Fact-checked by Grok 2 weeks ago

Auditory cortex

The auditory cortex is a region of the cerebral cortex in the temporal lobe responsible for the processing and interpretation of auditory stimuli, receiving pre-processed signals from the cochlea via subcortical pathways including the medial geniculate nucleus of the thalamus.^[1] Located bilaterally in the superior temporal gyrus, primarily within Heschl's gyrus on the supratemporal plane deep to the lateral sulcus, it transforms mechanical sound vibrations into neural representations essential for hearing.^[2] This area is organized tonotopically, with neurons arranged in a systematic map of sound frequencies—high frequencies represented caudally and medially, low frequencies rostrally and laterally—enabling precise frequency discrimination.^[3] The auditory cortex is subdivided into core, belt, and parabelt regions, with the core encompassing the primary auditory cortex (A1) that handles initial sensory processing, while surrounding belt and parabelt areas integrate more complex features such as sound localization, pitch, and temporal patterns.^[4] In humans and non-human primates, these subdivisions form a hierarchical processing stream: core areas receive direct thalamic inputs for basic tonotopic analysis, belt regions contribute to spatial and spectral processing (e.g., via excitation-inhibition patterns for binaural cues), and parabelt areas connect to higher-order regions in the temporal, parietal, and frontal lobes for advanced functions like speech recognition and auditory scene analysis.^[2] Blood supply to this region primarily derives from branches of the middle cerebral artery, making it vulnerable to vascular insults that can impair auditory perception.^[1] Functionally, the auditory cortex not only decodes acoustic features but also exhibits plasticity, adapting to environmental demands, learning, and attentional modulation, as evidenced by its role in recovering from lesions or reorganizing in response to training.^[3] Damage to these areas, such as from stroke or congenital conditions, can lead to deficits in sound discrimination, localization, or comprehension, underscoring its critical integration with cognitive processes like language and memory.^[1] Overall, this cortical network bridges peripheral hearing mechanisms with central perceptual and behavioral responses, forming the neural basis for auditory experience.

Anatomy

Location and Gross Structure

The primary auditory cortex (A1), the initial cortical site for auditory processing, is located in the posterior portion of the superior temporal gyrus within the temporal lobe, corresponding to Brodmann areas 41 and 42.^[5] This region is buried in the lateral sulcus and forms the core of the auditory cortex, receiving direct thalamocortical projections essential for sound perception.^[2] Surrounding A1 are secondary auditory areas, often referred to as belt regions, which extend laterally and anteriorly into the superior temporal sulcus and adjacent parts of the superior temporal gyrus, contributing to more complex auditory analysis.^[6] The auditory cortex exhibits bilateral symmetry across the two cerebral hemispheres, ensuring redundant processing of auditory information from both ears.^[1] However, subtle structural asymmetries exist, particularly in right-handed individuals, where the left hemisphere's auditory regions, including the planum temporale, tend to be larger, supporting specialized roles in language comprehension and phonological processing.^[7] These hemispheric differences arise early in development and influence functional lateralization, though the core auditory processing remains largely balanced.^[8] Macroscopically, the primary auditory cortex is embedded within Heschl's gyrus, a prominent transverse folding of the superior temporal plane that gives rise to the transverse temporal gyri, typically one or two per hemisphere.^[9] Adjacent to this is the planum temporale, a flattened posterior extension of the superior temporal gyrus, which encompasses non-primary auditory association areas involved in integrating sound with linguistic and spatial cues.

Subdivisions and Cytoarchitecture

The auditory cortex is organized into three main regions: the core, belt, and parabelt, distinguished primarily by their connectivity patterns and histological characteristics. The core region, encompassing the primary auditory cortex (A1, also known as Te1 or hA1 in humans), is located centrally and receives direct thalamic inputs from the ventral division of the medial geniculate nucleus.^[10] Surrounding the core is the belt region, comprising secondary auditory areas such as the medial belt (MB), lateral belt (LB), and rostral belt (RB), which exhibit intermediate connectivity between core and higher-order areas.^[10] Lateral to the belt lies the parabelt region, a broader expanse of auditory association areas with more diffuse projections to prefrontal and multimodal cortices.^[10] Cytoarchitectonically, the core is characterized as koniocortex, featuring a prominently developed layer IV rich in small granule cells that impart a granular appearance, reflecting its role in receiving dense thalamocortical afferents.^[11] In contrast, belt areas display prokoniocortex architecture, with a less pronounced layer IV and more balanced distribution across supragranular and infragranular layers, indicating transitional processing features.^[11] Parabelt regions show even sparser granularity, resembling parakoniocortex with reduced laminar differentiation overall.^[10] These distinctions are visualized through histological staining methods, such as Nissl staining for cell bodies, which highlights neuron packing density, and myelin staining, which delineates laminar boundaries via differential myelination patterns.^[11] Notable asymmetries exist in the size of auditory subdivisions, particularly in the planum temporale, which encompasses parts of the belt and parabelt and is typically larger on the left hemisphere in right-handed individuals.^[12]

