Network synchronization deficits caused by dementia and Alzheimer ’s disease serve as topographical biomarkers: a pilot study
AbstractMild cognitive impairment (MCI) is known as an early stage of cognitive decline. Amnestic MCI (aMCI) is considered as the preliminary stage of dementia which may progress to Alzheimer ’s disease (AD). While some aMCI patients may stay in this condition for years, others might develop dementia associated with AD. Early detection of MCI allows for potential treatments to prevent or decelerate the process of developing dementia. Standard methods of diagnosing MCI and AD employ str uctural (imaging), behavioral (cognitive tests), and genetic or molecular (blood or CSF tests) techniques. Our study proposes network-le...
Source: Anatomy and Embryology - August 23, 2022 Category: Anatomy Source Type: research
The structural connectivity of the human angular gyrus as revealed by microdissection and diffusion tractography
AbstractThe angular gyrus (AG) has been described in numerous studies to be consistently activated in various functional tasks. The angular gyrus is a critical connector epicenter linking multiple functional networks due to its location in the posterior part of the inferior parietal cortex, namely at the junction between the parietal, temporal, and occipital lobes. It is thus crucial to identify the different pathways that anatomically connect this high-order association region to the rest of the brain. Our study revisits the three-dimensional architecture of the structural AG connectivity by combining state-of-the-art pos...
Source: Anatomy and Embryology - August 22, 2022 Category: Anatomy Source Type: research
Multimodal tract-based MRI metrics outperform whole brain markers in determining cognitive impact of small vessel disease-related brain injury
AbstractIn cerebral small vessel disease (cSVD), whole brain MRI markers of cSVD-related brain injury explain limited variance to support individualized prediction. Here, we investigate whether considering abnormalities in brain tracts by integrating multimodal metrics from diffusion MRI (dMRI) and structural MRI (sMRI), can better capture cognitive performance in cSVD patients than established approaches based on whole brain markers. We selected 102 patients (73.7 ± 10.2 years old, 59 males) with MRI-visible SVD lesions and both sMRI and dMRI. Conventional linear models using demographics and established whole brai...
Source: Anatomy and Embryology - August 22, 2022 Category: Anatomy Source Type: research
The effects of concurrent bilateral anodal tDCS of primary motor cortex and cerebellum on corticospinal excitability: a randomized, double-blind sham-controlled study
AbstractTranscranial direct current stimulation (tDCS) applied to the primary motor cortex (M1), and cerebellum (CB) can change the level of M1 corticospinal excitability (CSE). A randomized double-blinded crossover, the sham-controlled study design was used to investigate the effects of concurrent bilateral anodal tDCS of M1 and CB (concurrent bilateral a-tDCSM1+CB) on the CSE. Twenty-one healthy participants were recruited in this study. Each participant received anodal-tDCS (a-tDCS) of 2 mA, 20 min in four pseudo-randomized, counterbalanced sessions, separated by at least 7 days (7.11 days ± 0.65). These sessio...
Source: Anatomy and Embryology - August 19, 2022 Category: Anatomy Source Type: research
Hypothalamic volume and asymmetry in the pediatric population: a retrospective MRI study
This study investigated age- and sex-related changes in the volumetric development and asymmetry of the normal hypothalamus from birth to 18. Individuals aged 0 –18 with MRI from 2012 to 2020 were selected for this retrospective study. Seven hundred individuals (369 [52.7%] Males) who had 3D-T1 sequences and were radiologically normal were included in the study. Hypothalamus volume was calculated using MRICloud automated segmentation pipelines. Hypothalam us asymmetry was calculated as the difference between right and left volumes divided by the mean (in percent). The measurement results of 23 age groups were analyzed wi...
Source: Anatomy and Embryology - August 16, 2022 Category: Anatomy Source Type: research
The human middle temporal cortex responds to both active leg movements and egomotion-compatible visual motion
AbstractThe human middle-temporal region MT+ is highly specialized in processing visual motion. However, recent studies have shown that this region is modulated by extraretinal signals, suggesting a possible involvement in processing motion information also from non-visual modalities. Here, we used functional MRI data to investigate the inf luence of retinal and extraretinal signals on MT+ in a large sample of subjects. Moreover, we used resting-state functional MRI to assess how the subdivisions of MT+ (i.e., MST, FST, MT, and V4t) are functionally connected. We first compared responses in MST, FST, MT, and V4t to ...
Source: Anatomy and Embryology - August 13, 2022 Category: Anatomy Source Type: research
Homology of neocortical areas in rats and primates based on cortical type analysis: an update of the Hypothesis on the Dual Origin of the Neocortex
AbstractSixty years ago, Friedrich Sanides traced the origin of the tangential expansion of the primate neocortex to two ancestral anlagen in the allocortex of reptiles and mammals, and proposed the Hypothesis on the Dual Origin of the Neocortex. According to Sanides, paraolfactory and parahippocampal gradients of laminar elaboration expanded in evolution by addition of successive concentric rings of gradually different cortical types inside the allocortical ring. Rodents had fewer rings and primates had more rings in the inner part of the cortex. In the present article, we perform cortical type analysis of the neocortex o...
