Effector regions alternate with somatocognitive networks

In a recent study published in Nature Journal, researchers performed precision functional mapping (PFM) and functional magnetic resonance imaging (fMRI) to map the functional organization of the motor cortex (M1) of the human brain.

study: Somatocognitive networks alternate with effector regions in the motor cortex. Image credit: r.classen/Shutterstock.com

Background

The human motor cortex was originally described as a continuously present homunculus. In contrast, non-human primate (NHP) studies divide M1 into anterior and posterior regions, with the body represented anteriorly and the motor effector region posteriorly.

Voluntary movements are regulated by the plexus zoster (CON). Animal studies have demonstrated an anterior motor cortex projecting into internally located organs involved in sympathetic arousal, and CON along with M1 not only mediates abstract behavior, but also coordinates movement. is also shown.

About research

In the present study, researchers presented a dual system that fuses behavior and body control into a common circuit, featuring a somatocognitive-behavioral network (SCAN) that alternates with M1 effector regions.

The team performed high-resolution (2.40 mm) PFM with resting-state functional connectivity (RSFC) values ​​of 172.0–1,813.0 min per participant (task: 353.0 min per person) to map functional networks in the brain. Diffusion information was used.

To validate our findings, data were obtained from three large fMRI studies: the Adolescent Cognitive Brain Development (ABCD) study, the UK Biobank (UKB) study, the Human Connectome Project (HCP) study, and the present study. was given. We compared the survey results.

In total, the dataset consisted of data from approximately 50,000 individuals. Furthermore, the findings utilize precision functional mapping (PFM) information to interspecies (macaques and humans), clinical (postnatal stroke), and developmental (neonatal, infancy, childhood, and adulthood) contexts. was placed in

The team used an MRI task battery of motor and behavioral functions to record concentric effector somatopy delineated by CON-related inter-effector regions (IERs). We compared the relative timing of resting functional MRI signals in the M1 region.

Functional MRI data were obtained from two highly sampled participants (64.0 runs, 244.0 minutes per person) with blocked performance of 25 movements and clear indications for planning and execution of limb movements. Taken from a new event-related task with phases (12.0 runs, 132.0 minutes). minutes per person).

For a formal test of concentric placement, single-peak and double-peak Gaussian curves were fitted to task activation profiles along the dorsomedial to ventrolateral axis of M1.

Task-related functional MRI data were also acquired while individuals repeatedly produced the ‘ee’ sound to isolate laryngeal movements while minimizing tongue and jaw movement and breathing. Motor stimuli were reanalyzed using data from previous large-scale studies by mapping them to the cortex.

result

Regions with distinct connectivity, structure, and function interrupt the classical homunculus and alternate with effector-specific (hand, mouth, and foot) regions. The expected neuroimaging pattern consisted of three RSFC-defined regions in each brain hemisphere, with connectivity restricted to the symtopic contralateral motor cortex and the adjacent primary somatosensory cortex.

Regions corresponded to task-evoked activity during tongue, hand, and foot movements. Three regions with strong ipsilateral and contralateral functional connections were intertwined between effector-specific regions. This generated interdigitated strands extending from the previously unidentified primary motor cortex (central gyrus).

Motifs were detected in all highly sampled adults and were reproducible at the intra-individual level. Three study datasets validated the interengagement of motor effector regions linked to behavioral control.

Furthermore, the functionally connected IER showed lower cortical thickness but greater fractional anisotropy and intracortical myelin content than the foot region.

IER showed a robust functional connection to CON that is essential for achieving behavioral and physiological control, sympathetic arousal, pain, and goal-directed cognitive control. Accurate fMRI of macaques and children showed interspecies homologs and progenitors of the developmental IER system.

IER was detected in an 11.0-month-old infant and was comparable to that observed in a 9-year-old child. This pattern can also be identified among postpartum severe bilateral stroke patients.

Furthermore, the motor and action fMRI task battery showed concentrically arranged effector somatopies separated by CON-linked IERs. The IER was strongly associated with the supplementary motor area (SMA) and the caudal-located cingulate of the dorsal anterior cingulate cortex (dACC) and associated with the anterior aspect of the insula and prefrontal cortex.

In the striatum, IER showed strong linkage with the dorsolateral putamen. Her IER connections in the thalamus were specifically observed in the central median nucleus and posteromedial nucleus, intermediate nucleus, and ventral inferior posteronucleus.

The IER was also tightly associated with the surrounding cerebellar regions and the fundus of the median sulcus, Brodmann’s area (BA) 3a, which is involved in proprioception.

Furthermore, the IER was associated with the mid-island, which is involved in the processing of interoceptive and pain signals. Lateral vermis Crus II. Cerebellar lobules V, VIIb, and VIIIa. and the dorsolateral putamen, which is important for motor function.

Our findings indicated that high-frequency delta activity may occur earlier in CON than in M1, and that M1 IER may partially enable action plan execution. Favorable movement topographies, double-peak fitter curves, and dual laryngeal representations were confirmed by reanalyzing previously published electrophysiological findings in the distal-proximal concentric tissue (second joining (excluding human hand movements).

Finally, the IER was not action-specific and was activated simultaneously during action planning (hand and foot coordination) and axial body movements (including eyebrows).

Conclusion

This study suggests that the system of whole-body action planning perforates the Samat cognitive-behavioral network, M1.

In M1, two parallel systems are intertwined to form an integrated segregation pattern of effector-specific regions important for fine motor control, linked to the SCAN and important for the integration of goals, body movements, and physiology.

SCAN also enables predictive respiratory, cardiovascular, and postural changes. A dual network aligns the mind and body with the sensory system.