The frontal longitudinal system as revealed through the fiber microdissection technique: structural evidence underpinning the direct connectivity of the prefrontal-premotor circuitry

2020 ◽  
Vol 133 (5) ◽  
pp. 1503-1515 ◽  
Author(s):  
Spyridon Komaitis ◽  
Aristotelis V. Kalyvas ◽  
Georgios P. Skandalakis ◽  
Evangelos Drosos ◽  
Evgenia Lani ◽  
...  
Keyword(s):  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Frontal Area ◽  
Frontal Pole ◽  
Fiber System ◽  
Dorsolateral Prefrontal ◽  
Anterior Extension ◽  
Brodmann Areas ◽  
Longitudinal Fiber ◽  
Long Fibers

OBJECTIVEThe purpose of this study was to investigate the morphology, connectivity, and correlative anatomy of the longitudinal group of fibers residing in the frontal area, which resemble the anterior extension of the superior longitudinal fasciculus (SLF) and were previously described as the frontal longitudinal system (FLS).METHODSFifteen normal adult formalin-fixed cerebral hemispheres collected from cadavers were studied using the Klingler microdissection technique. Lateral to medial dissections were performed in a stepwise fashion starting from the frontal area and extending to the temporoparietal regions.RESULTSThe FLS was consistently identified as a fiber pathway residing just under the superficial U-fibers of the middle frontal gyrus or middle frontal sulcus (when present) and extending as far as the frontal pole. The authors were able to record two different configurations: one consisting of two distinct, parallel, longitudinal fiber chains (13% of cases), and the other consisting of a single stem of fibers (87% of cases). The fiber chains’ cortical terminations in the frontal and prefrontal area were also traced. More specifically, the FLS was always recorded to terminate in Brodmann areas 6, 46, 45, and 10 (premotor cortex, dorsolateral prefrontal cortex, pars triangularis, and frontal pole, respectively), whereas terminations in Brodmann areas 4 (primary motor cortex), 47 (pars orbitalis), and 9 were also encountered in some specimens. In relation to the SLF system, the FLS represented its anterior continuation in the majority of the hemispheres, whereas in a few cases it was recorded as a completely distinct tract. Interestingly, the FLS comprised shorter fibers that were recorded to interconnect exclusively frontal areas, thus exhibiting different fiber architecture when compared to the long fibers forming the SLF.CONCLUSIONSThe current study provides consistent, focused, and robust evidence on the morphology, architecture, and correlative anatomy of the FLS. This fiber system participates in the axonal connectivity of the prefrontal-premotor cortices and allegedly subserves cognitive-motor functions. Based in the SLF hypersegmentation concept that has been advocated by previous authors, the FLS should be approached as a distinct frontal segment within the superior longitudinal system.

scholarly journals Cerebellar rTMS and PAS effectively induce cerebellar plasticity

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Martje G. Pauly ◽  
Annika Steinmeier ◽  
Christina Bolte ◽  
Feline Hamami ◽  
Elinor Tzvi ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Healthy Subjects ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Premotor Cortex ◽  
Motor Pathways ◽  
Non Invasive ◽  
Cerebellar Plasticity

AbstractNon-invasive brain stimulation techniques including repetitive transcranial magnetic stimulation (rTMS), continuous theta-burst stimulation (cTBS), paired associative stimulation (PAS), and transcranial direct current stimulation (tDCS) have been applied over the cerebellum to induce plasticity and gain insights into the interaction of the cerebellum with neo-cortical structures including the motor cortex. We compared the effects of 1 Hz rTMS, cTBS, PAS and tDCS given over the cerebellum on motor cortical excitability and interactions between the cerebellum and dorsal premotor cortex / primary motor cortex in two within subject designs in healthy controls. In experiment 1, rTMS, cTBS, PAS, and tDCS were applied over the cerebellum in 20 healthy subjects. In experiment 2, rTMS and PAS were compared to sham conditions in another group of 20 healthy subjects. In experiment 1, PAS reduced cortical excitability determined by motor evoked potentials (MEP) amplitudes, whereas rTMS increased motor thresholds and facilitated dorsal premotor-motor and cerebellum-motor cortex interactions. TDCS and cTBS had no significant effects. In experiment 2, MEP amplitudes increased after rTMS and motor thresholds following PAS. Analysis of all participants who received rTMS and PAS showed that MEP amplitudes were reduced after PAS and increased following rTMS. rTMS also caused facilitation of dorsal premotor-motor cortex and cerebellum-motor cortex interactions. In summary, cerebellar 1 Hz rTMS and PAS can effectively induce plasticity in cerebello-(premotor)-motor pathways provided larger samples are studied.

