Responses of Neurons in Primary Auditory Cortex (A1) to Pure Tones in the Halothane-Anesthetized Cat

2006 ◽  
Vol 95 (6) ◽  
pp. 3756-3769 ◽  
Author(s):  
Dina Moshitch ◽  
Liora Las ◽  
Nachum Ulanovsky ◽  
Omer Bar-Yosef ◽  
Israel Nelken
Keyword(s):  
Auditory Cortex ◽  
Frequency Tuning ◽  
Sensory Information ◽  
Primary Auditory Cortex ◽  
Response Patterns ◽  
Neural Responses ◽  
Standard Classification ◽  
A1 Neurons ◽  
Pure Tones ◽  
Stimulus Offset

The responses of primary auditory cortex (A1) neurons to pure tones in anesthetized animals are usually described as having mostly narrow, unimodal frequency tuning and phasic responses. Thus A1 neurons are believed not to carry much information about pure tones beyond sound onset. In awake cats, however, tuning may be wider and responses may have substantially longer duration. Here we analyze frequency-response areas (FRAs) and temporal-response patterns of 1,828 units in A1 of halothane-anesthetized cats. Tuning was generally wide: the total bandwidth at 40 dB above threshold was 4 octaves on average. FRA shapes were highly variable and many were diffuse, not fitting into standard classification schemes. Analyzing the temporal patterns of the largest responses of each unit revealed that only 9% of the units had pure onset responses. About 40% of the units had sustained responses throughout stimulus duration (115 ms) and 13% of the units had significant and informative responses lasting 300 ms and more after stimulus offset. We conclude that under halothane anesthesia, neural responses show many of the characteristics of awake responses. Furthermore, A1 units maintain sensory information in their activity not only throughout sound presentation but also for hundreds of milliseconds after stimulus offset, thus possibly playing a role in sensory memory.

Representations of Cat Meows and Human Vowels in the Primary Auditory Cortex of Awake Cats

2008 ◽  
Vol 99 (5) ◽  
pp. 2305-2319 ◽  
Author(s):  
Ling Qin ◽  
Jing Yu Wang ◽  
Yu Sato
Keyword(s):  
Auditory Cortex ◽  
Neuronal Response ◽  
Primary Auditory Cortex ◽  
Stimulus Onset ◽  
Response Patterns ◽  
Amplitude Envelope ◽  
Neural Responses ◽  
Continuous Responses ◽  
A1 Neurons ◽  
Sustained Responses

Previous investigation of neural responses to cat meows in the primary auditory cortex (A1) of the anesthetized cat revealed a preponderance of phasic responses aligned to stimulus onset, offset, or envelope peaks. Sustained responses during stationary components of the stimulus were rarely seen. This observation motivates further investigation into how stationary components of naturalistic auditory stimuli are encoded by A1 neurons. We therefore explored neuronal response patterns in A1 of the awake cat using natural meows, time-reversed meows, and human vowels as stimuli. We found heterogeneous response types: ∼2/3 of units classified as “phasic cells” responding only to amplitude envelope variations and the remaining 1/3 were “phasic-tonic cells” with continuous responses during the stationary components. The classification was upheld across all stimuli tested for a given cell. The differences of phasic responses were correlated with amplitude-envelope differences in the early stimulus portion (<100 ms), whereas the differences between tonic responses were correlated with ongoing spectral differences in the later stimulus portion. Phasic-tonic cells usually had a characteristic frequency (CF) <5 kHz, which corresponded to the dominant spectral range of vocalizations, suggesting that the cells encode spectral information. Phasic cells had CFs across the tested frequency range (<16 kHz). Instantaneous firing rates for natural and time-reversed meows were different, but mean rates for different categories of stimuli were similar. Evidence for cat's A1 preferring conspecific meows was not found. These functionally heterogeneous responses may serve to encode ongoing changes in sound spectra or amplitude envelope occurring throughout the entirety of the sound stimulus.

scholarly journals Local Homogeneity of Tonotopic Organization in the Primary Auditory Cortex of Marmosets

2018 ◽  
Author(s):  
Huan-huan Zeng ◽  
Jun-feng Huang ◽  
Ming Chen ◽  
Yun-qing Wen ◽  
Zhi-ming Shen ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Large Scale ◽  
Frequency Tuning ◽  
Primary Auditory Cortex ◽  
Primate Species ◽  
Tonotopic Organization ◽  
Brain Structure And Function ◽  
A1 Neurons ◽  
Cortical Regions

