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Neurosurgery Apr 2024The piriform cortex (PC) is part of the primary olfactory network in humans. Recent findings suggest that it plays a role in pathophysiology of epilepsy. Therefore,...
BACKGROUND AND OBJECTIVES
The piriform cortex (PC) is part of the primary olfactory network in humans. Recent findings suggest that it plays a role in pathophysiology of epilepsy. Therefore, studying its connectivity can further our understanding of seizure propagation in epilepsy. We aimed to explore the structural connectivity of PC using high-quality human connectome project data coupled with segmentation of PC on anatomic MRI.
METHODS
Twenty subjects were randomly selected from the human connectome project database, and PC was traced on each hemisphere. Probabilistic whole-brain tractography was then used to visualize PC connectivity.
RESULTS
The strongest connectivity was noted between PC and ipsilateral insula in both hemispheres. Specifically, the posterior long gyrus of each insula was predominantly connected to PC. This was followed by connections between PC and basal ganglia as well as orbital frontal cortices.
CONCLUSION
The PC has the strongest connectivity with the insula bilaterally. Specifically, the posterior long gyri of insula have the strongest connectivity. This finding may provide additional insight for localizing and treating temporo-insular epilepsy.
Topics: Humans; Cerebral Cortex; Piriform Cortex; Epilepsy; Magnetic Resonance Imaging; Connectome; Frontal Lobe
PubMed: 37955443
DOI: 10.1227/neu.0000000000002756 -
Journal of Neurosurgery Apr 2024The authors aimed to review the frontal lobe's surgical anatomy, describe their keyhole frontal lobectomy technique, and analyze the surgical results.
OBJECTIVE
The authors aimed to review the frontal lobe's surgical anatomy, describe their keyhole frontal lobectomy technique, and analyze the surgical results.
METHODS
Patients with newly diagnosed frontal gliomas treated using a keyhole approach with supramaximal resection (SMR) from 2016 to 2022 were retrospectively reviewed. Surgeries were performed on patients asleep and awake. A human donor head was dissected to demonstrate the surgical anatomy. Kaplan-Meier curves were used for survival analysis.
RESULTS
Of the 790 craniotomies performed during the study period, those in 47 patients met our inclusion criteria. The minimally invasive approach involved four steps: 1) debulking the frontal pole; 2) subpial dissection identifying the sphenoid ridge, olfactory nerve, and optic nerve; 3) medial dissection to expose the falx cerebri and interhemispheric structures; and 4) posterior dissection guided by motor mapping, avoiding crossing the inferior plane defined by the corpus callosum. A fifth step could be added for nondominant lesions by resecting the inferior frontal gyrus. Perioperative complications were recorded in 5 cases (10.6%). The average hospital length of stay was 3.3 days. High-grade gliomas had a median progression-free survival of 14.8 months and overall survival of 23.9 months.
CONCLUSIONS
Keyhole approaches enabled successful SMR of frontal gliomas without added risks. Robust anatomical knowledge and meticulous surgical technique are paramount for obtaining successful resections.
Topics: Humans; Brain Neoplasms; Retrospective Studies; Glioma; Neurosurgical Procedures; Craniotomy
PubMed: 38564815
DOI: 10.3171/2023.7.JNS231363 -
Translational Psychiatry Feb 2024Pregnancy and the postpartum period are characterized by an increased neuroplasticity in the maternal brain. To explore the dynamics of postpartum changes in gray matter...
Pregnancy and the postpartum period are characterized by an increased neuroplasticity in the maternal brain. To explore the dynamics of postpartum changes in gray matter volume (GMV), magnetic resonance imaging was performed on 20 healthy postpartum women immediately after childbirth and at 3-week intervals for 12 postpartum weeks. The control group comprised 20 age-matched nulliparous women. The first 6 postpartum weeks (constituting the subacute postpartum period) are associated with decreasing progesterone levels and a massive restructuring in GMV, affecting the amygdala/hippocampus, the prefrontal/subgenual cortex, and the insula, which approach their sizes in nulliparous women only around weeks 3-6 postpartum. Based on the amygdala volume shortly after delivery, the maternal brain can be reliably distinguished from the nulliparous brain. Even 12 weeks after childbirth, the GMV in the dorsomedial prefrontal cortex, and the cortical thickness of the subgenual and lateral prefrontal cortices do not reach the pre-pregnancy levels. During this period, a volume decrease is seen in the cerebellum, the thalamus, and the dorsal striatum. A less hostile behavior toward the child at 6-12 weeks postpartum is predicted by the GMV change in the amygdala, the temporal pole, the olfactory gyrus, the anterior cingulate, the thalamus and the cerebellum in the same period. In summary, the restructuring of the maternal brain follows time-dependent trajectories. The fact that the volume changes persist at 12 weeks postpartum indicates that the maternal brain does not fully revert to pre-pregnancy physiology. Postpartum neuroplasticity suggests that these changes may be particularly significant in the regions important for parenting.