scholarly journals Periinfarct rewiring supports recovery after primary motor cortex stroke

2021 ◽  
pp. 0271678X2110029
Author(s):  
Mitsouko van Assche ◽  
Elisabeth Dirren ◽  
Alexia Bourgeois ◽  
Andreas Kleinschmidt ◽  
Jonas Richiardi ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Spatial Scales ◽  
Premotor Cortex ◽  
Core Network ◽  
Small Spatial Scale ◽  
The Core ◽  
Hand Dexterity ◽  
Motor Network ◽  
Motor Improvement

After stroke restricted to the primary motor cortex (M1), it is uncertain whether network reorganization associated with recovery involves the periinfarct or more remote regions. We studied 16 patients with focal M1 stroke and hand paresis. Motor function and resting-state MRI functional connectivity (FC) were assessed at three time points: acute (<10 days), early subacute (3 weeks), and late subacute (3 months). FC correlates of recovery were investigated at three spatial scales, (i) ipsilesional non-infarcted M1, (ii) core motor network (M1, premotor cortex (PMC), supplementary motor area (SMA), and primary somatosensory cortex), and (iii) extended motor network including all regions structurally connected to the upper limb representation of M1. Hand dexterity was impaired only in the acute phase ( P = 0.036). At a small spatial scale, clinical recovery was more frequently associated with connections involving ipsilesional non-infarcted M1 (Odds Ratio = 6.29; P = 0.036). At a larger scale, recovery correlated with increased FC strength in the core network compared to the extended motor network (rho = 0.71; P = 0.006). These results suggest that FC changes associated with motor improvement involve the perilesional M1 and do not extend beyond the core motor network. Core motor regions, and more specifically ipsilesional non-infarcted M1, could hence become primary targets for restorative therapies.

scholarly journals Interactions between pairs of transcranial magnetic stimuli over the human left dorsal premotor cortex differ from those seen in primary motor cortex

2007 ◽  
Vol 578 (2) ◽  
pp. 551-562 ◽  
Author(s):  
Giacomo Koch ◽  
Michele Franca ◽  
Hitoshi Mochizuki ◽  
Barbara Marconi ◽  
Carlo Caltagirone ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Dorsal Premotor Cortex

Contribution of the Premotor Cortex to Consolidation of Motor Sequence Learning in Humans During Sleep

2010 ◽  
Vol 104 (5) ◽  
pp. 2603-2614 ◽  
Author(s):  
Michael A. Nitsche ◽  
Michaela Jakoubkova ◽  
Nivethida Thirugnanasambandam ◽  
Leonie Schmalfuss ◽  
Sandra Hullemann ◽  
...  
Keyword(s):  
Reaction Time ◽  
Task Performance ◽  
Rem Sleep ◽  
Sequence Learning ◽  
Memory Consolidation ◽  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Reaction Time Task ◽  
Motor Memory ◽  
Motor Sequence

Motor learning and memory consolidation require the contribution of different cortices. For motor sequence learning, the primary motor cortex is involved primarily in its acquisition. Premotor areas might be important for consolidation. In accordance, modulation of cortical excitability via transcranial DC stimulation (tDCS) during learning affects performance when applied to the primary motor cortex, but not premotor cortex. We aimed to explore whether premotor tDCS influences task performance during motor memory consolidation. The impact of excitability-enhancing, -diminishing, or placebo premotor tDCS during rapid eye movement (REM) sleep on recall in the serial reaction time task (SRTT) was explored in healthy humans. The motor task was learned in the evening. Recall was performed immediately after tDCS or the following morning. In two separate control experiments, excitability-enhancing premotor tDCS was performed 4 h after task learning during daytime or immediately before conduction of a simple reaction time task. Excitability-enhancing tDCS performed during REM sleep increased recall of the learned movement sequences, when tested immediately after stimulation. REM density was enhanced by excitability-increasing tDCS and reduced by inhibitory tDCS, but did not correlate with task performance. In the control experiments, tDCS did not improve performance. We conclude that the premotor cortex is involved in motor memory consolidation during REM sleep.

