Cerebral Cortical Areas Research Articles (Page 1)

We review the current state of our knowledge of the neural control of vergence and ocular accommodation in primates including humans. We first describe the critical need for these behaviors for viewing in a three-dimensional world. We then consider the sensory stimuli that drive vergence eye movements and lens accommodation and describe models of the sensorimotor transformations required to drive these motor systems. We discuss the interaction of vergence with saccades to produce high-speed shifts in gaze between objects at different distances and eccentricities. We also cover the normal development of these eye movements as well as the sequelae associated with their maldevelopment. In particular, we examine the neural substrates that produce vergence and lens accommodation, including motoneurons, immediate premotor circuitry, cerebellar and precerebellar regions, and cerebral cortical areas.

In functional magnetic resonance imaging (fMRI), neural activity is inferred from the associated hemodynamic response. However, the degree to which hemodynamics can track dynamic changes in neuronal activity, and thus the ultimate temporal resolution of fMRI, remains unknown. To evaluate the detectability of stimulus-driven high-frequency blood oxygenation level dependent (BOLD) signal oscillations in functionally and vascularly distinct cerebral cortical areas, stimuli up to 0.5 Hz were used to evoke activation in the primary somatosensory and motor cortex. Despite their functional and vascular differences, a similar frequency dependence was observed in both cortical areas. We then proceeded to investigate these signals at different levels of the cortical vascular hierarchy, using cortical depth as a proxy. We observed that, above 0.33 Hz, the BOLD response amplitude decreased faster with increasing frequency near the pial surface than in the parenchyma, suggesting that, in addition to exhibiting high spatial specificity, parenchymal signals-accessible with high spatial resolution imaging-also attenuate less rapidly when the stimulus frequency is increased. In addition, as the stimulus frequency increased, we observed larger relative phase differences in the BOLD oscillations across cortical depths. When averaged across depths, these signals can thus interfere destructively, suggesting that high spatial resolutions can avoid this phase cancellation and thereby aid in the detection of rapid BOLD oscillations.

The vestibular system is associated with alterations in the structure and function of the central nervous system. Yet, whether age-related vestibular loss is related to volume loss in the cerebral cortical areas that have been reported to receive vestibular input remains unknown. In this cross-sectional study of 117 healthy, older adults from the Baltimore Longitudinal Study of Aging, we examine the relationships between age-related vestibular functions and the gray matter volumes of the prefrontal cortex and its subregions and of the sensorimotor cortex-regions known to process vestibular information. T1-weighted MRI scans were automatically segmented using MRICloud. Log-linear multiple regression was used to investigate the relationships between average regional volume and vestibular function, adjusting for age, sex, and intracranial volume. Permutation testing was used for hypothesis testing, and bootstrapping was used to estimate confidence intervals. We found that age-related changes in vestibular end-organ function are associated with differentially altered gray matter volumes in the prefrontal and sensorimotor cortices, with many findings persisting when considering left (or right) side only. Concomitant with age-related, global brain atrophy, lower canal and utricular function were associated with additional volume atrophy of the prefrontal cortex and middle frontal gyrus, respectively. Lower saccular and utricular function were associated with the preservation of the volumes of the sensorimotor cortex and the pole of the superior frontal gyrus, respectively, against age-related, global brain atrophy. Canal and utricular function were not associated with the volumes of the sensorimotor cortex, and saccular function was not associated with the relative volumes of the prefrontal cortex. Together, these findings of relative volume preservation or additional atrophy suggest that vestibular function may play a role in the resilience to or magnification of global age effects on cerebral cortical structure.

Corticobasal degeneration (CBD) is one of the primary tauopathies with a disease onset in the 5th to 7th decade. CBD is a progressive condition of unknown aetiology, which is characterised neuropathologically by neuronal loss, astrogliosis and deposition of filamentous tau inclusions, composed entirely of 4-repeat tau isoforms, in neurons and glial cells in cerebral cortical areas, basal ganglia, brainstem and cerebellar nuclei. The term CBD is now a neuropathological diagnostic one and for the canonical clinical syndrome associated with CBD neuropathological changes, the corticobasal syndrome (CBS) term is used. In addition to CBS, the clinical spectrum also includes a behavioural variant of frontotemporal dementia syndrome, speech disorders, Richardson’s syndrome and, rarely, posterior cortical syndrome. In addition to CBD, CBS can also be caused by other pathologies. A number of genetic risk factors of CBD have been identified. As specific biomarkers confirming CBD as the underlying pathology responsible for CBS or other clinical manifestations are still lacking, for a definitive diagnosis of CBD neuropathological investigation is required. Recent cryo-electron microscopic studies have proven that CBD is a distinct tauopathy associated with a unique molecular structure of the tau filaments, which firmly differentiates it from other primary tauopathies.

