Project Description

Eavesdropping on Neurons

Brain Electrical Activity


The brain is made up of billions of neurons with trillions of synaptic connections. To assure that signals are quickly propagated across these large networks, neurons use a combination of electrical and chemical signals to communicate with each other. Neurophysiology merges neuroscience and physiology to observe the electrical activity of neurons, and their functions in the nervous system. By implanting electrodes into neurons, it is possible to monitor electrical activity under differing conditions.

The brain’s language is electrical in nature. Neurons conduct very low levels of electricity in the form of charged atoms called ions. Electrical impulses traveling down axons trigger the release of neurotransmitters. These chemicals can trigger electrical impulses in neighboring neurons. This combination of electrical and chemical signals is the basis of information flow in the brain.

Ida Henrietta Hyde

Ida Henrietta Hyde

Ida Henrietta Hyde (1857-1945), an American physiologist, was the first woman to do research at the Harvard Medical School and to be elected to the American Physiological Society. She was an early pioneer in the application of electrophysiology to make single unit recordings from a nerve cell. Hyde invented the microelectrode in the 1930’s. The microelectrode is a small device that electrically (or chemically) stimulates a living cell and records the electrical activity within that cell.

tungsten electrode

Tungsten Electrode

The Tungsten Electrode, was a further refinement of the earlier device.  It was invented by David Hubel, a founding member of the Department of Neurobiology at Harvard Medical School.  There is a lot more about this invention and the work of Hubel & Wiesel at Harvard on Braintour.

Electroencephalography (EEG) is an electrophysiological monitoring method to record electrical activity of the brain. The Harvard Collection of Historical Scientific Instruments displays a model of the first EEG machine.

Matthias Minderer

Today’s Labs

Neurophysiology techniques facilitate inquiries into many key questions in neuroscience.

How do neurons respond to sensory input? By recording from neurons during exposure to particular forms of stimulation, it is possible to understand how neurons encode and process sensory information in the brain, such as scents, visual information, and even touch. This work is going on in the labs of John Assad, Richard Born, David Ginty, Clifford Woolf and Rachel Wilson.

The electrical behavior of neurons tells us about how sensory information is processed by the brain in real time. Christopher Harvey characterizes the electrical properties of neurons in a mouse’s brain while the rodent navigates a virtual reality world (image to the left).  The Harvey Lab thus develops insights into the brain’s processes in decision making.

Electrophysiological probes can reveal the basics of cellular communication in the brain, allowing us to decipher the rules that regulate the release of neurochemicals.  The labs of Bernardo Sabatini, Wade Regehr and Pascal Kaeser use these techniques to observe how are neurochemical processes are altered in disease states.

In the labs of Bruce Bean, Jonathan Cohen and Gary Yellen, observations of how pharmacological agents and other molecules inside and outside of neurons, control the excitability of neurons.