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Human Brain Mapping Jun 2024Neuroimaging studies have consistently demonstrated concurrent activation of the human precuneus and temporal pole (TP), both during resting-state conditions and various...
Neuroimaging studies have consistently demonstrated concurrent activation of the human precuneus and temporal pole (TP), both during resting-state conditions and various higher-order cognitive functions. However, the precise underlying structural connectivity between these brain regions remains uncertain despite significant advancements in neuroscience research. In this study, we investigated the connectivity of the precuneus and TP by employing parcellation-based fiber micro-dissections in human brains and fiber tractography techniques in a sample of 1065 human subjects and a sample of 41 rhesus macaques. Our results demonstrate the connectivity between the posterior precuneus area POS2 and the areas 35, 36, and TG of the TP via the fifth subcomponent of the cingulum (CB-V) also known as parahippocampal cingulum. This finding contributes to our understanding of the connections within the posteromedial cortices, facilitating a more comprehensive integration of anatomy and function in both normal and pathological brain processes. PRACTITIONER POINTS: Our investigation delves into the intricate architecture and connectivity patterns of subregions within the precuneus and temporal pole, filling a crucial gap in our knowledge. We revealed a direct axonal connection between the posterior precuneus (POS2) and specific areas (35, 35, and TG) of the temporal pole. The direct connections are part of the CB-V pathway and exhibit a significant association with the cingulum, SRF, forceps major, and ILF. Population-based human tractography and rhesus macaque fiber tractography showed consistent results that support micro-dissection outcomes.
Topics: Humans; Macaca mulatta; Temporal Lobe; Parietal Lobe; Animals; Diffusion Tensor Imaging; Male; Adult; Female; Neural Pathways; Young Adult; Axons; Connectome; White Matter; Gyrus Cinguli
PubMed: 38925589
DOI: 10.1002/hbm.26771 -
Human Brain Mapping Jun 2024The corpus callosum (CC) is a large white matter fiber bundle in the brain and is involved in various cognitive, sensory, and motor processes. While implicated in...
The corpus callosum (CC) is a large white matter fiber bundle in the brain and is involved in various cognitive, sensory, and motor processes. While implicated in various developmental and psychiatric disorders, much is yet to be uncovered about the normal development of this structure, especially in young children. Additionally, while sexual dimorphism has been reported in prior literature, observations have not necessarily been consistent. In this study, we use morphometric measures including surface tensor-based morphometry (TBM) to investigate local changes in the shape of the CC in children between the ages of 12 and 60 months, in intervals of 12 months. We also analyze sex differences in each of these age groups. We observed larger significant clusters in the earlier ages between 12 v 24 m and between 48 v 60 m and localized differences in the anterior region of the body of the CC. Sex differences were most pronounced in the 12 m group. This study adds to the growing literature of work aiming to understand the developing brain and emphasizes the utility of surface TBM as a useful tool for analyzing regional differences in neuroanatomical morphometry.
Topics: Humans; Corpus Callosum; Male; Female; Infant; Child, Preschool; Sex Characteristics; Diffusion Tensor Imaging; Magnetic Resonance Imaging; Image Processing, Computer-Assisted
PubMed: 38924235
DOI: 10.1002/hbm.26693 -
Movement Disorders : Official Journal... Jun 2024
Topics: Humans; Motor Cortex; Tremor; Parkinson Disease; Parkinsonian Disorders; Nerve Net
PubMed: 38924141
DOI: 10.1002/mds.29872 -
PloS One 2024Sleep spindles are one of the prominent EEG oscillatory rhythms of non-rapid eye movement sleep. In the memory consolidation, these oscillations have an important role...
