The ERP Systems Lab
People
Faculty
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Shimin Fu, Ph.D., Research Assistant Professor |
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Pamela Greenwood, Ph.D., Associate Professor |
Students
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Autumn Brown |
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Marla Zinni (currently in Steve Hillyard’s lab at UC San Diego)
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EEG and ERPs
Event-related potentials (ERPs) represent the brain’s neural response to specific sensory, motor, and cognitive events. ERPs are computed by recording the electroencephalogram (EEG) from the scalp of a human participant and by averaging EEG epochs time-locked to a particular event. Information on the neural mechanisms underlying cognitive processes can be obtained by examining changes in the amplitude, latency, scalp distribution, and neural sources of different components of the ERP waveform.
ERPs hold a unique position in cognitive neuroscience research because of their high temporal resolution in assessing neural activity. Other neuroimaging techniques such as positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) are based on cerebral hemodynamics as opposed to neuronal activity, and are therefore more sluggish than ERPs, which have millisecond resolution. As such, ERPs are being increasingly used whenever there is a need to examine the relative timing of neural mechanisms underlying cognitive processes. Although the spatial resolution of ERPs is not as good as these other neuroimaging methods, when high-density scalp recording (64 or 128 channels) is used in conjunction with source-localization techniques, the spatial resolution of ERPs can be enhanced. Importantly, ERP collection involves benign, noninvasive techniques that can be used across a wide spectrum of the population, from infancy to old age.
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Current Research
Current ERP research in the Arch Lab is focused on the neural mechanisms of a number of different aspects of cognition. One large group headed by Raja Parasuraman, Shimin Fu, and Pamela Greenwood is investigating visual attention and working memory. We are interested in examining the early-latency components of the visual ERP, including the C1, P1, and N1 components, in relation to cue-driven shifts of visual attention, particularly under varying conditions of perceptual load. We are examining the neural underpinnings of both voluntary and involuntary shifts of attention, as well as changes in the scale of attentional focus. In related research we are investigating age-related changes in attention-sensitive ERP components. We are also investigating the role of genetic polymorphisms in modulating individual differences in ERP correlates of visual attention.
Jim Thompson’s Perception and Action Neuroscience Group within the Arch Lab is interested in the neural mechanisms that underlie the recognition of human movement. We use ERPs to examine the timing of brain responses to biological motion, focusing on a negative component at around 200ms (N170) and a slightly later negative component at around 300-350ms (N300). Of particular interest to our group is the relative role of form and motion to these components, the degree to which these components can index gait-selective processing, and the dependence of these components on attention. As our research continues we plan to integrate ERP measures of the timing of responses to biological motion with fMRI measures of the location of neural responses.
Developmental psychologist Koraly Perez-Edgar employs ERPs to examine the changing role attention plays in shaping behavior from infancy through adolescence. Trained as a temperament researcher, she takes an individual differences approach to examine how differing patterns of attentional control and attention biases are related to higher order profiles of behavior and socioemotional development. In particular, Dr. Perez-Edgar has taken standard cued-attention tasks and tracked changes in behavior and physiology as the context of performance shifts with the addition of affect-laden stimuli or the introduction of an affective motivator. For example, the affective Posner task was designed to examine individual differences in response to threat and has been used with children at temperamental risk for anxiety (Perez-Edgar & Fox, 2005), children with a familial risk for depression (Perez-Edgar et al, 2006), children with a diagnosed bipolar disorder (Rich et al, 2005), and children with severe mood disorder (Rich et al, 2007). Current work is incorporating the task with additional populations, including children with a genetic predisposition to attention difficulties (Perez-Edgar et al, in prep) and children institutionalized in Romanian orphanages (Fox et al, in progress).
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Hardware
The Arch Lab has three systems for non-invasive recording of human brain electrical activity installed in the Arch Lab Annex (David King 1005).