ABSTRACT Efforts to treat epileptic seizures likely date back to primitive, manmade skull openings or trephinations at the site of previous scalp or skull injuries. The purpose may have been the release of “evil spirits,” removal of “cerebral excitement,” and “restoral of bodily and intellectual functions.” With progressive discoveries in brain function over the past 100 to 300 years, the cerebral cortical locations enabling voluntary movements, sensation, and speech have been well delineated. The locations of these functions have become surgical targets for the amelioration of disease processes. Disease entities in particular cerebral-cortical areas may predispose to the onset of focal and or generalized seizures, which secondarily interfere with normal cortical functioning. Modern neuroimaging and electroencephalography usually delineate the location of seizures and often the type of structural pathology. If noneloquent brain regions are involved, open surgical biopsy or removal of only abnormal tissue may be undertaken successfully. A number of the early neurosurgical pioneers in the development of epilepsy surgery are credited and discussed in this article.

The massive axonal projection from the cerebrum to the cerebellum through the pontine nuclei supports the cerebrocerebellar coordination of motor and nonmotor functions. However, the cerebrum and cerebellum have distinct patterns of functional localization in their cortices. We addressed this issue by bidirectional neuronal tracing from 22 various locations of the pontine nuclei in the mouse in a comprehensive manner. Cluster analyses of the distribution patterns of labeled cortical pyramidal cells and cerebellar mossy fiber terminals classified all cases into six groups located in six different subareas of the pontine nuclei. The lateral (insular), mediorostral (cingulate and prefrontal), and caudal (visual and auditory) cortical areas of the cerebrum projected to the medial, rostral, and lateral subareas of the pontine nuclei, respectively. These pontine subareas then projected mainly to the crus I, central vermis, and paraflocculus divergently. The central (motor and somatosensory) cortical areas projected to the centrorostral, centrocaudal and caudal subareas of the pontine nuclei, which then projected mainly to the rostral and caudal lobules with a somatotopic arrangement. The results indicate a new pontine nuclei-centric view of the corticopontocerebellar projection: the generally parallel corticopontine projection to pontine nuclei subareas is relayed to the highly divergent pontocerebellar projection terminating in overlapping specific lobules of the cerebellum. Consequently, the mode of the pontine nuclei relay underlies the cerebellar functional organization.

IntroductionThe cerebellum and basal ganglia were initially considered anatomically distinct regions, each connected via thalamic relays which project to the same cerebral cortical targets, such as the motor cortex. In the last two decades, transneuronal viral transport studies in non-human primates showed bidirectional connections between the cerebellum and basal ganglia at the subcortical level, without involving the cerebral cortical motor areas. These findings have significant implications for our understanding of neurodevelopmental and neurodegenerative diseases. While these subcortical connections were established in smaller studies on humans, their evolution with natural aging is less understood.MethodsIn this study, we validated and expanded the previous findings of the structural connectivity within the cerebellum-basal ganglia subcortical network, in a larger dataset of 64 subjects, across different age ranges. Tractography and fixel-based analysis were performed on the 3 T diffusion-weighted dataset using Mrtrix3 software, considering fiber density and cross-section as indicators of axonal integrity. Tractography of the well-established cerebello-thalamo-cortical tract was conducted as a control. We tested the relationship between the structural white matter integrity of these connections with aging and with the performance in different domains of Addenbrooke’s Cognitive Examination.ResultsTractography analysis isolated connections from the dentate nucleus to the contralateral putamen via the thalamus, and reciprocal tracts from the subthalamic nucleus to the contralateral cerebellar cortex via the pontine nuclei. Control tracts of cerebello-thalamo-cortical tracts were also isolated, including associative cerebello-prefrontal tracts. A negative linear relationship was found between the fiber density of both the ascending and descending cerebellum-basal ganglia tracts and age. Considering the cognitive assessments, the fiber density values of cerebello-thalamo-putaminal tracts correlated with the registration/learning domain scores. In addition, the fiber density values of cerebello-frontal and subthalamo-cerebellar (Crus II) tracts correlated with the cognitive assessment scores from the memory domain.ConclusionWe validated the structural connectivity within the cerebellum-basal ganglia reciprocal network, in a larger dataset of human subjects, across wider age range. The structural features of the subcortical cerebello-basal ganglia tracts in human subjects display age-related neurodegeneration. Individual morphological variability of cerebellar tracts to the striatum and prefrontal cortex was associated with different cognitive functions, suggesting a functional contribution of cerebellar tracts to cognitive decline with aging. This study offers new perspectives to consider the functional role of these pathways in motor learning and the pathophysiology of movement disorders involving the cerebellum and striatum.

