scholarly journals How the flow and processing of information shapes the cerebrum

2015 ◽  
Author(s):  
Marc H.E. de Lussanet
Keyword(s):  
White Matter ◽  
Long Range ◽  
Information Flow ◽  
Information Transfer ◽  
Regular Structure ◽  
Cortical Surface ◽  
Local Networks ◽  
Trade Off ◽  
Processing Power ◽  
Underlying Mechanisms

The cerebrum of mammals spans a vast range of sizes and yet has a very regular structure. The amount of folding of the cortical surface and the proportion of white matter gradually increase with size, but the underlying mechanisms remain elusive. Here, two laws are derived to fully explain these cerebral scaling relations. The two general laws are derived from the notion that total processing power of the cortex is determined by the total cortical surface (i.e., the number of neurons), whereas the most efficient over-all flow of information is governed by the size of local networks (cortical columns). Since information is transferred by axonal connections which have a definite volume, a trade-off can be formulated from theoretical considerations between local, inter-gyral information transfer and long-range information transfer. It can be shown that this trade-off is governed by a single parameter describing the size of local networks, tlocal. Despite having just one free parameter, the first law fits the mammalian cerebrum better than any existing function, both across species and within humans. According to the second law, the scaling of white matter volume is also determined by the information principles. It follows that large cerebrums have much local processing and little global information flow. Moreover, paradoxically, a further increase in long-range connections would decrease the efficiency of information flow. These theoretical scaling principles help to compare the cerebrums across mammals regardless their size.

scholarly journals How the flow and processing of information shapes the cerebrum

2014 ◽  
Author(s):  
Marc HE de Lussanet
Keyword(s):  
White Matter ◽  
Long Range ◽  
Information Flow ◽  
Information Transfer ◽  
Regular Structure ◽  
Cortical Surface ◽  
Local Networks ◽  
Trade Off ◽  
Processing Power ◽  
Underlying Mechanisms

The cerebrum of mammals spans a vast range of sizes and yet has a very regular structure. The amount of folding of the cortical surface and the proportion of white matter gradually increase with size, but the underlying mechanisms remain elusive. Here, two laws are derived to fully explain these cerebral scaling relations. The two general laws are derived from the notion that total processing power of the cortex is determined by the total cortical surface (i.e., the number of neurons), whereas the most efficient over-all flow of information is governed by the size of local networks (cortical columns). Since information is transferred by axonal connections which have a definite volume, a trade-off can be formulated from theoretical considerations between local, inter-gyral information transfer and long-range information transfer. It can be shown that this trade-off is governed by a single parameter describing the size of local networks, \(t_{local}\). Despite having just one free parameter, the first law fits the mammalian cerebrum better than any existing function, both across species and within humans. According to the second law, the scaling of white matter volume is also determined by the information principles. It follows that large cerebrums have much local processing and little global information flow. Moreover, paradoxically, a further increase in long-range connections would decrease the efficiency of information flow. These theoretical scaling principles help to compare the cerebrums across mammals regardless their size.

scholarly journals How the flow and processing of information shapes the cerebrum

2015 ◽  
Author(s):  
Marc H.E. de Lussanet
Keyword(s):  
White Matter ◽  
Long Range ◽  
Information Flow ◽  
Information Transfer ◽  
Regular Structure ◽  
Cortical Surface ◽  
Local Networks ◽  
Trade Off ◽  
Processing Power ◽  
Underlying Mechanisms

The cerebrum of mammals spans a vast range of sizes and yet has a very regular structure. The amount of folding of the cortical surface and the proportion of white matter gradually increase with size, but the underlying mechanisms remain elusive. Here, two laws are derived to fully explain these cerebral scaling relations. The two general laws are derived from the notion that total processing power of the cortex is determined by the total cortical surface (i.e., the number of neurons), whereas the most efficient over-all flow of information is governed by the size of local networks (cortical columns). Since information is transferred by axonal connections which have a definite volume, a trade-off can be formulated from theoretical considerations between local, inter-gyral information transfer and long-range information transfer. It can be shown that this trade-off is governed by a single parameter describing the size of local networks, tlocal. Despite having just one free parameter, the first law fits the mammalian cerebrum better than any existing function, both across species and within humans. According to the second law, the scaling of white matter volume is also determined by the information principles. It follows that large cerebrums have much local processing and little global information flow. Moreover, paradoxically, a further increase in long-range connections would decrease the efficiency of information flow. These theoretical scaling principles help to compare the cerebrums across mammals regardless their size.

scholarly journals Superficial white matter fiber systems impede detection of long-range cortical connections in diffusion MR tractography