- 32-Channel EEG/ERP System
- 64-Channel EEG/ERP System
- 128-Channel EEG/ERP System
All three systems are manufactured by Neuroscan, a part of Compumedics Inc. The 64-channel and 128-channel systems use Synamps2 amplifiers, which provide for high-input impedance, low-noise amplification of microvolt level brain signals recorded from the scalp.
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64-channel EEG system
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32-channel EEG computer
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32-channel EEG system
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The associated hardware and software allows for simultaneous testing of up to three participants in separate testing rooms.
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Software
The Arch Lab EEG/ERP lab has a number of software packages available for stimulus presentation, computation of ERPs, and source localization of ERP components. For stimulus presentation we use STIM (NeuroScan), E-Prime (Psychological Tools) and Presentation software. STIM is an old DOS-based software package that uses *.CUT and *.PCX picture files. E-Prime and Presentation are both Windows-based and are commonly used in psychological as well as in ERP and neuroimaging studies.
For EEG/ERP data analysis we used the SCAN software for basic analysis for EEG/ERP data, including filtering, artifact rejection, averaging, etc. The SCAN output can be used for statistical analysis and plotting. For source localization, we have available three software tools: Curry 4.6, Source, and EMSE. Source uses an Equivalent Current Density (ECD) approach, whereas EMSE uses a distributed approach to solving the “inverse problem” of source localization. Both these two general approaches are available in Curry 4.6.
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Recent Publications
- Jiang, Y., Luo, Y., & Parasuraman, R. (2002). Neural correlates of perceptual priming of visual motion. Brain Research Bulletin, 57, 211-219.
- Pérez-Edgar, K., & Fox, N. A. (2003). Individual differences in children during an emotional Stroop task: A behavioral and electrophysiological study. Brain & Cognition, 52, 33-51.
- Fu, S., Caggiano, D. M., Greenwood, P. M., & Parasuraman, R. (2005a). Event-related potentials reveal dissociable mechanisms for orienting and focusing visuospatial attention. Cognitive Brain Research, 23, 341-353.
- Fu, S., Greenwood, P. M., & Parasuraman, R. (2005b). Brain mechanisms of involuntary visuospatial attention: An event-related potential study. Human Brain Mapping, 25, 378–390.
- Pérez-Edgar, K., & Fox, N. A. (2005). A behavioral and electrophysiological study of children’s selective attention under neutral and affective conditions Journal of Cognition & Development, 6, 89-116.
- Rich, B. A., Schmajuk, M., Pérez-Edgar, K., Pine, D. S., Fox, N. A., & Leibenluft, E. (2005). The impact of reward, punishment, and frustration on attention in pediatric bipolar disorder. Biological Psychiatry, 58, 532-539.
- Caggiano, D., Fu, S., Zinni, M., Kumar, R., Squire, P. N., & Parasuraman, R. (2006, October). Voluntary and involuntary zooming of attention differentially affect visual search: an event-related potential study. Abstracts of the Annual Meeting of the Society for Neuroscience, Atlanta, GA.
- Pérez-Edgar, K., Fox, N. A., Cohn, J. F., & Kovacs, M. (2006). Behavioral and electrophysiological markers of selective attention in children of parents with a history of depression. Biological Psychiatry, 60, 1131-1138.
- Rich, B. A., Schmajuk, M., Pérez-Edgar, K., Fox, N. A., Pine, D. S., & Leibenluft, E. (2007). Response to contingencies and frustration in pediatric bipolar disorder and severe mood dysregulation. American Journal of Psychiatry, 164, 309-317.
- Fu, R., & Parasuraman, R. (2007). Event-related brain potentials in neuroergonomics. In R. Parasuraman, & M. Rizzo (Eds.) Neuroergonomics: The Brain at Work. (pp. 32-50). New York: Oxford University Press.
- Pérez-Edgar, K., & Fox, N. A. (in press). Temperamental contributions to children’s performance in an emotion-word processing task: A behavioral and electrophysiological study. Brain & Cognition.
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