BackgroundExploring neural network dynamics during social interaction could help to identify biomarkers of Autism Spectrum Disorders (ASD). A cerebellar involvement in autism has long been suspected and recent methodological advances now enable studying cerebellar functioning in a naturalistic setting. Here, we investigated the electrophysiological activity of the cerebro-cerebellar network during real-time social interaction in ASD. We focused our analysis on theta oscillations (3–8 Hz), which have been associated with large-scale coordination of distant brain areas and might contribute to interoception, motor control, and social event anticipation, all skills known to be altered in ASD. MethodsWe combined the Human Dynamic Clamp, a paradigm for studying realistic social interactions using a virtual avatar, with high-density electroencephalography (HD-EEG). Using source reconstruction, we investigated power in the cortex and the cerebellum, along with coherence between the cerebellum and three cerebral-cortical areas, and compared our findings in a sample of participants with ASD (n = 107) and with typical development (TD) (n = 33). We developed an open-source pipeline to analyse neural dynamics at the source level from HD-EEG data. ResultsIndividuals with ASD showed a significant increase in theta band power over the cerebellum and the frontal and temporal cortices during social interaction compared to resting state, along with significant coherence increases between the cerebellum and the sensorimotor, frontal and parietal cortices. However, a phase-based connectivity measure did not support a strict activity increase in the cortico-cerebellar functional network. We did not find any significant differences between the ASD and the TD group. ConclusionsThis exploratory study uncovered increases in the theta band activity of participants with ASD during social interaction, pointing at the presence of neural interactions between the cerebellum and cerebral networks associated with social cognition. It also emphasizes the need for complementary functional connectivity measures to capture network-level alterations. Future work will focus on optimizing artifact correction to include more participants with TD and increase the statistical power of group-level contrasts.

Korsakoff syndrome and altered pain perception: a search of underlying neural mechanisms.

An increasing number of research teams are investigating the efficacy of brain-computer interface (BCI)-mediated interventions for promoting motor recovery following stroke. A growing body of evidence suggests that of the various BCI designs, most effective are those that deliver functional electrical stimulation (FES) of upper extremity (UE) muscles contingent on movement intent. More specifically, BCI-FES interventions utilize algorithms that isolate motor signals—user-generated intent-to-move neural activity recorded from cerebral cortical motor areas—to drive electrical stimulation of individual muscles or muscle synergies. BCI-FES interventions aim to recover sensorimotor function of an impaired extremity by facilitating and/or inducing long-term motor learning-related neuroplastic changes in appropriate control circuitry. We developed a non-invasive, electroencephalogram (EEG)-based BCI-FES system that delivers closed-loop neural activity-triggered electrical stimulation of targeted distal muscles while providing the user with multimodal sensory feedback. This BCI-FES system consists of three components: (1) EEG acquisition and signal processing to extract real-time volitional and task-dependent neural command signals from cerebral cortical motor areas, (2) FES of muscles of the impaired hand contingent on the motor cortical neural command signals, and (3) multimodal sensory feedback associated with performance of the behavioral task, including visual information, linked activation of somatosensory afferents through intact sensorimotor circuits, and electro-tactile stimulation of the tongue. In this report, we describe device parameters and intervention protocols of our BCI-FES system which, combined with standard physical rehabilitation approaches, has proven efficacious in treating UE motor impairment in stroke survivors, regardless of level of impairment and chronicity.

BackgroundTinnitus is a common disease, and sound therapy is an effective method to alleviate it. Previous studies have shown that notched sound not only changes levels of cortical blood oxygen, but affects blood oxygen in specific cerebral cortical areas, such as Brodmann area 46 (BA46), which is associated with emotion. Extensive evidence has confirmed that tinnitus is closely related to emotion. Whether notched sound plays a role in regulating the emotional center is still unclear.MethodsThis study included 29 patients with newly diagnosed chronic tinnitus who were treated with notched sound. Functional near-infrared spectroscopy (fNIRS) was conducted before and after treatment to observe bilateral changes in cortical blood oxygen in the cerebral hemispheres. We compared the changes in connectivity between the two regions of interest (the superior temporal gyrus and BA46), as wells as other cortical regions before and after treatment.ResultsThe results showed (1) That global connectivity between the bilateral auditory cortex of the superior temporal sulcus and the ipsilateral cortex did not change significantly between baseline and the completion of treatment, and (2) That the connectivity between channel 14 and the right superior temporal sulcus decreased after treatment. The overall connectivity between the right BA46 region and the right cortex decreased after treatment, and decreases in connectivity after treatment were specifically found for channels 10 and 14 in the right parietal lobe and channels 16, 20, 21, and 22 in the frontal lobe, while there was no significant change on the left side. There were no significant changes in the questionnaire measures of tinnitus, anxiety, or depression before and after treatment.ConclusionThe results of the study indicate that cerebral cortex reorganization occurs in tinnitus patients after submitted to treatment with notched sound for 1 month, and that notched sound decreases the connectivity between the auditory cortex and specific brain regions.SignificanceNotched sound not only regulates the auditory center through lateral inhibition, but also alleviates tinnitus by reorganizing the emotional control center.

