Title - Feature Finding
Feature Finding Figure
The challenges involved in identifying the neuropathological substrates of the clinical syndrome recognized as schizophrenia are well known. Stereological sampling provides a means to obtain accurate and precise quantitative estimates of components of neural circuits, and thus offers promise of an enhanced capacity to detect subtle alterations in brain structure associated with schizophrenia. For example, fractionator sampling is used to estimate cell number. A) The region of interest is split into a number of blocks and a fraction of these is sampled. As every second block is sampled in the example, the block samplings fraction bsf is ˝ in the figure. B) Sections are sampled from each block with a constant section sampling fraction ssf. Sections could be sampled by exhaustive sectioning of all blocks and sampling. Alternatively, if the blocks are cut as slabs with a known thickness T, ssf can be calculated as the microtome block advance BA divided by T. C) The sections are subsampled in the area with a constant area sampling fraction asf—typically by a uniformly random grid of unbiased counting frames. asf is then calculated as the ratio between the counting frame area a and the area A of the basic tile of the grid. D) When using optical disector probes, the sections are subsampled in the thickness. Often the final section thickness varies due to an uneven shrinkage of the mounted section. This results in a varying local sampling fraction from frame to frame as illustrated here. Therefore, the height sampling fraction hsf should be calculated based upon the number-weighted mean section thickness ¯¯¯t as indicated, where ti is the local section thickness and i the corresponding disector cell count of the i’th frame.
Dorph-Petersen KA, Lewis DA: Stereological approaches to identifying neuropathology in psychosis. Biol Psychiatry, 69:113-126, 2011.

• Translational Neuroscience Program •
| Home |

David A. Lewis, M.D. | Department of Psychiatry | University of Pittsburgh
3811 O'Hara Street, Biomedical Science Tower W1654
Pittsburgh, Pennsylvania 15213-2593
Phone: (412) 624-3894 - Fax: (412) 624-9910