scholarly journals Frequency and Intensity Response Properties of Single Neurons in the Auditory Cortex of the Behaving Macaque Monkey

2000 ◽  
Vol 83 (4) ◽  
pp. 2315-2331 ◽  
Author(s):  
Gregg H. Recanzone ◽  
Darren C. Guard ◽  
Mimi L. Phan
Keyword(s):  
Auditory Cortex ◽  
Cortical Neurons ◽  
Spatial Organization ◽  
Frequency Tuning ◽  
Response Property ◽  
Cortical Function ◽  
Lateral Field ◽  
Response Properties ◽  
Cortical Areas ◽  
Physiological Differences

Response properties of auditory cortical neurons measured in anesthetized preparations have provided important information on the physiological differences between neurons in different auditory cortical areas. Studies in the awake animal, however, have been much less common, and the physiological differences noted may reflect differences in the influence of anesthetics on neurons in different cortical areas. Because the behaving monkey is gaining popularity as an animal model in studies exploring auditory cortical function, it has become critical to physiologically define the response properties of auditory cortical neurons in this preparation. This study documents the response properties of single cortical neurons in the primary and surrounding auditory cortical fields in monkeys performing an auditory discrimination task. We found that neurons with the shortest latencies were located in the primary auditory cortex (AI). Neurons in the rostral field had the longest latencies and the narrowest intensity and frequency tuning, neurons in the caudomedial field had the broadest frequency tuning, and neurons in the lateral field had the most monotonic rate/level functions of the four cortical areas studied. These trends were revealed by comparing response properties across the population of studied neurons, but there was considerable variability between neurons for each response parameter other than characteristic frequency (CF) in each cortical area. Although the neuronal CFs showed a systematic spatial organization across AI, no such systematic organization was apparent for any other response property in AI or the adjacent cortical areas. The results of this study indicate that there are physiological differences between auditory cortical fields in the behaving monkey consistent with previous studies in the anesthetized animal and provide insights into the functional role of these cortical areas in processing acoustic information.

Spatial Organization of Frequency Response Areas and Rate/Level Functions in the Developing AI

2004 ◽  
Vol 91 (2) ◽  
pp. 841-854 ◽  
Author(s):  
Ben H. Bonham ◽  
Steven W. Cheung ◽  
Benoit Godey ◽  
Christoph E. Schreiner
Keyword(s):  
Cortical Neurons ◽  
Spatial Organization ◽  
Frequency Tuning ◽  
Primary Auditory Cortex ◽  
Two Dimensions ◽  
Cortical Region ◽  
Response Properties ◽  
Rate Level ◽  
Bandwidth Tuning ◽  
Adult Cats

The current study was conducted to extend our understanding of changes in spatial organization and response properties of cortical neurons in the developing mammalian forebrain. Extracellular multiunit responses to tones were recorded from a dense array of penetrations covering entire isofrequency contours in the primary auditory cortex (AI) of pentobarbital anesthetized kittens. Ages ranged from postnatal day 14 (P14), shortly after acquisition of normal auditory response thresholds, through postnatal day 111 (P111), when the kittens were largely mature. Spatial organization of the AI was tonotopically ordered by P14. The tonotopic gradient decreased with chronological maturation. At P14 the gradient was about 3.5 kHz/mm. By P111 it had declined to about 2.5 kHz/mm, so that the cortical region encompassing a fixed 3- to 15-kHz frequency range enlarged along its posterior-anterior dimension. Response properties of developing AI neurons changed in both frequency selectivity and intensity selectivity. The mean frequency tuning bandwidth increased with age. Initially, tuning bandwidths were narrow throughout the entire AI. With progressive maturation, broader bandwidths were observed in areas dorsal and ventral to a central region in which neurons remained narrowly tuned. The resulting spatial organization of tuning bandwidth was similar to that reported in adult cats. The majority of recording sites manifested nonmonotonic rate/level functions at all ages. However, the proportion of sites with monotonic rate/level functions increased with age. No spatial organization of rate/level functions (monotonic and nonmonotonic) was observed through P111. The relatively late development of bandwidth tuning in the AI compared with the early presence of tonotopic organization suggests that different developmental processes are responsible for structuring these two dimensions of acoustic selectivity.

