of contrast on response amplitude, orientation and spatial frequency selectivity, and response variance of neurons in the cat's striate cortex. Orientation and spatial frequency selectivity vary little with contrast. Also, the ratio of response variance to response mean is unaffected by contrast. Although, in many cells, response amplitude increases approximately linearly with log contrast over most of the visible range, some cells show complete or partial saturation of response amplitude at medium contrasts. Therefore, some cells show a clear increase in slope of the orientation and spatial frequency tuning functions with increasing contrast, whereas in others the slopes reach maximum values at medium contrasts. Using receiver operating characteristic analysis, we estimated the minimum orientation and spatial frequency differences that can be signaled reliably as a response change by an individual cell. This analysis shows that, on average, the discrimination of orientation or spatial frequency improves with contrast at low contrasts more than at higher contrasts. Using the optimal stimulus for each cell, we estimated the contrast threshold of 48 neurons. Most cells had contrast thresholds below 5%. Thresholds were only slightly higher for nonoptimal stimuli. Therefore, increasing the contrast of sinusoidal gratings above approximately 10% will not produce large increases in the number of responding cells. The observed effects of contrast on the response characteristics of nonsaturating cortical cells do not appear consistent with the psychophysical results. Cells that reach their maximum response at low-to-medium contrasts may account for the contrast independence of psychophysical orientation and spatial frequency discrimination thresholds at medium and high contrasts.

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Selective Corticofugal Modulation on Sound Processing in Auditory Thalamus of Awake Marmosets

10.1101/2021.03.13.435231 ◽

2021 ◽

Author(s):

Yuanqing Zhang ◽

Xiaohui Wang ◽

Lin Zhu ◽

Siyi Bai ◽

Rui Li ◽

...

Keyword(s):

Sensory Processing ◽

Frequency Tuning ◽

Signal To Noise Ratio ◽

Medial Geniculate Body ◽

Primary Auditory Cortex ◽

Medial Geniculate ◽

Auditory Response ◽

Corticofugal Feedback ◽

Corticothalamic Feedback

Cortical feedback has long been considered crucial for modulation of sensory processing. In the mammalian auditory system, studies have suggested that corticofugal feedback can have excitatory, inhibitory, or both effects on the response of subcortical neurons, leading to controversies regarding the role of corticothalamic influence. This has been further complicated by studies conducted under different brain states. In the current study, we used cryo-inactivation in the primary auditory cortex (A1) to examine the role of corticothalamic feedback on medial geniculate body (MGB) neurons in awake marmosets. The primary effects of A1 inactivation were a frequency-specific decrease in the auditory response of MGB neurons coupled with an increased spontaneous firing rate, which together resulted in a decrease in the signal-to-noise ratio. In addition, we report for the first-time that A1 robustly modulated the long-lasting sustained response of MGB neurons which changed the frequency tuning after A1 inactivation, e.g., neurons with sharp tuning increased tuning bandwidth whereas those with broad tuning decreased tuning bandwidth. Taken together, our results demonstrate that corticothalamic modulation in awake marmosets serves to enhance sensory processing in a way similar to center-surround models proposed in visual and somatosensory systems, a finding which supports common principles of corticothalamic processing across sensory systems.

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

Frontiers in Neuroscience ◽

10.3389/fnins.2021.749923 ◽

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.

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

Journal of Neurophysiology ◽

10.1152/jn.1999.82.5.2327 ◽

1999 ◽

Vol 82 (5) ◽

pp. 2327-2345 ◽

Cited By ~ 42

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.

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Responses of single neurons in physiologically defined primary auditory cortex (AI) of the cat: frequency tuning and responses to intensity.

Journal of Neurophysiology ◽

10.1152/jn.1981.45.1.48 ◽

1981 ◽

Vol 45 (1) ◽

pp. 48-58 ◽

Cited By ~ 138

Author(s):

D P Phillips ◽

D R Irvine

Keyword(s):

Auditory Cortex ◽

Frequency Tuning ◽

Primary Auditory Cortex ◽

Single Neurons

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Representation of Spectral and Temporal Sound Features in Three Cortical Fields of the Cat. Similarities Outweigh Differences

Journal of Neurophysiology ◽

10.1152/jn.1998.80.5.2743 ◽

1998 ◽

Vol 80 (5) ◽

pp. 2743-2764 ◽

Cited By ~ 106

Author(s):

Jos J. Eggermont

Keyword(s):

