Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Monkeys had one eye closed at about 30 days of age for 14, 30, 60, or 90 days, then opened, and the fellow eye closed for another 120 days. The animals then had at least 10 months of binocular visual experience before extensive behavioral training and testing were carried out. In terminal experiments concluded more than 18 months later, microelectrode investigations of the striate cortex demonstrated that there was almost a complete absence of binocular neurons in all animals. The initially deprived eyes (IDEs) dominated the majority of cortical neurons, even when soma size measurements of lateral geniculate neurons indicated that the LGN cells driven by the IDE had not regained their normal size. The monkeys which had significant interocular differences in spatial vision also exhibited abnormalities in the distribution of the metabolic enzyme, cytochrome oxidase (CO), within the striate cortex. These results demonstrate that many of the severe alterations in cortical physiology and eye dominance produced by early monocular form deprivation can be reversed, with recovery of normal cortical function, via the reverse-deprivation procedure.
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PMID:The effects of reverse monocular deprivation in monkeys. II. Electrophysiological and anatomical studies. 253 42

The tree shrew Tupaia belangeri has three functional pathways (ON-center, OFF-center, and W-like cells) that arise in the retina and proceed through separate LGN laminae to separate cortical targets. To determine whether these pathways have consistent differences in activity, cytochrome oxidase (C.O.) patterns were examined in the retina, LGN, and striate cortex. In six normal tree shrews the outer and inner plexiform layers of the retina were highly reactive for C.O. A pale, vascularized cleft zone separated the a (OFF) and b (ON) inner plexiform sublaminae, which seemed about equally reactive for C.O. In the LGN, laminae 1 and 2 (ON-center cells) and laminae 4 and 5 (mostly OFF-center cells) were highly reactive for C.O. LGN lamina 3 and 6 are part of an W-like afferent pathway. Lamina 3 was distinctly paler than laminae 1, 2, 4, and 5 while lamina 6 was intermediate. In the striate cortex, layer IV was the most reactive layer. Sublayer IVb (predominantly an OFF region) was consistently more reactive than sublayer IVa (predominantly ON). The middle portion, layer IVm, was paler than either IVa or IVb. This paler region includes, but extends above and below, the cell-sparse "cleft" region. Thus, considering all three levels of the retinogeniculostriate pathway, the ON and OFF systems were equally active until they reached the striate cortex, where the OFF system appeared to be more active than the ON. The W-cell laminae in the LGN exhibited the lowest level of activity. The contribution of ganglion cell activity to these patterns was assessed by intravitreal administration of tetrodotoxin (TTX) blockade either monocularly (three animals) or binocularly (two animals). In the TTX-treated retinae, the inner plexiform a and b sublaminae were paler for C.O., although visible, and were still separated by the pale cleft. The ganglion cell layer was very pale in comparison to the normal. In the LGN, monocular TTX blockade reduced the C.O. reactivity in the ON and OFF laminae that received input from the treated eye but had little effect on the W-like cell laminae. The ipsilaterally innervated ON and OFF laminae were more affected than were the contralaterally innervated laminae. Binocular TTX treatment resulted in a decrease of C.O. activity in the binocular segment of the ON and OFF LGN laminae. In the striate cortex, the most marked changes following TTX treatment occurred in layer IV.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Histochemical localization of cytochrome oxidase activity in the visual system of the tree shrew:normal patterns and the effect of retinal impulse blockage. 284 84

The distribution of cytochrome oxidase (C.O.) was examined in the lateral geniculate nucleus of the kitten during the first postnatal month and compared with the adult pattern. During the first week, most of the C.O. was localized within the perikarya of geniculate neurons. Perigeniculate neurons had darkly reactive dendrites as well as perikaya. A population of relatively large, darkly reactive neurons became distinguishable around the end of the first week, as the level of reactivity diminished to moderate-to-light within most medium and small neurons. On the basis of their relative size and pattern of distribution, most of the darkly reactive neurons are likely to represent ones that will later have class 1 morphology and develop Y receptive field properties. These cells normally undergo rapid growth earlier, and their growth is more adversely affected by early short-term monocular suture than other classes of less reactive geniculate neurons. Thus, in the LGN of developing kitten, C.O. histochemistry may be used as a functional marker for future class 1 Y-cells. The reactivity of the neuropil gradually increases as synapses with dendrites mature. At the electronmicroscopic level the increased reactivity of the neuropil is due mainly to an increase in the number of reactive mitochondria localized within the growing dendrites. In the developing striate cortex of postnatal kittens dark reactivity is localized in the outer part of layer II for the first 2 weeks and then disappears. Dark reactivity gradually increases in layer IV after the third week. The changes in C.O. reactivity accompany pathway-specific physiological and anatomical changes that occur during early postnatal development.
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PMID:The localization of cytochrome oxidase in the LGN and striate cortex of postnatal kittens. 300 67