Monaural inhibition in cat auditory cortex

1995 ◽  
Vol 73 (5) ◽  
pp. 1876-1891 ◽  
Author(s):  
M. B. Calford ◽  
M. N. Semple
Keyword(s):  
Auditory Cortex ◽  
Lateral Inhibition ◽  
Cortical Neurons ◽  
Frequency Tuning ◽  
Inhibitory Response ◽  
Forward Masking ◽  
Excitatory Response ◽  
Rate Level ◽  
Wide Range ◽  
Response Area

1. Several studies of auditory cortex have examined the competitive inhibition that can occur when appropriate sounds are presented to each ear. However, most cortical neurons also show both excitation and inhibition in response to presentation of stimuli at one ear alone. The extent of such inhibition has not been described. Forward masking, in which a variable masking stimulus was followed by a fixed probe stimulus (within the excitatory response area), was used to examine the extent of monaural inhibition for neurons in primary auditory cortex of anesthetized cats (barbiturate or barbiturate-ketamine). Both the masking and probe stimuli were 50-ms tone pips presented to the contralateral ear. Most cortical neurons showed significant forward masking at delays beyond which masking effects in the auditory nerve are relatively small compared with those seen in cortical neurons. Analysis was primarily concerned with such components. Standard rate-level functions were also obtained and were examined for nonmonotonicity, an indication of level-dependent monaural inhibition. 2. Consistent with previous reports, a wide range of frequency tuning properties (excitatory response area shapes) was found in cortical neurons. This was matched by a wide range of forward-masking-derived inhibitory response areas. At the most basic level of analysis, these were classified according to the presence of lateral inhibition, i.e., where a probe tone at a neuron's characteristic frequency was masked by tones outside the limits of the excitatory response area. Lateral inhibition was a property of 38% of the sampled neurons. Such neurons represented 77% of those with nonmonotonic rate-level functions, indicating a strong correlation between the two indexes of monaural inhibition; however, the shapes of forward masking inhibitory response areas did not usually correspond with those required to account for the "tuning" of a neuron. In addition, it was found that level-dependent inhibition was not added to by forward masking inhibition. 3. Analysis of the discharges to individual stimulus pair presentations, under conditions of partial masking, revealed that discharges to the probe occurred independently of discharges to the preceding masker. This indicates that even when the masker is within a neuron's excitatory response area, forward masking is not a postdischarge habituation phenomenon. However, for most neurons the degree of masking summed over multiple stimulus presentations appears determined by the same stimulus parameters that determine the probability of response to the masker.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

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

1998 ◽  
Vol 80 (5) ◽  
pp. 2743-2764 ◽  
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.

Noradrenergic Induction of Selective Plasticity in the Frequency Tuning of Auditory Cortex Neurons

2004 ◽  
Vol 92 (3) ◽  
pp. 1445-1463 ◽  
Author(s):  
Yves Manunta ◽  
Jean-Marc Edeline
Keyword(s):  
Auditory Cortex ◽  
Cortical Neurons ◽  
Cortical Plasticity ◽  
Frequency Tuning ◽  
Tone Frequency ◽  
Cortical Cells ◽  
Tuning Curves ◽  
Alpha Receptors ◽  
Frequency Changes ◽  
Selective Effects

Neuromodulators have long been viewed as permissive factors in experience-induced cortical plasticity, both during development and in adulthood. Experiments performed over the last two decades have reported the potency of acetylcholine to promote changes in functional properties of cortical cells in the auditory, visual, and somatosensory modality. In contrast, very few attempts were made with the monoaminergic systems. The present study evaluates how repeated presentation of brief pulses of noradrenaline (NA) concomitant with presentation of a particular tone frequency changes the frequency tuning curves of auditory cortex neurons determined at 20 dB above threshold. After 100 trials of NA-tone pairing, 28% of the cells (19/67) exhibited selective tuning modifications for the frequency paired with NA. All the selective effects were obtained when the paired frequency was within 1/4 of an octave from the initial best frequency. For these cells, selective decreases were prominent (15/19 cases), and these effects lasted ≥15 min after pairing. No selective effects were observed under various control conditions: tone alone ( n = 10 cells), NA alone ( n = 11 cells), pairing with ascorbic acid ( n = 6 cells), or with GABA ( n = 20 cells). Selective effects were observed when the NA-tone pairing was performed in the presence of propranolol (4/10 cells) but not when it was performed in the presence phentolamine (0/13 cells), suggesting that the effects were mediated by alpha receptors. These results indicate that brief increases in noradrenaline concentration can trigger selective modifications in the tuning curves of cortical neurons that, in most of the cases, go in opposite direction compared with those usually reported with acetylcholine.

