John Rolston, MD, PhD
Neurosurgical Resident
Department of Neurological Surgery
University of California, San Francisco

 
 

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  Research Interests

My research is devoted to three main questions.  1) How is information processed by the brain?  2) How does this processing fail in psychiatric and neurological disorders?  3) How can we fix it?

While trying to answer these questions, I've developed useful hardware and software, all freely available.  My hope is that this work allows others to engage in similar research, so that we can more rapidly cure disease and better understand the human mind. 
 

Electrophysiology of seizure

 

Information Processing in Disease

Seizures are frightening disturbances of normal brain function.  Normally, the neurons of the brain fire with a relatively low degree of synchrony.  But if the activity becomes too synchronous, seizures result.  How such hypersynchronous activity arises is not understood, but likely involves changes in local and distant neural connectivity.  By examining the activity of groups of neurons in epileptic animals, we hope to gain insight as to how seizures begin, stop, and spread.
 

Microstimulator headstage, for use in awake and moving animals

 

Suppressing Seizures

Epilepsy affects about 1 out of every 100 people.  More than a third of these, about 1 million Americans, aren't helped by medications.  While some of these patients are candidates for surgery, many more are not.  Cleary, there is a great need for new therapies to address their needs.

Neural cultures and slices spontaneously "burst."  That is, they display frequent network-wide barrages of activity, reminiscent of seizures.  This activity can be completely suppressed in vitro, using distributed microelectrode stimulation (see this article in The Economist).  An analogy would liken seizures to forest fires.  If the forest is dry and a fire starts (a seizure begins in the seizure focus), nothing prevents it from spreading.  However, if you conduct controlled burns (distributed microstimulation), you can stop the fire's propagation.

I'm currently attempting this in vivo.  I've built a microstimulator, capable of simultaneous recording and stimulation from microelectrodes chronically implanted in the brain.  The stimulator is small, less than a square inch, and light, so it's easy for epileptic animals to carry around.  We're currently investigating the properties of microstimulation in various brain regions, as well as developing algorithms to use recorded activity to better suppress seizures.

A multielectrode array (MEA) with a culture of neurons growing on top

 

Neural Information Processing

The main cells of the brain, neurons, communicate via action potentials, brief pulses of electrical activity.  Each neuron, by itself, is a fairly simple device.  But when 100 billion are combined in the human brain, there suddenly emerges extraordinarily complex processing.  People can see, speak, and feel through the interaction of these cells with each other and their environment.  How is this possible?  How is complicated information, like music or speech, represented by the coordinated activity of billions of neurons?

     
 

Copyright, John Rolston