Event-Related Potentials
Event-related potentials (ERPs) are
components of the scalp-recorded electroencephalogram (EEG).
This non-invasive technology records the brain's
electrical signals that are time-locked to selected tasks/stimuli.
A set of small gelled electrodes held onto the scalp allow analysis systems to collect and analyze these brainwaves.
We use a stretch cap to painlessly collect signals from up to 64 sites on the scalp at a time.
From this mix of ongoing EEG, brainwave potentials are collected
at the scalp. These coordinated brain responses to visual, auditory,
or somatosensory trigger events can
be analyzed using signal
averaging techniques.
Event-related potentials (e.g. the N1, P2, N2 and P3 peaks) are the averaged responses time-locked to the
experimental trigger event. These ERP components reflect the
brain activation that is consistently coordinated in response to the
triggering events in experimental tasks.
These ERP responses, high in temporal resolution, can reveal minute changes in sensory and cognitive brain responses to selected tasks and subtle differences between subject groups. These analyses provide an exciting complement to the excellent spatial resolution of brain activities provided by fMRI.
Thus, we are developing neuropsychological paradigms that can be used in both ERP and fMRI environments, with the goal of acquiring ERPs/EEG simultaneously with fMRI recordings (in collaboration with Giorgio Bonmassar, Ph.D.).
Reward Processing in Cocaine Addiction
For example, we examined the effect of monetary reward salience on ERP components and behavior using a response inhibition paradigm in 16 healthy participants. The ERPs were recorded from 64 channels while subjects performed a warned reaction time Go/No-Go task; monetary reward conditions (high, low, none) varied across blocks of trials. This study showed sensitivity of the P3 (but not CNV) to this sustained and graded monetary reward in young healthy adults (Goldstein et al., 2006).
Replicating our fMRI results Goldstein et al., 2007b), recent ERP results suggest a compromised P3 sensitivity to the same monetary reward in age-matched cocaine addicted individuals (Goldstein et al., 2008 in press).