We investigate the neural mechanisms underlying human cognition by using electrophysiological techniques, including electroencephalography (EEG) and event-related potentials (ERP), to explore the brain's response to various kinds of stimuli. For example, much of our research focuses on the domain of language processing, where we investigate how the brain recognizes words and combines their meanings into larger, complex representations, such as phrases, sentences, and discourse-level representations.
What is EEG?
Neurons communicate by generating electro-chemical signals several hundred times per second. Although each individual neuron's electrical activity is much too small to be detectable from outside the brain, the behavior of large populations of neurons acting in concert can be reliably measured with sensors placed on the scalp. Electroencephalography is the technique of recording ongoing electrical activity in this way.
What are ERPs?
Whenever you see, hear, feel or think something, there is a transient change in your brain's electrical activity in response to that event — the event-related potential. Unfortunately, ERPs can't be seen directly in the EEG because there are also many other, unrelated forms of brain activity occurring simultaneously, all of which serve to obscure the signal of interest. However, by averaging together the brain response to multiple instances of the same kind of event, any brain activity that is not highly similar over the multiple instances is washed out. This signal-averaging technique isolates the underlying brain response that is specifically associated with the event of interest, and provides a millisecond-by-millisecond record of neural information processing. Analyzing the polarity, timing, amplitude, and scalp distribution of this activity can help us make inferences about what kinds of processes are triggered by the stimuli and where in the brain that processing occurs.
If you have any questions or would like to find out more, please feel free to contact Dr. Amanda Elam.