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Every fall, the black-capped chickadee must store seeds for the winter by stashing small quantities of seeds in various sites. This use of multiple hiding places is to assure that all is not lost in one big theft. But how does the chickadee remember all those hiding places?
Biologists Fernando Nottebohm of Rockefeller University and Anat Barnea of Tel Aviv University have shown that the chickadee loses some old cells and grows a new set of brain cells each fall.
These scientists manipulated the independent variable of environment by confining some birds to an enclose where they were provided with all the seeds they could eat. Other birds, the control group, were allowed to free-forage in their natural environment. Those birds raised in the enclosure showed only half the neuronal (brain cell) turnover (dependent variable) compared to birds in their normal environment. This cell death and re-growth occurred in an area of the brain called the hippocampus, an area known to be important for long-term memory.
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