Recognition memory and the parietal lobe: Insights from functional magnetic resonance imaging, electroencephalography, and transcranial magnetic stimulation

Although not conventionally associated with memory, numerous neuroimaging studies have indicated that the parietal cortex systematically tracks the retrieval of information from memory. I report 4 experiments investigating this phenomenon. Experiments 1 and 2 found that successful retrieval effects in the lateral parietal cortex are lateralized to the left for both words and non-famous faces. This indicates that the tendency of successful retrieval effects to be lateralized to the left cerebral hemisphere is not due to the left hemisphere's role in linguistic representation. Experiment 3 used a frequency discrimination paradigm and found that parietal cortex tracks the amount of information retrieved from memory even when this is not the basis of the decision. This calls into question models that posit that the parietal cortex is part of the decision making process. The final experiment employed a combination of functional magnetic resonance imaging, event-related potentials, and transcranial magnetic stimulation and found that the parietal cortex makes a causal contribution to recognition memory decisions. Taken together, the results suggest that parietal cortex helps orchestrate a high level, multi-modal representation of episodic content.