1. Neuroscience
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Distinct neural mechanisms underlie the success, precision, and vividness of episodic memory

  1. Franziska R Richter
  2. Rose A Cooper
  3. Paul M Bays
  4. Jon S Simons  Is a corresponding author
  1. University of Cambridge, United Kingdom
Research Article
Cite this article as: eLife 2016;5:e18260 doi: 10.7554/eLife.18260
7 figures and 1 video

Figures

Behavioral responses for all retrieval trials.

(a) Distribution of errors (difference between reported feature value and target feature value), across all 5724 trials across all participants, also visualized in circular space by wrapping the distribution around a circle. (b) Distribution of vividness responses across all 954 vividness ratings for all participants.

https://doi.org/10.7554/eLife.18260.003
Figure 1—source data 1

Data associated with the error distribution and vividness rating analyses.

https://doi.org/10.7554/eLife.18260.004
Relationship between the three measures of retrieval performance.

Correlation between (a) retrieval success and precision, (b) retrieval success and vividness ratings, and (c) precision and vividness ratings. Shaded areas indicate the standard error of the correlation.

https://doi.org/10.7554/eLife.18260.005
Figure 2—source data 1

Data associated with the pairwise correlation analyses.

https://doi.org/10.7554/eLife.18260.006
ROI analyses.

(a) Significant effects of the general linear model (GLM) as revealed by the ROI analyses. Each contrast was assessed in each of the a priori defined ROIs by determining the significance of peak ROI activity using small-volume correction at p < 0.05. Significant effects of retrieval success were found in the hippocampal ROI, of precision in the AnG ROI, and of vividness in the precuneus ROI. (Contrasts displayed at p < 0.01, uncorrected, for visualization.) (b) Mean first level t-values observed across voxels in each anatomical ROI for the three measures of retrieval performance. Error bars show standard error of the mean.

https://doi.org/10.7554/eLife.18260.007
Figure 3— source data 1

Data associated with the ROI analyses.

https://doi.org/10.7554/eLife.18260.008
Activity for each contrast of interest.

Activity was assessed throughout the brain to reveal any areas of overlap (at a liberal statistical threshold of p < 0.001, uncorrected). Activations are displayed on the cortical surface using Pysurfer software (https://pysurfer.github.io), visualized at an even more liberal threshold of p < 0.01 (uncorrected). Red = Retrieval Success; Blue = Precision; Green = Vividness. Greater activity is indicated by increasing brightness of the color. Purple = overlap between Retrieval Success and Precision; Cyan = overlap between Precision and Vividness; Yellow = Overlap between Retrieval Success and Vividness.

https://doi.org/10.7554/eLife.18260.009
Task design.

(a) Examples of displays learnt during encoding and (b) part of the sequence of retrieval questions for a single display illustrating the manipulation of the objects with the continuous dial. During retrieval, the order in which features (color/orientation/location) were tested was counterbalanced. Two out of the three objects associated with an encoded display were tested during retrieval. A video of an example retrieval trial can be accessed online (Video 1).

https://doi.org/10.7554/eLife.18260.010
Models fitted to the error distribution.

(a) Components used to model the error data. (bd) Illustrations of the three models compared to analyze participants’ error distributions, including von Mises alone (b), von Mises + uniform (c), and von Mises + uniform + additional von Mises distributions modeling non-target errors (d).

https://doi.org/10.7554/eLife.18260.011
Simulated data illustrating the possibility of statistical independence of retrieval success (proportion of responses in the von Mises distribution vs. the uniform distribution) and retrieval precision (the concentration of the von Mises distribution).
https://doi.org/10.7554/eLife.18260.012

Videos

Video 1
Example of a retrieval trial.

The video demonstrates the use of the continuous response options for the vividness question (00:01–00:09), and the three feature questions for the first (00:09–00:29), as well as the second object (00:30–00:51). Participants were able to adjust their responses continuously by moving around the slider (vividness question) or the circular dial (feature questions). Once they were happy with their response, they locked their response with a button press. For the first five feature questions in the example the participant entered their response within the first 4 s of the question, and therefore the font color of the cue word ('Orientation'/'Colour'/'Location') remains white. For the last feature question, the color of the cue changes to red as no response was given within the first 4 s of the question interval, indicating to the participant that 2 s remain to respond.

https://doi.org/10.7554/eLife.18260.013

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