Auditory Cortex ◽

Frequency Tuning ◽

Tuning Curve ◽

Primary Auditory Cortex ◽

Temporal Coding ◽

Modulation Transfer ◽

Temporal Response ◽

Response Latencies ◽

Response Properties ◽

Sound Features

Eggermont, Jos J. Representation of spectral and temporal sound features in three cortical fields of the cat. Similarities outweigh differences. J. Neurophysiol. 80: 2743–2764, 1998. This study investigates the degree of similarity of three different auditory cortical areas with respect to the coding of periodic stimuli. Simultaneous single- and multiunit recordings in response to periodic stimuli were made from primary auditory cortex (AI), anterior auditory field (AAF), and secondary auditory cortex (AII) in the cat to addresses the following questions: is there, within each cortical area, a difference in the temporal coding of periodic click trains, amplitude-modulated (AM) noise bursts, and AM tone bursts? Is there a difference in this coding between the three cortical fields? Is the coding based on the temporal modulation transfer function (tMTF) and on the all-order interspike-interval (ISI) histogram the same? Is the perceptual distinction between rhythm and roughness for AM stimuli related to a temporal versus spatial representation of AM frequency in auditory cortex? Are interarea differences in temporal response properties related to differences in frequency tuning? The results showed that: 1) AM stimuli produce much higher best modulation frequencies (BMFs) and limiting rates than periodic click trains. 2) For periodic click trains and AM noise, the BMFs and limiting rates were not significantly different for the three areas. However, for AM tones the BMF and limiting rates were about a factor 2 lower in AAF compared with the other areas. 3) The representation of stimulus periodicity in ISIs resulted in significantly lower mean BMFs and limiting rates compared with those estimated from the tMTFs. The difference was relatively small for periodic click trains but quite large for both AM stimuli, especially in AI and AII. 4) Modulation frequencies <20 Hz were represented in the ISIs, suggesting that rhythm is coded in auditory cortex in temporal fashion. 5) In general only a modest interdependence of spectral- and temporal-response properties in AI and AII was found. The BMFs were correlated positively with characteristic frequency in AAF. The limiting rate was positively correlated with the frequency-tuning curve bandwidth in AI and AII but not in AAF. Only in AAF was a correlation between BMF and minimum latency was found. Thus whereas differences were found in the frequency-tuning curve bandwidth and minimum response latencies among the three areas, the coding of periodic stimuli in these areas was fairly similar with the exception of the very poor representation of AM tones in AII. This suggests a strong parallel processing organization in auditory cortex.

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Auditory motion processing after early blindness

Journal of Vision ◽

10.1167/14.13.4 ◽

2014 ◽

Vol 14 (13) ◽

pp. 4-4 ◽

Cited By ~ 29

Author(s):

F. Jiang ◽

G. C. Stecker ◽

I. Fine

Keyword(s):

Motion Processing ◽

Auditory Motion ◽

Early Blindness

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Modulation of thalamic auditory neurons by the primary auditory cortex

Journal of Neurophysiology ◽

10.1152/jn.00251.2012 ◽

2012 ◽

Vol 108 (3) ◽

pp. 935-942 ◽

Cited By ~ 17

Author(s):

Jie Tang ◽

Weiguo Yang ◽

Nobuo Suga

Keyword(s):

Signal Processing ◽

Electric Stimulation ◽

Frequency Tuning ◽

Primary Auditory Cortex ◽

Auditory Signal ◽

Tuning Curves ◽

Auditory Responses ◽

Auditory Signal Processing ◽

Plastic Changes ◽

Stimulation Of

The central auditory system consists of the lemniscal and nonlemniscal pathways or systems, which are anatomically and physiologically different from each other. In the thalamus, the ventral division of the medial geniculate body (MGBv) belongs to the lemniscal system, whereas its medial (MGBm) and dorsal (MGBd) divisions belong to the nonlemniscal system. Lemniscal neurons are sharply frequency-tuned and provide highly frequency-specific information to the primary auditory cortex (AI), whereas nonlemniscal neurons are generally broadly frequency-tuned and project widely to cortical auditory areas including AI. These two systems are presumably different not only in auditory signal processing, but also in eliciting cortical plastic changes. Electric stimulation of narrowly frequency-tuned MGBv neurons evokes the shift of the frequency-tuning curves of AI neurons toward the tuning curves of the stimulated MGBv neurons (tone-specific plasticity). In contrast, electric stimulation of broadly frequency-tuned MGBm neurons augments the auditory responses of AI neurons and broadens their frequency-tuning curves (nonspecific plasticity). In our current studies, we found that electric stimulation of AI evoked tone-specific plastic changes of the MGBv neurons, whereas it degraded the frequency tuning of MGBm neurons by inhibiting their auditory responses. AI apparently modulates the lemniscal and nonlemniscal thalamic neurons in quite different ways. High MGBm activity presumably makes AI neurons less favorable for fine auditory signal processing, whereas high MGBv activity makes AI neurons more suitable for fine processing of specific auditory signals and reduces MGBm activity.

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