Cognitive processes involve precisely coordinated neuronal communications between multiple cerebral cortical structures in a task specific manner. Rich new evidence now implicates the cerebellum in cognitive functions. There is general agreement that cerebellar cognitive function involves interactions between the cerebellum and cerebral cortical association areas. Traditional views assume reciprocal interactions between one cerebellar and one cerebral cortical site, via closed-loop connections. We offer evidence supporting a new perspective that assigns the cerebellum the role of a coordinator of communication. We propose that the cerebellum participates in cognitive function by modulating the coherence of neuronal oscillations to optimize communications between multiple cortical structures in a task specific manner.

Convergent and Divergent Topographic Projection of Cerebral Cortical Areas to Cerebellar Lobules Through Distinct Regions of the Pontine Nucleus

Stroke is a leading cause of acquired long-term upper extremity motor disability. Current standard of care trajectories fail to deliver sufficient motor rehabilitation to stroke survivors. Recent research suggests that use of brain-computer interface (BCI) devices improves motor function in stroke survivors, regardless of stroke severity and chronicity, and may induce and/or facilitate neuroplastic changes associated with motor rehabilitation. The present sub analyses of ongoing crossover-controlled trial NCT02098265 examine first whether, during movements of the affected hand compared to rest, ipsilesional Mu rhythm desynchronization of cerebral cortical sensorimotor areas [Brodmann’s areas (BA) 1-7] is localized and tracks with changes in grip force strength. Secondly, we test the hypothesis that BCI intervention results in changes in frequency-specific directional flow of information transmission (direct path functional connectivity) in BA 1-7 by measuring changes in isolated effective coherence (iCoh) between cerebral cortical sensorimotor areas thought to relate to electrophysiological signatures of motor actions and motor learning. A sample of 16 stroke survivors with right hemisphere lesions (left hand motor impairment), received a maximum of 18–30 h of BCI intervention. Electroencephalograms were recorded during intervention sessions while outcome measures of motor function and capacity were assessed at baseline and completion of intervention. Greater desynchronization of Mu rhythm, during movements of the impaired hand compared to rest, were primarily localized to ipsilesional sensorimotor cortices (BA 1-7). In addition, increased Mu desynchronization in the ipsilesional primary motor cortex, Post vs. Pre BCI intervention, correlated significantly with improvements in hand function as assessed by grip force measurements. Moreover, the results show a significant change in the direction of causal information flow, as measured by iCoh, toward the ipsilesional motor (BA 4) and ipsilesional premotor cortices (BA 6) during BCI intervention. Significant iCoh increases from ipsilesional BA 4 to ipsilesional BA 6 were observed in both Mu [8–12 Hz] and Beta [18–26 Hz] frequency ranges. In summary, the present results are indicative of improvements in motor capacity and behavior, and they are consistent with the view that BCI-FES intervention improves functional motor capacity of the ipsilesional hemisphere and the impaired hand.

The resting-state cerebro-cerebellar function connectivity and associations with verbal working memory performance

Parallel cognitive processing streams in human prefrontal cortex: Parsing areal-level brain network for response inhibition.