Development

Prenatal Formation

The auditory cortex emerges during early embryonic development from the prosencephalon, the most anterior vesicle of the neural tube, which divides into telencephalon and diencephalon around gestational week 5-7. Telencephalic progenitors within the ventricular zone of the developing telencephalon begin to specify the temporal lobe anlage, the primordial structure that will give rise to the temporal cortex including auditory areas, by gestational weeks 6-8. This initial patterning establishes the foundational framework for neocortical regions, with progenitor proliferation driving the expansion of the pallial germinal zones that contribute to sensory cortical fields.^[13] Genetic factors play a critical role in arealization, the process defining cortical region identities. Transcription factors such as Pax6, expressed in a high rostral-to-low caudal gradient, and Emx1/Emx2, enriched in caudal-medial progenitors, regulate the positional identity of cortical areas; Emx2 in particular promotes the development of posterior regions encompassing the auditory cortex, while Pax6 favors anterior domains. Complementary signaling gradients, notably fibroblast growth factor 8 (FGF8) emanating from the rostromedial telencephalon, act as an organizer to establish boundaries between cortical fields, with modulated FGF8 levels shifting area maps to include or exclude primary auditory territories in experimental models. These molecular cues interact to partition the neocortex into functional domains prior to overt morphological differentiation.^[14]^[15] By mid-gestation, around weeks 20-24, the gross morphology of the auditory cortex becomes evident with the formation of Heschl's gyrus, the transverse temporal gyrus housing the core primary auditory area, visible on fetal MRI as an emerging sulcal fold paralleling the onset of auditory pathway functionality. Initial thalamocortical projections from the medial geniculate nucleus (MGN) of the thalamus begin to invade the subplate zone around weeks 12-16, extending axons that arborize and form transient synapses before penetrating the cortical plate by weeks 24-28, laying the groundwork for sensory input relay.^[16]^[17] Prior to functional hearing onset at approximately weeks 24-26, spontaneous activity waves, propagated via gap junctions and involving connexin hemichannels in cortical progenitors, refine early circuitry by coordinating calcium transients and neuronal bursting across thalamic and cortical networks, thereby influencing area size and connectivity patterns.^[18]^[19]^[20]

Postnatal Maturation

The postnatal maturation of the auditory cortex is marked by a critical period that commences at birth with the onset of functional hearing, enabling rapid synaptogenesis in response to auditory stimuli. This phase of heightened plasticity allows for the proliferation of synaptic connections, particularly in the primary auditory cortex (A1), as sensory input from the periphery drives circuit formation and refinement. In animal models, such as cats, functional synaptogenesis peaks within the first 40 postnatal days, underscoring the immediate role of experience in establishing basic tonotopic organization and responsiveness.^[21] Human studies similarly show an early surge in synaptic density in the auditory cortex, reaching a maximum around 3 months of age, which supports the integration of thalamocortical inputs for initial sound encoding.^[22] Synaptic pruning follows, eliminating superfluous connections to optimize neural efficiency; in the auditory cortex, this process is gradual and protracted, continuing until approximately 12 years of age to achieve adult-like circuitry. Concurrent structural changes include the myelination of thalamocortical fibers, which begins around 1 year of age and progresses into early childhood, reaching near-adult levels by approximately 4 years, accelerating signal propagation from the medial geniculate nucleus to cortical layers and enhancing temporal precision in sound processing. Additionally, dendritic spine density in layers II and III increases during early childhood, peaking between ages 2-8 years, to facilitate intracortical connectivity and higher-order integration of auditory features.^[22]^[23]^[24]^[25] Experience-dependent plasticity profoundly shapes this maturation, as demonstrated by sensory deprivation studies. Congenital deafness disrupts normal development, resulting in delayed synaptogenesis and altered pruning, leading to changes in cortical thickness and cytoarchitecture, particularly in deeper layers of A1.^[26]^[27] Developmental milestones further illustrate maturation timelines. Auditory evoked potentials, such as the P1 and N1 components, exhibit decreasing latencies and increasing amplitudes with experience, achieving stability by ages 12-14 years in hearing individuals, indicative of mature cortical processing. Hemispheric asymmetry in the auditory cortex also emerges postnatally, with a leftward bias for language-related sounds developing in association with early linguistic exposure, supporting specialized speech perception.^[21]^[28]

Function

Basic Sound Processing

The auditory cortex exhibits a fundamental tonotopic organization, where neurons are arranged in a spatial gradient that mirrors the frequency selectivity of the cochlea, with low frequencies represented laterally and high frequencies medially along Heschl's gyrus in the core fields (such as the primary auditory cortex, A1) and extending into rostral fields.^[29] This organization was first systematically mapped in mammals, revealing a systematic progression from high to low frequencies across the cortical surface. In humans, functional imaging confirms this gradient, with distinct tonotopic maps in the core (CF) and rostral (RF) areas of the superior temporal gyrus.^[30] Neurons in the auditory cortex respond to sound stimuli with phase-locking to the onset of acoustic events, typically exhibiting latencies of 20-50 milliseconds, which reflects the temporal precision of cortical encoding for basic sound timing.^[31] Intensity coding occurs through rate-level functions, where firing rates increase with sound level up to a saturation point, allowing neurons to represent acoustic amplitude across a dynamic range.^[32] These properties enable the cortex to faithfully relay fundamental stimulus attributes from thalamic inputs.^[31] Processing in the auditory cortex follows a hierarchical structure, with the core area A1 primarily encoding basic spectral features through sharply tuned frequency receptive fields, often V-shaped in tuning curves that indicate the range of frequencies eliciting maximal responses.^[33] Surrounding belt regions integrate these elemental features into combinations, such as multi-frequency patterns, broadening tuning and supporting more complex spectral analysis.^[33] Binaural integration begins in the auditory cortex, where neurons process interaural time differences (ITD) and interaural level differences (ILD) as cues for sound localization, with cortical responses sensitive to these disparities in ways that complement subcortical mechanisms.^[34] This integration allows for the computation of azimuthal position, though full spatial maps emerge across higher cortical stages.^[35]

