feature article
Dr. Daniel Johnston. Photo by: Matt Lankes.
Unlocking the Mysteries of Learning
and Memory, One Cell at a Time
Dr. Dan Johnston studies how neurons change during learning and gets a new center
for research on learning and memory off the ground and running
he human brain is the ultimate learning machine. In Learning Changes Neurons
the blink of an eye, the great mass of ten billion neu- When learning occurs, neurons in the hippocampus change, and
rons can learn a new word, memorize a phone num- much attention has focused on how learning changes synapses—
ber, and recall vivid memories from childhood based the contact points where neurons connect. Synapses connect
on a simple smell. But how the brain accomplishes these feats the axon end of one neuron to the dendrites of another. During
remains one of life’s greatest mysteries. Dr. Dan Johnston, profes- learning, synapses go through molecular and physical changes that
sor of neurobiology, aims to solve this big mystery by understand- help information flow more easily between affected neurons, like
ing how learning and memory works at the most basic level—in widening a bridge allows more cars to travel across.
the single neuron cell. “When learning and memory events occur, changes in synapses
“I’ve always been interested in how neurons process and store increase the throughput [of information through] learned syn-
information,” says Johnston, director of the college’s Center for apses,” explains Johnston. But synapses aren’t the only parts of a
Learning and Memory and the Institute for Neuroscience. neuron affected by learning and memory.
Johnston works on neurons in the hippocampus, an important Johnston and his colleagues are finding that learning changes
region of the brain for learning and short-term memory. “The hip- neurons throughout their dendrites—the long, branchlike exten-
pocampus is a fast learner,” he describes. “It takes in information sions of these cells. “Originally we thought that dendrites were
from everyday activities, holds it temporarily, gets rid of what isn’t passive and that only synapses changed during learning,” says
important, and helps slowly develop a long-term memory where Johnston. “Our work strongly supports the idea that learning
appropriate.” Without a hippocampus, you wouldn’t be able to
learn or remember any new information. Did you know that sleep helps your long-term memory? Sleeping allows your
The hippocampus is also one of the first regions of the brain to hippocampus to playback information that occurred during the day and helps
suffer from Alzheimer’s disease and is prone to epileptic seizures. lay down lasting memories in the neocortex. It keeps the important memories
“It turns out that the things that make the hippocampus a fast and throws out the rest. Without sleep, your memory doesn’t function well.
learner—the circuitry and the connections—also make it the most “If you’re sleep-deprived, you go crazy,” says Johnston. “You can’t playback
prone area of the brain to have seizures,” says Johnston. the information you acquired during the day.”
4 s p r i n g 2 0 0 6
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24