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Cerebral Cortex (New York, N.Y. : 1991) Mar 2020The mouse auditory cortex (ACtx) contains two core fields-primary auditory cortex (A1) and anterior auditory field (AAF)-arranged in a mirror reversal tonotopic...
The mouse auditory cortex (ACtx) contains two core fields-primary auditory cortex (A1) and anterior auditory field (AAF)-arranged in a mirror reversal tonotopic gradient. The best frequency (BF) organization and naming scheme for additional higher order fields remain a matter of debate, as does the correspondence between smoothly varying global tonotopy and heterogeneity in local cellular tuning. Here, we performed chronic widefield and two-photon calcium imaging from the ACtx of awake Thy1-GCaMP6s reporter mice. Data-driven parcellation of widefield maps identified five fields, including a previously unidentified area at the ventral posterior extreme of the ACtx (VPAF) and a tonotopically organized suprarhinal auditory field (SRAF) that extended laterally as far as ectorhinal cortex. Widefield maps were stable over time, where single pixel BFs fluctuated by less than 0.5 octaves throughout a 1-month imaging period. After accounting for neuropil signal and frequency tuning strength, BF organization in neighboring layer 2/3 neurons was intermediate to the heterogeneous salt and pepper organization and the highly precise local organization that have each been described in prior studies. Multiscale imaging data suggest there is no ultrasonic field or secondary auditory cortex in the mouse. Instead, VPAF and a dorsal posterior (DP) field emerged as the strongest candidates for higher order auditory areas.
Topics: Acoustic Stimulation; Animals; Auditory Cortex; Auditory Pathways; Brain; Brain Mapping; Female; Male; Mice; Neurons; Sound
PubMed: 31667491
DOI: 10.1093/cercor/bhz190 -
Cortex; a Journal Devoted To the Study... Jul 2020The architectonical organization of putatively higher auditory areas in the human superior temporal gyrus and sulcus is not yet well understood. To provide a coherent...
The architectonical organization of putatively higher auditory areas in the human superior temporal gyrus and sulcus is not yet well understood. To provide a coherent map of this part of the brain, which is involved in language and other functions, we examined the cytoarchitecture and cortical parcellation of this region in histological sections of ten human postmortem brains using an observer-independent mapping approach. Two new areas were identified in the temporo-insular region (areas TeI, TI). TeI is medially adjacent to the primary auditory cortex (area Te1). TI is located between TeI and the insular cortex. Laterally adjacent to previously mapped areas Te2 and Te3, two new areas (STS1, STS2) were identified in the superior temporal sulcus. All four areas were mapped over their whole extent in serial, cell-body stained sections, and their cytoarchitecture was analyzed using quantitative image analysis and multivariate statistics. Interestingly, area TeI, which is located between area Te1 and area TI at the transition to the insula, was more similar in cytoarchitecture to lateral area Te2.1 than to the directly adjacent areas TI and Te1. Such structural similarity of areas medially and laterally to Te1 would be in line with the core-belt-parabelt concept in macaques. The cytoarchitectonic probabilistic maps of all areas show the localization of the areas and their interindividual variability. The new maps are publicly available and provide a basis to further explore structural-functional relationship of the language network in the temporal cortex.
Topics: Auditory Cortex; Brain Mapping; Humans; Neurons; Temporal Lobe
PubMed: 32298845
DOI: 10.1016/j.cortex.2020.02.021 -
Hearing Research Jul 2007Auditory streaming refers to the perceptual parsing of acoustic sequences into "streams", which makes it possible for a listener to follow the sounds from a given source... (Review)
Review
Auditory streaming refers to the perceptual parsing of acoustic sequences into "streams", which makes it possible for a listener to follow the sounds from a given source amidst other sounds. Streaming is currently regarded as an important function of the auditory system in both humans and animals, crucial for survival in environments that typically contain multiple sound sources. This article reviews recent findings concerning the possible neural mechanisms behind this perceptual phenomenon at the level of the auditory cortex. The first part is devoted to intra-cortical recordings, which provide insight into the neural "micromechanisms" of auditory streaming in the primary auditory cortex (A1). In the second part, recent results obtained using functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) in humans, which suggest a contribution from cortical areas other than A1, are presented. Overall, the findings concur to demonstrate that many important features of sequential streaming can be explained relatively simply based on neural responses in the auditory cortex.
Topics: Acoustic Stimulation; Animals; Auditory Cortex; Auditory Perception; Humans; Magnetic Resonance Imaging; Magnetoencephalography; Pitch Perception; Psychoacoustics
PubMed: 17307315
DOI: 10.1016/j.heares.2007.01.007 -
Neuron Nov 2012Musical training has emerged as a useful framework for the investigation of training-related plasticity in the human brain. Learning to play an instrument is a highly... (Review)
Review
Musical training has emerged as a useful framework for the investigation of training-related plasticity in the human brain. Learning to play an instrument is a highly complex task that involves the interaction of several modalities and higher-order cognitive functions and that results in behavioral, structural, and functional changes on time scales ranging from days to years. While early work focused on comparison of musical experts and novices, more recently an increasing number of controlled training studies provide clear experimental evidence for training effects. Here, we review research investigating brain plasticity induced by musical training, highlight common patterns and possible underlying mechanisms of such plasticity, and integrate these studies with findings and models for mechanisms of plasticity in other domains.