Topics: Pregnancy; Humans; Female; Brain; Gray Matter; Prefrontal Cortex; Temporal Lobe; Magnetic Resonance Imaging; Mother-Child Relations
PubMed: 38331939
DOI: 10.1038/s41398-024-02805-2 -
Brain, Behavior, & Immunity - Health Mar 2024COVID-19 remains a significant international public health concern. Yet, the mechanisms through which symptomatology emerges remain poorly understood. While SARS-CoV-2...
COVID-19 remains a significant international public health concern. Yet, the mechanisms through which symptomatology emerges remain poorly understood. While SARS-CoV-2 infection may induce prolonged inflammation within the central nervous system, the evidence primarily stems from limited small-scale case investigations. To address this gap, our study capitalized on longitudinal UK Biobank neuroimaging data acquired prior to and following COVID-19 testing (N = 416 including n = 224 COVID-19 cases; M = 58.6). Putative neuroinflammation was assessed in gray matter structures and white matter tracts using non-invasive Diffusion Basis Spectrum Imaging (DBSI), which estimates inflammation-related cellularity (DBSI-restricted fraction; DBSI-RF) and vasogenic edema (DBSI-hindered fraction; DBSI-HF). We hypothesized that COVID-19 case status would be associated with increases in DBSI markers after accounting for potential confound (age, sex, race, body mass index, smoking frequency, and data acquisition interval) and multiple testing. COVID-19 case status was not significantly associated with DBSI-RF (|β|'s < 0.28, p >0.05), but with greater DBSI-HF in left pre- and post-central gyri and right middle frontal gyrus (β's > 0.3, all p = 0.03). Intriguingly, the brain areas exhibiting increased putative vasogenic edema had previously been linked to COVID-19-related functional and structural alterations, whereas brain regions displaying subtle differences in cellularity between COVID-19 cases and controls included regions within or functionally connected to the olfactory network, which has been implicated in COVID-19 psychopathology. Nevertheless, our study might not have captured acute and transitory neuroinflammatory effects linked to SARS-CoV-2 infection, possibly due to symptom resolution before the imaging scan. Future research is warranted to explore the potential time- and symptom-dependent neuroinflammatory relationship with COVID-19.
PubMed: 38298902
DOI: 10.1016/j.bbih.2023.100722 -
Neuropathology : Official Journal of... Apr 2024Transactive response DNA-binding protein 43 (TDP-43) pathological inclusions are found in frontotemporal lobar degeneration (FTLD-TDP) and Alzheimer's disease (AD-TDP)....
Transactive response DNA-binding protein 43 (TDP-43) pathological inclusions are found in frontotemporal lobar degeneration (FTLD-TDP) and Alzheimer's disease (AD-TDP). While clinically different, TDP-43 inclusions in FTLD-TDP and AD can have similar morphological characteristics. However, TDP-43 colocalizing with tau and forming "apple-bite" or "flame-shaped" neuronal cytoplasmic inclusions (NCI) are only found in AD-TDP. Here, we describe a case with AD and neuritic plaque-associated TDP-43. The patient was a 96-year-old right-handed Caucasian woman who had developed a slowly progressive amnestic syndrome compatible with typical AD at age 80. Genetic testing revealed APOE ε3/ε4, GRN r5848 CT, and MAPT H1/H2 genotype. Consistent with the old age at onset and long disease duration, limbic-predominant AD was found at autopsy, with high hippocampal yet low cortical neurofibrillary tangle (NFT) counts. Hippocampal and amygdala sclerosis were present. Immunohistochemistry for phospho-TDP-43 showed NCIs, dystrophic neurites, and rare neuronal intranuclear inclusions consistent with FTLD-TDP type A, as well as tau NFT-associated TDP-43 inclusions. These were frequent in the amygdala, entorhinal cortex, hippocampus, occipitotemporal gyrus, and inferior temporal gyrus but sparse in the mid-frontal cortex. Additionally, there were TDP-43-immunoreactive inclusions forming plaque-like structures in the molecular layer of the dentate fascia of the hippocampus. The presence of neuritic plaques in the same region was confirmed using thioflavin-S fluorescent microscopy and immunohistochemistry for phospho-tau. Double labeling immunofluorescence showed colocalization of TDP-43 and tau within neuritic plaques. Other pathologies included mild Lewy body pathology predominantly affecting the amygdala and olfactory bulb, aging-related tau astrogliopathy, and mixed small vessel disease (arteriolosclerosis and amyloid angiopathy) with several cortical microinfarcts. In conclusion, we have identified TDP-43 colocalizing with tau in neuritic plaques in AD, which expands the association of TDP-43 and tau in AD beyond NFTs. The clinical correlate of this plaque-associated TDP-43 appears to be a slowly progressive amnestic syndrome.
