Biomedical subjects

Yongchang Wang

Publications and source records attributed to Yongchang Wang.

3 recordsLinked to original sources

PubMed2006

Functional degradation of visual cortical cells in old cats.

Visual function declines with age. Using extracellular single-unit in vivo recordings, we compared the function of primary visual cortical (area 17) cells in young and old paralyzed, anesthetized cats. The results reveal that cortical neurons in old cats exhibit higher visually evoked responses, higher spontaneous activities, lower signal-to-noise ratios, and weaker orientation and direction selectivity than do cells in young adult cats. These findings are consistent with previously reported age related declines in cortical function in senescent macaque monkeys. Thus, similar declines in cortical function accompany old age in different mammalian species with well developed cortices.

Action Potentials↗

PubMed2005

Degradation of signal timing in cortical areas V1 and V2 of senescent monkeys.

Senescence in monkeys results in a degradation of the functional properties of cortical cells as well as prolonged hyperactivity. We have now compared the spontaneous and visually evoked activity levels, as well as the visual response latencies of cells in cortical areas V1 and V2 of young and very old monkeys. We found that V1 cells within layer 4 exhibit normal latencies. In contrast, in other parts of V1 and throughout V2 hyperactivity in old monkeys is accompanied by dramatic delays in both the intracortical and intercortical transfer of information. Extrastriate cortex (area V2) is affected more severely than striate cortex (V1). Delayed information processing in cerebral cortex should contribute to the declines in cortical function that accompany old age.

Aging↗

PubMed2003

GABA and its agonists improved visual cortical function in senescent monkeys.

Human cerebral cortical function degrades during old age. Much of this change may result from a degradation of intracortical inhibition during senescence. We used multibarreled microelectrodes to study the effects of electrophoretic application of gamma-aminobutyric acid (GABA), the GABA type a (GABAa) receptor agonist muscimol, and the GABAa receptor antagonist bicuculline, respectively, on the properties of individual V1 cells in old monkeys. Bicuculline exerted a much weaker effect on neuronal responses in old than in young animals, confirming a degradation of GABA-mediated inhibition. On the other hand, the administration of GABA and muscimol resulted in improved visual function. Many treated cells in area V1 of old animals displayed responses typical of young cells. The present results have important implications for the treatment of the sensory, motor, and cognitive declines that accompany old age.

Aging↗