The automatic reconstruction of 3-D structures from stacks of 2-D images is an important problem in medical image analysis. In neuroscience, in particular, the availability of explicit 3-D models of the dendritic tree...
详细信息
The automatic reconstruction of 3-D structures from stacks of 2-D images is an important problem in medical image analysis. In neuroscience, in particular, the availability of explicit 3-D models of the dendritic tree structure of a neuron can be a valuable tool for understanding the complexity of neuronal function and neuronal morphology. In this work, the dendritic tree structure is imaged at different levels through the tissue using a laser scanning confocal microscope. The aim of the software is to deliver an explicit representation of the tree as a generalised cylinder model. Automatic techniques often fail to produce a continuous 3-D model and manual or semi-automatic techniques can be particularly labour intensive. In this paper we describe algorithms which lead to a continuous 3-D cylinder model representation of the dendritic tree with a minimum of user involvement. The initial stage of the approach involves the identification of voxels with a high probability of being on the centre-lines of the dendritic structure. These points are linked to form a skeleton using cost minimisation techniques. In the final stage the full 3-D structure is extracted around the centre-lines and represented by generalised cylinders. This paper provides details of the algorithms in each of the stages together with some of the results of using the method on both synthetic and real data sets.
High intensity chirped pulses can be used for probing microscopic chemical environments through the use of a particular choice of dye, for instance SNAFL2. The basis for this technique is that the excited state popula...
详细信息
ISBN:
(纸本)0819430757
High intensity chirped pulses can be used for probing microscopic chemical environments through the use of a particular choice of dye, for instance SNAFL2. The basis for this technique is that the excited state populations can be manipulated through control over the temporal order of the excitation frequencies in the excitation pulse - i.e. chirp - with the outcoming fluorescence as the reporting parameter. A chirp dependent fluorescence response can also be observed in larger molecular systems with more degrees of freedom like for instance green fluorescent proteins. In preparation for application of the technique to microscopy we use a facility permitting observation of this phenomenon in various dyes with high sensitivity. High power, 30 fs pulses from an OPA, tunable from 400 nm to 1.5 micron are used. These pulses with a repetition rate of 1 kHz are sufficiently intense that a relatively large sample region can be excited to saturation from which then a sub-region with uniform excitation conditions can be selected for signal collection.
暂无评论