The links between nerve cells, called synapses, allow us to learn and adapt, and hold clues to conditions such as autism, schizophrenia and more
By Amber Dance 08.18.2020
If you were to take a human brain and toss it in a blender — not that you should — the resulting slurry of cells wouldn’t be special in the way that the human brain is. No thoughts, no worries, no wonder or awe.
That’s because it’s the connections between those cells that make the brain so amazing. By sending electrical signals from nerve cell to nerve cell within a great network of connections, the brain creates thoughts as mundane as “Where are my keys?” or as profound as “I think, therefore I am.”
CREDIT: JAMES PROVOST (CC BY-ND)
Neuroscientist Kimberley McAllister
Kimberley McAllister has been fascinated by the human brain since college. As a graduate student in the 1990s studying developmental neurobiology, she was drawn to the question of how the brain is built: how individual brain cells in a growing fetus somehow organize themselves into an organ capable one day of pondering the mysteries of life.
Now director of the Center for Neuroscience at the University of California, Davis, McAllister continues to investigate how the brain’s nerve cells — called neurons — find each other, connect and disengage. She spoke with Knowable Magazine about key discoveries in the study of brain networks, and new work revealing their importance in disease.
This conversation has been edited for length and clarity.
The links between neurons are called synapses. What exactly is a synapse, and what happens there?
It’s basically a connection: one cell talking to another. A brain cell, or a neuron, has a large main body, with small strands sticking out. So one neuron, the transmitter, uses a really thin strand called an axon. A second neuron, the receiver, can receive contacts along its main body, or along strands that branch out like a tree, called dendrites. When the axon tip of a transmitter connects to a receiver, that’s a synapse.
Neurons run on electricity. If an electrical signal passes down an axon, its tip releases chemicals called neurotransmitters into the synapse. These neurotransmitters tell the receiver cell to either activate its own electrical charge, which sends the signal to the next neuron in the chain, or tell the receiver cell to stay quiet.