Using spatially diffuse stimuli (or sinusoidal gratings of very low spatial frequency), levels of 14C-2-deoxy-d-glucose (DG) uptake produced by color-varying stimuli are much greater than those produced by luminance-varying stimuli in macaque striate cortex. Such a difference in DG results is consistent with previous psychophysical and electrophysiological results from man and monkey. In DG experiments with color-varying gratings of low and middle spatial frequencies, or with spatially diffuse color variations, DG uptake was highest in the cytochrome oxidase blobs, as was also seen with low-spatial-frequency luminance gratings. High-spatial-frequency, color-varying uptake patterns were shifted to cover both blob and interblob regions in a manner similar to that of the patterns obtained with middle-spatial-frequency luminance stimuli. However, in no instance did chromatic gratings produce uptake restricted to the interblob regions, as with the pattern seen with the highest-spatial-frequency luminance gratings. Thus, DG uptake is relatively higher in the interblob regions when comparing luminance with color-varying gratings that are otherwise similar. It was also possible to show DG evidence for receptive-field double-opponency in the upper-layer blobs, but color sensitivity in layer 4Cb appears single-opponent. The DG results suggest that color sensitivity is also high in the lower-layer (layers 5 + 6) blobs, and that many layer 5 receptive fields are double-opponent. Striate layers 4Ca and 4B-appeared color-insensitive in a wide variety of DG tests; this supports the idea of a color-insensitive stream running from the magnocellular LGN layers through striate layers 4Ca and 4B to extrastriate areas MT and V3. There was also a major effect due to wavelength: long and short wavelengths produced much more uptake than did middle wavelengths, even when all colors were equated for luminance and saturation. No variation with eccentricity was seen in cortical color sensitivity, at least between 0 degrees and 10 degrees.
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PMID:Functional anatomy of macaque striate cortex. III. Color. 336 11

When macaque monkeys view achromatic, sinusoidal gratings of a single spatial frequency, the pattern of 14C-2-deoxy-d-glucose (DG) uptake produced by the gratings is shown to depend on the spatial frequency chosen. When a relatively high (5-7 cycles/deg) spatial frequency is shown binocularly at systematically varied orientations, uptake in parafoveal striate cortex is highest between the cytochrome oxidase blobs (that is, in the interblobs) in layers 1, 2, and 3. In layers 4B, 5, and 6, where the cytochrome oxidase blobs are faint or absent, DG uptake is highest in a periodic pattern that lies in register with the interblobs of layers 2 + 3. When the grating is, instead, of relatively low (1-1.5 cycles/deg) spatial frequency, DG uptake is highest in the blobs, in the blob-aligned portions of layers 1-4B, and in the lower-layer blobs as well. These variations in DG topography are confirmed in stimulus comparisons within a single hemisphere. Presumably, this shift in functional topography within the extra-granular layer is the primate homolog of "spatial frequency columns" shown earlier in the cat (Tootell et al., 1981; Silverman, 1984). In the well-differentiated architecture of primate striate cortex, laminar differences produced by high- versus low-spatial-frequency gratings are visible as well. Gratings of very high spatial frequency produce much higher uptake in 4Cb (which receives input from the parvocellular LGN layers) than in 4Ca (which gets its input from the magnocellular LGN layers). Gratings of low spatial frequency produce the converse result. Presumably, cells in the magnocellular LGN layers and/or in the magnocellular-dominated layer 4Ca have lower average spatial frequency tuning (larger receptive fields) than their counterparts in the parvocellular LGN and/or in striate layer 4Cb. The DG patterns produced by various spatial frequencies also vary with eccentricity, in a manner consistent with known, eccentricity-dependent variations of receptive-field size and spatial frequency tuning. Thus, gratings of a "middle"-spatial-frequency range (4-5 cycles/deg) produce high uptake in the blobs near the foveal representation and high uptake in the interblobs at more peripheral eccentricities, including 5 degrees. This shift in DG topography also includes the transition zone near 3 degrees, where the level of stimulus-driven uptake is as high in the blob regions as it is in interblob regions. Variations in uptake between layers 4Ca and 4Cb, as a function of eccentricity, shift in parallel with the changes in the upper-layer topography.
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PMID:Functional anatomy of macaque striate cortex. V. Spatial frequency. 336 13

