Thursday, June 6, 2013

Physiology of color categorization

Up to today there have been quite a few people writing off color naming and categorization as unserious hogwash. As of today, we know of a possible physiological basis, giving us a little more credibility.

In fact, now we know that neurogenesis it taking place in the hippocampus of adult humans. Fresh adult neurons have a specific function facilitating cognitive plasticity in the hippocampus—for example, in helping the brain distinguish between things that belong to the same category, or comparing new information to what it has already learned from experience. The ability to distinguish between vermilion and pink, yet still identify both as flamingo colors, is one example of this type of task in humans.

Kirsty L. Spalding et al. have found that a large subpopulation of hippocampal neurons constituting one-third of the neurons is subject to exchange. In adult humans, 700 new neurons are added in each hippocampus per day, corresponding to an annual turnover of 1.75% of the neurons within the renewing fraction, with a modest decline during aging. They conclude that neurons are generated throughout adulthood and that the rates are comparable in middle-aged humans and mice, suggesting that adult hippocampal neurogenesis may contribute to human brain function.

Reference: Dynamics of Hippocampal Neurogenesis in Adult Humans, Kirsty L. Spalding, Olaf Bergmann, Kanar Alkass, Samuel Bernard, Mehran Salehpour, Hagen B. Huttner, Emil Boström, Isabelle Westerlund, Céline Vial, Bruce A. Buchholz, Göran Possnert, Deborah C. Mash, Henrik Druid, Jonas Frisén: Dynamics of Hippocampal Neurogenesis in Adult Humans. Cell, Volume 153, Issue 6, 1219-1227, 6 June 2013.