Topics: Auditory Cortex; Auditory Perception; Brain; Humans; Learning; Music; Neuronal Plasticity; Psychomotor Performance
PubMed: 23141061
DOI: 10.1016/j.neuron.2012.10.011 -
Cerebral Cortex (New York, N.Y. : 1991) Mar 2021Accumulating evidence shows that auditory cortex (AC) of humans, and other primates, is involved in more complex cognitive processes than feature segregation only, which...
Accumulating evidence shows that auditory cortex (AC) of humans, and other primates, is involved in more complex cognitive processes than feature segregation only, which are shaped by experience-dependent plasticity and thus likely show substantial individual variability. However, thus far, individual variability of ACs has been considered a methodological impediment rather than a phenomenon of theoretical importance. Here, we examined the variability of ACs using intrinsic functional connectivity patterns in humans and macaques. Our results demonstrate that in humans, interindividual variability is greater near the nonprimary than primary ACs, indicating that variability dramatically increases across the processing hierarchy. ACs are also more variable than comparable visual areas and show higher variability in the left than in the right hemisphere, which may be related to the left lateralization of auditory-related functions such as language. Intriguingly, remarkably similar modality differences and lateralization of variability were also observed in macaques. These connectivity-based findings are consistent with a confirmatory task-based functional magnetic resonance imaging analysis. The quantification of variability in auditory function, and the similar findings in both humans and macaques, will have strong implications for understanding the evolution of advanced auditory functions in humans.
Topics: Adult; Animals; Auditory Cortex; Auditory Pathways; Biological Variation, Individual; Female; Functional Neuroimaging; Humans; Macaca mulatta; Magnetic Resonance Imaging; Male; Young Adult
PubMed: 33350445
DOI: 10.1093/cercor/bhaa366 -
The Journal of Comparative Neurology Feb 2019Mouse lemurs are the smallest of the living primates, and are members of the understudied radiation of strepsirrhine lemurs of Madagascar. They are thought to closely...
Mouse lemurs are the smallest of the living primates, and are members of the understudied radiation of strepsirrhine lemurs of Madagascar. They are thought to closely resemble the ancestral primates that gave rise to present day primates. Here we have used multiple histological and immunochemical methods to identify and characterize sensory areas of neocortex in four brains of adult lemurs obtained from a licensed breeding colony. We describe the laminar features for the primary visual area (V1), the secondary visual area (V2), the middle temporal visual area (MT) and area prostriata, somatosensory areas S1(3b), 3a, and area 1, the primary motor cortex (M1), and the primary auditory cortex (A1). V1 has "blobs" with "nonblob" surrounds, providing further evidence that this type of modular organization might have evolved early in the primate lineage to be retained in all extant primates. The laminar organization of V1 further supports the view that sublayers of layer 3 of primates have been commonly misidentified as sublayers of layer 4. S1 (area 3b) is proportionately wider than the elongated area observed in anthropoid primates, and has disruptions that may distinguish representations of the hand, face, teeth, and tongue. Primary auditory cortex is located in the upper temporal cortex and may include a rostral area, R, in addition to A1. The resulting architectonic maps of cortical areas in mouse lemurs can usefully guide future studies of cortical connectivity and function.
Topics: Animals; Auditory Cortex; Brain Mapping; Cheirogaleidae; Motor Cortex; Neocortex; Somatosensory Cortex; Vesicular Glutamate Transport Protein 2
PubMed: 29484648
DOI: 10.1002/cne.24419 -
PloS One 2018Blast exposure is an increasingly significant health hazard and can have a range of debilitating effects, including auditory dysfunction and traumatic brain injury. To...
Blast exposure is an increasingly significant health hazard and can have a range of debilitating effects, including auditory dysfunction and traumatic brain injury. To assist in the development of effective treatments, a greater understanding of the mechanisms of blast-induced auditory damage and dysfunction, especially in the central nervous system, is critical. To elucidate this area, we subjected rats to a unilateral blast exposure at 22 psi, measured their auditory brainstem responses (ABRs), and histologically processed their brains at 1 day, 1 month, and 3-month survival time points. The left and right auditory cortices was assessed for astrocytic reactivity and axonal degenerative changes using glial fibrillary acidic protein immunoreactivity and a silver impregnation technique, respectively. Although only unilateral hearing loss was induced, astrocytosis was bilaterally elevated at 1 month post-blast exposure compared to shams, and showed a positive trend of elevation at 3 months post-blast. Axonal degeneration, on the other hand, appeared to be more robust at 1 day and 3 months post-blast. Interestingly, while ABR threshold shifts recovered by the 1 and 3-month time-points, a positive correlation was observed between rats' astrocyte counts at 1 month post-blast and their threshold shifts at 1 day post-blast. Taken together, our findings suggest that central auditory damage may have occurred due to biomechanical forces from the blast shockwave, and that different indicators/types of damage may manifest over different timelines.
