Memories form when networks of neurons learn to fire in new patterns. Biophysicists have now put that assumption to the test by inducing synchronized firings in neurons sitting on a chip.
Itay Baruchi and Eshel Ben-Jacob, two biophysicists at Tel Aviv University in Israel, extracted neurons from rat embryos and grew the nerve cells on a chip equipped with 64 electrodes to detect neuron activity. Repeatedly dropping tiny amounts of nerve-stimulating chemicals at a chosen spot, the researchers saw the same cascade of firings each time the neurons relayed signals to their neighbors. Eventually, the neurons began firing in that pattern without the chemical stimulation. The neurons had formed a memory, the researchers say.