Memory: a glossary of terms

Genes: Strings of amino acids that make up an organism’s genome, a sort of blueprint from which the organism is built. Individual genes are strings of amino acids; each string contains instructions for building a particular protein.

FOR THE RECORD:
Chasing memory: The glossary accompanying the memory articles in Sunday and Monday’s Section A defined genes as “strings of amino acids that make up an organism’s genome, a sort of blueprint from which the organism is built. Individual genes are strings of amino acids; each string contains instructions for building a particular protein.” The definition should have said: “Genes: strings of DNA that form a blueprint from which the organism is built. Each gene contains instructions for building a particular protein.” —

Hippocampus: A structure near the center of the brain in mammals, including humans, that is involved in memory, learning, timing and spatial awareness, among other functions.

Integrin: One of the most common types of molecules in mammalian biology, integrins mainly function to tie things into place. For example, they cause blood cells to clot, allowing wounds to heal. Lynch Lab hypothesized that integrins solidified LTP, locking molecular changes into place.

LTP, or long-term potentiation: The strengthening of connections between brain cells that occurs when they communicate, making subsequent communication more efficient. The communication consists of electrochemical exchanges between two neurons at the place where they meet, called the synapse.

Neuron: The most common type of cell in the brain (numbering in the hundreds of millions); LTP occurs between two neurons.

Protein: Molecules that perform most of the work within cells. Each protein’s composition, and thus function, is dictated by a gene.

Theta rhythm: A naturally occurring rhythm in the brain that is hypothesized to initiate LTP, and thus memory.

Synapse: The point at which two neurons communicate in the brain. It is actually not a structure but a gap of about 20 nanometers (20-billionths of a meter) across which one neuron sends chemical signals that are received by the other. The chemicals set off cascades of events inside the receiving neuron. There are estimated to be 100 trillion to 10 quadrillion synapses in a human brain, allowing for immense memory capacity.