Higher-Order Auditory Features

The auditory cortex, particularly in its belt and parabelt regions surrounding the core areas, plays a crucial role in forming auditory objects by segregating overlapping sound streams into distinct perceptual entities. This process involves grouping spectrotemporal regularities, such as harmonic structures or rhythmic patterns, to identify sources like a single voice amid background noise. In the belt cortex, neurons exhibit sensitivity to complex features like timbre and vocalization categories, while parabelt areas, including the planum temporale, encode invariant representations that support object stability across variations in intensity or spatial position.^[36] Stream segregation relies on mechanisms like temporal coherence, where synchronous spectral components are bound into a single stream, preventing perceptual fragmentation. For instance, in the cocktail party effect, listeners selectively attend to a target conversation in a noisy environment; belt and parabelt regions facilitate this by enhancing neural representations of the attended stream while suppressing distractors, as demonstrated in multi-talker speech scenarios where posterior auditory cortex activity tracks the focused object. This hierarchical processing builds on core tonotopic maps to enable scene analysis, with studies showing that frequency-separated tones in phase form one perceptual stream, whereas out-of-phase presentations yield two.^[36]^[37]^[38] Specialization within the auditory cortex further refines higher-order processing, with anterior fields, such as the anterior superior temporal gyrus and planum polare, preferentially handling sound identity and vocalizations. These regions discriminate features like amplitude-modulated frequencies or speaker-specific cues, supporting recognition of communicative signals. In contrast, posterior fields, including the planum temporale and posterior superior temporal gyrus, specialize in spatial and motion processing, computing sound location and trajectory through cues like interaural time differences. This anterior-posterior dichotomy, evidenced by transcranial magnetic stimulation studies showing delayed reaction times in identity tasks for anterior inhibition and spatial tasks for posterior inhibition, enables parallel "what" and "where" pathways.^[39] The auditory cortex also contributes to music perception by processing pitch and harmony in higher-order areas. Pitch-selective neurons in the core-belt border respond to the fundamental frequency of complex tones, forming the basis for melody recognition, while harmonic-sensitive cells in the planum temporale and superior temporal gyrus detect consonant intervals, with right-hemisphere dominance for spectral resolution. In language, these regions handle prosody through pitch and rhythm cues, where melodic expectancy violations elicit event-related potentials like the P600 for re-analysis, enhanced in musicians due to shared neural resources between musical and intonational processing.^[40]^[41] Emotional processing in the auditory cortex involves amygdala-linked circuits that modulate responses to affective sounds. Unpleasant or aversive stimuli, such as cries or alarms, activate the amygdala alongside bilateral auditory cortex regions, enhancing salience detection via connectivity that amplifies negative valence processing. Pleasant sounds engage medial prefrontal and anterior cingulate interactions with the auditory cortex for reward evaluation, creating distinct circuits for valence. Recent findings from 2023–2025 highlight synaptic recruitment in the primary auditory cortex (A1) for fear encoding, where social stress paradigms in mice increase associative memory neurons (up to 17% of A1 cells) through neuroligin-3-mediated synapse formation from inputs like the medial geniculate body, linking battle sounds to anxiety-like behaviors.^[42]^[43] Attention exerts top-down modulation on the auditory cortex, enhancing responses to relevant frequencies and suppressing irrelevant ones to prioritize perceptual objects. This frequency-specific spotlight, observed in functional MRI, boosts neural activity by approximately 20–50% in attended channels, particularly in core and belt areas, improving signal-to-noise ratios during tasks like dichotic listening. Such modulation sharpens tuning curves, with early sensory components like the N1 potential amplified for targets, facilitating selective processing in complex acoustic environments.^[44]^[45]

Connections

Afferent Pathways

The afferent pathways to the auditory cortex originate in the cochlea, where mechanosensory hair cells convert sound-induced vibrations into action potentials transmitted via the auditory nerve (cranial nerve VIII) to the cochlear nucleus in the brainstem.^[46] This initial relay site bifurcates inputs into dorsal and ventral cochlear nuclei, preserving both temporal and spectral features of the acoustic signal before projecting to the superior olivary complex for early binaural comparisons.^[46] From the superior olivary complex, ascending fibers travel through the lateral lemniscus to the inferior colliculus in the midbrain, where multisensory integration and further refinement of auditory features occur.^[46] The inferior colliculus then conveys processed signals via the brachium of the inferior colliculus to the ventral division of the medial geniculate nucleus (MGNv) in the thalamus, the primary thalamic relay for auditory information.^[47] Projections from the MGNv terminate predominantly in layer IV of the primary auditory cortex (A1), providing the main driver of thalamocortical excitation in this granular layer.^[48] Parallel processing streams emerge along this ascending route, with the lemniscal pathway emphasizing precise spectral resolution and temporal timing, while the non-lemniscal pathway supports broader contextual integration. The lemniscal stream, routed through the ventral MGN, delivers tonotopically organized inputs tuned for frequency-specific and phase-locked responses, enabling detailed sound localization and pitch discrimination.^[49] In contrast, the non-lemniscal stream, involving dorsal and medial (shell) divisions of the MGN, carries less sharply tuned signals with multisensory influences, projecting primarily to belt areas surrounding the core A1 region for higher-level feature binding.^[50] These shell inputs to belt areas facilitate parallel computation of auditory objects and environmental salience, distinct from the core's focus on elementary acoustic elements.^[49] Thalamocortical transmission involves both feedforward relay mechanisms and local feedback loops within the thalamus to sharpen signal selectivity. Feedforward projections from the MGNv directly drive cortical layer IV spiny stellate cells, with each cortical neuron receiving convergent input from multiple thalamic afferents, typically in a ratio of approximately 20–25:1 thalamic-to-cortical connections, enhancing reliability and gain control.^[51] Intrathalamic feedback, mediated by the thalamic reticular nucleus, modulates MGN activity through GABAergic inhibition, gating afferent signals based on attentional states before cortical relay.^[52] This convergence amplifies weak thalamic inputs while suppressing noise, ensuring robust representation of salient auditory features in the cortex.^[53]

