The architecture of functional lateralisation and its relationship to callosal connectivity in the human brain

Karolis, Vyacheslav; Corbetta, Maurizio; Schotten, Michel Thiebaut de

doi:10.1038/s41467-019-09344-1

Cited by 209 publications

(194 citation statements)

References 73 publications

(75 reference statements)

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“…In addition, more symmetrical functional organization is found for higher probability in callosal connectivity (Karolis et al 2019) and corresponds to the apexes of the gradient in the present study. This is in line with studies showing that stronger callosal connections are associated with a decrease in perceptual processing asymmetries.…”

Section: Discussionsupporting

confidence: 81%

“…In order to map the gradient along the white mater connections, we employed the Disconnectome within the BCBtoolkit (Foulon et al 2018) using a study-specific HCP dataset of 163 participants to generate the underlying white matter tractograms (Karolis et al 2019). The scanning parameters have been described previously (Vu et al 2015).…”

Section: Gradient Percentage Mapsmentioning

confidence: 99%

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Mapping the principal gradient onto the corpus callosum

Friedrich

Forkel

Schotten

2020

Preprint

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AbstractGradients capture some of the variance of the resting-state functional magnetic resonance imaging (rsfMRI) signal. Amongst these, the principal gradient depicts a functional processing hierarchy that spans from sensory-motor cortices to regions of the default-mode network. While the cortex has been well characterised in terms of gradients little is known about its underlying white matter. For instance, comprehensive mapping of the principal gradient on the largest white matter tract, the corpus callosum, is still missing. We hence mapped the principal gradient onto the callosal midsection using the 7T human connectome project dataset. We further explored how quantitative measures and variability in callosal midsection connectivity relate to the principal gradient values. In so doing, we demonstrated that the extreme values of the principal gradient are located within the callosal genu and the posterior body, have lower connectivity variability but a larger spatial extent along the midsection of the corpus callosum than mid-range values. Our results shed light on the relationship between the brain’s functional hierarchy and the corpus callosum. We further speculate about how these results may bridge the gap between functional hierarchy, brain asymmetries, and evolution.

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Section: Discussionsupporting

confidence: 81%

Section: Gradient Percentage Mapsmentioning

confidence: 99%

Mapping the principal gradient onto the corpus callosum

Friedrich

Forkel

Schotten

2020

Preprint

Self Cite

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“…In our study, reward responsivity was investigated in the context of decision making. Interestingly, a recent metaanalysis of lateralization of function suggested that decision making rather than emotion, communication, or perception/action is associated with OFC lateralization (16). Although the adaptive consequences of lateralized functions are not well understood, it is thought that hemispheric specialization could increase processing abilities by reducing bilateral redundancy (20).…”

Section: Discussionmentioning

confidence: 99%

“…Asymmetrical OFC responses in healthy subjects have also been reported in functional magnetic resonance imaging (fMRI) studies (for metaanalyses, see refs. 15,16). However, this result has rarely been discussed.…”

mentioning

confidence: 99%

Differential functional connectivity underlying asymmetric reward-related activity in human and nonhuman primates

Lopez-Persem

Roumazeilles

Folloni

et al. 2020

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

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The orbitofrontal cortex (OFC) is a key brain region involved in complex cognitive functions such as reward processing and decision making. Neuroimaging studies have reported unilateral OFC response to reward-related variables; however, those studies rarely discussed this observation. Nevertheless, some lesion studies suggest that the left and right OFC contribute differently to cognitive processes. We hypothesized that the OFC asymmetrical response to reward could reflect underlying hemispherical difference in OFC functional connectivity. Using resting-state and reward-related functional MRI data from humans and from rhesus macaques, we first identified an asymmetrical response of the lateral OFC to reward in both species. Crucially, the subregion showing the highest reward-related asymmetry (RRA) overlapped with the region showing the highest functional connectivity asymmetry (FCA). Furthermore, the two types of asymmetries were found to be significantly correlated across individuals. In both species, the right lateral OFC was more connected to the default mode network compared to the left lateral OFC. Altogether, our results suggest a functional specialization of the left and right lateral OFC in primates.

