Manifestations of cutaneous sarcoidosis: a case report of an African American woman.

Cutaneous sarcoidosis is challenging to diagnose due to its many nonspecific manifestations. In this report we describe a case of cutaneous sarcoidosis in a patient presenting with multiple lesions. Diagnosis of the disease involves not only clinical and pathologic findings but also multiple exclusions.

The organization of spatial frequency maps measured by cortical flavoprotein autofluorescence.

To determine the organization of spatial frequency (SF) preference within cat Area 17, we imaged responses to stimuli with different SFs using optical intrinsic signals (ISI) and flavoprotein autofluorescence (AFI). Previous studies have suggested that neurons cluster based on SF preference, but a recent report argued that SF maps measured with ISI were artifacts of the vascular bed. Because AFI derives from a non-hemodynamic signal, it is less contaminated by vasculature. The two independent imaging methods produced similar SF preference maps in the same animals, suggesting that the patchy organization of SF preference is a genuine feature of Area 17.

The representation of complex images in spatial frequency domains of primary visual cortex.

The organization of cat primary visual cortex has been well mapped using simple stimuli such as sinusoidal gratings, revealing superimposed maps of orientation and spatial frequency preferences. However, it is not yet understood how complex images are represented across these maps. In this study, we ask whether a linear filter model can explain how cortical spatial frequency domains are activated by complex images. The model assumes that the response to a stimulus at any point on the cortical surface can be predicted by its individual orientation, spatial frequency, and temporal frequency tuning curves. To test this model, we imaged the pattern of activity within cat area 17 in response to stimuli composed of multiple spatial frequencies. Consistent with the predictions of the model, the stimuli activated low and high spatial frequency domains differently: at low stimulus drift speeds, both domains were strongly activated, but activity fell off in high spatial frequency domains as drift speed increased. To determine whether the filter model quantitatively predicted the activity patterns, we measured the spatiotemporal tuning properties of the functional domains in vivo and calculated expected response amplitudes from the model. The model accurately predicted cortical response patterns for two types of complex stimuli drifting at a variety of speeds. These results suggest that the distributed activity of primary visual cortex can be predicted from cortical maps like those of orientation and SF preference generated using simple, sinusoidal stimuli, and that dynamic visual acuity is degraded at or before the level of area 17.

Functional imaging of primary visual cortex using flavoprotein autofluorescence.

Neuronal autofluorescence, which results from the oxidation of flavoproteins in the electron transport chain, has recently been used to map cortical responses to sensory stimuli. This approach could represent a substantial improvement over other optical imaging methods because it is a direct (i.e., nonhemodynamic) measure of neuronal metabolism. However, its application to functional imaging has been limited because strong responses have been reported only in rodents. In this study, we demonstrate that autofluorescence imaging (AFI) can be used to map the functional organization of primary visual cortex in both mouse and cat. In cat area 17, orientation preference maps generated by AFI had the classic pinwheel structure and matched those generated by intrinsic signal imaging in the same imaged field. The spatiotemporal profile of the autofluorescence signal had several advantages over intrinsic signal imaging, including spatially restricted fluorescence throughout its response duration, reduced susceptibility to vascular artifacts, an improved spatial response profile, and a faster time course. These results indicate that AFI is a robust and useful measure of large-scale cortical activity patterns in visual mammals.

Trace amines differentially regulate adult locomotor activity, cocaine sensitivity, and female fertility in Drosophila melanogaster.

The trace biogenic amines tyramine and octopamine are found in the nervous systems of animals ranging in complexity from nematodes to mammals. In insects such as Drosophila melanogaster, the trace amine octopamine is a well-established neuromodulator that mediates a diverse range of physiological processes, but an independent role for tyramine is less clear. Tyramine is synthesized from tyrosine by the enzyme tyrosine decarboxylase (TDC). We previously reported the identification of two Tdc genes in Drosophila: the peripherally-expressed Tdc1 and the neurally-expressed Tdc2. To further clarify the neural functions of the trace amines in Drosophila, we examined normal and cocaine-induced locomotor activity in flies that lack both neural tyramine and octopamine because of mutation in Tdc2 (Tdc2(RO54)). Tdc2(RO54) flies have dramatically reduced basal locomotor activity levels and are hypersensitive to an initial dose of cocaine. Tdc2-targeted expression of the constitutively active inward rectifying potassium channel Kir2.1 replicates these phenotypes, and Tdc2-driven expression of Tdc1 rescues the phenotypes. However, flies that contain no measurable neural octopamine and an excess of tyramine due to a null mutation in the tyramine beta-hydroxylase gene (TbetaH(nM18)) exhibit normal locomotor activity and cocaine responses in spite of showing female sterility due to loss of octopamine. The ability of elevated levels of neural tyramine in TbetaH(nM18) flies to supplant the role of octopamine in adult locomotor and cocaine-induced behaviors, but not in functions related to female fertility, indicates mechanistic differences in the roles of trace amines in these processes.