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PubMed2004

Processing of band-passed noise in the lateral auditory belt cortex of the rhesus monkey.

Neurons in the lateral belt areas of rhesus monkey auditory cortex were stimulated with band-passed noise (BPN) bursts of different bandwidths and center frequencies. Most neurons responded much more vigorously to these sounds than to tone bursts of a single frequency, and it thus became possible to elicit a clear response in 85% of lateral belt neurons. Tuning to center frequency and bandwidth of the BPN bursts was analyzed. Best center frequency varied along the rostrocaudal direction, with 2 reversals defining borders between areas. We confirmed the existence of 2 belt areas (AL and ML) that were laterally adjacent to the core areas (R and A1, respectively) and a third area (CL) adjacent to area CM on the supratemporal plane (STP). All 3 lateral belt areas were cochleotopically organized with their frequency gradients collinear to those of the adjacent STP areas. Although A1 neurons responded best to pure tones and their responses decreased with increasing bandwidth, 63% of the lateral belt neurons were tuned to bandwidths between 1/3 and 2 octaves and showed either one or multiple peaks. The results are compared with previous data from visual cortex and are discussed in the context of spectral integration, whereby the lateral belt forms a relatively early stage of processing in the cortical hierarchy, giving rise to parallel streams for the identification of auditory objects and their localization in space.

Acoustic Stimulation↗
PubMed2001

Responses of human auditory association cortex to the omission of an expected acoustic event.

Unexpected auditory events initiate a complex set of event-related potentials (ERPs) that vary in their latency and anatomical localization. Such "mismatch" responses include active responses to the omission of an expected event or the omission of elements in expected stimulus composites. Here we describe intracranial recordings of middle-latency ERPs elicited by the omission of an auditory event. We first presented a sequence of tones at regular temporal intervals and the tone was omitted 20% of the time. In a second condition, we presented a sequence of tone pairs and the second tone of the pair was omitted 20% of the time. These two conditions are complementary in that the single tone conformed to the expectancy in one condition, but violated the expectancy in the other. All patients demonstrated localized cortical responses to missing tones that were topographically similar to the responses evoked by actual tones. Responses to both actual and omitted tones were observed bilaterally in the vicinity of the temporal--parietal junction, where we also obtained midlatency ERPs to a variety of other auditory stimuli. Responses that appeared to be selective for the nonoccurrence of expected tones were also observed in a number of subjects. We interpret these effects in terms of processes associated with the comparison of sensory inputs to the contents of a short-term auditory memory. Such a system could automatically detect deviant auditory events, and provide input to higher-level, task-dependent cognitive processes.

Acoustic Stimulation↗
PubMed1989

Nuclear terminations of corticoreticular fiber systems in rats.

Corticoreticular fiber systems were examined in adult albino and hooded rats using anterograde transport of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) and anterograde degeneration. WGA-HRP injections were made stereotactically into the medial prefrontal cortex, the medial agranular cortex, the anterior cingulate cortex, the face motor cortex, the forelimb motor cortex, the trunk-hindlimb motor cortex, the face somatosensory cortex, the primary auditory cortex, the secondary visual cortex and the primary visual cortex. With exception of the cingulate cortex (which is relatively inaccessible to lesioning methods) and the primary visual cortex, electrocautery lesions were made into these same cortical areas. The precise locations of cortical injection/lesion sites were corroborated on the basis of cortical cytoarchitectonic criteria, patterns of retrograde and anterograde thalamic labeling, and patterns of anterograde labeling in non-reticular brainstem nuclei such as the red nucleus, trigeminal nuclei and dorsal column nuclei. The heaviest corticoreticular projections arise from the medial agranular cortex. The medial prefrontal cortex also gives rise to consistently strong corticoreticular projections. The anterior cingulate cortex sends robust corticoreticular projections to the upper brainstem but relatively weak projections to the lower brainstem. With respect to the primary motor cortex, the face area gives rise to the densest corticoreticular projections, rivaling those emanating from the medial agranular cortex. The trunk-hindlimb area gives rise to substantial corticoreticular projections, but those originating from the forelimb area are modest and directed chiefly to midbrain and medullary levels. The face area of the somatosensory cortex gives rise to rather weak corticoreticular projections, while those arising from the primary auditory cortex are fewer still. Descending projections from the secondary visual cortex are sparse, with labeled terminals occurring in a few pontine and medullary reticular nuclei. Only one brainstem reticular nucleus (nucleus cuneiformis) was found to receive projections from the primary visual cortex, and this input was extremely sparse. Corticoreticular projections to the upper brainstem terminate predominantly ipsilateral to the cortical injection site, whereas medullary corticoreticular projections distribute bilaterally. Corticoreticular fibers from the medial agranular, face motor and trunk-hindlimb motor cortex terminate heavily in somatomotor brainstem reticular nuclei such as the pontis oralis, the pontis caudalis and the gigantocellularis.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed2006

