Making and breaking connections in the brain

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.”

Illustrated portrait of Kimberley McAllister


Neuroscientist Kimberley McAllister

UC Davis

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.

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About S. R. Zelenz 119 Articles
S.R. Zelenz has worked in education for 20 years. Working with students from all walks of life, cultures, races, and social diversity, Zelenz’s research in Educational Leadership led to finding a better way to approach learning for students with trauma histories. Many were juvenile offenders, gang members, diagnosed with varying behavioral disorders, or had family histories of violence, murder, or narcissistic parenting. This research could not be effectively accomplished without further understanding: how epigenetic trauma inheritance may be impacting these students; how brain development from trauma may be impacting their behavioral and emotional development; as well as deep understanding of psychology and its varying classifications for behavioral and personality disorders. The goal is to find solutions for changing the conversation and making a real difference for these students. She has also worked with nonprofits of varying focus areas for the last 25 years. Her undergraduate degree in Arts Administration and Music prepared her for managing nonprofits of any size as well as procuring funding so that they can achieve their goals. Pairing her nonprofit background with her education background, she has been able to make a difference for over 200 nonprofits worldwide, written curriculum for schools across the globe, and assisted many arts organizations through performance and management.