Sleep spindles are one of the prominent EEG oscillatory rhythms of non-rapid eye movement sleep. In the memory consolidation, these oscillations have an important role in the processes of long-term potentiation and synaptic plasticity. Moreover, the activity (spindle density and/or sigma power) of spindles has a linear association with learning performance in different paradigms. According to the experimental observations, the sleep spindle activity can be improved by closed loop acoustic stimulations (CLAS) which eventually improve memory performance. To examine the effects of CLAS on spindles, we propose a biophysical thalamocortical model for slow oscillations (SOs) and sleep spindles. In addition, closed loop stimulation protocols are applied on a thalamic network. Our model results show that the power of spindles is increased when stimulation cues are applied at the commencing of an SO Down-to-Up-state transition, but that activity gradually decreases when cues are applied with an increased time delay from this SO phase. Conversely, stimulation is not effective when cues are applied during the transition of an Up-to-Down-state. Furthermore, our model suggests that a strong inhibitory input from the reticular (RE) layer to the thalamocortical (TC) layer in the thalamic network shifts leads to an emergence of spindle activity at the Up-to-Down-state transition (rather than at Down-to-Up-state transition), and the spindle frequency is also reduced (8-11 Hz) by thalamic inhibition.
Topics: Humans; Sleep, Slow-Wave; Electroencephalography; Thalamus; Acoustic Stimulation; Computer Simulation; Models, Neurological; Sleep
PubMed: 38924001
DOI: 10.1371/journal.pone.0306218 -
Proceedings of the National Academy of... Jul 2024Biologically detailed models of brain circuitry are challenging to build and simulate due to the large number of neurons, their complex interactions, and the many...
Biologically detailed models of brain circuitry are challenging to build and simulate due to the large number of neurons, their complex interactions, and the many unknown physiological parameters. Simplified mathematical models are more tractable, but harder to evaluate when too far removed from neuroanatomy/physiology. We propose that a multiscale model, coarse-grained (CG) while preserving local biological details, offers the best balance between biological realism and computability. This paper presents such a model. Generally, CG models focus on the interaction between groups of neurons-here termed "pixels"-rather than individual cells. In our case, dynamics are alternately updated at intra- and interpixel scales, with one informing the other, until convergence to equilibrium is achieved on both scales. An innovation is how we exploit the underlying biology: Taking advantage of the similarity in local anatomical structures across large regions of the cortex, we model intrapixel dynamics as a single dynamical system driven by "external" inputs. These inputs vary with events external to the pixel, but their ranges can be estimated . Precomputing and tabulating all potential local responses speed up the updating procedure significantly compared to direct multiscale simulation. We illustrate our methodology using a model of the primate visual cortex. Except for local neuron-to-neuron variability (necessarily lost in any CG approximation) our model reproduces various features of large-scale network models at a tiny fraction of the computational cost. These include neuronal responses as a consequence of their orientation selectivity, a primary function of visual neurons.
Topics: Models, Neurological; Animals; Neurons; Visual Cortex; Humans; Nerve Net; Cerebral Cortex; Computer Simulation
PubMed: 38923983
DOI: 10.1073/pnas.2320454121 -
Journal of Biochemical and Molecular... Jul 2024Inflammatory bowel disease (IBD) is a chronic gastrointestinal disorder. Oxidative stress and inflammatory responses have a vital role in the pathophysiology of IBD as...
Inflammatory bowel disease (IBD) is a chronic gastrointestinal disorder. Oxidative stress and inflammatory responses have a vital role in the pathophysiology of IBD as well as seizure. IBD is associated with extraintestinal manifestations. This study aimed to explore the relationship between colitis and susceptibility to seizures, with a focus on the roles of neuroinflammation and oxidative stress in acetic acid-induced colitis in mice. Forty male Naval Medical Research Institute mice were divided into four groups: control, colitis, pentylenetetrazole (PTZ), and colitis + PTZ. Colitis was induced by intrarectal administration of acetic acid, and seizures were induced by intravenous injection of PTZ 7 days postcolitis induction. Following the measurement of latency to seizure, the mice were killed, and their colons and prefrontal cortex (PFC) were dissected. Gene expression of inflammatory markers including interleukin-1β, tumor necrosis factor-alpha, NOD-like receptor protein 3, and toll-like receptor 4, as well as total antioxidant capacity (TAC), malondialdehyde (MDA), and nitrite levels were measured in the colon and PFC. Histopathological evaluations were performed on the colon samples. Data were analyzed by t-test or one-way variance analysis. Colitis decreased latency to seizure, increased gene expression of inflammatory markers, and altered levels of MDA, nitrite, and TAC in both the colon and PFC. Simultaneous induction of colitis and seizure exacerbated the neuroimmune response and oxidative stress in the PFC and colon. Results concluded that neuroinflammation and oxidative stress in the PFC at least partially mediate the comorbid decrease in seizure latency in mice with colitis.