2015 ◽  
Vol 112 (21) ◽  
pp. E2820-E2828 ◽  
Author(s):  
Colin Reveley ◽  
Anil K. Seth ◽  
Carlo Pierpaoli ◽  
Afonso C. Silva ◽  
David Yu ◽  
...  
Keyword(s):  
White Matter ◽  
High Resolution ◽  
Human Brain ◽  
Long Range ◽  
Ex Vivo ◽  
Cortical Surface ◽  
Tracer Injection ◽  
Axonal Projections ◽  
Probabilistic Tracking

In vivo tractography based on diffusion magnetic resonance imaging (dMRI) has opened new doors to study structure–function relationships in the human brain. Initially developed to map the trajectory of major white matter tracts, dMRI is used increasingly to infer long-range anatomical connections of the cortex. Because axonal projections originate and terminate in the gray matter but travel mainly through the deep white matter, the success of tractography hinges on the capacity to follow fibers across this transition. Here we demonstrate that the complex arrangement of white matter fibers residing just under the cortical sheet poses severe challenges for long-range tractography over roughly half of the brain. We investigate this issue by comparing dMRI from very-high-resolution ex vivo macaque brain specimens with histological analysis of the same tissue. Using probabilistic tracking from pure gray and white matter seeds, we found that ∼50% of the cortical surface was effectively inaccessible for long-range diffusion tracking because of dense white matter zones just beneath the infragranular layers of the cortex. Analysis of the corresponding myelin-stained sections revealed that these zones colocalized with dense and uniform sheets of axons running mostly parallel to the cortical surface, most often in sulcal regions but also in many gyral crowns. Tracer injection into the sulcal cortex demonstrated that at least some axonal fibers pass directly through these fiber systems. Current and future high-resolution dMRI studies of the human brain will need to develop methods to overcome the challenges posed by superficial white matter systems to determine long-range anatomical connections accurately.

Abstract W MP87: PDGF Contributes to BMSC Treatment Induced Neurogenesis and White Matter and Axonal Remodeling in T2DM Stroke Rats

Stroke ◽  
2015 ◽  
Vol 46 (suppl_1) ◽  
Author(s):  
Alex Zacharek ◽  
Tao Yan ◽  
Michael Chopp` ◽  
Poornima Venkat ◽  
Ruizhou Ning ◽  
...  
Keyword(s):  
Cell Migration ◽  
White Matter ◽  
Artery Occlusion ◽  
Border Zone ◽  
Axonal Outgrowth ◽  
Ischemic Brain ◽  
Neuroblast Migration ◽  
Gene And Protein Expression ◽  
Underlying Mechanisms

Objective: Our previous studies have found that bone-marrow-stromal cell (BMSC) treatment of stroke in Type two DM (T2DM) rats, initiated at 3 days after stroke, improved functional recovery. Neurogenesis and white matter (WM) remodeling play an important role in neurorestorative effects after stroke. In this study, we tested whether BMSCs regulate neurogenesis and WM remodeling and the underlying mechanisms of BMSC induced neurorestorative effects in T2DM stroke rats. Methods: T2DM was induced with streptozotocin injection in addition to a high fat diet. T2DM rats were subjected to 2h of middle cerebral artery occlusion (MCAo), then treated with human BMSCs (5X106) or vehicle control (n=8/group) initiated at 3 days after MCAo and rats were monitored for 28 days. Neuroblast migration, WM changes, and gene and protein expression were measured in the ischemic brain. Subventricular zone (SVZ) explant cell migration and primary cortical neuron (PCN) axonal outgrowth measurements were performed in vitro. Results: BMSC treatment in T2DM rats significantly improves functional outcome and increases WM remodeling identified by increased myelin and axonal density. BMSCs also increase the neuroblast migration protein doublecortin (DCX, 25.0±4.3% vs control: 4.5±1.1%), platelet-derived growth factor (PDGF)-AA, and bFGF expression in the ischemic border zone. Angiogenic ELISA array data are consistent with the immunostaining data, showing that BMSC treatment increases PDGF-AA (2.1 fold), PDGF-BB (2.5 fold) and bFGF (1.8 fold) in the ischemic brain. Using an in vitro cell culture model, we found that BMSCs secrete high levels of PDGF. PDGF treatment significantly increases SVZ explant cell migration (1.7 fold) and PCN axonal outgrowth (1.9 fold) compared to non-treatment control. Inhibition of PDGF with neutralized anti-PDGF antibody significantly attenuates BMSC conditioned medium induced SVZ cell migration and PCN axon outgrowth. Conclusion: BMSC treatment of stroke in T2DM increases WM remodeling and neurogenesis as well as increases PDGF expression. PDGF not only promotes neuronal migration, but also increases axonal outgrowth. Therefore, increasing PDGF likely contributes to BMSC induced neurogenesis and WM remodeling in T2DM stroke rats.

scholarly journals Photoreceptive retinal ganglion cells control the information rate of the optic nerve