AbstractMarmoset has emerged as a useful non-human primate species for studying the brain structure and function. Previous studies on the mouse primary auditory cortex (A1) showed that neurons with preferential frequency tuning responses are mixed within local cortical regions, despite a large-scale tonotopic organization. Here we found that frequency tuning properties of marmoset A1 neurons are highly uniform within local cortical regions. We first defined tonotopic map of A1 using intrinsic optical imaging, and then used in vivo two-photon calcium imaging of large neuronal populations to examine the tonotopic preference at the single-cell level. We found that tuning preferences of layer 2/3 neurons were highly homogeneous over hundreds of micrometers in both horizontal and vertical directions. Thus, marmoset A1 neurons are distributed in a tonotopic manner at both macro- and microscopic levels. Such organization is likely to be important for the organization of auditory circuits in the primate brain.

scholarly journals Local homogeneity of tonotopic organization in the primary auditory cortex of marmosets

2019 ◽  
Vol 116 (8) ◽  
pp. 3239-3244 ◽  
Author(s):  
Huan-huan Zeng ◽  
Jun-feng Huang ◽  
Ming Chen ◽  
Yun-qing Wen ◽  
Zhi-ming Shen ◽  
...  
Keyword(s):  
Auditory Cortex ◽  
Large Scale ◽  
Frequency Tuning ◽  
Primary Auditory Cortex ◽  
Primate Species ◽  
Tonotopic Organization ◽  
Brain Structure And Function ◽  
A1 Neurons ◽  
Cortical Regions

Marmoset has emerged as a useful nonhuman primate species for studying brain structure and function. Previous studies on the mouse primary auditory cortex (A1) showed that neurons with preferential frequency-tuning responses are mixed within local cortical regions, despite a large-scale tonotopic organization. Here we found that frequency-tuning properties of marmoset A1 neurons are highly uniform within local cortical regions. We first defined the tonotopic map of A1 using intrinsic optical imaging and then used in vivo two-photon calcium imaging of large neuronal populations to examine the tonotopic preference at the single-cell level. We found that tuning preferences of layer 2/3 neurons were highly homogeneous over hundreds of micrometers in both horizontal and vertical directions. Thus, marmoset A1 neurons are distributed in a tonotopic manner at both macro- and microscopic levels. Such organization is likely to be important for the organization of auditory circuits in the primate brain.

Auditory Imagery Modulates Frequency-specific Areas in the Human Auditory Cortex

2013 ◽  
Vol 25 (2) ◽  
pp. 175-187 ◽  
Author(s):  
Jihoon Oh ◽  
Jae Hyung Kwon ◽  
Po Song Yang ◽  
Jaeseung Jeong
Keyword(s):  
Auditory Cortex ◽  
High Frequency ◽  
Low Frequency ◽  
Primary Auditory Cortex ◽  
Auditory Imagery ◽  
Neural Responses ◽  
Top Down ◽  
Visual Areas ◽  
Control Functional ◽  
Response Area

Neural responses in early sensory areas are influenced by top–down processing. In the visual system, early visual areas have been shown to actively participate in top–down processing based on their topographical properties. Although it has been suggested that the auditory cortex is involved in top–down control, functional evidence of topographic modulation is still lacking. Here, we show that mental auditory imagery for familiar melodies induces significant activation in the frequency-responsive areas of the primary auditory cortex (PAC). This activation is related to the characteristics of the imagery: when subjects were asked to imagine high-frequency melodies, we observed increased activation in the high- versus low-frequency response area; when the subjects were asked to imagine low-frequency melodies, the opposite was observed. Furthermore, we found that A1 is more closely related to the observed frequency-related modulation than R in tonotopic subfields of the PAC. Our findings suggest that top–down processing in the auditory cortex relies on a mechanism similar to that used in the perception of external auditory stimuli, which is comparable to early visual systems.

Neural Responses in Primary Auditory Cortex Mimic Psychophysical, Across-Frequency-Channel, Gap-Detection Thresholds

2000 ◽  
Vol 84 (3) ◽  
pp. 1453-1463 ◽  
Author(s):  
Jos J. Eggermont
Keyword(s):  
Auditory Cortex ◽  
Cortical Neurons ◽  
Primary Auditory Cortex ◽  
Noise Burst ◽  
Gap Detection ◽  
Frequency Content ◽  
Neural Responses ◽  
Frequency Channel ◽  
Interval Representations ◽  
Onset Response

Responses of single- and multi-units in primary auditory cortex were recorded for gap-in-noise stimuli for different durations of the leading noise burst. Both firing rate and inter-spike interval representations were evaluated. The minimum detectable gap decreased in exponential fashion with the duration of the leading burst to reach an asymptote for durations of 100 ms. Despite the fact that leading and trailing noise bursts had the same frequency content, the dependence on leading burst duration was correlated with psychophysical estimates of across frequency channel (different frequency content of leading and trailing burst) gap thresholds in humans. The duration of the leading burst plus that of the gap was represented in the all-order inter-spike interval histograms for cortical neurons. The recovery functions for cortical neurons could be modeled on basis of fast synaptic depression and after-hyperpolarization produced by the onset response to the leading noise burst. This suggests that the minimum gap representation in the firing pattern of neurons in primary auditory cortex, and minimum gap detection in behavioral tasks is largely determined by properties intrinsic to those, or potentially subcortical, cells.