Efferent Projections

The efferent projections of the auditory cortex facilitate interhemispheric integration through commissural fibers that traverse the corpus callosum, connecting homologous and heterotopic regions bilaterally. In cats, these projections originate primarily from layers III and V of auditory cortical areas, with approximately 75% being homotopic (topographically aligned) and the remainder heterotopic, linking functionally related zones across hemispheres.^[54] Callosal fibers from core auditory areas, such as the primary auditory cortex (A1), modulate acoustically evoked activity in the contralateral A1, enhancing response specificity during acoustic exposure.^[55] Ipsilateral connections are less prominent but contribute to intrahemispheric coordination within the auditory fields. Within the auditory cortex, efferent projections follow a hierarchical organization, with core areas sending feedforward outputs primarily to surrounding belt regions, terminating in layer 4 for excitatory integration, while belt areas project to parabelt and association zones.^[56] Feedback projections from belt and parabelt back to core areas target layer 1, providing modulatory influences that refine sensory processing.^[56] This core-belt-parabelt architecture supports progressive elaboration of auditory features, with caudal belt and parabelt areas converging on rostral regions to integrate complex stimuli.^[56] Auditory cortical efferents extend to higher-order regions, including the prefrontal cortex for attentional and cognitive modulation, the amygdala for emotional processing, and motor areas involved in vocalization. In rhesus monkeys, rostral belt and parabelt project densely to orbital prefrontal areas (e.g., 10, 12), while caudal belt and parabelt target the principal sulcus (area 46) and periarcuate cortex (area 8a), diverging acoustic information into distinct cognitive streams.^[57] Projections to the amygdala cascade from primary auditory cortex (TE1) via ventral temporal areas (TE1v, TE3v) to the lateral amygdaloid nucleus, enabling rapid emotional valuation of sounds.^[58] Outputs to motor cortex, particularly orofacial regions, support vocal-motor coupling, as seen in suppression of auditory responses during self-vocalization to distinguish self-generated sounds.^[59] Descending efferents from auditory cortex layers V and VI target subcortical structures, including the inferior colliculus for midbrain modulation and the olivocochlear bundle for peripheral control. Corticocollicular projections to the inferior colliculus and its brachium nucleus form excitatory synapses on both GABAergic and glutamatergic neurons, sharpening spatial and frequency tuning in ascending pathways.^[60] Via the olivocochlear system, auditory cortex influences cochlear mechanics; deactivation of cortical activity reduces cochlear microphonic amplitudes by 2.7–3.4 dB and compound action potentials by 4.3–5.0 dB in chinchillas, indicating tonic modulation of hair cell sensitivity.^[61] Recent studies highlight how these high-level feedback loops reshape early subcortical processing, adapting responses to environmental statistics over seconds to longer timescales for enhanced foreground detection.^[62]

Clinical Significance

Associated Disorders

Auditory agnosia, also known as pure word deafness in its verbal form, arises from damage to the bilateral superior temporal regions, impairing the recognition of speech sounds while preserving basic auditory detection and peripheral hearing.^[63] This condition typically results from lesions in the temporal lobes, often bilateral, affecting the superior temporal sulcus and sparing primary auditory pathways, leading to difficulties in phoneme discrimination and word comprehension without impacting non-verbal sound localization.^[64] Patients exhibit intact audiometric thresholds but struggle with verbal auditory processing, as documented in case studies showing evolution from cortical deafness to selective agnosia post-bilateral temporal infarcts.^[65] Central auditory processing disorder (CAPD) manifests as deficits in sound localization, temporal processing of auditory signals, and dichotic listening, despite normal peripheral hearing, and is associated with dysmaturation of the primary auditory cortex (A1).^[66] This neurodevelopmental delay disrupts the maturation of cortical auditory evoked potentials in A1, leading to altered neural synchronization and reduced efficiency in processing complex acoustic environments.^[67] Children with CAPD often show atypical brain network topology involving A1, contributing to challenges in auditory figure-ground segregation and temporal resolution.^[68] Tinnitus involves hyperactivity in the auditory belt areas of the cortex following hearing loss, where maladaptive neuroplastic changes amplify phantom sound perception through increased synaptic plasticity and altered firing rates.^[69] These belt regions, surrounding the core auditory cortex, exhibit enhanced spontaneous activity and disrupted inhibitory-excitatory balance post-peripheral deafferentation, correlating with tinnitus severity.^[70] Recent 2025 studies highlight neuroplastic alterations including increased fractional anisotropy and reduced regional homogeneity in subregions like TE3.0, with reduced functional connectivity to the inferior temporal gyrus serving as a biomarker predicting poorer outcomes in sound therapy.^[71] Auditory hallucinations in schizophrenia stem from aberrant hyperactivity in the parabelt regions of the superior temporal gyrus, disrupting predictive coding and leading to misattribution of internal speech as external voices.^[46] These higher-order auditory areas show reduced gray matter volume and altered functional connectivity, exacerbating hallucinations through impaired NMDA-mediated circuits.^[72]

