Minicolumn thinning in temporal lobe association cortex but not primary auditory cortex in normal human ageing

Using high-field (3 Tesla) functional magnetic resonance imaging (fMRI), we demonstrate that auditory and somatosensory inputs converge in a subregion of human auditory cortex along the superior temporal gyrus. Further, simultaneous stimulation in both sensory modalities resulted in activity exceeding that predicted by summing the responses to the unisensory inputs, thereby showing multisensory integration in this convergence region. Recently, intracranial recordings in macaque monkeys have shown similar auditory-somatosensory convergence in a subregion of auditory cortex directly caudomedial to primary auditory cortex (area CM). The multisensory region identified in the present investigation may be the human homologue of CM. Our finding of auditory-somatosensory convergence in early auditory cortices contributes to mounting evidence for multisensory integration early in the cortical processing hierarchy, in brain regions that were previously assumed to be unisensory.

Download Full-text

Diffusion tensor imaging of dolphin brains reveals direct auditory pathway to temporal lobe

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2015.1203 ◽

2015 ◽

Vol 282 (1811) ◽

pp. 20151203 ◽

Cited By ~ 20

Author(s):

Gregory S. Berns ◽

Peter F. Cook ◽

Sean Foxley ◽

Saad Jbabdi ◽

Karla L. Miller ◽

...

Keyword(s):

Diffusion Tensor Imaging ◽

Auditory Cortex ◽

Auditory System ◽

Temporal Lobe ◽

Diffusion Tensor ◽

Primary Auditory Cortex ◽

Post Mortem ◽

Terrestrial Mammals ◽

Medial Geniculate ◽

Archival Specimens

The brains of odontocetes (toothed whales) look grossly different from their terrestrial relatives. Because of their adaptation to the aquatic environment and their reliance on echolocation, the odontocetes' auditory system is both unique and crucial to their survival. Yet, scant data exist about the functional organization of the cetacean auditory system. A predominant hypothesis is that the primary auditory cortex lies in the suprasylvian gyrus along the vertex of the hemispheres, with this position induced by expansion of ‘associative′ regions in lateral and caudal directions. However, the precise location of the auditory cortex and its connections are still unknown. Here, we used a novel diffusion tensor imaging (DTI) sequence in archival post-mortem brains of a common dolphin ( Delphinus delphis ) and a pantropical dolphin ( Stenella attenuata ) to map their sensory and motor systems. Using thalamic parcellation based on traditionally defined regions for the primary visual (V1) and auditory cortex (A1), we found distinct regions of the thalamus connected to V1 and A1. But in addition to suprasylvian-A1, we report here, for the first time, the auditory cortex also exists in the temporal lobe, in a region near cetacean-A2 and possibly analogous to the primary auditory cortex in related terrestrial mammals (Artiodactyla). Using probabilistic tract tracing, we found a direct pathway from the inferior colliculus to the medial geniculate nucleus to the temporal lobe near the sylvian fissure. Our results demonstrate the feasibility of post-mortem DTI in archival specimens to answer basic questions in comparative neurobiology in a way that has not previously been possible and shows a link between the cetacean auditory system and those of terrestrial mammals. Given that fresh cetacean specimens are relatively rare, the ability to measure connectivity in archival specimens opens up a plethora of possibilities for investigating neuroanatomy in cetaceans and other species.

Download Full-text

Author response: Shorter cortical adaptation in dyslexia is broadly distributed in the superior temporal lobe and includes the primary auditory cortex

10.7554/elife.30018.009 ◽

2018 ◽

Author(s):

Sagi Jaffe-Dax ◽

Eva Kimel ◽

Merav Ahissar

Keyword(s):

Auditory Cortex ◽

Temporal Lobe ◽

Primary Auditory Cortex ◽

Author Response ◽

Cortical Adaptation

Download Full-text

Stimulation-mapping of the upper human auditory pathway

Journal of Neurosurgery ◽

10.3171/jns.1973.38.3.0320 ◽

1973 ◽

Vol 38 (3) ◽

pp. 320-325 ◽

Cited By ~ 9

Author(s):

Ronald R. Tasker ◽

L. W. Organ

Keyword(s):

