Mesoscale hierarchical organization of primary somatosensory cortex captured by resting-state-fMRI in humans

AbstractHippocampal down-regulation is associated with genetic predisposition to Alzheimer’s disease (AD), neurodevelopmental processes and disease symptoms. Resting state eigenvector centrality (EC) patterns resemble those of FDG-PET in AD, they can predict self-regulation performance and they are related to functional compensation across the pathophysiological continuum of AD. We acquired cerebrospinal fluid (CSF) biomarkers from a cognitively unimpaired sample at risk for AD (N=48), to investigate the effect of β- amyloid peptide 42 (Aβ42) and phosphorylated tau (p-Tau) levels on EC during the down-regulation of hippocampal subfield cornu ammonis 1, with real-time fMRI closed-loop neurofeedback. Controlling the effects of confounding variables (age, sex, number of APOE ε4 alleles, cognitive reserve, brain reserve and hippocampal down-regulation performance), CSF Aβ42 levels correlated positively with EC in the anterior cingulate cortex (BA24, BA32) and primary motor cortex (BA4). CSF p-Tau levels correlated with EC positively in the ACC (BA32, BA10) ventral striatum (caudate, nucleus accumbens, putamen) and left primary somatosensory cortex (BA2), as well as negatively in the posterior cingulate cortex, precuneus, cuneus and left frontal pole (BA9). Controlling for CSF biomarkers and other prognosis variables, age correlated negatively with EC in the midcingulate cortex, insula, primary somatosensory cortex (BA2) and inferior parietal lobule (BA40), as well as positively with EC in the inferior temporal gyri. Taken together, we identified patterns of functional connectomics in individuals at risk of AD during hippocampal down-regulation, which resemble those found during resting state at advanced AD stages. Moreover, we provide a standard paradigm to replicate and extend this work on a global level. This opens new avenues for further research applications, which quantify and monitor disease progression, by identifying early alterations in the self-regulation of brain function, with potential for non-invasive prognostic screening.HighlightsACC centrality decreases with early Aβ42ACC centrality increases with p-TauPCC centrality decreases with p-TauMCC centrality decreases in healthy aging

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Hierarchical disruption in the cortex of anesthetized monkeys as a new signature of consciousness loss

10.1101/2020.06.04.133538 ◽

2020 ◽

Author(s):

Camilo Miguel Signorelli ◽

Lynn Uhrig ◽

Morten Kringelbach ◽

Bechir Jarraya ◽

Gustavo Deco

Keyword(s):

Neural Activity ◽

Resting State ◽

Resting State Fmri ◽

Hierarchical Organization ◽

Brain Dynamics ◽

Depth Of Anesthesia ◽

Functional Changes ◽

Cortical Hierarchy ◽

Brain States ◽

Structure Similarity

AbstractAnesthesia induces a reconfiguration of the repertoire of functional brain states leading to a high function-structure similarity. However, it is unclear how these functional changes lead to loss of consciousness. Here we suggest that the mechanism of conscious access is related to a general dynamical rearrangement of the intrinsic hierarchical organization of the cortex. To measure cortical hierarchy, we applied the Intrinsic Ignition analysis to resting-state fMRI data acquired in awake and anesthetized macaques. Our results reveal the existence of spatial and temporal hierarchical differences of neural activity within the macaque cortex, with a strong modulation by the depth of anesthesia and the employed anesthetic agent. Higher values of Intrinsic Ignition correspond to rich and flexible brain dynamics whereas lower values correspond to poor and rigid, structurally driven brain dynamics. Moreover, spatial and temporal hierarchical dimensions are disrupted in a different manner, involving different hierarchical brain networks. All together suggest that disruption of brain hierarchy is a new signature of consciousness loss.

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Differential Organization of Touch and Pain in Human Primary Somatosensory Cortex

Journal of Neurophysiology ◽

10.1152/jn.2000.83.3.1770 ◽

2000 ◽

Vol 83 (3) ◽

pp. 1770-1776 ◽

Cited By ~ 128

Author(s):

Markus Ploner ◽

Frank Schmitz ◽

Hans-Joachim Freund ◽

Alfons Schnitzler

Keyword(s):

Somatosensory Cortex ◽

Pain Perception ◽

Hierarchical Organization ◽

Primary Somatosensory Cortex ◽

Nociceptive Response ◽

Tactile Stimuli ◽

Somatosensory Cortices ◽

Cortical Responses ◽

Nociceptive Processing ◽

Nociceptive Afferents

Processing of tactile stimuli within somatosensory cortices has been shown to be complex and hierarchically organized. However, the precise organization of nociceptive processing within these cortices has remained largely unknown. We used whole-head magnetoencephalography to directly compare cortical responses to stimulation of tactile and nociceptive afferents of the dorsum of the hand in humans. Within the primary somatosensory cortex (SI), nociceptive stimuli activated a single source whereas tactile stimuli activated two sequentially peaking sources. Along the postcentral gyrus, the nociceptive SI source was located 10 mm more medially than the early tactile SI response arising from cytoarchitectonical area 3b and corresponded spatially to the later tactile SI response. Considering a mediolateral location difference between the hand representations of cytoarchitectonical areas 3b and 1, the present results suggest generation of the single nociceptive response in area 1, whereas tactile stimuli activate sequentially peaking sources in areas 3b and 1. Thus nociceptive processing apparently does not share the complex and hierarchical organization of tactile processing subserving elaborated sensory capacities. This difference in the organization of both modalities may reflect that pain perception rather requires reactions to and avoidance of harmful stimuli than sophisticated sensory capacities.