Effects of the frequency of interaural time difference in the human brain.

The two cues to the horizontal location sound sources are interaural time differences and interaural level differences. For low-frequency tones, interaural time differences provide effective and unambiguous information. For higher frequency sounds, however, interaural time differences provide ambiguous cues. In order to evaluate the effect of frequency of interaural time differences in the human auditory cortex, the auditory evoked fields to different interaural time differences of pure tone were examined. The results showed that the N1m magnitudes varied with the interaural time differences when the frequency of the pure tone was 800 Hz. The N1m magnitudes, however, did not vary with the interaural time differences when the frequency of the pure tone was 1600 Hz. These results indicate that localization performance might be reflected in N1m magnitudes.

Acoustic Stimulation↗
PubMed2003

BOLD-fMRI response vs. transcranial magnetic stimulation (TMS) pulse-train length: testing for linearity.

PURPOSE: To measure motor and auditory cortex blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) response to impulse-like transcranial magnetic stimulation (TMS) pulses as a function of train length. MATERIALS AND METHODS: Interleaved with fMRI at 1.5 T, TMS pulses 0.3-msec long were applied at 1 Hz to the motor cortex area for thumb. Six subjects were studied in a TR = 1 second session administering trains of 1, 2, 4, 8, and 16 pulses, and a TR = 3 seconds session administering trains of 1, 2, 4, 8, 16, and 24 pulses. A simple hemodynamic model with finite recovery and saturation was used to quantitatively characterize the BOLD-fMRI response as a function of train length. RESULTS: In both the activations directly induced in motor cortex by TMS and the indirect activations in auditory cortex caused by the sound of the TMS coil firing, the BOLD-fMRI responses to multiple pulses were well described by a summation of single-pulse impulse functions. CONCLUSION: Up to 24 discrete pulses, BOLD-fMRI response to 1 Hz TMS in both motor cortex and auditory cortex were consistent with a linear increase in amplitude and length with train length, possibly suggesting that stimuli of 1 to 2 seconds may be too long to represent impulses.

Adult↗
PubMed2000

[Auditory cortical response to monaural stimulation as detected by functional magnetic resonance imaging].

In order to confirm the crossed-innervation between auditory cortex and the ear that receives monosyllabic sound, the auditory cortical response to monaural monosyllabic stimulation as detected by functional magnetic resonance imaging (fMRI) was investigated in six normal hearing subjects. Stimulus amplitude averaged 95 dBSPL at the distal end of the audio system. A series of 440 echo planar images was acquired during the acoustic stimulation within the four OFF-ON cycle paradigm. Five image series with 10 slices were collected within each OFF or On period. Each scanning session began with four baseline images before the OFF-ON paradigm. Monosyllabic sounds were presented monaurally during the ON period at a rate of one monosyllable/sec. Functional MRI data were analyzed with SPM99b software (Statistical Parametric Mapping). The background scanner noise averaged 97dBSPL. The selicon ear plug and headphone as acoustic shields attenuated the noise as much as 17 dB. A broad and intense auditory cortical response was observed bilaterally in response to monaural monosyllable stimulation. Sound presentation to the right ear was followed by a larger response in the left auditory cortex than in the right, and left ear stimulation evoked a larger response in the right auditory cortex than in the left. This pattern was consistent in all subjects examined. The primary auditory cortex responded to monosyllabic words presented to the contralateral ear. The results confirmed the crossed-innervation between the auditory cortex and ear for listening to monosyllables. Functional MRI is a useful tool for investigating auditory cortex function, if the scanner noise is adequated controlled.

Acoustic Stimulation↗
PubMed1994

Tonotopic organization of human auditory association cortex.