Source: Anatomy and Embryology - August 12, 2022 Category: Anatomy Source Type: research
Association between salivary oxytocin levels and the amygdala and hippocampal volumes
This study aimed to investigate whether the salivary oxytocin level is associated with the volume of the amygdala and hippocampus in 178 adults (92 women and 86 men) in their third to seventh decade of life. We performed volumetric analysis of the amygdala and hippocampus using FreeSurfer and measured salivary oxytocin levels using enzyme-linked immunosorbent assay. The results showed contradictory effects of the salivary oxytocin level on the amygdala volume by sex and no significant effect on the hippocampal volume. Specifically, men showed a positive correlation between the salivary oxytocin level and amygdala volume, w...
Source: Anatomy and Embryology - August 9, 2022 Category: Anatomy Source Type: research
Origin of thyrotropin-releasing hormone neurons that innervate the tuberomammillary nuclei
AbstractHypophysiotropic thyrotropin-releasing hormone (TRH) neurons function as metabolic sensors that regulate the thyroid axis and energy homeostasis. Less is known about the role of other hypothalamic TRH neurons. As central administration of TRH decreases food intake and increases histamine in the tuberomammillary nuclei (TMN), and TMN histamine neurons are densely innervated by TRH fibers from an unknown origin, we mapped the location of TRH neurons that project to the TMN. The retrograde tracer, cholera toxin B subunit (CTB), was injected into the TMN E1 –E2, E4–E5 subdivisions of adult Sprague–Dawley male rat...
Source: Anatomy and Embryology - August 7, 2022 Category: Anatomy Source Type: research
Presence or absence of a prefrontal sulcus is linked to reasoning performance during child development
AbstractThe relationship between structural variability in late-developing association cortices like the lateral prefrontal cortex (LPFC) and the development of higher-order cognitive skills is not well understood. Recent findings show that the morphology of LPFC sulci predicts reasoning performance; this work led to the observation of substantial individual variability in the morphology of one of these sulci, the para-intermediate frontal sulcus (pimfs). Here, we sought to characterize this variability and assess its behavioral significance. To this end, we identified the pimfs in a developmental cohort of 72 participants...
Source: Anatomy and Embryology - August 6, 2022 Category: Anatomy Source Type: research
Right-side spatial neglect and white matter disconnection after left-hemisphere strokes
AbstractSpatial neglect usually concerns left-sided events after right-hemisphere damage. Its anatomical correlates are debated, with evidence suggesting an important role for fronto-parietal white matter disconnections in the right hemisphere. Here, we describe the less frequent occurrence of neglect for right-sided events, observed in three right-handed patients after a focal stroke in the left hemisphere. Patients were tested 1 month and 3 months after stroke. They performed a standardized paper-and-pencil neglect battery and underwent brain MRI with both structural and diffusion tensor (DT) sequences, in order to asses...
Source: Anatomy and Embryology - August 4, 2022 Category: Anatomy Source Type: research
The organization of individually mapped structural and functional semantic networks in aging adults
AbstractLanguage function in the brain, once thought to be highly localized, is now appreciated as relying on a connected but distributed network. The semantic system is of particular interest in the language domain because of its hypothesized integration of information across multiple cortical regions. Previous work in healthy individuals has focused on group-level functional connectivity (FC) analyses of the semantic system, which may obscure interindividual differences driving variance in performance. These studies also overlook the contributions of white matter networks to semantic function. Here, we identified semanti...
Source: Anatomy and Embryology - August 4, 2022 Category: Anatomy Source Type: research
Analysis of lateral orbitofrontal cortex activation on acquisition of fear extinction and neuronal activities in fear circuit
In this study, we aimed to examine the role of lOFC activation in extinction acquisition and explore the potential functional lateralization of lOFC on extinction. We bilaterally or unilaterally activated the lOFC withN-methyl-D-aspartate (NMDA) before fear extinction acquisition in rats. Our data suggested that both left and bilateral lOFC activation interfered with the in-session expression of conditioned fear, whereas activation of the right lOFC did not. In addition, pre-extinction unilateral or bilateral activation of the lOFC, regardless of the side, impaired the acquisition of fear extinction. We also quantified the...
Source: Anatomy and Embryology - August 2, 2022 Category: Anatomy Source Type: research
Direct intracranial recordings in the human angular gyrus during arithmetic processing
AbstractThe role of angular gyrus (AG) in arithmetic processing remains a subject of debate. In the present study, we recorded from the AG, supramarginal gyrus (SMG), intraparietal sulcus (IPS), and superior parietal lobule (SPL) across 467 sites in 30 subjects performing addition or multiplication with digits or number words. We measured the power of high-frequency-broadband (HFB) signal, a surrogate marker for regional cortical engagement, and used single-subject anatomical boundaries to define the location of each recording site. Our recordings revealed the lowest proportion of sites with activation or deactivation with...
Source: Anatomy and Embryology - July 30, 2022 Category: Anatomy Source Type: research
Angular gyrus: an anatomical case study for association cortex
AbstractThe angular gyrus is associated with a spectrum of higher order cognitive functions. This mini-review undertakes a broad survey of putative neuroanatomical substrates, guided by the premise that area-specific specializations derive from a combination of extrinsic connections and intrinsic area properties. Three levels of spatial resolution are discussed: cellular, supracellular connectivity, and synaptic micro-scale, with examples necessarily drawn mainly from experimental work with nonhuman primates. A significant factor in the functional specialization of the human parietal cortex is the pronounced enlargement. I...
Source: Anatomy and Embryology - July 29, 2022 Category: Anatomy Source Type: research