Anesthesia Changes Frequency Tuning of Neurons in the Rat Primary Auditory Cortex

2001 ◽  
Vol 86 (2) ◽  
pp. 1062-1066 ◽  
Author(s):  
Bernhard H. Gaese ◽  
Joachim Ostwald
Keyword(s):  
Auditory Processing ◽  
Cortical Neurons ◽  
Frequency Tuning ◽  
Primary Auditory Cortex ◽  
Acoustic Stimulation ◽  
Experimental Manipulation ◽  
Central Auditory Processing ◽  
Auditory Neurons ◽  
Response Properties ◽  
Central Auditory Neurons

The vast majority of investigations on central auditory processing so far were conducted under the influence of an anesthetic agent. It remains unclear, however, to what extend even basic response properties of central auditory neurons are influenced by this experimental manipulation. We used a combination of chronic recording in unrestrained animals, computer-controlled randomized acoustic stimulation, and statistical evaluation of responses to directly compare the response characteristics of single neurons in the awake and anesthetized state. Thereby we were able to quantify the effects of pentobarbital/chloral hydrate anesthesia (Equithesin) on rat auditory cortical neurons. During Equithesin anesthesia, only a portion of central neurons were active and some of their basic response properties were changed. Only 29% of the neurons still had a frequency response area. Their tuning sharpness was increased under anesthesia. Most changes are consistent with an enhancement of inhibitory influences during Equithesin anesthesia. Thus when describing response properties of central auditory neurons, the animal's anesthetic state has to be taken into account.

scholarly journals Temporal Modulation Transfer Functions in Cat Primary Auditory Cortex: Separating Stimulus Effects From Neural Mechanisms

2002 ◽  
Vol 87 (1) ◽  
pp. 305-321 ◽  
Author(s):  
Jos J. Eggermont
Keyword(s):  
Auditory Cortex ◽  
Cortical Neurons ◽  
Transfer Functions ◽  
Frequency Tuning ◽  
Primary Auditory Cortex ◽  
Modulation Transfer ◽  
Temporal Modulation ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Low Pass

We present here a comparison between the local field potentials (LFP) and multiunit (MU) responses, comprising 401 single units, in primary auditory cortex (AI) of 31 cats to periodic click trains, gamma-tone and time-reversed gamma-tone trains, AM noise, AM tones, and frequency-modulated (FM) tones. In a large number of cases, the response to all six stimuli was obtained for the same neurons. We investigate whether cortical neurons are likely to respond to all types of repetitive transients and modulated stimuli and whether a dependence on modulating waveform, or tone or noise carrier, exists. In 97% of the recordings, a temporal modulation transfer function (tMTF) for MU activity was obtained for gamma-tone trains, in 92% for periodic click trains, in 83% for time-reversed gamma-tone trains, in 82% for AM noise, in 71% for FM tones, and only in 53% for AM tones. In 31% of the cases, the units responded to all six stimuli in an envelope-following way. These particular units had significantly larger onset responses to each stimulus compared with all other units. The overall response distribution shows the preference of AI units for stimuli with short rise times such as clicks and gamma tones. It also shows a clear asymmetry in the ability to respond to AM noise and AM tones and points to a strong effect of the frequency content of the carrier on the subcortical processing of AM stimuli. Yet all temporal response properties were independent of characteristic frequency and frequency-tuning curve bandwidth. We show that the observed differences in the tMTFs for different stimuli are to a large extent produced by the different degree of phase locking of the neuronal firings to the envelope of the first stimulus in the train or first modulation period. A normalization procedure, based on these synchronization differences, unified the tMTFs for all stimuli except clicks and allowed the identification of a largely stimulus-invariant, low-pass temporal filter function that most likely reflects the properties of synaptic depression and facilitation. For nonclick stimuli, the low-pass filter has a cutoff frequency of ∼10 Hz and a slope of ∼6 dB/octave. For nonclick stimuli, there was a systematic difference between the vector strength for LFPs and MU activity that can likely be attributed to postactivation suppression mechanisms.

scholarly journals Effects of Locomotion in Auditory Cortex Are Not Mediated by the VIP Network

2021 ◽  
Vol 15 ◽  
Author(s):  
Iryna Yavorska ◽  
Michael Wehr
Keyword(s):  
Auditory Cortex ◽  
Cortical Neurons ◽  
Cortical Layers ◽  
Firing Rates ◽  
Cortical Areas ◽  
Layer 4 ◽  
Evoked Activity ◽  
Opposing Effects ◽  
Neuronal Encoding