Neuromagnetic studies of responses in human auditory association cortex for tone burst stimuli provide evidence for a tonotopic organization. The magnetic source image for the 100 ms component evoked by the onset of a tone is qualitatively similar to that of primary cortex, with responses lying deeper beneath the scalp for progressively higher tone frequencies. However, the tonotopic sequence of association cortex in three subjects is found largely within the superior temporal sulcus, although in the right hemisphere of one subject some sources may be closer to the inferior temporal sulcus. The locus of responses for individual subjects suggests a progression across the cortical surface that is approximately proportional to the logarithm of the tone frequency, as observed previously for primary cortex, with the span of 10 mm for each decade in frequency being comparable for the two areas.

Acoustic Stimulation↗
PubMed2006

Central auditory development in children with cochlear implants: clinical implications.

A common finding in developmental neurobiology is that stimulation must be delivered to a sensory system within a narrow window of time (a sensitive period) during development in order for that sensory system to develop normally. Experiments with congenitally deaf children have allowed us to establish the existence and time limits of a sensitive period for the development of central auditory pathways in humans. Using the latency of cortical auditory evoked potentials (CAEPs) as a measure we have found that central auditory pathways are maximally plastic for a period of about 3.5 years. If the stimulation is delivered within that period CAEP latencies reach age-normal values within 3-6 months after stimulation. However, if stimulation is withheld for more than 7 years, CAEP latencies decrease significantly over a period of approximately 1 month following the onset of stimulation. They then remain constant or change very slowly over months or years. The lack of development of the central auditory system in congenitally deaf children implanted after 7 years is correlated with relatively poor development of speech and language skills [Geers, this vol, pp 50-65]. Animal models suggest that the primary auditory cortex may be functionally decoupled from higher order auditory cortex due to restricted development of inter- and intracortical connections in late-implanted children [Kral and Tillein, this vol, pp 89-108]. Another aspect of plasticity that works against late-implanted children is the reorganization of higher order cortex by other sensory modalities (e.g. vision). The hypothesis of decoupling of primary auditory cortex from higher order auditory cortex in children deprived of sound for a long time may explain the speech perception and oral language learning difficulties of children who receive an implant after the end of the sensitive period.

Auditory Cortex↗
PubMed2006

Attention to visual speech gestures enhances hemodynamic activity in the left planum temporale.

Observing a speaker's articulatory gestures can contribute considerably to auditory speech perception. At the level of neural events, seen articulatory gestures can modify auditory cortex responses to speech sounds and modulate auditory cortex activity also in the absence of heard speech. However, possible effects of attention on this modulation have remained unclear. To investigate the effect of attention on visual speech-induced auditory cortex activity, we scanned 10 healthy volunteers with functional magnetic resonance imaging (fMRI) at 3 T during simultaneous presentation of visual speech gestures and moving geometrical forms, with the instruction to either focus on or ignore the seen articulations. Secondary auditory cortex areas in the bilateral posterior superior temporal gyrus and planum temporale were active both when the articulatory gestures were ignored and when they were attended to. However, attention to visual speech gestures enhanced activity in the left planum temporale compared to the situation when the subjects saw identical stimuli but engaged in a nonspeech motion discrimination task. These findings suggest that attention to visually perceived speech gestures modulates auditory cortex function and that this modulation takes place at a hierarchically relatively early processing level.

Adult↗
PubMed2006

Neural representations of temporally modulated signals in the auditory thalamus of awake primates.

In sensory systems, the thalamus has historically been considered a relay station. Neural representations of temporal modulations in the auditory system undergo considerable changes as they pass from the inferior colliculus (IC) to the auditory cortex. We sought to determine in awake primates the extent to which auditory thalamic neurons contribute to these transformations. We tested the temporal processing capabilities of medial geniculate body (MGB) neurons in awake marmoset monkeys using repetitive click stimuli. MGB neurons were able to synchronize to periodic clicks at repetition rates significantly higher than auditory cortex neurons. Unlike responses in the MGB of anesthetized animals, >40% of MGB neurons in awake marmosets displayed nonsynchronized discharges when stimulated by high click rates (short interclick intervals). Such nonsynchronized MGB responses typically occurred at higher repetition rates than those observed in auditory cortex. In contrast to auditory cortex neurons, many MGB neurons exhibited both synchronized and nonsynchronized discharge patterns. In both MGB and auditory cortex, synchronized and nonsynchronized responses represented complementary ranges of interclick intervals (1/click rate). Furthermore, the temporal processing abilities of some MGB neurons were sensitive to the spectrotemporal parameters of the click stimuli used. Together, these findings suggest that MGB neurons participate in active transformations of the neural representations of temporal modulations from IC to auditory cortex. In particular, the MGB appears to be the first station in the auditory ascending pathway in which substantial nonsynchronized responses emerge.

