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Brain activation during autobiographical memory retrieval with special reference to default mode network.

Ino T, Nakai R, Azuma T, Kimura T, Fukuyama H - Open Neuroimag J (2011)

Bottom Line: We delineated the overlap between the regions that showed less activation during semantic memory and number counting relative to rest, which correspond to the DMN, and the areas that showed greater or less activation during ABM relative to rest.ABM-specific activation was defined as the overlap between the contrast of ABM versus rest and the contrast of ABM versus semantic memory.ABM-specific activation was observed in the left-lateralized brain regions and most of them fell within the DMN.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Rakuwakai-Otowa Hospital, Otowachinjicho 2, Yamashina-ku, Kyoto 607-8062, Japan.

ABSTRACT
Recent neuroimaging studies have suggested that brain regions activated during retrieval of autobiographical memory (ABM) overlap with the default mode network (DMN), which shows greater activation during rest than cognitively demanding tasks and is considered to be involved in self-referential processing. However, detailed overlap and segregation between ABM and DMN remain unclear. This fMRI study focuses first on revealing components of the DMN which are related to ABM and those which are unrelated to ABM, and second on extracting the neural bases which are specifically devoted to ABM. Brain activities relative to rest during three tasks matched in task difficulty assessed by reaction time were investigated by fMRI; category cued recall from ABM, category cued recall from semantic memory, and number counting task. We delineated the overlap between the regions that showed less activation during semantic memory and number counting relative to rest, which correspond to the DMN, and the areas that showed greater or less activation during ABM relative to rest. ABM-specific activation was defined as the overlap between the contrast of ABM versus rest and the contrast of ABM versus semantic memory. The fMRI results showed that greater activation as well as less activation during ABM relative to rest overlapped considerably with the DMN, indicating that the DMN is segregated to the regions which are functionally related to ABM and the regions which are unrelated to ABM. ABM-specific activation was observed in the left-lateralized brain regions and most of them fell within the DMN.

No MeSH data available.


Regions which showed greater activation during ABM relative to rest, semantic memory and number counting, superimposed on the axial images of the MNI T1 template. SEM = semantic memory; REST = rest. NC = number counting.
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Figure 1: Regions which showed greater activation during ABM relative to rest, semantic memory and number counting, superimposed on the axial images of the MNI T1 template. SEM = semantic memory; REST = rest. NC = number counting.

Mentions: The brain regions which showed greater activation during ABM compared with other condition, namely, rest, semantic memory, and number counting are shown in Fig. (1). The brain regions which showed less activation during ABM, semantic memory, and number counting, relative to rest, are shown in Fig. (2). In order to visualize which parts of greater activation and less activation during ABM relative to rest overlapped with the DMN, they were shown simultaneously with the regions which showed less activation during semantic memory and number counting relative to rest. These maps are shown in Fig. (3), where the overlap between greater activation during ABM (ABM > rest) and less activation during semantic memory (semantic memory < rest) or number counting (number counting < rest) are shown in yellow color, and the overlap between less activation during ABM (ABM < rest) and less activation during semantic memory or number counting are shown in light blue. There was a high level of overlap between greater activation during ABM and less activation during number counting; extensive areas including bilateral posterior cingulate gyrus, left dorsal premotor area, left ventromedial PFC, left hippocampal region, left inferior parietal lobule, left middle temporal gyrus, and left inferior frontal gyrus showed greater activation during ABM and less activation during number counting (Fig. 3, Table 1b). However, there was a relatively little overlap between greater activation during ABM and less activation during semantic memory; bilateral posterior cingulate gyri, left precuneus, left ventrolateral PFC, and left inferior parietal lobule showed greater activation during ABM and less activation during semantic memory (Fig. 3, Table 1a). This is consistent with our prediction that less activation during semantic memory will reveal a limited part of the DMN, since semantic memory is related to a certain level of personal relevance. A sizable portion of the less activation during ABM overlapped with less activation during both semantic memory and number counting; extensive brain regions including bilateral paracentral lobules extending to the anterior part of the precuneus, bilateral inferior parietal lobules, bilateral posterior insula extending to the superior temporal gyri, right premotor area, right ventrolateral PFC, and right frontopolar cortex showed less activation during ABM, semantic memory, and number counting (Fig. 3, Table 2a, b). In particular, a large cluster including precuneus and paracentral lobule with a right side dominance was found in the medial parietal region (8068 voxels for ABM < rest & semantic memory < rest, 8078 voxels for ABM < rest & number counting < rest), and it situated dorsally to the cluster in the medial parietal area which showed the overlap between greater activation during ABM and less activation during semantic memory or number counting (Fig. 3).