Neuroplasticity and Interventions

The auditory cortex exhibits significant neuroplasticity in response to sensory deprivation, particularly in cases of congenital deafness, where cross-modal reorganization occurs. In individuals with congenital deafness, primary auditory cortex (A1) regions become responsive to visual stimuli, reflecting a takeover by visual inputs that compensates for absent auditory experience.^[73] This visual cross-modal plasticity is evident in higher-order auditory areas and does not necessarily impair overall auditory potential, as demonstrated in animal models of congenital deafness.^[74] A 2024 study in prelingually deaf children shows that this reorganization involves elevated electromagnetic activity in auditory-visual cortical regions pre-cochlear implant (CI), peaking shortly after implantation but declining thereafter.^[75] Cochlear implantation can reverse this cross-modal plasticity, restoring auditory dominance in the cortex. By 12 months post-CI, cortical activity normalizes, with no significant differences from hearing controls, and reduced visual reorganization correlates with improved auditory and speech outcomes.^[75] In animal models of early deafness, timely CI activation rescues tonotopic organization in the auditory cortex, preventing permanent loss of frequency mapping, though some functional deficits may persist.^[76] In adulthood, auditory cortex reorganization manifests in conditions like tinnitus, where peripheral hearing loss triggers maladaptive plasticity. Tinnitus is associated with expanded cortical representations of the tinnitus frequency, with magnetic source imaging revealing a significant shift (mean 5.3 mm) in tonotopic maps compared to controls, correlating strongly with perceived tinnitus intensity (r = 0.82).^[77] Cochlear implants in adult-onset deafness restore tonotopic organization within months, as electrical stimulation reactivates deprived cortical maps and reduces aberrant expansions.^[78] Therapeutic interventions leverage this plasticity to enhance auditory processing. Auditory training programs induce changes in cortical representations, improving connectivity in non-primary auditory areas such as the belt regions, which support higher-order sound processing.^[79] Neuromodulation techniques, including repetitive transcranial magnetic stimulation (rTMS) targeting the auditory cortex, address hyperacusis by reducing hyperexcitability; low-frequency rTMS decreases cortical overactivity in auditory networks, alleviating sound intolerance in related auditory disorders.^[80] Advances in 2025 include stem cell therapies and gene editing for developmental auditory delays, which restore peripheral hearing and thereby normalize central cortical plasticity; for instance, cochlear gene therapy in congenital models rescues auditory processing circuits, mitigating downstream cortical reorganization deficits.^[81] Aging induces desynchronization in auditory cortical circuits, particularly after age 60, where sensorineural hearing loss reduces neural synchronization to sounds, broadening receptive fields and weakening temporal precision in A1.^[82] Hearing aids mitigate this by amplifying input, enhancing oscillatory synchronization, and promoting plasticity that preserves circuit integrity and cognitive-auditory integration.^[83]