Acoustic Stimulation↗
PubMed1995

Mapping of the consequences of bilirubin exposure in the immature rat: local cerebral metabolic rates for glucose during moderate and severe hyperbilirubinemia.

The regional cerebral metabolic consequences of bilirubin intoxication are not well known. With the quantitative autoradiographic [14C]2-deoxyglucose (2DG), we studied the effect of moderate or severe bilirubin infusion on local cerebral metabolic rates for glucose utilization (LCMRglcs) in 10 (P10) and 21 day-old (P21) rats. After an 80 or 160 mg/kg loading dose of bilirubin administered over 15 min, the speed of bilirubin infusion was reduced to 32 or 64 mg/kg/h for the following 105 min, for moderate or severe intoxication, respectively. This infusion protocol led to plasma bilirubin concentrations of 100-200 nmol/ml (moderate intoxication) or 200-300 nmol/ml (severe intoxication). Cerebral bilirubin concentration was 10 nmol/g at P10 and undetectable at P21 in moderate hyperbilirubinemia while it reached 22-34 nmol/g at both ages during severe hyperbilirubinemia. At P10, bilirubin infusion, moderate or severe, induced significant decreases in LCMRglcs in 17 and 15 brain regions of the 24 studied, respectively. At P21, moderate hyperbilirubinemia induced a decrease in LCMRglcs in only 2 regions, auditory cortex and auditory nerve. Conversely, at that age, severe bilirubin intoxication led to significant decreases in LCMRglcs in all regions studied. These results demonstrate that metabolic changes induced by bilirubin are directly correlated to its entry into the brain which occurs without any alteration in the blood-brain barrier. Indeed, the effects of the dye are quite discrete during moderate hyperbilirubinemia at P21 when no bilirubin is detectable in the brain while they are massive during severe hyperbilirubinemia at P21 and at both levels of intoxication at P10 when bilirubin has entered the brain in measurable amounts.

Animals↗
PubMed2006

Functional imaging of the central auditory system using PET.

In the last few decades functional neuroimaging tools have emerged to study the function of the human brain in vivo. These techniques have increased the knowledge of how the brain processes stimuli of different sensory modalities, including auditory processing. Positron emission tomography (PET) has been used for nearly 20 years to study changes in cerebral blood flow associated with auditory stimulation in normal and hearing impaired subjects. PET studies gave insight into the neural base of processing basic sound features such as frequency and intensity, but complex stimuli such as speech and music have also been investigated extensively. Knowledge of the normal auditory function of the brain helps us to understand the neural base of hearing deficits and provides ideas for possible treatments. Although functional magnetic resonance imaging (fMRI) is replacing PET in many neuroimaging studies nowadays, PET still holds unique advantages and can give us valuable knowledge about the auditory cortex and auditory perception.

Acoustic Stimulation↗
PubMed1996

[Changes in the auditory area of the cerebral cortex with clinical and experimental actions on the hypothalamus].

Neurohistological, newchistochemical and ultrastructural analysis in pia mater and brain cortex auditory zone in tumors of hypothalamo-hypophyseal localization (12 patients) and dozaged experimental influence on hypothalamus (60 rabbits with 30 control and 30 experimental ones) allowed to establish and follow up morphofunctional and pathological changes. The former appeared previously in adrenergic nerve structures of pia mater and cortical vascular bed and neuroglia, the latter--in cortical neurons. The results obtained may be used in otoneurology and neurosurgery in elucidation certain syndromes genesis, acoustic ones included in patients with tumors of mentioned localisation, directly influencing hypothalamic area.

Adenoma↗
PubMed2000

Auditory thalamocortical projections in the cat: laminar and areal patterns of input.

