Dendritic size of pyramidal neurons differs among mouse cortical regions

12 pages, 7 figures, 3 tables.-- PMID: 16195469 [PubMed].-- Available online Sep 29, 2005.Neocortical circuits share anatomical and physiological similarities among different species and cortical areas. Because of this, a ‘canonical’ cortical microcircuit could form the functional unit of the neocortex and perform the same basic computation on different types of inputs. However, variations in pyramidal cell structure between different primate cortical areas exist, indicating that different cortical areas could be built out of different neuronal cell types. In the present study, we have investigated the dendritic architecture of 90 layer II/III pyramidal neurons located in different cortical regions along a rostrocaudal axis in the mouse neocortex, using, for the first time, a blind multidimensional analysis of over 150 morphological variables, rather than evaluating along single morphological parameters. These cortical regions included the secondary motor cortex (M2), the secondary somatosensory cortex (S2), and the lateral secondary visual cortex and association temporal cortex (V2L/TeA). Confirming earlier primate studies, we find that basal dendritic morphologies are characteristically different between different cortical regions. In addition, we demonstrate that these differences are not related to the physical location of the neuron and cannot be easily explained assuming rostrocaudal gradients within the cortex. Our data suggest that each cortical region is built with specific neuronal components.R.B.-P. thanks the ‘Comunidad de Madrid’ (01/0782/2000) and I.B.-Y. the MEC (AP2001-0671) for support. J.D. is supported by the Spanish Ministry of Education and Science (BFI2003-02745) and the Comunidad de Madrid (08.5/0027/2001.1). R.Y. thanks the NEI (EY11787) and the John Merck Fund for support and the Cajal Institute for hosting him as a visiting professor.Peer reviewe

Bilateral Basal Ganglia Hemorrhage in a Patient with Confirmed COVID-19

Bilateral basal ganglia hemorrhage is exceedingly rare. To our knowledge, our patient is the first reported case of a confirmed coronavirus disease 2019 (COVID-19) patient who had bilateral basal ganglia hemorrhage. In the absence of other risk factors for bilateral deep cerebral involvement, we suspect that COVID-19 may be contributing to these rare pathologies. Most published data represent a correlation between COVID-19 and neurologic complications, and more research is still needed to prove causation

J Comp Neurol

Although the concept of left-hemispheric lateralization of neural processes during speech production has been known since the times of Broca, its physiological underpinnings still remain elusive. We sought to assess the modulatory influences of a major neurotransmitter, dopamine, on hemispheric lateralization during real-life speaking using a multimodal analysis of functional MRI, intracranial EEG recordings, and large-scale neural population simulations based on diffusion-weighted MRI. We demonstrate that speech-induced phasic dopamine release into the dorsal striatum and speech motor cortex exerts direct modulation of neuronal activity in these regions and drives left-hemispheric lateralization of speech production network. Dopamine-induced lateralization of functional activity and networks during speaking is not dependent on lateralization of structural nigro-striatal and nigro-motocortical pathways. Our findings provide the first mechanistic explanation for left-hemispheric lateralization of human speech that is due to left-lateralized dopaminergic modulation of brain activity and functional networks. This article is protected by copyright. All rights reserved

Differences in Hemodynamics and Rupture Rate of Aneurysms at the Bifurcation of the Basilar and Internal Carotid Arteries