References

[1]
Neuroanatomy, Cortical Primary Auditory Area - StatPearls - NCBI
The auditory system functions to collect sound waves from the environment, transform mechanical vibrations from those sound waves into electrical nerve ...Introduction · Structure and Function · Embryology · Surgical Considerations
[2]
The Auditory Cortex - Neuroscience - NCBI Bookshelf
The primary auditory cortex (A1) is located on the superior temporal gyrus in the temporal lobe and receives point-to-point input from the ventral division of ...
[3]
https://www.cell.com/current-biology/fulltext/S0960-9822(07)00885-8
[4]
The auditory cortex - PMC - NIH
This is thought to contain three 'core' or primary-like areas, A1, R and RT, which receive independent thalamic inputs mainly from the ventral part of the ...
[5]
Brodmann areas | Radiology Reference Article - Radiopaedia.org
Oct 23, 2016 · Brodmann areas 41 and 42: primary auditory cortex (Heschl gyrus). Brodmann area 43: primary gustatory cortex. Brodmann area 44: part of Broca ...
[6]
Auditory cortex: anatomy - Voyage au centre de l'audition
Primary auditory cortex (AI) is situated in the posterior third of the superior temporal gyrus (also known as Brodmann area 41), next to Wernicke's area (W).
[7]
Planum temporale asymmetry and language dominance - PubMed
All subjects who had language lateralized to the left hemisphere (11 right-handers) had a leftward asymmetry of the planum temporale. One subject who had ...
[8]
Neurophysiological origin of human brain asymmetry for speech and ...
Our online concurrent EEG and BOLD fMRI data suggest that leftward asymmetry in language processing originates in auditory, somatosensory (37), articulatory ...
[9]
Heschl's gyrus | Radiology Reference Article | Radiopaedia.org
Sep 6, 2023 · Heschl's gyrus, also known as transverse temporal gyrus, is the gyrus on the superior surface of the temporal lobe that contains the primary auditory cortex.
[10]
Cortical Surface Area and Cortical Thickness Demonstrate ...
May 3, 2013 · The findings suggest that auditory-related cortical areas demonstrate larger leftward asymmetry with respect to the CSA, while a clear rightward ...
[11]
https://doi.org/10.1006/nimg.2000.0715
[12]
https://pubmed.ncbi.nlm.nih.gov/9974150/
[13]
The planum temporale: a systematic, quantitative review of its ...
The planum temporale (PT) is a triangular area on the superior temporal gyrus, thought to be involved in language function and related to disorders like ...
[14]
The Basics of Brain Development - PMC - PubMed Central
Human brain development is a protracted process that begins in the third gestational week (GW) with the differentiation of the neural progenitor cells and ...
[15]
Distinct Actions of Emx1, Emx2, andPax6 in Regulating the ... - NIH
Our findings indicate that EMX2 and PAX6 regulate, in opposing manners, arealization of the neocortex and impart positional identity to cortical cells.
[16]
Fibroblast Growth Factor 8 Organizes the Neocortical Area Map and ...
May 23, 2012 · In the caudal NP, ectopic FGF8 induced a second, inclusive area map, containing frontal cortex, S1, V1, and primary auditory areas. Moreover, ...
[17]
Fetal MR Imaging Anatomy of the Transverse Temporal Gyrus ...
Nov 1, 2023 · The primary auditory cortex is located in the transverse temporal gyrus and was first described in 1878 by Heschl on postmortem specimens, and ...
[18]
Development of the human fetal auditory cortex: growth of ... - PubMed
In the oldest fetuses (22-28 weeks) AChE-positive fibres of thalamic origin penetrate the developing cortical plate of the auditory cortex.Missing: anlage | Show results with:anlage
[19]
Connexin hemichannels contribute to spontaneous electrical activity ...
Sep 2, 2014 · These data suggest that connexin hemichannels contribute to spontaneous depolarizations in the human fetal cortex during the second trimester of gestation.
[20]
Prenatal thalamic waves regulate cortical area size prior to sensory ...
Feb 3, 2017 · Abolishing spontaneous calcium waves in the auditory nucleus of the thalamus alters the pattern of spontaneous waves in the neighbouring ...
[21]
https://doi.org/10.1016/j.neuroscience.2013.05.021
[22]
Regional differences in synaptogenesis in human cerebral cortex
Synaptic density increases more rapidly in auditory cortex, where the maximum is reached near postnatal age 3 months. Maximum synaptic density in middle frontal ...
[23]
The Developing Brain - From Neurons to Neighborhoods - NCBI - NIH
The development of myelin is a protracted process extending well into the postnatal period. The rate and extent of myelination is also affected by experience.
[24]
Dendritic Spine Initiation in Brain Development, Learning ... - MDPI
Dendritic spine density in normal human brain increases rapidly before and after birth achieving the highest density around 2–8 years. Density decreases during ...
[25]
Modified Areal Cartography in Auditory Cortex Following Early
Feb 14, 2013 · Overall, the volume of A1 was significantly reduced in both early- and late-deaf cats. Interestingly, while PAF, DZ, and AAF did not show any ...
[26]
Congenital deafness affects deep layers in primary and secondary ...
Jun 23, 2017 · Congenital deafness leads to functional deficits in the auditory cortex for which early cochlear implantation can effectively compensate.
[27]
Auditory Cortex Asymmetry Associations with Individual Differences ...
Dec 23, 2023 · Landmark case studies linking a history of written and oral language learning problems to atypical planum temporale asymmetry (PTA) [1] provided ...Missing: postnatal | Show results with:postnatal
[28]
Tonotopic organization of human auditory cortex - PubMed Central
Abstract. The organization of tonotopic fields in human auditory cortex was investigated using functional magnetic resonance imaging.Missing: seminal | Show results with:seminal
[29]
Extensive Tonotopic Mapping across Auditory Cortex Is ...
Dec 13, 2017 · We demonstrate that human primary and nonprimary auditory cortical activation is modulated by spectrally directed attention in a manner that recapitulates its ...
[30]
Auditory processing in the human cortex: An intracranial ...