Topics: Animals; Male; Oxidative Stress; Mice; Prefrontal Cortex; Seizures; Colitis; Neuroimmunomodulation; Disease Models, Animal
PubMed: 38923727
DOI: 10.1002/jbt.23755 -
Human Brain Mapping Jun 2024Closed-loop neurofeedback training utilizes neural signals such as scalp electroencephalograms (EEG) to manipulate specific neural activities and the associated...
Closed-loop neurofeedback training utilizes neural signals such as scalp electroencephalograms (EEG) to manipulate specific neural activities and the associated behavioral performance. A spatiotemporal filter for high-density whole-head scalp EEG using a convolutional neural network can overcome the ambiguity of the signaling source because each EEG signal includes information on the remote regions. We simultaneously acquired EEG and functional magnetic resonance images in humans during the brain-computer interface (BCI) based neurofeedback training and compared the reconstructed and modeled hemodynamic responses of the sensorimotor network. Filters constructed with a convolutional neural network captured activities in the targeted network with spatial precision and specificity superior to those of the EEG signals preprocessed with standard pipelines used in BCI-based neurofeedback paradigms. The middle layers of the trained model were examined to characterize the neuronal oscillatory features that contributed to the reconstruction. Analysis of the layers for spatial convolution revealed the contribution of distributed cortical circuitries to reconstruction, including the frontoparietal and sensorimotor areas, and those of temporal convolution layers that successfully reconstructed the hemodynamic response function. Employing a spatiotemporal filter and leveraging the electrophysiological signatures of the sensorimotor excitability identified in our middle layer analysis would contribute to the development of a further effective neurofeedback intervention.
Topics: Humans; Electroencephalography; Magnetic Resonance Imaging; Adult; Brain-Computer Interfaces; Male; Neurofeedback; Young Adult; Sensorimotor Cortex; Female; Neural Networks, Computer
PubMed: 38923184
DOI: 10.1002/hbm.26767 -
Developmental Psychobiology Sep 2024Repeated exposure to abused drugs leads to reorganizing synaptic connections in the brain, playing a pivotal role in the relapse process. Additionally, recent research...
Repeated exposure to abused drugs leads to reorganizing synaptic connections in the brain, playing a pivotal role in the relapse process. Additionally, recent research has highlighted the impact of parental drug exposure before gestation on subsequent generations. This study aimed to explore the influence of parental morphine exposure 10 days prior to pregnancy on drug-induced locomotor sensitization. Adult male and female Wistar rats were categorized into morphine-exposed and control groups. Ten days after their last treatment, they were mated, and their male offspring underwent morphine, methamphetamine, cocaine, and nicotine-induced locomotor sensitization tests. The results indicated increased locomotor activity in both groups after drug exposure, although the changes were attenuated in morphine and cocaine sensitization among the offspring of morphine-exposed parents (MEPs). Western blotting analysis revealed altered levels of D2 dopamine receptors (D2DRs) in the prefrontal cortex and nucleus accumbens of the offspring from MEPs. Remarkably, despite not having direct in utero drug exposure, these offspring exhibited molecular alterations affecting morphine and cocaine-induced sensitization. The diminished sensitization to morphine and cocaine suggested the development of a tolerance phenotype in these offspring. The changes in D2DR levels in the brain might play a role in these adaptations.
Topics: Animals; Female; Morphine; Male; Cocaine; Pregnancy; Prenatal Exposure Delayed Effects; Rats, Wistar; Rats; Receptors, Dopamine D2; Nucleus Accumbens; Prefrontal Cortex; Locomotion; Behavior, Animal; Narcotics; Paternal Exposure; Dopamine Uptake Inhibitors; Motor Activity
PubMed: 38922890
DOI: 10.1002/dev.22514 -
Journal of Clinical Neurophysiology :... Jul 2024The corpus callosum is crucial for interhemispheric interactions in the motor control of limb functions. Human and animal studies suggested spinal cord pathologies may...