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“…On the functional level, neuroimaging studies have indicated major differences in movement-associated activation patterns between the motor-dominant and motor-non-dominant hemispheres 13 , while TMS studies have shown significant interhemispheric differences between the cortical motor representation areas 14 and the stimulation intensities required to elicit motor responses from the two M1 (with the motor-dominant hemisphere typically requiring lower stimulation intensities than the motor-non-dominant hemisphere) 15,16 . On the structural level, alongside interhemispheric differences in transcallosal 17 and cortico-cortical M1 connectivity 18 , significant interhemispheric differences in local intracortical M1 circuits are noted 19 . For example, regional asymmetries of cortical thickness and local gyrification between the hand-knob areas of the two M1 have been associated with the degree of handedness, with evidence of robust leftward asymmetries (i.e., greater gyrification and cortical thickness in the motor-dominant M1) in consistent right-handers 20 .…”

mentioning

confidence: 99%

Interhemispheric symmetry of µ-rhythm phase-dependency of corticospinal excitability

Stefanou

Galevska

Zrenner

et al. 2020

Sci Rep

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oscillatory activity in the µ-frequency band (8-13 Hz) determines excitability in sensorimotor cortex. In humans, the primary motor cortex (M1) in the two hemispheres shows significant anatomical, connectional, and electrophysiological differences associated with motor dominance. It is currently unclear whether the µ-oscillation phase effects on corticospinal excitability demonstrated previously for the motordominant M1 are also different between motor-dominant and motor-non-dominant M1 or, alternatively, are similar to reflect a ubiquitous physiological trait of the motor system at rest. Here, we applied singlepulse transcranial magnetic stimulation to the hand representations of the motor-dominant and the motornon-dominant M1 of 51 healthy right-handed volunteers when electroencephalography indicated a certain µ-oscillation phase (positive peak, negative peak, or random). We determined resting motor threshold (RMT) as a marker of corticospinal excitability in the three µ-phase conditions. RMT differed significantly depending on the pre-stimulus phase of the µ-oscillation in both M1, with highest RMT in the positive-peak condition, and lowest RMT in the negative-peak condition. µ-phase-dependency of RMt correlated directly between the two M1, and interhemispheric differences in µ-phase-dependency were absent. In conclusion, µ-phase-dependency of corticospinal excitability appears to be a ubiquitous physiological trait of the motor system at rest, without hemispheric dominance.The hypothesis that µ-oscillatory activity modulates cortical excitability in the sensorimotor cortex has recently received growing experimental support from electrophysiological studies in primates 1 and humans 2-6 . The ongoing oscillations of motor networks at rest have been shown to resonate at the µ-frequency band (8-13 Hz) 7 , while the phase of the µ-rhythm has been related to a periodical transition between high-and low-excitability states in neurons of sensorimotor cortex 1 . In a study based on local field potential (LFP) recordings in the right monkey primary motor cortex (M1), neuronal firing rate was highest during the trough of the µ-oscillation, and lowest during its peak 1 .The development of real-time electroencephalography (EEG)-triggered transcranial magnetic stimulation (TMS) has recently enabled a deterministic probing of the effects of the phase of a pre-stimulus oscillation on corticospinal excitability, as indexed by the motor evoked potential (MEP) amplitude, in the human M1. Using real-time brain-state-dependent TMS, we have shown that the EEG negative peak of the µ-oscillation represents a high-excitability state of corticospinal neurons (i.e., larger MEP amplitudes are elicited when TMS is triggered at the EEG negative peak of the µ-oscillation compared to the EEG positive peak) 2-5 . This effect has been demonstrated separately for the M1 of the motor-dominant 2,3 and the motor-non-dominant 4 hemisphere of right-handed subjects.Although µ-oscillations are ubiquitously present in the sensorimotor cortex at rest 7...

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The architecture of functional lateralisation and its relationship to callosal connectivity in the human brain

Cited by 209 publications

References 73 publications

Mapping the principal gradient onto the corpus callosum

Mapping the principal gradient onto the corpus callosum

Differential functional connectivity underlying asymmetric reward-related activity in human and nonhuman primates

Interhemispheric symmetry of µ-rhythm phase-dependency of corticospinal excitability

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