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All surfaces can be classified by the conformal equivalence relation. Conformal invariants, which are shape indices that can be defined intrinsically on a surface, may be used to identify which surfaces are conformally equivalent, and they can also be used to measure surface deformation. Here we propose to compute a conformal invariant, or shape index, that is associated with the perimeter of the...
We develop an algorithm for the registration of surfaces representing the contours of various subcortical structures of the human brain. We employ a scale-space representation of shape based on the heat kernel, which only depends on the intrinsic geometry of the surfaces. The multi-scale representation is used in conjunction with the non-linear Iterative Closest Point algorithm based on thin-plate-spline...
High-resolution Magnetic resonance imaging (MRI) is helpful in diagnosing diseases such as schizophrenia, alzheimer, dementia etc. Brain segmentation is an important preprocess in medical imaging applications. In this study we compare atlas based segmentation and manual segmentation of hippocampus for volumetric measures. A statistically difference was obtained between automatic and manual measurement...
Previous studies suggested that gamma oscillations in the brain are associated with higher order cognitive function including selective visual attention, motor task planning, sensory perception, working memory and dreaming REM sleep. These oscillations are mainly observed in cortical regions and also occur in neocortical and subcortical areas and the hippocampus. In this paper, we investigate the...
It has been widely proposed that, higher cognitive functions such as learning, memory, attention and exploratory behavior could be represented in the CA1 region of the hippocampal area of the brain by a distributed neuronal network synchronization on an oscillatory mode as the gamma-band or 40 Hz (30-80 Hz) oscillations. In this paper, we have studied the effect of nicotine on the dynamics of the...
Epileptic seizures were experimentally induced in the CA3 region of rat hippocampus in vivo. Recordings of seizure activity were made in both hippocampi as well as anteromedial region of the thalamus in order to analyze the instantaneous activity for synchronous oscillators. A new method is introduced for detecting this synchrony which combines empirical mode decomposition, the Hilbert analytic signal...
Neural circuits of the brain are strongly affected by sensory and other stimuli during development, and abnormal response to incoming stimuli can result in psychiatric and neurological disorders. The neural circuits are stimulated by axonal projections from other brain areas. We have developed an in vitro platform that mimics the axonal projection to the hippocampus to understand the mechanisms involved...
Place cells are located in the hippocampus of the brain and play an important role for spatial navigation. In this study neural spike activity of freely moving rats along with the position of the rats was acquired. The study was performed to investigate if position reconstruction is possible if the rat is freely moving in open arenas with and without barriers of different rectangular sizes based on...
The neurotrophic effects of Nerve growth factor (NGF) on basal forebrain cholinergic neurons are well established. However, its potential actions as a fast-acting neuromodulator and the related receptor are not as well understood. The aim of this study is to investigate NGF-induced spatiotemporal neuronal activity changes in cultured rat organotypic hippocampal slices (OHCs), using a multielectrode...
Traumatic brain injury (TBI) is caused by in response to mechanical loading of the head. An extended biological cascade is initiated by the deformation and results in delayed cell death and dysfunction. Using an in vitro model of TBI based on organotypic brain slice cultures, we have quantitatively studied the relationship between tissue deformation and outcome. In the current study, we asked the...
To explore the difference of gene expression in rat mesenchymal stem cell (MSC) and in the hippocampus of the Alzheimerpsilas disease (AD) model rats on Natural Brain-Kinetine by Gene chips. Methods: Rat MSC is primary cultured according to method-routie. The MSCs have two groups, the control group and treatment group without or with Natural Brain-Kinetine (NBK) respectively. MSCs gene expression...
This study aims to examine the phase synchronization of characteristic frequency band of local field potentials (LFPs) in anterior cingulated cortex (ACC) of rats under fear conditioning. The 16-channel LFPs were recorded in ACC of rats implicated in microelectrode array under fear conditioning. The rats were trained to freezing when they hear the conditioned tone. Theta-band synchronization of the...
Grid cells in dorsocaudal region of medial entorhinal cortex, introduced by Hafting et al. recently in 2005, show an activity pattern correlated with animal's position. These cells increase firing frequency at multiple regions in the environment, arranged in regular triangular grids. Each cell has some properties including spacing, orientation, and phase shift of the nodes of its grid. Grid cells...
Present work describes the effect of microwave radiation on various biochemical changes of developing rat brain. Thirty days old male Wistar rats were exposed 2 h/day for 35 days at, 2.45 GHz and 9.9 GHz at power density of 0.344 and 0.125 mW/cm2 (SAR, 0.1 W/kg). Activities of ornithine decarboxylase, protein kinase C and calcium ion efflux were assayed in whole brain as well as hippocampus and hypothalamus...
The blood-brain barrier (BBB) is a specialized brain protection system consisting of endothelial cell, tight junctions and glial processes. BBB is the major limiting factor to therapeutic agents to the brain for disease treatment. Focused ultrasound (FUS) in the presence of microbubbles has the capability to deliver large molecules across BBB. In this study, we qualitatively and quantitatively analyzed...
This study is to investigate the inhibitive effect on the characteristic coding pattern of firing neuron at hippocampus for temporal lobe epilepsy (TLE) rats via repetitive transcranial magnetic stimulation (rTMS). 20 lithium-pilocarpine models of TLE rats were divided into two groups randomly, and a 0.5Hz rTMS was performed for rTMS group. The spike trains recorded at dentate gyrus in hippocampus...
The purpose of this study is to segment hippocampus, amygdala and entorhinal cortex in magnetic resonance images (MRI) of temporal lobe epilepsy (TLE) patients. The proposed method consists of two separate parts. First, we use an atlas-based segmentation method to obtain initial segmentation results for desired structures. Using additional preprocessing steps for image registration and gray matter...
We studied the properties of GFAP-expressing cells in adult mouse striatum using acute brain slices from transgenic animals expressing EGFP under GFAP promoter. Under physiological conditions, two distinct populations of GFAPEGFP cells could be identified: (1) brightly fluorescent cells had bushy processes, passive membrane properties, glutamate transporter activity, and high gap junction coupling...
We propose a constrained, three-dimensional, nonparametric, entropy-based, coupled, multi-shape approach to segment subcortical brain structures from magnetic resonance images (MRI). The proposed method uses PCA to develop shape models that capture structural variability. It integrates geometrical relationship between different structures into the algorithm by coupling them (limiting their independent...
This paper presents preliminary work on the construction of a computational anatomical atlas of the human hippocampus. The atlas is derived from high-resolution 9.4 Tesla MRI of postmortem samples. The main subfields of the hippocampus (cornu Ammonis fields CA1, CA2/3 and CA4; dentate gyrus; and the vestigial hippocampal sulcus) are labeled in the images manually using a combination of distinguishable...
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