2018 ◽  
Vol 115 (50) ◽  
pp. E11817-E11826 ◽  
Author(s):  
Nina Milosavljevic ◽  
Riccardo Storchi ◽  
Cyril G. Eleftheriou ◽  
Andrea Colins ◽  
Rasmus S. Petersen ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Retinal Ganglion Cells ◽  
Information Flow ◽  
Information Transfer ◽  
Ganglion Cells ◽  
Retinal Ganglion ◽  
Ambient Light ◽  
Visual Responses ◽  
Light Irradiance ◽  
The Brain

Information transfer in the brain relies upon energetically expensive spiking activity of neurons. Rates of information flow should therefore be carefully optimized, but mechanisms to control this parameter are poorly understood. We address this deficit in the visual system, where ambient light (irradiance) is predictive of the amount of information reaching the eye and ask whether a neural measure of irradiance can therefore be used to proactively control information flow along the optic nerve. We first show that firing rates for the retina’s output neurons [retinal ganglion cells (RGCs)] scale with irradiance and are positively correlated with rates of information and the gain of visual responses. Irradiance modulates firing in the absence of any other visual signal confirming that this is a genuine response to changing ambient light. Irradiance-driven changes in firing are observed across the population of RGCs (including in both ON and OFF units) but are disrupted in mice lacking melanopsin [the photopigment of irradiance-coding intrinsically photosensitive RGCs (ipRGCs)] and can be induced under steady light exposure by chemogenetic activation of ipRGCs. Artificially elevating firing by chemogenetic excitation of ipRGCs is sufficient to increase information flow by increasing the gain of visual responses, indicating that enhanced firing is a cause of increased information transfer at higher irradiance. Our results establish a retinal circuitry driving changes in RGC firing as an active response to alterations in ambient light to adjust the amount of visual information transmitted to the brain.

scholarly journals White matter abnormalities in the corpus callosum with cognitive impairment in Parkinson disease

Neurology ◽  
2018 ◽  
Vol 91 (24) ◽  
pp. e2244-e2255 ◽  
Author(s):  
Ian O. Bledsoe ◽  
Glenn T. Stebbins ◽  
Doug Merkitch ◽  
Jennifer G. Goldman
Keyword(s):  
Cognitive Impairment ◽  
White Matter ◽  
Corpus Callosum ◽  
Parkinson Disease ◽  
Information Transfer ◽  
Diffusion Tensor ◽  
Anterior Segment ◽  
Mean Diffusivity ◽  
Cognitive Domain ◽  
White Matter Abnormalities

ObjectiveTo evaluate microstructural characteristics of the corpus callosum using diffusion tensor imaging (DTI) and their relationships to cognitive impairment in Parkinson disease (PD).MethodsSeventy-five participants with PD and 24 healthy control (HC) participants underwent structural MRI brain scans including DTI sequences and clinical and neuropsychological evaluations. Using Movement Disorder Society criteria, PD participants were classified as having normal cognition (PD-NC, n = 23), mild cognitive impairment (PD-MCI, n = 35), or dementia (PDD, n = 17). Cognitive domain (attention/working memory, executive function, language, memory, visuospatial function) z scores were calculated. DTI scalar values, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD), were established for 5 callosal segments on a midsagittal plane, single slice using a topographically derived parcellation method. Scalar values were compared among participant groups. Regression analyses were performed on cognitive domain z scores and DTI metrics.ResultsParticipants with PD showed increased AD values in the anterior 3 callosal segments compared to healthy controls. Participants with PDD had significantly increased AD, MD, and RD in the anterior 2 segments compared to participants with PD-NC and most anterior segment compared to participants with PD-MCI. FA values did not differ significantly between participants with PD and participants with HC or among PD cognitive groups. The strongest associations for the DTI metrics and cognitive performance occurred in the most anterior and most posterior callosal segments, and also reflected fronto-striatal and posterior cortical type cognitive deficits, respectively.ConclusionsMicrostructural white matter abnormalities of the corpus callosum, as measured by DTI, may contribute to PD cognitive impairment by disrupting information transfer across interhemispheric and callosal–cortical projections.

scholarly journals The Concurrence of Cortical Surface Area Expansion and White Matter Myelination in Human Brain Development

2018 ◽  
Vol 29 (2) ◽  
pp. 827-837 ◽  
Author(s):  
Riccardo Cafiero ◽  
Jens Brauer ◽  
Alfred Anwander ◽  
Angela D Friederici
Keyword(s):  
White Matter ◽  
Human Brain ◽  
Brain Development ◽  
Surface Area ◽  
Cortical Surface ◽  
Cortical Surface Area ◽  
Human Brain Development ◽  
Area Expansion

scholarly journals CSF1R-related leukoencephalopathy

Neurology ◽  
2018 ◽  
Vol 91 (24) ◽  
pp. 1092-1104 ◽  
Author(s):  
Takuya Konno ◽  
Koji Kasanuki ◽  
Takeshi Ikeuchi ◽  
Dennis W. Dickson ◽  
Zbigniew K. Wszolek
Keyword(s):  
White Matter ◽  
Cultured Cells ◽  
Clinical Symptoms ◽  
Current Knowledge ◽  
Gene Mutations ◽  
Future Research ◽  
Primary Role ◽  
Extrapyramidal Signs ◽  
Underlying Mechanisms