Topics: Female; Humans; Aged, 80 and over; Alzheimer Disease; Plaque, Amyloid; Frontotemporal Dementia; Frontotemporal Lobar Degeneration; DNA-Binding Proteins; Memory Disorders
PubMed: 37525358
DOI: 10.1111/neup.12938 -
Journal of Neural Engineering Feb 2024. This study presents a novel methodological approach for incorporating information related to the peripheral sympathetic response into the investigation of neural...
. This study presents a novel methodological approach for incorporating information related to the peripheral sympathetic response into the investigation of neural dynamics. Particularly, we explore how hedonic contextual olfactory stimuli influence the processing of neutral faces in terms of sympathetic response, event-related potentials and effective connectivity analysis. The objective is to investigate how the emotional valence of odors influences the cortical connectivity underlying face processing and the role of face-induced sympathetic arousal in this visual-olfactory multimodal integration.. To this aim, we combine electrodermal activity (EDA) analysis and dynamic causal modeling to examine changes in cortico-cortical interactions.. The results reveal that stimuli arising sympathetic EDA responses are associated with a more negative N170 amplitude, which may be a marker of heightened arousal in response to faces. Hedonic odors, on the other hand, lead to a more negative N1 component and a reduced the vertex positive potential when they are unpleasant or pleasant. Concerning connectivity, unpleasant odors strengthen the forward connection from the inferior temporal gyrus (ITG) to the middle temporal gyrus, which is involved in processing changeable facial features. Conversely, the occurrence of sympathetic responses after a stimulus is correlated with an inhibition of this same connection and an enhancement of the backward connection from ITG to the fusiform face gyrus.. These findings suggest that unpleasant odors may enhance the interpretation of emotional expressions and mental states, while faces capable of eliciting sympathetic arousal prioritize identity processing.
Topics: Odorants; Facial Recognition; Galvanic Skin Response; Emotions; Evoked Potentials; Facial Expression; Electroencephalography
PubMed: 38290158
DOI: 10.1088/1741-2552/ad2403 -
Frontiers in Cellular Neuroscience 2024Deep brain stimulation (DBS) is a highly effective treatment option in Parkinson's disease. However, the underlying mechanisms of action, particularly effects on...
INTRODUCTION
Deep brain stimulation (DBS) is a highly effective treatment option in Parkinson's disease. However, the underlying mechanisms of action, particularly effects on neuronal plasticity, remain enigmatic. Adult neurogenesis in the subventricular zone-olfactory bulb (SVZ-OB) axis and in the dentate gyrus (DG) has been linked to various non-motor symptoms in PD, e.g., memory deficits and olfactory dysfunction. Since DBS affects several of these non-motor symptoms, we analyzed the effects of DBS in the subthalamic nucleus (STN) and the entopeduncular nucleus (EPN) on neurogenesis in 6-hydroxydopamine (6-OHDA)-lesioned hemiparkinsonian rats.
METHODS
In our study, we applied five weeks of continuous bilateral STN-DBS or EPN-DBS in 6-OHDA-lesioned rats with stable dopaminergic deficits compared to 6-OHDA-lesioned rats with corresponding sham stimulation. We injected two thymidine analogs to quantify newborn neurons early after DBS onset and three weeks later. Immunohistochemistry identified newborn cells co-labeled with NeuN, TH and GABA within the OB and DG. As a putative mechanism, we simulated the electric field distribution depending on the stimulation site to analyze direct electric effects on neural stem cell proliferation.
RESULTS
STN-DBS persistently increased the number of newborn dopaminergic and GABAergic neurons in the OB but not in the DG, while EPN-DBS does not impact neurogenesis. These effects do not seem to be mediated via direct electric stimulation of neural stem/progenitor cells within the neurogenic niches.
DISCUSSION
Our data support target-specific effects of STN-DBS on adult neurogenesis, a putative modulator of non-motor symptoms in Parkinson's disease.
PubMed: 38746080
DOI: 10.3389/fncel.2024.1396780