Modeling dendritic arborization based on 3D-reconstructions of adult rat phrenic Motoneurons
Obregon-Henao, G. (Gabriel) | 2014-04-24
Stereological techniques that rely on morphological assumptions and direct three-dimensional (3D) confocal
measurements have been previously used to estimate the dendritic surface areas of phrenic motoneurons (PhrMNs). Given that
97% of a motoneuron’s receptive area is provided by dendrites, dendritic branching and overall extension are physiologically
important in determining the output of their synaptic receptive fields. However, limitations intrinsic to shape-based estimations
and incomplete labeling of dendritic trees by retrograde techniques have hindered systematic approaches to examine dendritic
morphology of PhrMNs. In this study, a novel method that improves dendritic filling of PhrMNs in lightly-fixed samples was used.
Confocal microscopy allowed accurate 3D reconstruction of dendritic arbors from adult rat PhrMNs. Following pre-processing,
segmentation was semi-automatically performed in 3D, and direct measurements of dendritic surface area were obtained. A
quadratic model for estimating dendritic tree surface area based on measurements of primary dendrite diameter was derived (r2 =
0.932; p<0.0001). This method may enhance interpretation of motoneuron plasticity in response to injury or disease by permitting
estimations of dendritic arborization of PhrMNs since measurements of primary dendrite diameter can be reliably obtained from a
number of retrograde labeling techniques.