Movement has a prominent impact on activity in sensory cortex, but has opposing effects on visual and auditory cortex. Both cortical areas feature a vasoactive intestinal peptide-expressing (VIP) disinhibitory circuit, which in visual cortex contributes to the effect of running. In auditory cortex, however, the role of VIP circuitry in running effects remains poorly understood. Running and optogenetic VIP activation are known to differentially modulate sound-evoked activity in auditory cortex, but it is unknown how these effects vary across cortical layers, and whether laminar differences in the roles of VIP circuitry could contribute to the substantial diversity that has been observed in the effects of both movement and VIP activation. Here we asked whether VIP neurons contribute to the effects of running, across the layers of auditory cortex. We found that both running and optogenetic activation of VIP neurons produced diverse changes in the firing rates of auditory cortical neurons, but with distinct effects on spontaneous and evoked activity and with different patterns across cortical layers. On average, running increased spontaneous firing rates but decreased evoked firing rates, resulting in a reduction of the neuronal encoding of sound. This reduction in sound encoding was observed in all cortical layers, but was most pronounced in layer 2/3. In contrast, VIP activation increased both spontaneous and evoked firing rates, and had no net population-wide effect on sound encoding, but strongly suppressed sound encoding in layer 4 narrow-spiking neurons. These results suggest that VIP activation and running act independently, which we then tested by comparing the arithmetic sum of the two effects measured separately to the actual combined effect of running and VIP activation, which were closely matched. We conclude that the effects of locomotion in auditory cortex are not mediated by the VIP network.

Temporally precise population coding of dynamic sounds by auditory cortex

2021 ◽  
Author(s):  
Joshua D Downer ◽  
James Bigelow ◽  
Melissa Runfeldt ◽  
Brian James Malone
Keyword(s):  
Auditory Cortex ◽  
Cortical Neurons ◽  
Frequency Tuning ◽  
Average Rate ◽  
Relative Effectiveness ◽  
Primary Auditory Cortex ◽  
Population Based ◽  
Population Coding ◽  
Complex Sounds ◽  
Animal Vocalizations

Fluctuations in the amplitude envelope of complex sounds provide critical cues for hearing, particularly for speech and animal vocalizations. Responses to amplitude modulation (AM) in the ascending auditory pathway have chiefly been described for single neurons. How neural populations might collectively encode and represent information about AM remains poorly characterized, even in primary auditory cortex (A1). We modeled population responses to AM based on data recorded from A1 neurons in awake squirrel monkeys and evaluated how accurately single trial responses to modulation frequencies from 4 to 512 Hz could be decoded as functions of population size, composition, and correlation structure. We found that a population-based decoding model that simulated convergent, equally weighted inputs was highly accurate and remarkably robust to the inclusion of neurons that were individually poor decoders. By contrast, average rate codes based on convergence performed poorly; effective decoding using average rates was only possible when the responses of individual neurons were segregated, as in classical population decoding models using labeled lines. The relative effectiveness of dynamic rate coding in auditory cortex was explained by shared modulation phase preferences among cortical neurons, despite heterogeneity in rate-based modulation frequency tuning. Our results indicate significant population-based synchrony in primary auditory cortex and suggest that robust population coding of the sound envelope information present in animal vocalizations and speech can be reliably achieved even with indiscriminate pooling of cortical responses. These findings highlight the importance of firing rate dynamics in population-based sensory coding.

scholarly journals Recent advances in understanding the auditory cortex

F1000Research ◽  
2018 ◽  
Vol 7 ◽  
pp. 1555 ◽  
Author(s):  
Andrew J. King ◽  
Sundeep Teki ◽  
Ben D.B. Willmore
Keyword(s):  
Auditory Cortex ◽  
Cortical Neurons ◽  
Spatial Organization ◽  
Real Life ◽  
Brain Regions ◽  
Perceptual Decision Making ◽  
Cognitive Demands ◽  
Complex Sound ◽  
Sound Features ◽  
Specific Contribution

Our ability to make sense of the auditory world results from neural processing that begins in the ear, goes through multiple subcortical areas, and continues in the cortex. The specific contribution of the auditory cortex to this chain of processing is far from understood. Although many of the properties of neurons in the auditory cortex resemble those of subcortical neurons, they show somewhat more complex selectivity for sound features, which is likely to be important for the analysis of natural sounds, such as speech, in real-life listening conditions. Furthermore, recent work has shown that auditory cortical processing is highly context-dependent, integrates auditory inputs with other sensory and motor signals, depends on experience, and is shaped by cognitive demands, such as attention. Thus, in addition to being the locus for more complex sound selectivity, the auditory cortex is increasingly understood to be an integral part of the network of brain regions responsible for prediction, auditory perceptual decision-making, and learning. In this review, we focus on three key areas that are contributing to this understanding: the sound features that are preferentially represented by cortical neurons, the spatial organization of those preferences, and the cognitive roles of the auditory cortex.

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