Evidence Accumulator or Decision Threshold - Which Cortical Mechanism are We Observing?
1Department of Neuroscience, Oberlin College Oberlin, OH, USA.
Frontiers in Psychology
|June 28, 2012
Summary
This study analyzes decision thresholds in perceptual decision making. It suggests that observed neural activity may reflect threshold mechanisms, not just evidence accumulation, impacting interpretations of brain function.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Computational Neuroscience
Background:
- Perceptual decision making models often focus on evidence accumulation.
- Neural basis of accumulation is studied in parietal and prefrontal cortex.
- Threshold mechanisms and their neural basis are less understood.
Purpose of the Study:
- Analyze a decision threshold model implementable in cortical areas.
- Investigate if ramping neural activity reflects evidence accumulation or threshold readout.
- Determine if speed-accuracy tradeoffs are modulated by thresholds or accumulation rates.
Main Methods:
- Theoretical analysis of a decision threshold model.
- Comparison of model behavior with existing decision neuroscience questions.
- Examination of implications for interpreting neural data.
Main Results:
- Ramping neural activity alone is weak evidence for evidence accumulation.
- Task-modulated ramping activity could indicate threshold readout.
- Observed accumulation signs may reflect threshold adaptation as much as rate/starting point changes.
Conclusions:
- Rethinking threshold modeling is crucial for interpreting neural data in decision making.
- Cortical areas may implement both evidence accumulation and threshold readout.
- Distinguishing between accumulation and threshold mechanisms is vital for understanding brain function.
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