Parametric mapping and quantitative analysis of the human calvarium

Voie, Arne; Dirnbacher, Maximilian; Fisher, David J.; Hölscher, Thilo

doi:10.1016/j.compmedimag.2014.06.022

Cited by 10 publications

(10 citation statements)

References 23 publications

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“…It is likely that the varying anatomical conditions are one reason for different tDCS effects. Because skull thickness determines the flow of current through the brain and thus the strength of tDCS effects (Datta et al, 2011 ; Giordano et al, 2017 ), one plausible reason for smaller tDCS effects over V1 compared to M1 can be seen in the relatively greater skull thickness and density of the occipital bone compared to the parietal bone (Voie et al, 2014 ; Zarghooni et al, 2016 ). The tDCS effects are also dependent on the distance and orientation of neuronal axons to the electrode (Paulus, 2003 ): the drift of membrane potential is higher and the tDCS effect more intense when current flow directs longitudinal to the neuronal axons, like in M1, than cross the axons (Nitsche et al, 2008 ).…”

Section: Discussionmentioning

confidence: 99%

Long-Lasting Enhancement of Visual Perception with Repetitive Noninvasive Transcranial Direct Current Stimulation

Behrens

Kraft

Irlbacher³

et al. 2017

Front. Cell. Neurosci.

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Understanding processes performed by an intact visual cortex as the basis for developing methods that enhance or restore visual perception is of great interest to both researchers and medical practitioners. Here, we explore whether contrast sensitivity, a main function of the primary visual cortex (V1), can be improved in healthy subjects by repetitive, noninvasive anodal transcranial direct current stimulation (tDCS). Contrast perception was measured via threshold perimetry directly before and after intervention (tDCS or sham stimulation) on each day over 5 consecutive days (24 subjects, double-blind study). tDCS improved contrast sensitivity from the second day onwards, with significant effects lasting 24 h. After the last stimulation on day 5, the anodal group showed a significantly greater improvement in contrast perception than the sham group (23 vs. 5%). We found significant long-term effects in only the central 2–4° of the visual field 4 weeks after the last stimulation. We suspect a combination of two factors contributes to these lasting effects. First, the V1 area that represents the central retina was located closer to the polarization electrode, resulting in higher current density. Second, the central visual field is represented by a larger cortical area relative to the peripheral visual field (cortical magnification). This is the first study showing that tDCS over V1 enhances contrast perception in healthy subjects for several weeks. This study contributes to the investigation of the causal relationship between the external modulation of neuronal membrane potential and behavior (in our case, visual perception). Because the vast majority of human studies only show temporary effects after single tDCS sessions targeting the visual system, our study underpins the potential for lasting effects of repetitive tDCS-induced modulation of neuronal excitability.

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Section: Discussionmentioning

confidence: 99%

Long-Lasting Enhancement of Visual Perception with Repetitive Noninvasive Transcranial Direct Current Stimulation

Behrens

Kraft

Irlbacher³

et al. 2017

Front. Cell. Neurosci.

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“…Human skulls were obtained from the University of California San Diego, Department of Anatomy skull bank. Each skull was UCSD-tagged with an inventory number, sex and age All human skull information has been previously documented by Voie et al [ 33 ]. Throughout the manuscript, skull #12–325 data is highlighted since it was used in the photographic series in Figs 2 , 4 and 5 .…”

Section: Methodsmentioning

confidence: 99%

“…According to the certificate of inspection, the uncertainty of measurement is U = 0.000044 inches. Human skull thickness and density were measured using the methods developed and described in detail by Voie et al[ 33 ]. Briefly, the skull was placed in the bore of a Discovery CT750 HD (GE Medical Systems, Waukesha, WI, USA) CT scanner and scanned to create a set of DICOM images (OsiriX, OsiriX Foundation, Geneva, Switzerland), which were read into MATLAB (The MathWorks Inc., Natick, MA, USA) to create 3D matrix of CT values, along with the voxel coordinates.…”