Anatomical and physiological studies of the primate visual system have suggested that the signals relayed by the magnocellular and parvocellular subdivisions of the LGN remain segregated in visual cortex. It has been suggested that this segregation may account for the known differences in visual function between the parietal and temporal cortical processing streams in extrastriate visual cortex. To test directly the hypothesis that the temporal stream of processing receives predominantly parvocellular signals, we recorded visual responses from the superficial layers of V1 (striate cortex), which give rise to the temporal stream, while selectively inactivating either the magnocellular or parvocellular subdivisions of the LGN. Inactivation of the parvocellular subdivision reduced neuronal responses in the superficial layers of V1, but the effects of magnocellular blocks were generally as pronounced or slightly stronger. Individual neurons were found to receive contributions from both pathways. We furthermore found no evidence that magnocellular contributions were restricted to either the cytochrome oxidase blobs or interblobs in V1. Instead, magnocellular signals made substantial contributions to responses throughout the superficial layers. Thus, the regions within V1 that constitute the early stages of the temporal processing stream do not appear to contain isolated parvocellular signals. These results argue against a direct mapping of the subcortical magnocellular and parvocellular pathways onto the parietal and temporal streams of processing in cortex.
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PMID:Magnocellular and parvocellular contributions to the responses of neurons in macaque striate cortex. 815 57

Mitochondrial respiratory complexes such as cytochrome oxidase (CO) contain both mitochondrial- and nuclear-encoded subunits. To determine whether mitochondrial and nuclear gene expression are regulated proportionately in neurons, we analyzed CO subunit mRNA and mitochondrial DNA (mtDNA) levels by in situ hybridization and grain counting in the visual system of normal and monocular TTX-treated monkeys. We compared the regulation of these molecules with the regulation of CO activity and CO protein, analyzed by histochemistry and immunohistochemistry, respectively. In normal animals, CO activity was in general related more closely to mtDNA and CO subunit I (COI) (mitochondrial-encoded) mRNA levels than to COIV or COVIII (nuclear-encoded) mRNA levels. For example, puffs (also known as blobs) of high CO activity in striate cortex were enriched in mtDNA and COI mRNA, but not COIV or COVIII mRNA. In 3-7 d TTX-treated animals, proportionate decreases in CO activity and CO protein were observed in specific visual centers; these changes were accompanied by disproportionate decreases in COI, COIV, and COVIII mRNA levels. After 7 d of TTX, COI mRNA fell by 49 +/- 3% (mean +/- SEM) in LGN neurons, while COIV and COVIII mRNAs fell by only 18 +/- 3% and 29 +/- 3%, respectively. In comparison, CO activity decreased by 23 +/- 2%, and mtDNA by 26 +/- 4%. Qualitative observations in striate cortex also indicated that COI mRNA changed more than COIV mRNA, COVIII mRNA, mtDNA, or CO activity. Our results suggest that the local distribution of CO within neurons, and acute regulatory changes in CO activity occurring over periods of days are controlled mainly by regulation of the mitochondrial genes that encode the catalytic subunits of the enzyme.
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PMID:Mitochondrial and nuclear gene expression for cytochrome oxidase subunits are disproportionately regulated by functional activity in neurons. 838 52

Cellular prion protein (PrP(c)) is a cell surface glycoprotein highly expressed in neurons, and a protease-resistant conformer of the protein accumulates in the brain parenchyma in prion diseases. In human prion diseases, visual cortex and visual function can be affected. We examined both the levels and the localization of PrP(c) in developing visual cortex of the common marmoset. Western blot analysis showed that PrP(c) increased from the day of birth through adulthood, and this increase correlated with the progression of synapse formation. Immunohistochemistry showed that PrP(c) was present in fiber tracts of the neonate, and this immunoreactivity was lost with maturation. Within the neuropil, the laminar distribution of PrP(c) changed with age. In the neonate, PrP(c) immunoreactivity was strongest in layer 1, where the earliest synapses form. At the end of the first postnatal week, layer 4C, as identified by its strong cytochrome oxidase activity, was noticeably lighter in terms of PrP(c) immunoreactivity than the adjacent layers. The contrast between the strong immunoreactivity in both supragranular and infragranular layers and weak immunoreactivity in layer 4C increased with age. Layers 2/3 and 5 contained more intense PrP(c) immunoreactivity; these layers receive thalamic input from the koniocellular division of the LGN, and these layers of the LGN also had strong PrP(c) immunoreactivity. Together, these results provide evidence for PrP(c) localization in an identified functional pathway and may shed some light on prion disease pathogenesis.
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PMID:Developmental changes in cellular prion protein in primate visual cortex. 1772 30