Mean signal and response time influences on multivoxel signals of contextual retrieval in the medial temporal lobe.

TitleMean signal and response time influences on multivoxel signals of contextual retrieval in the medial temporal lobe.
Publication TypeJournal Article
Year of Publication2015
AuthorsReas ET, Brewer JB
JournalBrain Behav
Date Published2015 Feb
KeywordsAdult, Brain Mapping, Female, Humans, Magnetic Resonance Imaging, Male, Memory, Photic Stimulation, Temporal Lobe, Young Adult

INTRODUCTION: The medial temporal lobe supports integrating the "what," "where," and "when" of an experience into a unified memory. However, it remains unclear how representations of these contextual features are neurally encoded and distributed across medial temporal lobe subregions.

METHODS: This study conducted functional magnetic resonance imaging of the medial temporal lobe, while participants retrieved pair, spatial, and temporal source memories. Multivoxel classifiers were trained to distinguish between retrieval conditions before and after correction for mean signal and response times, to more thoroughly characterize the multivoxel signal associated with memory context.

RESULTS: Activity in perirhinal and parahippocampal cortex dissociated between memory for associated items and memory for their spatiotemporal context, and hippocampal activity was linked to memory for spatial context. However, perirhinal and hippocampal classifiers were, respectively, driven by effects of mean signal amplitude and task difficulty, whereas the parahippocampal classifier survived correction for these effects.

CONCLUSION: These findings demonstrate dissociable coding mechanisms for episodic memory context across the medial temporal lobe, and further highlight a critical distinction between multivoxel representations driven by spatially distributed activity patterns, and those driven by the regional signal.

Alternate JournalBrain Behav
PubMed ID25646149
PubMed Central IDPMC4312925
Grant ListK02 NS067427 / NS / NINDS NIH HHS / United States
P50 AG005131 / AG / NIA NIH HHS / United States
T32 MH020002 / MH / NIMH NIH HHS / United States
K02NS067427 / NS / NINDS NIH HHS / United States
IRG Funded