PURPOSE
The corpus callosum is crucial for interhemispheric interactions in the motor control of limb functions. Human and animal studies suggested spinal cord pathologies may induce cortical reorganization in sensorimotor areas. We investigate participation of the corpus callosum in executions of a simple motor task in patients with cervical spondylotic myelopathy (CSM) using transcranial magnetic stimulation.
METHODS
Twenty patients with CSM with various MRI grades of severity of cord compression were compared with 19 normal controls. Ipsilateral silent period, contralateral silent period, central motor conduction time, and transcallosal conduction time (TCT) were determined.
RESULTS
In both upper and lower limbs, TCTs were significantly increased for patients with CSM than normal controls ( p < 0.001 for all), without side-to-side differences. Ipsilateral silent period and contralateral silent period durations were significantly increased bilaterally for upper limbs in comparison to controls ( p < 0.01 for all), without side-to-side differences. There were no significant correlations of TCT with central motor conduction time nor severity of CSM for both upper and lower limbs ( p > 0.05 for all) bilaterally.
CONCLUSIONS
Previous transcranial magnetic stimulation studies show increased motor cortex excitability in CSM; hence, increased TCTs observed bilaterally may be a compensatory mechanism for effective unidirectional and uniplanar execution of muscle activation in the distal limb muscles. Lack of correlation of TCTs with severity of CSM or central motor conduction time may be in keeping with a preexistent role of the corpus callosum as a predominantly inhibitory pathway for counteracting redundant movements resulting from increased motor cortex excitability occurring after spinal cord lesions.
Topics: Humans; Corpus Callosum; Male; Transcranial Magnetic Stimulation; Female; Middle Aged; Spondylosis; Evoked Potentials, Motor; Adult; Aged; Cervical Vertebrae; Neural Conduction; Spinal Cord Diseases; Spinal Cord Compression
PubMed: 38922289
DOI: 10.1097/WNP.0000000000000979 -
Einstein (Sao Paulo, Brazil) 2024This study aimed at assessing the alterations in upper limb motor impairment and connectivity between motor areas following the post-stroke delivery of cathodal... (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVE
This study aimed at assessing the alterations in upper limb motor impairment and connectivity between motor areas following the post-stroke delivery of cathodal transcranial direct current stimulation sessions.
METHODS
Modifications in the Fugl-Meyer Assessment scores, connectivity between the primary motor cortex of the unaffected and affected hemispheres, and between the primary motor and premotor cortices of the unaffected hemisphere were compared prior to and following six sessions of cathodal transcranial direct current stimulation application in 13 patients (active = 6; sham = 7); this modality targets the primary motor cortex of the unaffected hemisphere early after a stroke.
RESULTS
Clinically relevant distinctions in Fugl-Meyer Assessment scores (≥9 points) were observed more frequently in the Sham Group than in the Active Group. Between-group differences in the alterations in Fugl-Meyer Assessment scores were not statistically significant (Mann-Whitney test, p=0.133). ROI-to-ROI correlations between the primary motor cortices of the affected and unaffected hemispheres post-therapeutically increased in 5/6 and 2/7 participants in the Active and Sham Groups, respectively. Between-group differences in modifications in connectivity between the aforementioned areas were not statistically significant. Motor performance enhancements were more frequent in the Sham Group compared to the Active Group.
CONCLUSION
The results of this hypothesis-generating investigation suggest that heightened connectivity may not translate into early clinical benefits following a stroke and will be crucial in designing larger cohort studies to explore mechanisms underlying the impacts of this intervention. ClinicalTrials.gov Identifier: NCT02455427.
Topics: Humans; Transcranial Direct Current Stimulation; Pilot Projects; Male; Female; Motor Cortex; Middle Aged; Stroke Rehabilitation; Aged; Stroke; Treatment Outcome; Recovery of Function; Upper Extremity; Time Factors
PubMed: 38922218
DOI: 10.31744/einstein_journal/2024AO0450