Thalamocortical projections were studied in adult cats using biotinylated dextran amines, wheat germ agglutinin conjugated to horseradish peroxidase, and autoradiography with tritiated leucine and/or proline. The input from 7 architectonically defined nuclei to 14 auditory cortical fields was characterized qualitatively and quantitatively. The principal results were that 1) every thalamic nucleus projected to more than 1 field (range, 4-14 fields; mean, 7 fields); 2) only the projection from the ventral division to some primary fields (primary auditory cortex and posterior auditory cortex) had a periodic, clustered distribution, whereas the input from other divisions to nonprimary areas was continuous; 3) layers III-V received >85% of the total axonal profiles; 4) in most experiments, five or more layers were labeled; 5) the projections to nonprimary auditory areas had many laterally oriented axons; 6) the heaviest input to layer I in all experiments was usually in its upper half, suggesting a sublaminar arrangement; 7) the largest axonal trunks (up to 6 microm in diameter) arose from the medial division and ended in layer Ia, where they ran laterally for long distances; 8) there were three projection patterns: type 1 had its peak in layers III-IV with little input to layer I, and it arose from the ventral division and the dorsal superficial, dorsal, and suprageniculate nuclei of the dorsal division; type 2 had heavy labeling in layer I and less in layers III-IV, arising from the dorsal division nuclei primarily, especially the caudal dorsal and deep dorsal nuclei; and type 3 was a trimodal concentration in layers I, III-IV, and VI that originated chiefly in the medial division and had the lowest density of labeling; and 9) the quantitative profiles with the three methods were very similar. The results suggest that the subdivisions of the auditory thalamus have consistent patterns of laminar distribution to different cortical areas, that an average of five or more layers receive significant input in a specific area, that a given thalamic nucleus can influence areas as far as 20 mm apart, that the first information to arrive at the cortex may reach layer I by virtue of the giant axons, and that several laminar patterns of auditory thalamocortical projection exist. The view that the auditory thalamus (and perhaps other thalamic nuclei) serves mainly a relay function underestimates its many modes for influencing the cortex on a laminar basis.

Animals↗
PubMed2006

Transcranial fluorescence imaging of auditory cortical plasticity regulated by acoustic environments in mice.

Functional brain imaging using endogenous fluorescence of mitochondrial flavoprotein is useful for investigating mouse cortical activities via the intact skull, which is thin and sufficiently transparent in mice. We applied this method to investigate auditory cortical plasticity regulated by acoustic environments. Normal mice of the C57BL/6 strain, reared in various acoustic environments for at least 4 weeks after birth, were anaesthetized with urethane (1.7 g/kg, i.p.). Auditory cortical images of endogenous green fluorescence in blue light were recorded by a cooled CCD camera via the intact skull. Cortical responses elicited by tonal stimuli (5, 10 and 20 kHz) exhibited mirror-symmetrical tonotopic maps in the primary auditory cortex (AI) and anterior auditory field (AAF). Depression of auditory cortical responses regarding response duration was observed in sound-deprived mice compared with naïve mice reared in a normal acoustic environment. When mice were exposed to an environmental tonal stimulus at 10 kHz for more than 4 weeks after birth, the cortical responses were potentiated in a frequency-specific manner in respect to peak amplitude of the responses in AI, but not for the size of the responsive areas. Changes in AAF were less clear than those in AI. To determine the modified synapses by acoustic environments, neural responses in cortical slices were investigated with endogenous fluorescence imaging. The vertical thickness of responsive areas after supragranular electrical stimulation was significantly reduced in the slices obtained from sound-deprived mice. These results suggest that acoustic environments regulate the development of vertical intracortical circuits in the mouse auditory cortex.

Acoustic Stimulation↗
PubMed2001

Parvalbumin and calbindin are differentially distributed within primary and secondary subregions of the mouse auditory forebrain.