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Brain activity fluctuations propagate as waves traversing the cortical hierarchy

10.1101/2020.08.18.256610 ◽

2020 ◽

Author(s):

Yameng Gu ◽

Lucas E. Sainburg ◽

Sizhe Kuang ◽

Feng Han ◽

Jack W. Williams ◽

...

Keyword(s):

Functional Connectivity ◽

Spontaneous Activity ◽

Resting State ◽

Brain Activity ◽

Resting State Fmri ◽

Hierarchical Organization ◽

Subcortical Structures ◽

Cortical Hierarchy ◽

Neural Origin ◽

The Brain

AbstractThe brain exhibits highly organized patterns of spontaneous activity as measured by resting-state fMRI fluctuations that are being widely used to assess the brain’s functional connectivity. Some evidence suggests that spatiotemporally coherent waves are a core feature of spontaneous activity that shapes functional connectivity, though this has been difficult to establish using fMRI given the temporal constraints of the hemodynamic signal. Here we investigated the structure of spontaneous waves in human fMRI and monkey electrocorticography. In both species, we found clear, repeatable, and directionally constrained activity waves coursed along a spatial axis approximately representing cortical hierarchical organization. These cortical propagations were closely associated with activity changes in distinct subcortical structures, particularly those related to arousal regulation, and modulated across different states of vigilance. The findings demonstrate a neural origin of spatiotemporal fMRI wave propagation at rest and link it to the principal gradient of resting-state fMRI connectivity.

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Brain Activity Fluctuations Propagate as Waves Traversing the Cortical Hierarchy

Cerebral Cortex ◽

10.1093/cercor/bhab064 ◽

2021 ◽

Author(s):

Yameng Gu ◽

Lucas E Sainburg ◽

Sizhe Kuang ◽

Feng Han ◽

Jack W Williams ◽

...

Keyword(s):

Functional Connectivity ◽

Spontaneous Activity ◽

Resting State ◽

Brain Activity ◽

Resting State Fmri ◽

Hierarchical Organization ◽

Subcortical Structures ◽

Cortical Hierarchy ◽

Neural Origin ◽

The Brain

Abstract The brain exhibits highly organized patterns of spontaneous activity as measured by resting-state functional magnetic resonance imaging (fMRI) fluctuations that are being widely used to assess the brain’s functional connectivity. Some evidence suggests that spatiotemporally coherent waves are a core feature of spontaneous activity that shapes functional connectivity, although this has been difficult to establish using fMRI given the temporal constraints of the hemodynamic signal. Here, we investigated the structure of spontaneous waves in human fMRI and monkey electrocorticography. In both species, we found clear, repeatable, and directionally constrained activity waves coursed along a spatial axis approximately representing cortical hierarchical organization. These cortical propagations were closely associated with activity changes in distinct subcortical structures, particularly those related to arousal regulation, and modulated across different states of vigilance. The findings demonstrate a neural origin of spatiotemporal fMRI wave propagation at rest and link it to the principal gradient of resting-state fMRI connectivity.

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Palm-to-finger cortical functional interactions in primary somatosensory cortex: a 7T fMRI study

10.1101/2020.09.07.286062 ◽

2020 ◽

Author(s):

Michel Akselrod ◽

Roberto Martuzzi ◽

Wietske van der Zwaag ◽

Olaf Blanke ◽

Andrea Serino

Keyword(s):

Somatosensory Cortex ◽

Resting State ◽

Primary Somatosensory Cortex ◽

Spatial Proximity ◽

Single Subject ◽

Functional Interactions ◽

Somatotopic Organization ◽

Pattern Similarity ◽

Resting State Connectivity ◽

7T Fmri

ABSTRACTMany studies focused on the cortical representations of fingers, while the palm is relatively neglected despite its importance for hand function. Here, we investigated palm representation (PR) and its interactions with finger representations (FRs) in primary somatosensory cortex (S1). Few studies in humans suggested that PR is located medially with respect to FRs in S1, yet to date, no study directly quantified the somatotopic organization of PR and the five FRs. Importantly, the relationship between the somatotopic organization and the cortical functional interactions between PR and FRs remains largely unexplored. Using 7T fMRI, we mapped PR and the five FRs at the single subject level. First, we analyzed the cortical distance between PR and FRs to determine their somatotopic organization. Results show that the PR was located medially with respect to D5. Second, we tested whether the observed cortical distances would predict palm-finger functional interactions. Using three complementary measures of functional interactions (co-activations, pattern similarity and resting-state connectivity), we show that palm-finger functional interactions were not determined by their somatotopic organization, that is, there was no gradient moving from D5 to D1, except for resting-state connectivity, which was predicted by the somatotopy. Instead, we show that the representational geometry of palm-finger functional interactions reflected the physical structure of the hand. Collectively, our findings suggest that the spatial proximity between topographically organized neuronal populations do not necessarily predicts their functional interactions, rather the structure of the sensory space (e.g. the hand shape) better predicts the observed functional interactions.

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