Section: Methodsmentioning

confidence: 99%

Transcranial Near-Infrared Laser Transmission (NILT) Profiles (800 nm): Systematic Comparison in Four Common Research Species

et al. 2015

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Background and PurposeTranscranial near-infrared laser therapy (TLT) is a promising and novel method to promote neuroprotection and clinical improvement in both acute and chronic neurodegenerative diseases such as acute ischemic stroke (AIS), traumatic brain injury (TBI), and Alzheimer’s disease (AD) patients based upon efficacy in translational animal models. However, there is limited information in the peer-reviewed literature pertaining to transcranial near-infrared laser transmission (NILT) profiles in various species. Thus, in the present study we systematically evaluated NILT characteristics through the skull of 4 different species: mouse, rat, rabbit and human.ResultsUsing dehydrated skulls from 3 animal species, using a wavelength of 800nm and a surface power density of 700 mW/cm2, NILT decreased from 40.10% (mouse) to 21.24% (rat) to 11.36% (rabbit) as skull thickness measured at bregma increased from 0.44 mm in mouse to 0.83 mm in rat and then 2.11 mm in rabbit. NILT also significantly increased (p<0.05) when animal skulls were hydrated (i.e. compared to dehydrated); but there was no measurable change in thickness due to hydration.In human calvaria, where mean thickness ranged from 7.19 mm at bregma to 5.91 mm in the parietal skull, only 4.18% and 4.24% of applied near-infrared light was transmitted through the skull. There was a slight (9.2-13.4%), but insignificant effect of hydration state on NILT transmission of human skulls, but there was a significant positive correlation between NILT and thickness at bregma and parietal skull, in both hydrated and dehydrated states.ConclusionThis is the first systematic study to demonstrate differential NILT through the skulls of 4 different species; with an inverse relationship between NILT and skull thickness. With animal skulls, transmission profiles are dependent upon the hydration state of the skull, with significantly greater penetration through hydrated skulls compared to dehydrated skulls. Using human skulls, we demonstrate a significant correlation between thickness and penetration, but there was no correlation with skull density. The results suggest that TLT should be optimized in animals using novel approaches incorporating human skull characteristics, because of significant variance of NILT profiles directly related to skull thickness.

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“…The data utilized is collected from studies by Loder [23], Kriewall [24], Li [25], Garfin [26], Wong [27], Desouza [28], Moreira [29], Sullivan [30], Voie [31] and Lillie [32] on adult and pediatric parietal bone structure and thickness as shown in Figure 8(a) In order to include data regarding gestational period skull thicknesses, the point of birth was considered to be 9 months after conception, with a post conception age of 36 weeks corresponding to the 0 point on the X-axis. Furthermore, whenever the thickness was given in tandem with an age range and sample size, an average age between the extremes was assumed, with the number of identical points corresponding to the given sample size.…”

Section: Figure 7: (A) Schematic Illustrating the Location Of Parietamentioning

confidence: 99%

Biomechanical Root Cause Analysis of Complications in Head Immobilization Devices for Pediatric Neurosurgery

Abdulhafez

Kadry

Zaazoue

et al. 2018

Volume 1: Additive Manufacturing; Bio and Sustainable Manufacturing

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Precise and firm fixation of the cranium is critical during craniotomy and delicate brain neurosurgery making head immobilization devices (HIDs) a staple instrument in brain neurosurgical operations today. However, despite their popularity, there is no standard procedure for their use and many complications arise from using HIDs in pediatric neurosurgery. In this paper, we identify biomechanical causes of complications and quantify risks in pin-type HIDs including clamping force selection, positioning and age effects. Based on our root cause analysis, we develop a framework to address the biomechanical factors that influence complications and understand the biomechanics of the clamping process. We develop an age-dependent finite element model (FEM) of a single pin on a cranial bone disc with the representative properties and skull thickness depending on age. This model can be utilized to reduce risk of complications by design as well as to provide recommendations for current practices.

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Parametric mapping and quantitative analysis of the human calvarium

Cited by 10 publications

References 23 publications

Long-Lasting Enhancement of Visual Perception with Repetitive Noninvasive Transcranial Direct Current Stimulation

Long-Lasting Enhancement of Visual Perception with Repetitive Noninvasive Transcranial Direct Current Stimulation

Transcranial Near-Infrared Laser Transmission (NILT) Profiles (800 nm): Systematic Comparison in Four Common Research Species

Biomechanical Root Cause Analysis of Complications in Head Immobilization Devices for Pediatric Neurosurgery

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