Understanding the Network That Controls Synapses

Human brains are made up of billions of neurons interconnected by trillions of synapses. All those links are controlled by a massively-complex, enzyme-regulated chemical system that currently is only known in part. A new study saw a team of experts develop a way to study these interactions.

Synapses are not only influenced by this chemical system, but also by a myriad of other factors, chief among them being our experiences. If we are exposed to the same things over and over again, then the synapses coding for them will become stronger, while others will become weaker.

The fact that our brains evolved to give their all for things we care about and nothing at all for the things we shun is outstanding all by itself, study leader Mary Kennedy remarks. The expert is the Allen and Lenabelle Davis professor of biology at the California Institute of Technology (Caltech).

According to the expert, scientists working towards understanding mental health issues could benefit extensively from a deeper understanding of how synaptic connections are formed, strengthened, weakened or destroyed altogether.

“It's becoming increasingly clear that slight mutations in some of these pathways make people more vulnerable to many disorders, including schizophrenia, bipolar disorder, and autism,” she explains.

For the past three decades, the investigator says, teams of scientists have created “cartoon” maps showing the interactions between regulatory pathways and enzymes. Even in their simplicity, these maps provide a hint to the real complexity hidden within the system's intricate workings.

“We know how little strings of enzymatic processes can get activated. But we don't have very good ways of asking what happens when, say, 20 of these processes are interacting and you tweak one or two,” Kennedy goes on to say.

The way she proposes to go about solving this issue is rather simple, yet ingenious. Why not simply stop these interactions in a series of samples, capturing how the processes change from one second to the next? These snapshots could then be deciphered in detail to reveal their underpinnings.

“That will let us map out the changes that happen in this large network immediately after a synchronized synaptic input,” the expert adds. She believes that freezing technology has evolved to the point where a brain tissue sample can be entirely frozen just one second after electrical stimulation.

“That means we'll be able to measure much more globally how these complex pathways interact with each other – which ones are more important at early stages, and which ones come in later – all of which has been very difficult to understand,” Kennedy concludes.

The Allen and Lenabelle Davis Foundation and the US National Institute of Mental Health (NIH) are supporting her work now, and will continue to do so as further progress is made.