Brain activation during autobiographical memory retrieval with special reference to default mode network.

Ino T, Nakai R, Azuma T, Kimura T, Fukuyama H - Open Neuroimag J (2011)

Regions which showed greater activation during ABM relative to rest, semantic memory and number counting, superimposed on the axial images of the MNI T1 template. SEM = semantic memory; REST = rest. NC = number counting.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3106359&req=5

Figure 1: Regions which showed greater activation during ABM relative to rest, semantic memory and number counting, superimposed on the axial images of the MNI T1 template. SEM = semantic memory; REST = rest. NC = number counting.
Mentions: The brain regions which showed greater activation during ABM compared with other condition, namely, rest, semantic memory, and number counting are shown in Fig. (1). The brain regions which showed less activation during ABM, semantic memory, and number counting, relative to rest, are shown in Fig. (2). In order to visualize which parts of greater activation and less activation during ABM relative to rest overlapped with the DMN, they were shown simultaneously with the regions which showed less activation during semantic memory and number counting relative to rest. These maps are shown in Fig. (3), where the overlap between greater activation during ABM (ABM > rest) and less activation during semantic memory (semantic memory < rest) or number counting (number counting < rest) are shown in yellow color, and the overlap between less activation during ABM (ABM < rest) and less activation during semantic memory or number counting are shown in light blue. There was a high level of overlap between greater activation during ABM and less activation during number counting; extensive areas including bilateral posterior cingulate gyrus, left dorsal premotor area, left ventromedial PFC, left hippocampal region, left inferior parietal lobule, left middle temporal gyrus, and left inferior frontal gyrus showed greater activation during ABM and less activation during number counting (Fig. 3, Table 1b). However, there was a relatively little overlap between greater activation during ABM and less activation during semantic memory; bilateral posterior cingulate gyri, left precuneus, left ventrolateral PFC, and left inferior parietal lobule showed greater activation during ABM and less activation during semantic memory (Fig. 3, Table 1a). This is consistent with our prediction that less activation during semantic memory will reveal a limited part of the DMN, since semantic memory is related to a certain level of personal relevance. A sizable portion of the less activation during ABM overlapped with less activation during both semantic memory and number counting; extensive brain regions including bilateral paracentral lobules extending to the anterior part of the precuneus, bilateral inferior parietal lobules, bilateral posterior insula extending to the superior temporal gyri, right premotor area, right ventrolateral PFC, and right frontopolar cortex showed less activation during ABM, semantic memory, and number counting (Fig. 3, Table 2a, b). In particular, a large cluster including precuneus and paracentral lobule with a right side dominance was found in the medial parietal region (8068 voxels for ABM < rest & semantic memory < rest, 8078 voxels for ABM < rest & number counting < rest), and it situated dorsally to the cluster in the medial parietal area which showed the overlap between greater activation during ABM and less activation during semantic memory or number counting (Fig. 3).

Bottom Line: We delineated the overlap between the regions that showed less activation during semantic memory and number counting relative to rest, which correspond to the DMN, and the areas that showed greater or less activation during ABM relative to rest.ABM-specific activation was defined as the overlap between the contrast of ABM versus rest and the contrast of ABM versus semantic memory.ABM-specific activation was observed in the left-lateralized brain regions and most of them fell within the DMN.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurology, Rakuwakai-Otowa Hospital, Otowachinjicho 2, Yamashina-ku, Kyoto 607-8062, Japan.

ABSTRACT
Recent neuroimaging studies have suggested that brain regions activated during retrieval of autobiographical memory (ABM) overlap with the default mode network (DMN), which shows greater activation during rest than cognitively demanding tasks and is considered to be involved in self-referential processing. However, detailed overlap and segregation between ABM and DMN remain unclear. This fMRI study focuses first on revealing components of the DMN which are related to ABM and those which are unrelated to ABM, and second on extracting the neural bases which are specifically devoted to ABM. Brain activities relative to rest during three tasks matched in task difficulty assessed by reaction time were investigated by fMRI; category cued recall from ABM, category cued recall from semantic memory, and number counting task. We delineated the overlap between the regions that showed less activation during semantic memory and number counting relative to rest, which correspond to the DMN, and the areas that showed greater or less activation during ABM relative to rest. ABM-specific activation was defined as the overlap between the contrast of ABM versus rest and the contrast of ABM versus semantic memory. The fMRI results showed that greater activation as well as less activation during ABM relative to rest overlapped considerably with the DMN, indicating that the DMN is segregated to the regions which are functionally related to ABM and the regions which are unrelated to ABM. ABM-specific activation was observed in the left-lateralized brain regions and most of them fell within the DMN.

No MeSH data available.