Brain areas commonly activated at 3 months for to the retrieval of consistently episodic memories (RR) and initially episodic, then semantic memories (RK) (inclusive masking at p<0.001).

<p>x, y, z = coordinates in mm in the Montreal Neurological Institute space. For brevity, each region is listed only once; when several peaks were observed in the same region, the coordinates refer to the strongest activation. Minimum cluster size: 10 contiguous voxels.</p

Results of ROI analyses in the hippocampus.

<p>A. Hippocampal activity (mean ± SEM) according to the nature of memories (RR <i>vs</i> RK responses) and delay (3 days <i>v</i>s 3 months). *: p<0.05, ***: p<0.001. B. Hippocampal activity (mean ± SEM) for RR responses according to the delay (3 days <i>vs</i> 3 months) distinguishing the anterior and posterior parts. ***: p<0.001.</p

Brain areas in which activity during the retrieval of initially episodic, later semantic memories (RK) compared to correct rejections is higher after the 3-day than the 3-month delay or conversely.

<p>x, y, z = coordinates in mm in the Montreal Neurological Institute space. All regions listed are statistically significant at p<0.05 (FWE corrected, *) or psvc<0.05 (**), after correction in a small spherical volume (10 mm) around coordinates previously reported in the literature (specified in the last column). For brevity, each region is listed only once; when several peaks were observed in the same region, the coordinates refer to the strongest activation. Minimum cluster size: 10 contiguous voxels.</p

Experimental design.

<p>On day 1, participants were instructed to rate the valence of a series of emotional (positive and negative) and neutral colored pictures and to memorize them. Memory performance was tested on day 4 () and day 90 (±7 days, ) using a recognition task associated with the Remember/Know/Guess paradigm. Functional MRI data were acquired during these recognition sessions. After each session, all pictures that received an R response were presented again outside the scanner during a debriefing interview, to obtain from subjects a justification of their R responses with contextual details. Note that the same learned (“old” pictures) were used for both retrieval sessions allowing to track the fate of memories and their possible qualitative change over time. Thus, we distinguished consistently familiar or semantic memories (KK), consistently episodic memories (RR) and those that were initially episodic and became later semantic (RK). Distracter stimuli were different between the two recognition sessions. The pictures used in the figure are not the original IAPS images, but similar items used for illustrative purposes only.</p

Brain areas associated to the retrieval of consistently episodic memories (RR responses) compared to correct rejections at the 3-month delay.

<p>x, y, z = coordinates in mm in the Montreal Neurological Institute space. All regions listed are statistically significant at p<0.05 (FWE corrected, *) or psvc<0.05 (**), after correction in a small spherical volume (10 mm) around coordinates previously reported in the literature (specified in the last column). For brevity, each region is listed only once; when several peaks were observed in the same region, the coordinates refer to the strongest activation. Minimum cluster size: 10 contiguous voxels.</p

Brain areas in which activity at 3 months is specifically activated during the retrieval of consistently episodic memories (RR) but not for initially episodic, then semantic memories (RK) and conversely.

<p>x, y, z = coordinates in mm in the Montreal Neurological Institute space. All regions listed are statistically significant at p<0.05 (FWE corrected, *) or psvc<0.05 (**), after correction in a small spherical volume (10 mm) around coordinates previously reported in the literature (specified in the last column). For brevity, each region is listed only once; when several peaks were observed in the same region, the coordinates refer to the strongest activation. Minimum cluster size: 10 contiguous voxels.</p

Brain areas associated to the retrieval of initially episodic, later semantic memories (RK responses) compared to correct rejections at the 3-month delay.

<p>x, y, z = coordinates in mm in the Montreal Neurological Institute space. All regions listed are statistically significant at p<0.05 (FWE corrected, *) or psvc<0.05 (**), after correction in a small spherical volume (10 mm) around coordinates previously reported in the literature (specified in the last column). For brevity, each region is listed only once; when several peaks were observed in the same region, the coordinates refer to the strongest activation. Minimum cluster size: 10 contiguous voxels.</p

Brain areas associated to the retrieval of initially episodic, later semantic memories (RK responses) compared to correct rejections at the 3-day delay.

<p>x,y,z = coordinates in mm in the Montreal Neurological Institute space. All regions listed are statistically significant at p<0.05 (FWE corrected, *) or psvc<0.05 (**), after correction in a small spherical volume (10 mm) around coordinates previously reported in the literature (specified in the last column). For brevity, each region is listed only once; when several peaks were observed in the same region, the coordinates refer to the strongest activation. Minimum cluster size: 10 contiguous voxels.</p

Brain areas in which activity during the retrieval of consistently episodic memories (RR) compared to correct rejections is higher after the 3-day than the 3-month delay or conversely.

<p>x, y, z = coordinates in mm in the Montreal Neurological Institute space. All regions listed are statistically significant at p_svc<0.05, after correction in a small spherical volume (10 mm) around coordinates previously reported in the literature (specified in the last column).</p

Common and specific activations for RR and RK memories, 3 months after encoding.

<p>Common activations (top) are displayed at p<0.05 (FWE corrected) and specific activations (bottom) at p<0.001 (uncorrected), on axial, sagittal and coronal slices of the MNI template. The red circle illustrates the specific activation of the hippocampus for RR memories.</p