Mapping the integration of sensory information across fingers in human sensorimotor cortex

The integration of somatosensory signals across fingers is essential for dexterous object manipulation. Previous experiments suggest that neural populations in the primary somatosensory cortex (S1) are responsible for this integration. However, the integration process has not been fully characterized, as previous studies have mainly used two-finger stimulation paradigms. Here, we addressed this gap by stimulating all 31 single- and multi-finger combinations. We measured population-wide activity patterns evoked during finger stimulation in human S1 and primary motor cortex (M1) using 7T functional magnetic resonance imaging (fMRI). Using multivariate fMRI analyses, we found clear evidence of unique non-linear interactions between fingers. In Brodmann area (BA) 3b, interactions predominantly occurred between pairs of neighboring fingers. In BA 2, however, we found equally strong interactions between spatially distant fingers, as well as interactions between finger triplets and quadruplets, suggesting the presence of rich, non-linear integration of somatosensory information across fingers.

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Differential effects of skilled reaching training on the temporal and spatial organization of somatosensory input to cortical and striatal motor circuits

Journal of Neurophysiology ◽

10.1152/jn.00464.2021 ◽

2021 ◽

Author(s):

Nedjeljka Ivica ◽

Luciano Censoni ◽

Joel Sjöbom ◽

Ulrike Richter ◽

Per Petersson

Keyword(s):

Skill Acquisition ◽

Spatial Organization ◽

Primary Motor Cortex ◽

Sensory Information ◽

Sensorimotor Training ◽

Motor Circuits ◽

Tactile Stimuli ◽

Somatosensory Information ◽

Temporal And Spatial ◽

Skilled Reaching

It has been hypothesized that in order to perform sensorimotor transformations efficiently, somatosensory information being fed back to a particular motor circuit is organized in accordance with the mechanical loading patterns of the skin that results from the motor activity generated by that circuit. Rearrangements of sensory information to different motor circuits could in this respect constitute a key component of sensorimotor learning. We have here explored if the organization of tactile input from the plantar forepaw of the rat to cortical and striatal circuits is affected by a period of extensive sensorimotor training in a skilled reaching and grasping task. Our data show that the representation of tactile stimuli in terms of both temporal and spatial response patterns changes as a consequence of the training, and that spatial changes particularly involve the primary motor cortex. Based on the observed reorganization, we propose that reshaping of the spatiotemporal representation of the tactile afference to motor circuits is an integral component of the learning process that underlies skill-acquisition in reaching and grasping.

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A critical re-evaluation of fMRI signatures of motor sequence learning

eLife ◽

10.7554/elife.55241 ◽

2020 ◽

Vol 9 ◽

Cited By ~ 6

Author(s):

Eva Berlot ◽

Nicola J Popp ◽

Jörn Diedrichsen

Keyword(s):

Sequence Learning ◽

Primary Motor Cortex ◽

Activity Patterns ◽

Motor Sequence Learning ◽

Functional Magnetic Resonance ◽

Motor Sequence ◽

Activation Patterns ◽

Fine Grained ◽

Human Motor ◽

Brain Changes

Despite numerous studies, there is little agreement about what brain changes accompany motor sequence learning, partly because of a general publication bias that favors novel results. We therefore decided to systematically reinvestigate proposed functional magnetic resonance imaging correlates of motor learning in a preregistered longitudinal study with four scanning sessions over 5 weeks of training. Activation decreased more for trained than untrained sequences in premotor and parietal areas, without any evidence of learning-related activation increases. Premotor and parietal regions also exhibited changes in the fine-grained, sequence-specific activation patterns early in learning, which stabilized later. No changes were observed in the primary motor cortex (M1). Overall, our study provides evidence that human motor sequence learning occurs outside of M1. Furthermore, it shows that we cannot expect to find activity increases as an indicator for learning, making subtle changes in activity patterns across weeks the most promising fMRI correlate of training-induced plasticity.

