Hippocampal activation for autobiographical memories over the entire lifetime in healthy aged subjects: an fMRI study - PubMed (original) (raw)

Hippocampal activation for autobiographical memories over the entire lifetime in healthy aged subjects: an fMRI study

Armelle Viard et al. Cereb Cortex. 2007 Oct.

Abstract

We used functional magnetic resonance imaging to determine the cerebral structures required during the recollection of episodic autobiographical memories according to 5 time periods covering the whole lifespan to test the 2 concurring models of memory consolidation, which propose either a temporary (standard model) or a permanent (multiple-trace model) role of the hippocampus in episodic memory retrieval. The experimental paradigm was specially designed to engage subjects (67.17 +/- 5.22 years old) in the retrieval of episodic autobiographical memories, whatever the time period, from personally relevant cues selected by questioning a family member. Moreover, the nature of the memories was checked at debriefing by means of behavioral measures to control the degree of episodicity. Behavioral data showed that recollected memories were characterized by specificity and details whatever their remoteness. Main neuroimaging data (Statistical Parametric Mapping 99) revealed the activation of a network including the left superior frontal gyri, bilateral precuneus/posterior cingulate and lingual gyri, left angular gyrus, and left hippocampus, although the subtraction analyses detected subtle differences between certain time periods. Small volume correction centered on the hippocampus detected left hippocampal activation for all time periods and additional right hippocampal activation for the intermediate periods. Further confirmation was provided by using a 3-way analysis of variance on blood oxygen level-dependent values, which revealed hippocampal activation whatever the time interval. The present data challenge the standard model of memory consolidation and support the multiple-trace model, instead. The comparison with previous literature stresses the idea that a bilateral involvement of the hippocampus characterizes rich episodic autobiographical memory recollection.

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Figures

Figure 1

Figure 1

General organization of the protocol. A: Experimental blocks (mental evocation of a personal memory). B: Control blocks (attentional task).

Figure 2

Figure 2

Statistical parametric maps showing the significant cerebral activations when subjects retrieve autobiographical memories regardless of the time-interval compared to the control condition (conjunction analysis). Stereotaxic coordinates are given on Table 3.

Figure 3

Figure 3

A: Images depicting results of the subtraction analyses. Top left and right: sagittal (right) and coronal (left) planes indicate activation of the bilateral precuneus when comparing memories retrieved from P5 to memories from P1 (crosshair indicates MNI coordinates: x = −12, y = −64, z = 36). Bottom left and right: transverse (right) and coronal (left) planes show activation of the right superior/middle temporal lobe when comparing memories retrieved from P2 to memories from P3 (crosshair indicates MNI coordinates: x = 48, y = 16, z = −10). Colour scale: voxel Z score values. Cross-hairs indicate MNI coordinates. B: Images depicting results of the small volume correction (SVC) analysis centered on the hippocampus. Coronal planes indicate left hippocampal activation for P1 (−16, −12, −16) and P5 (−14, −10, −16) and bilateral hippocampal activation for P2 (34, −38, −6 and −18, −12, −16), P3 (16, −12, −20 and −18, −18, −18) and P4 (24, −14, −20 and −16, −12, −14). Colour scale: voxel Z score values.

Figure 4

Figure 4

Results of the three-way ANOVA performed on the mean hippocampal values of BOLD activation, within each ROI, according to time-period, laterality and antero-posterior axis. Abbreviations: P1 = 0–17 years; P2 = 18–30 years; P3 = over 31 years old, except for the last 5 years; P4 = last 5 years, except the last 12 months; P5 = last 12 months.

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