The calcium binding proteins parvalbumin and calbindin are thought to differentially regulate physiological functions and often show complementary distributions in the CNS. Our goal was to determine parvalbumin and calbindin distributions in the different subdivisions of mouse auditory thalamus and auditory cortex. Following fixation, FVB mouse brains (postnatal days 38-80) were sectioned along coronal and horizontal planes, then processed for parvalbumin and calbindin immunohistochemistry (antibodies: parvalbumin pa-235, calbindin-d-28k cl-300). Strong complementary differences in calcium binding protein distributions were found in mouse auditory thalamus. The ventral division of the medial geniculate, which is the principal relay to primary auditory cortex, exhibited dense parvalbumin but weak calbindin immunoreactivity. In contrast, most of the 'secondary' auditory thalamic regions surrounding the ventral division showed strong calbindin and lighter parvalbumin levels. Thus, the mouse auditory thalamus is composed of a parvalbumin positive 'core' surrounded by a calbindin positive 'shell'. Parvalbumin immunoreactivity was also more prominent in the primary auditory cortex than in the secondary belt auditory cortex. Calbindin immunoreactivity in auditory cortex was less clearly divided along primary/secondary lines, especially in supragranular layers. However, within infragranular layers, there was heavier staining in belt areas than in primary auditory cortex. In auditory thalamus, parvalbumin labeling was largely confined to the neuropil, whereas calbindin labeling involved somata and neuropil. In auditory cortex, somata and neuropil were positive for both proteins.In summary, the calcium binding proteins parvalbumin and calbindin were found to be differentially distributed within the primary and non-primary regions of mouse auditory forebrain. These differences in protein distribution may contribute to the distinct types of physiological responses that occur in the primary vs. non-primary areas.

Animals↗
PubMed2006

Evidence of functional connectivity between auditory cortical areas revealed by amplitude modulation sound processing.

The human auditory cortex includes several interconnected areas. A better understanding of the mechanisms involved in auditory cortical functions requires a detailed knowledge of neuronal connectivity between functional cortical regions. In human, it is difficult to track in vivo neuronal connectivity. We investigated the interarea connection in vivo in the auditory cortex using a method of directed coherence (DCOH) applied to depth auditory evoked potentials (AEPs). This paper presents simultaneous AEPs recordings from insular gyrus (IG), primary and secondary cortices (Heschl's gyrus and planum temporale), and associative areas (Brodmann area [BA] 22) with multilead intracerebral electrodes in response to sinusoidal modulated white noises in 4 epileptic patients who underwent invasive monitoring with depth electrodes for epilepsy surgery. DCOH allowed estimation of the causality between 2 signals recorded from different cortical sites. The results showed 1) a predominant auditory stream within the primary auditory cortex from the most medial region to the most lateral one whatever the modulation frequency, 2) unidirectional functional connection from the primary to secondary auditory cortex, 3) a major auditory propagation from the posterior areas to the anterior ones, particularly at 8, 16, and 32 Hz, and 4) a particular role of Heschl's sulcus dispatching information to the different auditory areas. These findings suggest that cortical processing of auditory information is performed in serial and parallel streams. Our data showed that the auditory propagation could not be associated to a unidirectional traveling wave but to a constant interaction between these areas that could reflect the large adaptive and plastic capacities of auditory cortex. The role of the IG is discussed.

Acoustic Stimulation↗
PubMed2003

Directional sensitivity of neurons in the primary auditory (AI) cortex: effects of sound-source intensity level.

Transient sounds were delivered from different directions in virtual acoustic space while recording from single neurons in primary auditory cortex (AI) of cats under general anesthesia. The intensity level of the sound source was varied parametrically to determine the operating characteristics of the spatial receptive field. The spatial receptive field was constructed from the onset latency of the response to a sound at each sampled direction. Spatial gradients of response latency composing a receptive field are due partially to a systematic co-dependence on sound-source direction and intensity level. Typically, at any given intensity level, the distribution of response latency within the receptive field was unimodal with a range of approximately 3-4 ms, although for some cells and some levels, the spread could be as much as 20 or as little as 2 ms. Response latency, averaged across directions, differed among neurons for the same intensity level, and also differed among intensity levels for the same neuron. Generally, increases in intensity level resulted in decreases in the mean and variance, which follows an inverse Gaussian distribution. Receptive field models, based on response latency, are developed using multiple parameters (azimuth, elevation, intensity), validated with Monte Carlo simulation, and their spatial filtering described using spherical harmonic analysis. Observations from an ensemble of modeled receptive fields are obtained by linking the inverse Gaussian density to the probabilistic inverse problem of estimating sound-source direction and intensity. Upper bounds on acuity is derived from the ensemble using Fisher information, and the predicted patterns of estimation errors are related to psychophysical performance.

Acoustic Stimulation↗