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A critical re-evaluation of fMRI signatures of motor sequence learning

10.1101/2020.01.08.899229 ◽

2020 ◽

Cited By ~ 2

Author(s):

Eva Berlot ◽

Nicola J. Popp ◽

Jörn Diedrichsen

Keyword(s):

Sequence Learning ◽

Primary Motor Cortex ◽

Activity Patterns ◽

Motor Sequence Learning ◽

Functional Magnetic Resonance ◽

Motor Sequence ◽

Activation Patterns ◽

Fine Grained ◽

Human Motor ◽

Brain Changes

AbstractDespite numerous studies, there is little agreement about what brain changes accompany motor sequence learning, partly because of a general publication bias that favors novel results. We therefore decided to systematically reinvestigate proposed functional magnetic resonance imaging correlates of motor learning in a preregistered longitudinal study with four scanning sessions over 5 weeks of training. Activation decreased more for trained than untrained sequences in premotor and parietal areas, without any evidence of learning-related activation increases. Premotor and parietal regions also exhibited changes in the fine-grained, sequence-specific activation patterns early in learning, which stabilized later. No changes were observed in the primary motor cortex (M1). Overall, our study provides evidence that human motor sequence learning occurs outside of M1. Furthermore, it shows that we cannot expect to find activity increases as an indicator for learning, making subtle changes in activity patterns across weeks the most promising fMRI correlate of training-induced plasticity.

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Non-linear effects of cathodal transcranial direct current stimulation (tDCS) of the primary motor cortex on implicit motor learning

Experimental Brain Research ◽

10.1007/s00221-019-05477-3 ◽

2019 ◽

Vol 237 (4) ◽

pp. 919-925 ◽

Cited By ~ 4

Author(s):

Gali Shilo ◽

Michal Lavidor

Keyword(s):

Motor Cortex ◽

Motor Learning ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Primary Motor Cortex ◽

Direct Current Stimulation ◽

Implicit Motor Learning ◽

Non Linear ◽

Implicit Motor ◽

Linear Effects

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Different Brain Network Activations Induced by Modulation and Nonmodulation Laser Acupuncture

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2011/951258 ◽

2011 ◽

Vol 2011 ◽

pp. 1-8 ◽

Cited By ~ 17

Author(s):

Chang-Wei Hsieh ◽

Jih-Huah Wu ◽

Chao-Hsien Hsieh ◽

Qwa-Fun Wang ◽

Jyh-Horng Chen

Keyword(s):

Primary Motor Cortex ◽

Parietal Lobe ◽

Random Effect ◽

Sensory Information ◽

Brain Network ◽

Laser Acupuncture ◽

Middle Temporal Gyrus ◽

Left Frontal Lobe ◽

External Stimulation ◽

Acupuncture Stimulation

The aim of this study is to compare the distinct cerebral activation with continued wave (CW) and 10 Hz-modulated wave (MW) stimulation during low-level laser acupuncture. Functional magnetic resonance imaging (fMRI) studies were performed to investigate the possible mechanism during laser acupuncture stimulation at the left foot's yongquan (K1) acupoint. There are 12 healthy right-handed volunteers for each type of laser stimulation (10-Hz-Modulated wave: 8 males and 4 females; continued wave: 9 males and 3 females). The analysis of multisubjects in this experiment was applied by random-effect (RFX) analysis. In CW groups, significant activations were found within the inferior parietal lobule, the primary somatosensory cortex, and the precuneus of left parietal lobe. Medial and superior frontal gyrus of left frontal lobe were also aroused. In MW groups, significant activations were found within the primary motor cortex and middle temporal gyrus of left hemisphere and bilateral cuneus. Placebo stimulation did not show any activation. Most activation areas were involved in the functions of memory, attention, and self-consciousness. The results showed the cerebral hemodynamic responses of two laser acupuncture stimulation modes and implied that its mechanism was not only based upon afferent sensory information processing, but that it also had the hemodynamic property altered during external stimulation.

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