Layer‐specific BOLD activation in human V1

Koopmans, Peter J.; Barth, Markus; Norris, David G.

doi:10.1002/hbm.20936

Cited by 204 publications

(256 citation statements)

References 33 publications

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“…To investigate the nature of these computations, we analyzed cortical depth-dependent changes induced by different tasks. Previous literature has shown that fMRI can detect layer-dependent signal changes using both T 2 *-weighted and T 2 -weighted measurements (25)(26)(27)(28)(29)(30). We analyzed the differential changes induced by the auditory and visual tasks on the frequency population tuning and selectivity.…”

Section: Discussionmentioning

confidence: 99%

Frequency preference and attention effects across cortical depths in the human primary auditory cortex

Martino

Moerel

Uğurbil

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

162

189

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Columnar arrangements of neurons with similar preference have been suggested as the fundamental processing units of the cerebral cortex. Within these columnar arrangements, feed-forward information enters at middle cortical layers whereas feedback information arrives at superficial and deep layers. This interplay of feedforward and feedback processing is at the core of perception and behavior. Here we provide in vivo evidence consistent with a columnar organization of the processing of sound frequency in the human auditory cortex. We measure submillimeter functional responses to sound frequency sweeps at high magnetic fields (7 tesla) and show that frequency preference is stable through cortical depth in primary auditory cortex. Furthermore, we demonstrate that-in this highly columnar cortex-task demands sharpen the frequency tuning in superficial cortical layers more than in middle or deep layers. These findings are pivotal to understanding mechanisms of neural information processing and flow during the active perception of sounds.A uditory perception starts in our ears, where hair cells at different places in the cochlea respond to different sound frequencies. The spatially ordered arrangement of neural responses to frequencies (tonotopy) that arises from this transduction mechanism is preserved in subcortical (1, 2) and cortical stages of processing, where neuronal populations form multiple tonotopic maps (3, 4). At the cortical level, tonotopic maps describe systematic changes along the surface. In the orthogonal direction (i.e., perpendicular to the cortical surface), aggregates of neurons with parallel axons have been reported (5, 6). These anatomical observations of cortical microcolumns inspired invasive electrophysiological investigations in cats (7), demonstrating that frequency preference is constant across cortical depth (i.e., frequency columns). Since this early study, frequency columns have been observed in a variety of animals (3,(8)(9)(10), and a columnar organization has been suggested for other acoustic properties (10, 11). Despite this anatomical and physiological evidence from animal models, the role of cortical columns in auditory perception is not understood (6, 12, 13). To unravel intracolumnar computations, it is of fundamental importance to analyze the transformation of information across cortical depths. Differences in cell types and in patterns of input and output projections suggest a distinct role of cortical layers in neural information processing (5). In particular, behavioral demands and ongoing brain states can modulate the functional properties of layer 2/3 neurons, suggesting that supragranular neuronal populations may be of fundamental relevance for the processing of sensory information in a context-dependent manner (14). Recordings in the primary auditory cortex of animals have shown differences across layers in response latency (15, 16), in frequency selectivity (i.e., tuning width) (8, 16), and in the complexity of neuronal preference to acoustic information (i.e., recepti...

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Section: Discussionmentioning

confidence: 99%

Frequency preference and attention effects across cortical depths in the human primary auditory cortex

Martino

Moerel

Uğurbil

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

162

189

View full text Add to dashboard Cite

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“…Furthermore, here we selectively sampled the middle cortical depths when displaying statistical maps on the flattened surface to reduce the spatial spread of the GE-BOLD response (Polimeni et al, 2010). Despite the small voxel size used here, spatial inaccuracy of the order of a voxel could potentially result in signals from extra-cortical veins being mapped onto the central layer (Koopmans et al, 2010). The activation on the anterior bank of the CS in Figure 2A may originate from such inaccuracy.…”

Section: Comparison Of Functional Parcellation With Cytoarchitectonicmentioning

confidence: 99%

Within-Digit Functional Parcellation of Brodmann Areas of the Human Primary Somatosensory Cortex Using Functional Magnetic Resonance Imaging at 7 Tesla