Corticospinal Tract Microstructure Correlates With Beta Oscillatory Activity in the Primary Motor Cortex After Stroke

Stroke ◽  
2021 ◽  
Author(s):  
Robert Schulz ◽  
Marlene Bönstrup ◽  
Stephanie Guder ◽  
Jingchun Liu ◽  
Benedikt Frey ◽  
...  
Keyword(s):  
Motor Cortex ◽  
Fractional Anisotropy ◽  
Primary Motor Cortex ◽  
Supplementary Motor Area ◽  
Premotor Cortex ◽  
Motor Impairment ◽  
Motor Area ◽  
Oscillatory Activity ◽  
Premotor Area ◽  
Beta Power

Background and Purpose: Cortical beta oscillations are reported to serve as robust measures of the integrity of the human motor system. Their alterations after stroke, such as reduced movement-related beta desynchronization in the primary motor cortex, have been repeatedly related to the level of impairment. However, there is only little data whether such measures of brain function might directly relate to structural brain changes after stroke. Methods: This multimodal study investigated 18 well-recovered patients with stroke (mean age 65 years, 12 males) by means of task-related EEG and diffusion-weighted structural MRI 3 months after stroke. Beta power at rest and movement-related beta desynchronization was assessed in 3 key motor areas of the ipsilesional hemisphere that are the primary motor cortex (M1), the ventral premotor area and the supplementary motor area. Template trajectories of corticospinal tracts (CST) originating from M1, premotor cortex, and supplementary motor area were used to quantify the microstructural state of CST subcomponents. Linear mixed-effects analyses were used to relate tract-related mean fractional anisotropy to EEG measures. Results: In the present cohort, we detected statistically significant reductions in ipsilesional CST fractional anisotropy but no alterations in EEG measures when compared with healthy controls. However, in patients with stroke, there was a significant association between both beta power at rest ( P =0.002) and movement-related beta desynchronization ( P =0.003) in M1 and fractional anisotropy of the CST specifically originating from M1. Similar structure-function relationships were neither evident for ventral premotor area and supplementary motor area, particularly with respect to their CST subcomponents originating from premotor cortex and supplementary motor area, in patients with stroke nor in controls. Conclusions: These data suggest there might be a link connecting microstructure of the CST originating from M1 pyramidal neurons and beta oscillatory activity, measures which have already been related to motor impairment in patients with stroke by previous reports.

scholarly journals Motor Cortical Activity During Drawing Movements: Population Representation During Spiral Tracing

1999 ◽  
Vol 82 (5) ◽  
pp. 2693-2704 ◽  
Author(s):  
Daniel W. Moran ◽  
Andrew B. Schwartz
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Prediction Interval ◽  
Premotor Cortex ◽  
Cortical Activity ◽  
Simultaneous Action ◽  
Emg Activity ◽  
Radius Of Curvature ◽  
Time Interval ◽  
Population Vector

Monkeys traced spirals on a planar surface as unitary activity was recorded from either premotor or primary motor cortex. Using the population vector algorithm, the hand's trajectory could be accurately visualized with the cortical activity throughout the task. The time interval between this prediction and the corresponding movement varied linearly with the instantaneous radius of curvature; the prediction interval was longer when the path of the finger was more curved (smaller radius). The intervals in the premotor cortex fell into two groups, whereas those in the primary motor cortex formed a single group. This suggests that the change in prediction interval is a property of a single population in primary motor cortex, with the possibility that this outcome is due to the different properties generated by the simultaneous action of separate subpopulations in premotor cortex. Electromyographic (EMG) activity and joint kinematics were also measured in this task. These parameters varied harmonically throughout the task with many of the same characteristics as those of single cortical cells. Neither the lags between joint-angular velocities and hand velocity nor the lags between EMG and hand velocity could explain the changes in prediction interval between cortical activity and hand velocity. The simple spatial and temporal relationship between cortical activity and finger trajectory suggests that the figural aspects of this task are major components of cortical activity.