Through functional magnetic resonance imaging (fMRI) technology, it is planned to use complex brain network technology to track brain functional imaging tracking treatment of stroke hemiplegia with scalp acupuncture. Functional magnetic resonance imaging (fMRI) can continuously monitor the rehabilitation process of motor nerve function in patients with stroke and upper limb hemiplegia, and explore the mechanism of brain plasticity changes at different levels of neural function cortex, motor function neural circuit, and behavior level. First, the fMRI test uses a block design, and the subjects complete the movement of the thumb and index finger. After completing the dysfunction assessment, fMRI data collection was performed on the patient before the CIMT treatment using a magnetic resonance apparatus, and a second fMRI data collection was performed 2 weeks after the CIMT treatment; only one fMRI data collection was performed on the volunteers. The functional magnetic resonance data was processed using the AFNI software package, and the functional scores of subjects were calculated using SPSS software. Second, studying the remodeling of residual brain tissue and functional compensation pathways can help to further clarify the recovery mechanism of motor function after stroke hemiplegia. Finally, compulsory exercise therapy can effectively improve upper limb motor dysfunction in stroke patients. The forced use of upper extremities during treatment induces the reorganization and compensation of cerebral cortical functional areas. This change in brain functional areas is consistent with the increase of upper extremity movement and improvement of motor function, fMRI can provide neuronal reorganization after exercise therapy evidence with compensation.

The thalamus is a vital communication hub in the center of the brain and consists of distinct nuclei critical for consciousness and higher-order cortical functions. Structural and functional thalamic alterations are involved in the pathogenesis of common brain disorders, yet the genetic architecture of the thalamus remains largely unknown. Here, using brain scans and genotype data from 30,114 individuals, we identify 55 lead single nucleotide polymorphisms (SNPs) within 42 genetic loci and 391 genes associated with volumes of the thalamus and its nuclei. In an independent validation sample (n = 5173) 53 out of the 55 lead SNPs of the discovery sample show the same effect direction (sign test, P = 8.6e-14). We map the genetic relationship between thalamic nuclei and 180 cerebral cortical areas and find overlapping genetic architectures consistent with thalamocortical connectivity. Pleiotropy analyses between thalamic volumes and ten psychiatric and neurological disorders reveal shared variants for all disorders. Together, these analyses identify genetic loci linked to thalamic nuclei and substantiate the emerging view of the thalamus having central roles in cortical functioning and common brain disorders.

Awake craniotomy is a neurosurgical technique that involves an awake neurological testing during the resection of an intracranial lesion in eloquent cerebral cortical areas representing motor, language, and speech. This technique is highlighted by an intra-operative cortical mapping that requires active participation by the patient and poses unique challenges to the anesthesiologist. The surgical and anesthetic techniques have evolved significantly over time, as the neurosurgeon and the anesthesiologist learn new steps in making this technique safe to achieve reasonable patient satisfaction. A thorough understanding of this surgical technique's rationale will guide the anesthesiologist in planning the anesthetic management depending on the surgery and neurologic testing. Constant communication between the neurosurgeon, anesthesiologist, and the patient will define this surgical technique's success. It is already a well-established procedure; however, factors that contribute to failures in awake craniotomy procedures have not been well characterized in the literature. Failure is defined as the inability to conduct awake neurologic testing during the awake craniotomy procedure because of various factors which will be described. This paper aims to review the challenges in the performance of three (3) cases of awake craniotomies performed in the Philippine General Hospital. The challenges described in these three (3) cases reveal that this can be experienced by the neurosurgeon, neuroanesthesiologist, and most especially the patient in an acute critical condition. Identification of the procedures' failure and the steps taken to manage such situations with the patient's safety in mind are discussed.

The study of the neural mechanism of human gait control can provide a theoretical basis for the treatment of walking disorders or the improvement of rehabilitation strategies, and further promote the functional rehabilitation of patients with movement disorders. However, the performance and changes of cerebral cortex activity corresponding to gait adjustment intentions are still not clear. The purpose of this study was to detect the blood oxygen activation characterization of the cerebral cortex motor function area when people have the intention to adjust gait during walking. Thirty young volunteers (21 ± 1 years old) performed normal walking, speed increase, speed reduction, step increase, and step reduction, during which oxygenated hemoglobin (HbO), deoxygenated hemoglobin (HbR), and total oxyhemoglobin (HbT) information in the prefrontal cortex (PFC), premotor cortex (PMC), supplementary motor area (SMA) was continuous monitored using near-infrared brain functional imaging. (1) With the intention to adjust gait, the HbO concentration in the SMA increased significantly, while the HbT concentration in the medial-PFC decreased significantly. (2) In the HbO concentration, step reduction is more activated than the step increase in the left-PMC (p= 0.0130); step adjustment is more activated than speed adjustment in the right-PMC (p= 0.0067). In the HbR concentration, the speed reduction is more activated than the speed increase in the left-PFC (p= 0.0103). When the intention of gait adjustment occurs, the increase of HbO concentration in the SMA indicates the initial stage of gait adjustment will increase the cognitive-locomotor demand of the brain. The left brain area meets the additional nerve needs of speed adjustment. The preliminary findings of this study can lay an important theoretical foundation for the realization of gait control based on fNIRS-BCI technology.