Panchuelo¹,

et al. 2012

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The primary somatosensory cortex (S1) can be subdivided cytoarchitectonically into four distinct Brodmann areas (3a, 3b, 1, and 2), but these areas have never been successfully delineated in vivo in single human subjects. Here, we demonstrate the functional parcellation of four areas of S1 in individual human subjects based on high-resolution functional MRI measurements made at 7 T using vibrotactile stimulation. By stimulating four sites along the length of the index finger, we were able to identify and locate map reversals of the base to tip representation of the index finger in S1. We suggest that these reversals correspond to the areal borders between the mirrored representations in the four Brodmann areas, as predicted from electrophysiology measurements in nonhuman primates. In all subjects, maps were highly reproducible across scanning sessions and stable over weeks. In four of the six subjects scanned, four, mirrored, within-finger somatotopic maps defining the extent of the Brodmann areas could be directly observed on the cortical surface. In addition, by using multivariate classification analysis, the location of stimulation on the index finger (four distinct sites) could be decoded with a mean accuracy of 65% across subjects. Our measurements thus show that within-finger topography is present at the millimeter scale in the cortex and is highly reproducible. The ability to identify functional areas of S1 in vivo in individual subjects will provide a framework for investigating more complex aspects of tactile representation in S1.

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“…The use of ultra-high field strengths of 7 T and above and the resulting high SNR help linking of structure and function even on a single subject basis (S anchez-Panchuelo et al, 2012;Turner and Geyer, 2014). For the reasons mentioned above it is not surprising that the primary visual cortex is an area where a correlation between cortical lamination and executed function was studied in humans at 3 T Clare and Bridge, 2005;Koopmans et al, 2010) and at 7 T (S anchez-Panchuelo et al, 2012) in-vivo. By using the stria of Gennari as a landmark, it was possible to determine the border between primary visual cortex V1 and higher visual area V2 anatomically S anchez-Panchuelo et al, 2012).…”

Section: Studies Of the Stria Of Gennarimentioning

confidence: 99%

In-vivo magnetic resonance imaging (MRI) of laminae in the human cortex

et al. 2019

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The human neocortex is organized radially into six layers which differ in their myelination and the density and arrangement of neuronal cells. This cortical cyto-and myeloarchitecture plays a central role in the anatomical and functional neuroanatomy but is primarily accessible through invasive histology only. To overcome this limitation, several non-invasive MRI approaches have been, and are being, developed to resolve the anatomical cortical layers. As a result, recent studies on large populations and structure-function relationships at the laminar level became possible. Early proof-of-concept studies targeted conspicuous laminar structures such as the stria of Gennari in the primary visual cortex. Recent work characterized the laminar structure outside the visual cortex, investigated the relationship between laminar structure and function, and demonstrated layer-specific maturation effects. This paper reviews the methods and in-vivo MRI studies on the anatomical layers in the human cortex based on conventional and quantitative MRI (excluding diffusion imaging). A focus is on the related challenges, promises and potential future developments. The rapid development of MRI scanners, motion correction techniques, analysis methods and biophysical modeling promise to overcome the challenges of spatial resolution, precision and specificity of systematic imaging of cortical laminae. Need for non-invasive mapping of cortical laminationThe neocortex of the human brain consists of six layers which differ in their pattern of myelination (Nieuwenhuys, 2013;Vogt and Vogt, 1919) and the density and arrangement of neuronal cells (Brodmann, 1909;Zilles and Amunts, 2010). Those differences gave rise to the broad research field of myelo-and cyto-architecture, which is based on invasive histology. To facilitate studies of the human brain in large populations and longitudinally, non-invasive methods are much needed for visualizing intracortical anatomy in-vivo, since histological methods can only be applied ex-vivo. A promising approach is magnetic resonance imaging (MRI) as it is non-invasive and highly sensitive to the presence of myelin (and iron) in the cortex (Stüber et al., 2014). It is expected to reflect the myeloarchitecture rather than the cyto-architecture, although there is a strong correspondence between the two . Scope of the reviewThis paper reviews the recent in-vivo MRI studies on the anatomical layers in the human neocortex. An additional focus is on the related challenges, promises and potential future developments. Studies using diffusion weighted MRI are excluded from this review, since they are covered by Assaf et al. (2017) in the same special issue on "Prospects for cortical laminar MRI: functional and anatomical imaging of cerebral cortical layers". MRI studies of cortical layers Studies of the stria of GennariAs the cortex is only 2-4 mm thick and convoluted (Fischl and Dale, 2000), mapping cortical layers requires sub-millimeter isotropic resolution. Another challenge is that the differences in myelo-ar...

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Layer‐specific BOLD activation in human V1

Cited by 204 publications

References 33 publications

Frequency preference and attention effects across cortical depths in the human primary auditory cortex

Frequency preference and attention effects across cortical depths in the human primary auditory cortex

Within-Digit Functional Parcellation of Brodmann Areas of the Human Primary Somatosensory Cortex Using Functional Magnetic Resonance Imaging at 7 Tesla

In-vivo magnetic resonance imaging (MRI) of laminae in the human cortex

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