Since the discovery of CSF1R gene mutations in families with hereditary diffuse leukoencephalopathy with spheroids in 2012, more than 70 different mutations have been identified around the world. Through the analyses of mutation carriers, CSF1R-related leukoencephalopathy has been distinctly characterized clinically, radiologically, and pathologically. Typically, patients present with frontotemporal dementia-like phenotype in their 40s–50s, accompanied by motor symptoms, including pyramidal and extrapyramidal signs. Women tend to develop the clinical symptoms at a younger age than men. On brain imaging, in addition to white matter abnormalities, thinning of the corpus callosum, diffusion-restricted lesions in the white matter, and brain calcifications are hallmarks. Primary axonopathy followed by demyelination was suggested by pathology. Haploinsufficiency of colony-stimulating factor-1 receptor (CSF1R) is evident in a patient with a frameshift mutation, facilitating the establishment of Csf1r haploinsufficient mouse model. These mice develop clinical, radiologic, and pathologic phenotypes consistent with those of human patients with CSF1R mutations. In vitro, perturbation of CSF1R signaling is shown in cultured cells expressing mutant CSF1R. However, the underlying mechanisms by which CSF1R mutations selectively lead to white matter degeneration remains to be elucidated. Given that CSF1R mainly expresses in microglia, CSF1R-related leukoencephalopathy is representative of primary microgliopathies, of which microglia have a pivotal and primary role in pathogenesis. In this review, we address the current knowledge of CSF1R-related leukoencephalopathy and discuss the putative pathophysiology, with a focus on microglia, as well as future research directions.

scholarly journals Data-driven filtration and segmentation of mesoscale neural dynamics

2021 ◽  
Author(s):  
Sydney C. Weiser ◽  
Brian R. Mullen ◽  
Desiderio Ascencio ◽  
James B. Ackman
Keyword(s):  
Time Series ◽  
Information Flow ◽  
Background Noise ◽  
Activity Patterns ◽  
Data Driven ◽  
Neural Dynamics ◽  
Cortical Surface ◽  
Cerebral Function ◽  
Spatial Segmentation ◽  
Video Recordings

Recording neuronal group activity across the cortical hemispheres from awake, behaving mice is essential for understanding information flow across cerebral networks. Video recordings of cerebral function comes with challenges, including optical and movement-associated vessel artifacts, and limited references for time series extraction. Here we present a data-driven workflow that isolates artifacts from calcium activity patterns, and segments independent functional units across the cortical surface. Independent Component Analysis utilizes the statistical interdependence of pixel activation to completely unmix signals from background noise, given sufficient spatial and temporal samples. We also utilize isolated signal components to produce segmentations of the cortical surface, unique to each individual’s functional patterning. Time series extraction from these maps maximally represent the underlying signal in a highly compressed format. These improved techniques for data pre-processing, spatial segmentation, and time series extraction result in optimal signals for further analysis.

scholarly journals Self-organization and information transfer in Antarctic krill swarms

2021 ◽  
Author(s):  
Alicia L. Burns ◽  
Timothy M. Schaerf ◽  
Joseph T. Lizier ◽  
So Kawaguchi ◽  
Martin Cox ◽  
...  
Keyword(s):  
Information Flow ◽  
Social Factors ◽  
Information Transfer ◽  
Antarctic Krill ◽  
Keystone Species ◽  
Self Organization ◽  
Detailed Understanding ◽  
Individual Level ◽  
Directional Alignment ◽  
Swarming Behavior

AbstractAntarctic krill swarms are one of the largest known animal aggregations. However, despite being the keystone species of the Southern Ocean, little is known about how swarms are formed and maintained, and we lack a detailed understanding of the local interactions between individuals that provide the basis for these swarms. Here we analyzed the trajectories of captive, wild-caught krill in 3D to determine individual level interaction rules and quantify patterns of information flow. Our results suggest krill operate a novel form of collective organization, with measures of information flow and individual movement adjustments expressed most strongly in the vertical dimension, a finding not seen in other swarming species. In addition, local directional alignment with near neighbors, and strong regulation of both direction and speed relative to the positions of groupmates suggest social factors are vital to the formation and maintenance of swarms. This research represents a first step in understanding the fundamentally important swarming behavior of krill.

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