Atrophy and loss of dopaminergic mesencephalic neurons in heterozygous weaver mice.

The phenotypic effect of the weaver mutation in the ventral midbrain of homozygous mutants is associated with the progressive loss of dopaminergic neurons. To discover whether the number of mesencephalic dopaminergic cells is altered in weaver heterozygotes (wv/+), we studied mice between 20 and 365 days of age. We counted tyrosine hydroxylase (TH)-immunopositive cells in the substantia nigra (SN), retrorubral nucleus (RRN), and ventral tegmental area (VTA), and measured cross-sectional areas of neuronal somata in the SN of wv/+ and age-matched wild-type controls (+/+). The number of TH-positive cells in the wv/+ ventral midbrain was on average 13% lower than normal. Cell loss was detected selectively in the SN (12%) and VTA (23%). The areas of somatic profiles in the wv/+ nigral neurons were on average reduced by 9.8%. The neuronal losses in the SN and VTA correlated with a 13.8% reduction in dopamine level in the ventral striatum in wv/+ mice at 14-16 months of age. Our findings imply that a single dose of the weaver gene in the mouse is associated with cellular damage leading to a chronic deficiency in the mesostriatal dopaminergic system.

Hybrid multiplexing matched spatial filters in the Fourier plane for multiple object recognition.

An optical-digital approach to fabricating matched spatial filters for multiple image recognition is discussed. Multiplexing is accomplished in the Fourier plane following optical transformation. A screening filter is formed digitally by adding or subtracting the intensity spectra of the transformed images to be recognized or ignored. This screening filter is then used to construct optically a composite image which contains the essential features of the various images to be recognized and from which compromising features have been deleted. The composite image is then used to record the desired filter. Initial results for both recognition and discrimination are presented.