Electrical Stimulation ◽

Auditory Cortex ◽

Brain Stem ◽

Inferior Colliculus ◽

Primary Auditory Cortex ◽

Auditory Pathway ◽

Association Cortex ◽

Content Type ◽

Medial Geniculate ◽

Stimulation Of

✓ Auditory hallucinations were produced by electrical stimulation of the human upper brain stem during stereotaxic operations. The responses were confined to stimulation of the inferior colliculus, brachium of the inferior colliculus, medial geniculate body, and auditory radiations. Anatomical confirmation of an auditory site was obtained in one patient. The hallucination produced was a low-pitched nonspecific auditory “paresthesia” independent of the structure stimulated, the conditions of stimulation, or sonotopic factors. The effect was identical to that reported from stimulating the primary auditory cortex, and virtually all responses were contralateral. These observations have led to the following generalizations concerning electrical stimulation of the somesthetic, auditory, vestibular, and visual pathways within the human brain stem: the hallucination induced in each is the response to comparable conditions of stimulation, is nonspecific, independent of stimulation site, confined to the primary pathway concerned, chiefly contralateral, and identical to that induced by stimulating the corresponding primary auditory cortex. No sensory responses are found in the brain stem corresponding to those from the sensory association cortex.

Download Full-text

Shorter cortical adaptation in dyslexia is broadly distributed in the superior temporal lobe and includes the primary auditory cortex

eLife ◽

10.7554/elife.30018 ◽

2018 ◽

Vol 7 ◽

Cited By ~ 8

Author(s):

Sagi Jaffe-Dax ◽

Eva Kimel ◽

Merav Ahissar

Keyword(s):

Auditory Cortex ◽

Temporal Lobe ◽

Primary Auditory Cortex ◽

General Characteristic ◽

Frequency Discrimination ◽

Tone Frequency ◽

Cortical Dynamics ◽

Sensory Cortices ◽

Cortical Adaptation ◽

Cortical Distribution

Studies of the performance of individuals with dyslexia in perceptual tasks suggest that their implicit inference of sound statistics is impaired. Previously, using two-tone frequency discrimination, we found that the effect of previous trials' frequencies on the judgments of individuals with dyslexia decays faster than the effect on controls' judgments, and that the adaptation (decrease of neural response to repeated stimuli) of their ERP responses to tones is shorter (<xref ref-type="bibr" rid="bib22">Jaffe-Dax et al., 2017</xref>). Here, we show the cortical distribution of these abnormal dynamics of adaptation using fast-acquisition fMRI. We find that faster decay of adaptation in dyslexia is widespread, although the most significant effects are found in the left superior temporal lobe, including the auditory cortex. This broad distribution suggests that the faster decay of implicit memory of individuals with dyslexia is a general characteristic of their cortical dynamics, which also affects sensory cortices.

Download Full-text

Sparse Coding in Temporal Association Cortex Improves Complex Sound Discriminability

10.1101/2020.12.09.417303 ◽

2020 ◽

Author(s):

L Feigin ◽

G Tasaka ◽

I Maor ◽

A Mizrahi

Keyword(s):

Auditory Cortex ◽

Population Analysis ◽

Primary Auditory Cortex ◽

Association Cortex ◽

Temporal Association ◽

Neuronal Responses ◽

Complex Sound ◽

Pure Tones ◽

Auditory Cortices ◽

Auditory Field

AbstractThe mouse auditory cortex is comprised of several auditory fields spanning the dorso-ventral axis of the temporal lobe. The ventral most auditory field is the temporal association cortex (TeA), which remains largely unstudied. Using Neuropixels probes, we simultaneously recorded from primary auditory cortex (AUDp), secondary auditory cortex (AUDv) and TeA, characterizing neuronal responses to pure tones and frequency modulated (FM) sweeps in awake head-restrained mice. As compared to primary and secondary auditory cortices, single unit responses to pure tones in TeA were sparser, delayed and prolonged. Responses to FMs were also sparser. Population analysis showed that the sparser responses in TeA render it less sensitive to pure tones, yet more sensitive to FMs. When characterizing responses to pure tones under anesthesia, the distinct signature of TeA was changed considerably as compared to that in awake mice, implying that responses in TeA are strongly modulated by non-feedforward connections. Together with the known connectivity profile of TeA, these findings suggest that sparse representation of sounds in TeA supports selectivity to higher-order features of sounds and more complex auditory computations.

Download Full-text