Apr 12, 2017 · This review highlights recent intracranial studies of human auditory cortex and focuses on its basic response properties as well as modulation of cortical ...<|control11|><|separator|>
[31]
Level-Tuned Neurons in Primary Auditory Cortex Adapt Differently to ...
Many neurons in the auditory system utilize a nonmonotonic level coding scheme whereby the neuron responds most robustly to a particular best sound level, and ...
[32]
Hierarchical differences in population coding within auditory cortex
In both fields, neurons exhibit monotonic AM-depth tuning, with A1 neurons mostly exhibiting increasing rate-depth functions and ML neurons approximately evenly ...
[33]
Are Interaural Time and Level Differences Represented by ...
These results suggest that the auditory cortex contains an integrated code of sound laterality, but also retains independent information about ITD and ILD cues.
[34]
Evidence for cue-independent spatial representation in the human ...
Aug 21, 2017 · These results suggest a higher-order representation of auditory space in the human auditory cortex that at least partly integrates the specific underlying cues.
[35]
The what, where and how of auditory-object perception - PMC
Auditory objects are the computational result of the auditory system's capacity to detect, extract, segregate and group spectrotemporal regularities in the ...
[36]
https://pmc.ncbi.nlm.nih.gov/articles/PMC4082027/
[37]
https://doi.org/10.1016/j.neuron.2008.12.005
[38]
Evidence for distinct human auditory cortex regions for sound ...
Neurophysiological animal models suggest that anterior auditory cortex (AC) areas process sound-identity information, whereas posterior ACs specialize in sound ...Missing: vocalizations | Show results with:vocalizations
[39]
Neural Mechanisms Underlying Musical Pitch Perception and ... - NIH
Harmonically sensitive neurons have been found in the auditory cortex in various animal models. In fact, some cortical neurons respond best to harmonic tones ...
[40]
Musical training shapes neural responses to melodic and prosodic ...
In fact, besides harmony and syntax, pitch is another important feature, forming the melody in music and the intonation or prosody ('the melody of speech') in ...
[41]
Distinct neural circuits processing pleasant and unpleasant sounds
Aug 26, 2025 · The primary auditory system is linked to emotional processing centers primarily through the amygdala, which is strongly activated by aversive, ...
[42]
Auditory cortical neurons are recruited to encode fear signals and ...
Apr 11, 2025 · We have examined how auditory cortical neurons are recruited to encode stress signals that cause fear memory and anxiety.Missing: A1 | Show results with:A1
[43]
https://pmc.ncbi.nlm.nih.gov/articles/PMC12379371/
[44]
Top-down auditory attention modulates neural responses more ...
Top-down attention enhances neural responses to attended stimuli and suppresses those to ignored stimuli (Hillyard et al., 1973; Woldorff et al., 1993). ...Missing: boost | Show results with:boost
[45]
Auditory dysfunction in schizophrenia: integrating clinical and basic ...
The central auditory system begins with the auditory nerve. Auditory information then ascends via the cochlear nucleus, superior olivary complex and inferior ...Missing: A1 | Show results with:A1
[46]
Understanding rostral–caudal auditory cortex contributions to ...
The ventral medial geniculate nucleus (MGv) is, similar to the iC, organized tonotopically and is considered to be the main pathway to the auditory cortex, ...Missing: IV | Show results with:IV
[47]
Synaptic Properties of Thalamic Input to Layers 2/3 and 4 of Primary ...
We studied the synaptic profile of thalamic inputs to cells in layers 2/3 and 4 of primary somatosensory (S1) and auditory (A1) cortices using thalamocortical ...Results · Thalamocortical Response... · Thalamus As A Modulator Of...
[48]
Acoustic Radiation: Anatomy & Tractography Review
Mar 6, 2019 · Direct projections from the other MGN divisions to secondary auditory cortical regions are part of the extralemniscal (or non-lemniscal) ...
[49]
Structural organization of the ascending auditory pathway
2 The belt region of the auditory cortex. Areas that lie outside of the core region are often referred to as the non-lemniscal or belt areas (Fig. 2.13). These ...Missing: MGN | Show results with:MGN
[50]
Frequency transformation in the auditory lemniscal thalamocortical ...
A surprising finding from a comparison of classical and modern approaches is the similar degree of convergence from thalamic neurons to single A1 neurons and ...
[51]
Thalamic and cortical pathways supporting auditory processing - PMC
The neural processing of auditory information engages pathways that begin initially at the cochlea and that eventually reach forebrain structures.
[52]
Generation of Spike Latency Tuning by Thalamocortical Circuits in ...
Jul 18, 2012 · On one hand, the large convergence of relatively weak thalamocortical inputs improves the reliability and signal/noise ratio of cortical ...
[53]
DESCENDING PROJECTIONS TO THE AUDITORY MIDBRAIN
Although descending projections have been implicated in many types of behaviors, a unified understanding of their function has not yet emerged.
[54]
Cell type-specific inhibitory modulation of sound processing in the ...
Jun 29, 2024 · The medial geniculate body (MGB) located within the thalamus receives auditory information from the auditory brainstem, and MGB neurons shape ...
[55]
Cell type–specific plasticity in synaptic, intrinsic, and sound ...
Sep 19, 2025 · Communication between ACtx and the auditory thalamus, the medial geniculate body (MGB), is mediated by reciprocally connected corticothalamic ( ...
[56]
[PDF] Connections of cat auditory cortex: II. Commissural system
Commissural projec- tions arise from segregated and parallel groups of areas, with the main input to an area from reciprocal homotopic locations and orga- nized ...
[57]
Influence of Core Auditory Cortical Areas on Acoustically Evoked ...
Jan 9, 2013 · These findings demonstrate that during periods of acoustic exposure, callosal projections emanating from core auditory areas modulate A1 neuronal activity via ...
[58]
Feedforward and feedback projections of caudal belt and parabelt ...