Topics: Animals; Auditory Cortex; Axons; Blast Injuries; Gliosis; Kinetics; Male; Rats; Rats, Sprague-Dawley
PubMed: 29489862
DOI: 10.1371/journal.pone.0193389 -
Cerebral Cortex (New York, N.Y. : 1991) Mar 2023Understanding computational principles in hierarchically organized sensory systems requires functional parcellation of brain structures and their precise targeting for...
Understanding computational principles in hierarchically organized sensory systems requires functional parcellation of brain structures and their precise targeting for manipulations. Although brain atlases are widely used to infer area locations in the mouse neocortex, it has been unclear whether stereotaxic coordinates based on standardized brain morphology accurately represent functional domains in individual animals. Here, we used intrinsic signal imaging to evaluate the accuracy of area delineation in the atlas by mapping functionally-identified auditory cortices onto bregma-based stereotaxic coordinates. We found that auditory cortices in the brain atlas correlated poorly with the true complexity of functional area boundaries. Inter-animal variability in functional area locations predicted surprisingly high error rates in stereotaxic targeting with atlas coordinates. This variability was not simply attributed to brain sizes or suture irregularities but instead reflected differences in cortical geography across animals. Our data thus indicate that functional mapping in individual animals is essential for dissecting cortical area-specific roles with high precision.
Topics: Mice; Animals; Imaging, Three-Dimensional; Brain; Brain Mapping; Auditory Cortex; Head; Neocortex; Stereotaxic Techniques; Magnetic Resonance Imaging
PubMed: 35834935
DOI: 10.1093/cercor/bhac275 -
Scientific Reports Mar 2024Mouse auditory cortex is composed of six sub-fields: primary auditory field (AI), secondary auditory field (AII), anterior auditory field (AAF), insular auditory field...
Mouse auditory cortex is composed of six sub-fields: primary auditory field (AI), secondary auditory field (AII), anterior auditory field (AAF), insular auditory field (IAF), ultrasonic field (UF) and dorsoposterior field (DP). Previous studies have examined thalamo-cortical connections in the mice auditory system and learned that AI, AAF, and IAF receive inputs from the ventral division of the medial geniculate body (MGB). However, the functional and thalamo-cortical connections between nonprimary auditory cortex (AII, UF, and DP) is unclear. In this study, we examined the locations of neurons projecting to these three cortical sub-fields in the MGB, and addressed the question whether these cortical sub-fields receive inputs from different subsets of MGB neurons or common. To examine the distributions of projecting neurons in the MGB, retrograde tracers were injected into the AII, UF, DP, after identifying these areas by the method of Optical Imaging. Our results indicated that neuron cells which in ventral part of dorsal MGB (MGd) and that of ventral MGB (MGv) projecting to UF and AII with less overlap. And DP only received neuron projecting from MGd. Interestingly, these three cortical areas received input from distinct part of MGd and MGv in an independent manner. Based on our foundings these three auditory cortical sub-fields in mice may independently process auditory information.
Topics: Mice; Animals; Geniculate Bodies; Auditory Cortex; Neurons; Neurites; Auditory Pathways; Thalamus
PubMed: 38528192
DOI: 10.1038/s41598-024-57815-3 -
The Journal of Neuroscience : the... Jul 2009Neuroanatomical studies have revealed a vast network of corticocortical connections among the various fields that form cat auditory cortex. However, few studies have...
Neuroanatomical studies have revealed a vast network of corticocortical connections among the various fields that form cat auditory cortex. However, few studies have explored the functional communicative properties of these connections. The purpose of the present study was to examine the bidirectional processing contributions between the primary auditory cortex (A1) and the nonprimary anterior auditory field (AAF). Using acute recording techniques, multiunit neuronal activity was collected from the right hemisphere of nine mature cats. Cortical maps were generated, and the precise location of A1 and AAF was identified. Subsequently, the synaptic activity of A1 or AAF was suppressed with reversible thermal deactivation procedures while the neuronal response to tonal stimuli of the non-inactivated area (A1 or AAF) was measured. We examined response strength and latency, characteristic frequency, bandwidth, and neuronal threshold of A1 and AAF receptive fields before and during epochs of deactivation. Three major changes in A1 response properties were observed during AAF neuronal suppression: a decrease in response strength, an increase in neuronal thresholds, and a sharpening of receptive field bandwidths. In contrast, A1 deactivation did not produce any discernible changes in AAF neuronal responses. Collectively, these results suggest that the modulation of acoustic information between A1 and AAF in cat auditory cortex is dominated by a unidirectional AAF to A1 pathway.
Topics: Acoustic Stimulation; Animals; Auditory Cortex; Auditory Pathways; Auditory Threshold; Brain Mapping; Cats; Denervation; Evoked Potentials, Auditory; Functional Laterality; Linear Models; Neurons; Reaction Time; Temperature; Time Factors
PubMed: 19571126
DOI: 10.1523/JNEUROSCI.6001-08.2009