Heterogeneous Neuronal Responses to Frequency-Modulated Tones in the Primary Auditory Cortex of Awake Cats

2008 ◽  
Vol 100 (3) ◽  
pp. 1622-1634 ◽  
Author(s):  
Ling Qin ◽  
JingYu Wang ◽  
Yu Sato
Keyword(s):  
Receptive Field ◽  
Auditory Cortex ◽  
Response Pattern ◽  
Primary Auditory Cortex ◽  
Neuronal Responses ◽  
Discrete Response ◽  
A Cell ◽  
Pure Tones ◽  
Awake Cats ◽  
Sweep Speed

Previous studies in anesthetized animals reported that the primary auditory cortex (A1) showed homogenous phasic responses to FM tones, namely a transient response to a particular instantaneous frequency when FM sweeps traversed a neuron's tone-evoked receptive field (TRF). Here, in awake cats, we report that A1 cells exhibit heterogeneous FM responses, consisting of three patterns. The first is continuous firing when a slow FM sweep traverses the receptive field of a cell with a sustained tonal response. The duration and amplitude of FM response decrease with increasing sweep speed. The second pattern is transient firing corresponding to the cell's phasic tonal response. This response could be evoked only by a fast FM sweep through the cell's TRF, suggesting a preference for fast FM. The third pattern was associated with the off response to pure tones and was composed of several discrete response peaks during slow FM stimulus. These peaks were not predictable from the cell's tonal response but reliably reflected the time when FM swept across specific frequencies. Our A1 samples often exhibited a complex response pattern, combining two or three of the basic patterns above, resulting in a heterogeneous response population. The diversity of FM responses suggests that A1 use multiple mechanisms to fully represent the whole range of FM parameters, including frequency extent, sweep speed, and direction.

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.

Functional Organization of Squirrel Monkey Primary Auditory Cortex: Responses to Pure Tones

2001 ◽  
Vol 85 (4) ◽  
pp. 1732-1749 ◽  
Author(s):  
Steven W. Cheung ◽  
Purvis H. Bedenbaugh ◽  
Srikantan S. Nagarajan ◽  
Christoph E. Schreiner
Keyword(s):  
Receptive Field ◽  
Auditory Cortex ◽  
Squirrel Monkey ◽  
Spatial Organization ◽  
Functional Organization ◽  
Primary Auditory Cortex ◽  
Complex Sound ◽  
Sound Coding ◽  
Field Gradients ◽  
Pure Tones

The spatial organization of response parameters in squirrel monkey primary auditory cortex (AI) accessible on the temporal gyrus was determined with the excitatory receptive field to pure tone stimuli. Dense, microelectrode mapping of the temporal gyrus in four animals revealed that characteristic frequency (CF) had a smooth, monotonic gradient that systematically changed from lower values (0.5 kHz) in the caudoventral quadrant to higher values (5–6 kHz) in the rostrodorsal quadrant. The extent of AI on the temporal gyrus was ∼4 mm in the rostrocaudal axis and 2–3 mm in the dorsoventral axis. The entire length of isofrequency contours below 6 kHz was accessible for study. Several independent, spatially organized functional response parameters were demonstrated for the squirrel monkey AI. Latency, the asymptotic minimum arrival time for spikes with increasing sound pressure levels at CF, was topographically organized as a monotonic gradient across AI nearly orthogonal to the CF gradient. Rostral AI had longer latencies (range = 4 ms). Threshold and bandwidth co-varied with the CF. Factoring out the contribution of the CF on threshold variance, residual threshold showed a monotonic gradient across AI that had higher values (range = 10 dB) caudally. The orientation of the threshold gradient was significantly different from the CF gradient. CF-corrected bandwidth, residual Q10, was spatially organized in local patches of coherent values whose loci were specific for each monkey. These data support the existence of multiple, overlying receptive field gradients within AI and form the basis to develop a conceptual framework to understand simple and complex sound coding in mammals.

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.

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