Our working model of the primate auditory cortex recognizes three major regions (core, belt, parabelt), subdivided into thirteen areas.Introduction · Materials and Methods · Results · Discussion
[59]
Auditory belt and parabelt projections to the prefrontal cortex in the ...
Recent studies have shown that rostral and caudal belt and parabelt cortices have distinct patterns of connections and acoustic responsivity.Missing: cytoarchitecture | Show results with:cytoarchitecture
[60]
Information cascade from primary auditory cortex to the amygdala
These findings define the complete sequence of connections linking primary auditory cortex with the amygdala in the rat.
[61]
Sensory-Motor Interaction in the Primate Auditory Cortex During Self ...
We found that1) self-initiated vocalizations resulted in suppression of neural discharges in a majority of auditory cortical neurons. The vocalization-induced ...
[62]
Descending projections from auditory cortex to excitatory and ...
The nucleus of the brachium of the inferior colliculus (NBIC) is a large midbrain auditory nucleus that is a target of these descending cortical projections.
[63]
Auditory Cortex Basal Activity Modulates Cochlear Responses in ...
These results show that blocking ongoing auditory cortex activity modulates CM and CAP responses, demonstrating that cortico-olivocochlear circuits regulate ...
[64]
Listening loops and the adapting auditory brain - Frontiers
Mar 15, 2023 · When and how does the auditory cortex influence subcortical auditory structures? New insights about the roles of descending cortical projections ...
[65]
The Auditory Agnosias: a Short Review of Neurofunctional Evidence
Sep 25, 2023 · Global auditory agnosia frequently results from bilateral temporal damage. ... On pure word deafness, temporal processing, and the left ...
[66]
PURE WORD DEAFNESS FOLLOWING BILATERAL LESIONS | Brain
Abstract. A detailed clinical and psychophysical study of a woman who had developed pure word deafness associated with amusia after bilateral temporopariet.Missing: primary source
[67]
Lesion correlates of impaired acoustic-phonetic perception after ...
Apr 3, 2025 · Acquired impairment of acoustic-phonetic perception is known historically as 'pure word deafness' and typically follows bilateral lesions of the ...
[68]
Central Auditory Processing Disorder - StatPearls - NCBI Bookshelf
Mar 1, 2023 · Central auditory processing disorder is a rare, poorly understood condition that affects the central auditory nervous system.
[69]
Maturation of the Central Auditory Nervous System in Children with ...
The maturation of the auditory cortex is demonstrated by changes to the cortical auditory evoked potential (CAEP) from birth into adulthood, including changes ...
[70]
Altered brain network topology in children with auditory processing ...
This impairment in auditory perception is characterized as caused by deficiencies or developmental differences in the central auditory nervous system (CANS), ...1. Introduction · 2. Methods · 4. Discussion
[71]
Neural Plasticity in Tinnitus Mechanisms - MDPI
Nov 22, 2023 · The stimulation of the human auditory core and belt areas is difficult because they are mostly buried in the lateral fissure at a depth of 2–4 ...
[72]
Tinnitus and hyperacusis involve hyperactivity and enhanced ...
May 12, 2015 · Hearing loss often triggers an inescapable buzz (tinnitus) and causes everyday sounds to become intolerably loud (hyperacusis), ...Missing: belt | Show results with:belt
[73]
Changes in Auditory Cortex Subregions and Their Prediction for ...
Jul 22, 2025 · Our findings demonstrate extensive AC changes in bilateral TE3.0, offering new insights into the mechanism of tinnitus.Missing: hyperactivity belt
[74]
Abnormal auditory tonotopy in patients with schizophrenia - Nature
Oct 2, 2019 · Auditory hallucinations are among the most prevalent and most distressing symptoms of schizophrenia. Despite significant progress, it is ...
[75]
Aging reduces excitatory bandwidth, alters spectral tuning curve ...
Apr 2, 2025 · The primary auditory cortex (A1) of aging mice shows reduced suppressive responses and reduced diversity of temporal responses suggesting alteration of ...
[76]
Speech outcomes in cochlear implant users depend on visual cross ...
Feb 14, 2025 · Visual cross-modal plasticity, where auditory cortical neurons upregulate visual inputs to assist visual processing, is one factor proposed to ...
[77]
Evidence of visual crossmodal reorganization positively relates to ...
Oct 22, 2022 · Cross-modal plasticity in higher-order auditory cortex of congenitally deaf cats does not limit auditory responsiveness to cochlear implants.
[78]
https://www.jneurosci.org/content/27/29/7838.short
[79]
https://pmc.ncbi.nlm.nih.gov/articles/PMC4681549/
[80]
Reorganization of auditory cortex in tinnitus - PNAS
Magnetic source imaging was used to determine whether tonotopy in auditory cortex of individuals with tinnitus diverges from normative functional organization.
[81]
Evidence of a Tonotopic Organization of the Auditory Cortex in ...
Jul 18, 2007 · The purpose of the present study was to address whether the auditory cortex of cochlear implant subjects is tonotopically organized. The ...
[82]
Auditory Cortical Plasticity Drives Training-Induced Cognitive ... - NIH
These data suggest that computerized cognitive training that targets auditory and verbal learning operations enhances both sensory responses in auditory cortex ...
[83]
Implications of Transcranial Magnetic Stimulation as a Treatment ...
Nov 20, 2021 · Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive, neuromodulating technique for brain hyperexcitability disorders.
[84]
Cochlear gene therapy restores hearing and auditory processing in ...
Jun 12, 2025 · Our findings indicate that gene therapy may be an effective approach for treating all forms of otoferlin-related hearing loss.
[85]
Effects of Sensorineural Hearing Loss on Cortical Synchronization to ...
Mar 18, 2020 · People with age-related sensorineural hearing loss often struggle to follow speech in the presence of competing talkers.
[86]
Amount of Hearing Aid Use Impacts Neural Oscillatory...
This study is the first to investigate the impact of hearing aid use on the neural dynamics that underlie working memory function.<|control11|><|separator|>