BACKGROUND AND PURPOSE: Cerebral aneurysms in the posterior circulation are known to have a higher rupture risk than those in the anterior circulation. We sought to test the hypothesis that differences in hemodynamics can explain the difference in rupture rates. MATERIALS AND METHODS: A total of 117 aneurysms, 63 at the tip of the basilar artery (27 ruptured, 36 unruptured, rupture rate = 43%) and 54 at the bifurcation of the internal carotid artery (11 ruptured, 43 unruptured, rupture rate = 20%) were analyzed with image-based computational fluid dynamics. Several hemodynamic variables were compared among aneurysms at each location and between ruptured and unruptured aneurysms at each location. RESULTS: On average, aneurysms at the basilar tip had more concentrated inflow (P \u3c .001), a larger inflow rate (P \u3c .001), a larger maximum oscillatory shear index (P = .003), more complex flows (P = .033), and smaller areas under low wall shear stress (P \u3c .001) than aneurysms at the bifurcation of the internal carotid artery. In general, ruptured aneurysms had larger inflow concentration (P = .02), larger shear concentration (P = .02), more complex flows (P \u3c .001), and smaller minimum wall shear stress (P = .003) than unruptured aneurysms. CONCLUSIONS: High flow conditions, characterized by large and concentrated inflow jets, complex and oscillatory flow patterns, and wall shear stress distributions with focalized regions of high shear and large regions of low shear, are associated with aneurysm rupture, especially for basilar tip aneurysms. The higher flow conditions in basilar tip aneurysms could explain their increased rupture risk compared with internal carotid bifurcation aneurysms

Dendritic Size of Pyramidal Neurons Differs among Mouse Cortical Regions

Neocortical circuits share anatomical and physiological similarities among different species and cortical areas. Because of this, a ‘canonical ’ cortical microcircuit could form the functional unit of the neocortex and perform the same basic computation on different types of inputs. However, variations in pyramidal cell structure between different primate cortical areas exist, indicating that different cortical areas could be built out of different neuronal cell types. In the present study, we have investigated the dendritic architecture of 90 layer II/III pyramidal neurons located in different cortical regions along a rostrocaudal axis in the mouse neocortex, using, for the first time, a blind multidimensional analysis of over 150 morphological variables, rather than evaluating along single morphological parameters. These cortical regions included the secondary motor cortex (M2), the secondary somatosensory cortex (S2), and the lateral secondary visual cortex and association temporal cortex (V2L / TeA). Confirming earlier primate studies, we find that basal dendritic morphologies are characteristically different between different cortical regions. In addition, we demonstrate that these differences are not related to the physical location of the neuron and cannot be easily explained assuming rostrocaudal gradients within the cortex. Our data suggest that each cortical region is built with specific neuronal components

Differences in Hemodynamics and Rupture Rate of Aneurysms At the Bifurcation of the Basilar and Internal Carotid Arteries

Background and Purpose: Cerebral aneurysms in the posterior circulation are known to have a higher rupture risk than those in the anterior circulation. We sought to test the hypothesis that differences in hemodynamics can explain the difference in rupture rates. MATERIALS AND METHODS: A total of 117 aneurysms, 63 at the tip of the basilar artery (27 ruptured, 36 unruptured, rupture rate 43%) and 54 at the bifurcation of the internal carotid artery (11 ruptured, 43 unruptured, rupture rate 20%) were analyzed with image-based computational fluid dynamics. Several hemodynamic variables were compared among aneurysms at each location and between ruptured and unruptured aneurysms at each location. RESULTS: On average, aneurysms at the basilar tip had more concentrated inflow (P \u3c.001), a larger inflow rate (P \u3c.001), a larger maximum oscillatory shear index (P \u3c.003), more complex flows (P \u3c.033), and smaller areas under low wall shear stress (P \u3c.001) than aneurysms at the bifurcation of the internal carotid artery. In general, ruptured aneurysms had larger inflow concentration (P \u3c.02), larger shear concentration (P \u3c.02), more complex flows (P \u3c.001), and smaller minimum wall shear stress (P \u3c.003) than unruptured aneurysms. CONCLUSIONS: High flow conditions, characterized by large and concentrated inflow jets, complex and oscillatory flow patterns, and wall shear stress distributions with focalized regions of high shear and large regions of low shear, are associated with aneurysm rupture, especially for basilar tip aneurysms. The higher flow conditions in basilar tip aneurysms could explain their increased rupture risk compared with internal carotid bifurcation aneurysms