A novel dual-site transcranial magnetic stimulation paradigm to probe fast facilitatory inputs from ipsilateral dorsal premotor cortex to primary motor cortex

NeuroImage ◽  
2012 ◽  
Vol 62 (1) ◽  
pp. 500-509 ◽  
Author(s):  
Sergiu Groppa ◽  
Nicole Werner-Petroll ◽  
Alexander Münchau ◽  
Günther Deuschl ◽  
Matthew F.S. Ruschworth ◽  
...  
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Dorsal Premotor Cortex ◽  
Stimulation Paradigm ◽  
Dual Site

scholarly journals Area-specific thalamocortical synchronization underlies the transition from motor planning to execution

2021 ◽  
Vol 118 (6) ◽  
pp. e2012658118
Author(s):  
Abdulraheem Nashef ◽  
Rea Mitelman ◽  
Ran Harel ◽  
Mati Joshua ◽  
Yifat Prut
Keyword(s):  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Cell Activity ◽  
Motor Planning ◽  
Simultaneous Recording ◽  
Delayed Response ◽  
Neural Responses ◽  
Cortical Cells ◽  
Reaching Task ◽  
Motor Thalamus

We studied correlated firing between motor thalamic and cortical cells in monkeys performing a delayed-response reaching task. Simultaneous recording of thalamocortical activity revealed that around movement onset, thalamic cells were positively correlated with cell activity in the primary motor cortex but negatively correlated with the activity of the premotor cortex. The differences in the correlation contrasted with the average neural responses, which were similar in all three areas. Neuronal correlations reveal functional cooperation and opposition between the motor thalamus and distinct motor cortical areas with specific roles in planning vs. performing movements. Thus, by enhancing and suppressing motor and premotor firing, the motor thalamus can facilitate the transition from a motor plan to execution.

scholarly journals Voluntary Movements Discipline Audiovisual Perception

2020 ◽  
Author(s):  
Ahmad Yousef
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Primary Motor Cortex ◽  
Premotor Cortex ◽  
Brain Regions ◽  
Voluntary Movements ◽  
Deep Breathing ◽  
Audiovisual Perception ◽  
Cognitive Action ◽  
Actual Material

We had shown that deep breathing had been able to effectively and timely alter visual and auditory bistable perception, see reference 1, 2. Deep breathing requires cognitive control, and therefore, in this study, we decide to investigate whether voluntary movements of human hands are able to govern the audiovisual perception using an integrative stimulus that’s built up with the aforementioned visual and auditory stimuli. Astoundingly, when the human subjects moves the pen towards the actual physical direction, even without touching the screen; the original materials of the audiovisual stimulus appear. Reversed perception, namely, illusory motion reversals and illusory word appear when the pen is moved in the opposite direction of the actual motion. Cognitive actions’ brain areas, namely, dorsolateral prefrontal cortex, premotor cortex, and primary motor cortex may require high concentration of oxygenated hobgoblin red blood cells to achieve fulsome executive movements; and this could results in significant reduction of the concentrations of the oxygenated hobgoblin red blood cells in the visual and auditory cortices. Reductions that disallow one of two; the central versus the peripheral conscious brains dedicated for audiovisual perceptions, to rapidly alternate their conscious productions; and therefore, stoppage against bistable audiovisual perception will occur. We thus hypothesis that the DLPFC may send signals to deactivate the peripheral areas in the sensory brain regions when the cognitive action is harmonized with the actual material; but it may send a contrary signal to deactivate the central areas in the sensory brain regions when the cognitive action and the actual material are disharmonized.

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