Physics Division Seminars bring us speakers on a variety of physics related subjects. Usually these are held in the Building 6008 large Conference Room, at 3:00 pm on the chosen day, but times and locations may vary. For more information, contact our seminar chairman,
Tel (Office): (865) 574-6124 (FAX): (865) 574-1268
Adult neurogenesis has been firmly established in animals, but has been more difficult to fully assess in humans due to technical constraints. Above ground atomic bomb testing from 1954 to 1963 produced a sudden and dramatic increase in the atmospheric level of radiocarbon (14C) globally. An exponential decline in the levels of 14C has been occurring over the past 40 years, with a T1/2 of ~11 years. Since humans eat plants or eat animals that ate plants, the atmospheric 14C level is mirrored in human tissue. Genomic DNA is stable after a cell's last division, so that the carbon within the DNA can be used as a marker of cell birth. After extracting nuclei from cells of a given brain region, the neuronal population was isolated using fluorescence activated cell sorting with an antibody to NeuN. 14C analysis was performed on samples by accelerator mass spectrometry. The 14C data was related to the atmospheric 14C levels, and the birth date of the particular cell population was directly determined. We did not detect any postnatal neurogenesis within the occipital cortex. However, the non-neuronal population was found to be younger than the person's age, implying that some cellular turnover was occurring after birth. The technique is currently being applied to other long-lived cells.
Supported by: Human Frontiers Science Program. Work performed in part under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under contract W-7405-Eng-48