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)

Vibrissal representations in the brainstem trigeminal complex (BTC) of rodents are manifested as architectural sub-units called barrelettes. The development of barrelettes was studied by using Nissl staining, cytochrome oxidase histochemistry, and Golgi-impregnation methods. On the day of birth (PND-1), barrelettes are manifested as longitudinal, histochemical cylinders in sub-nuclei principalis, interpolaris and caudalis of the BTC. One day later (PND-2), fully formed histochemical barrelette formations are seen in the three sub-nuclei. The development of cytoarchitectural barrelettes lags behind histochemical barrelettes by about two days. Between PND-2 and PND-3, longitudinal cytoarchitectonic cylinders begin to appear. By PND-3, BTC neurons segregate into five rows of barrelettes in the coronal plane. Segmentation of rows into individual barrelettes begins on PND-4, and complete cytoarchitectonic barrelette formations are seen by PND-5. Golgi-impregnation shows that on the day of birth, primary afferent terminals and dendritic arbors of second-order trigeminal neurons within the BTC are short and poorly ramified. Over the next five post-natal days, lengthening of these processes as well as elaboration into secondary and tertiary branches take place. Growth of these processes continues for two additional weeks, contributing to the increase in barrelette neuropils (hollows). As the neuropils expand, neuronal somata are pushed toward barrelette sides. Morphometric measurements show that there is a relatively constant rate of growth of barrelettes over the first three post-natal weeks. The growth rate of the barrelette formations is identical to that of BTC as a whole. Thus, at the time of birth, the volume of neural tissue in the brainstem allotted to vibrissae is fixed relative to that allotted to other sensory receptors. Several features of the early development of barrelettes are identified: (1) Chemoarchitectural barrelettes appear before cytoarchitectural barrelettes, suggesting that terminal arbors of primary trigeminal afferents are organized before their target neurons form barrelettes. (2) Early cytoarchitecture is manifested in the form of unsegmented rows, suggesting that rough, row-based topological maps are first formed, which are then fine-tuned into individual sub-units. Recent evidence shows that other vibrissal representations--thalamic barreloids and cortical barrels--also follow these "afferent-before-target" and "row-before-individual units" sequences of development. This gradual, afferent-dependent fine-tuning of topological organization is analogous to similar events during the early development of the visual system, and may be a general feature of developing sensory systems.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Barrelettes--architectonic vibrissal representations in the brainstem trigeminal complex of the mouse. II. Normal post-natal development. 844 Jul 72

The physiological representation of the shoulder and surrounding body was examined in layer IV of somatosensory cortex (SI) in rats that had underground removal of the forelimb, either as newborns on postnatal day three (PND-3) or as adults (at least 8 weeks of age). Electrophysiological recordings were used to map the shoulder and body representations (physiological map), and the mitochondria marker, cytochrome oxidase (CO), was used to visualize recording sites in barrel and barrel-like structures (morphological map) in layer IV of deafferents and intact controls. The SI shoulder representation lies in a nebulously stained region that lies posterior to the forearm, wrist, and forepaw representations; the latter region is associated with the well-defined forepaw barrel subfield (FBS). The major findings are: (1) the shoulder is represented as a single zone located at the posterior extent of the SI body map in intact rats; (2) limb deafferentation in adult or neonatal rats that were physiologically mapped 6-16 weeks post-amputation resulted in two or more islets of "new" representation of the shoulder in the FBS in addition to the representation of the "original" shoulder in the posterior part of the body map; (3) deafferentations made in neonatal rats, physiologically mapped as adults, had a significantly greater (Mann-Whitney U) amount of "new" cortical representation within the FBS than did rats deafferented as adults; (4) fewer unresponsive sites in the FBS were found for neonate deafferents than for adult deafferents; (5) evoked response latencies following electrical stimulation of the shoulder were shortest for cortical sites within the "original" shoulder representation in intact controls, and latencies recorded at the "original" shoulder representation in deafferents were also shorter than latencies recorded in "new" shoulder representations in both groups of deafferents; and (6) morphological maps of the FBS were altered in neonate deafferents to the extent that the barrel structure was poorly formed, as exemplified by the absence of the four mediolateral running bands; however, the overall ovoid shape of the FBS was still apparent, but not as sharply defined as for intact controls or adult deafferents. Possible mechanisms for reorganization following large-scale deafferentation are discussed.
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PMID:Effects of large-scale limb deafferentation on the morphological and physiological organization of the forepaw barrel subfield (FBS) in somatosensory cortex (SI) in adult and neonatal rats. 1050 4