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Neural processing in a three-choice reaction-time task: a study using cerebral evoked-potentials and single-trial
T A Ortiz1, D S Goodin, M J Aminoff
1Department of Neurology, University of California, San Francisco 94143-0114.
Journal of Neurophysiology
|May 1, 1993
Summary
This study investigated a three-choice reaction time task, revealing a multi-stage sensory discrimination process. Findings suggest response preparation can precede stimulus onset, with distinct neural patterns for different stimulus frequencies.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Human Motor Control
Background:
- Long latency event-related potentials (ERPs) are linked to sensory discrimination, but their precise coupling to discrimination is variable.
- Previous research indicated a two-stage discrimination process in two-choice reaction time tasks, with faster discrimination for frequent stimuli.
- The current study hypothesizes a similar multi-stage discrimination process in a three-choice reaction time task.
Purpose of the Study:
- To examine if a three-choice reaction time task involves a three-stage discrimination process.
- To investigate the temporal and neural characteristics of stimulus discrimination based on frequency.
- To analyze electroencephalogram (EEG) and electromyogram (EMG) data to understand response preparation and execution.
Main Methods:
- Ten right-handed subjects performed a three-choice reaction time task.
- Continuous EEG and EMG recordings were collected.
- Data were analyzed using stimulus-synchronized and response-synchronized averages for correct and incorrect responses.
Main Results:
- Subject response speed to the most frequent tone predicted speed to the second most frequent tone, but not the least frequent.
- Pre-movement potentials, indicative of response preparation, were observed >200 ms before stimulus onset for the frequent tone.
- Hemispheric asymmetry in pre-movement potentials was observed for rare tones, suggesting anticipatory, potentially incorrect, hand selection.
Conclusions:
- The three-choice reaction time task appears to involve a multi-stage discrimination process, supporting the study's hypothesis.
- Response preparation can precede stimulus detection, particularly for predictable stimuli.
- Neural activity patterns, specifically hemispheric lateralization of pre-movement potentials, reflect complex decision-making and anticipation strategies during reaction time tasks.