The Role of the Uncinate Fasciculus in Memory and Emotional Recognition in Amnestic Mild Cognitive Impairment

Fujie, Saori; Namiki, Chihiro; Nishi, Hiroko; Yamada, Makiko; Miyata, Jun; Sakata, Daisuke; Sawamoto, Nobukatsu; Fukuyama, Hidenao; Hayashi, Takuji; Murai, Toshiya

doi:10.1159/000165381

Cited by 94 publications

(102 citation statements)

References 71 publications

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“…32 Previous diffusion tensor imaging studies, investigating one or the other tract in isolation, have shown correlations with episodic memory. 33,34 The present study extends these findings substantially both by demonstrating specificity of association-by comparison with both a control tract and control cognitive domains-and by assessing associations with multiple pathways of temporal interaction simultaneously. This is important because lesion studies in monkeys show that the significance of some connections for memory can be appreciated only when other pathways of interaction with the temporal lobe have been disconnected.…”

supporting

confidence: 62%

Temporal association tracts and the breakdown of episodic memory in mild cognitive impairment

et al. 2012

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Objective: To examine the pattern of association between microstructure of temporal lobe connections and the breakdown of episodic memory that is a core feature of mild cognitive impairment (MCI).Methods: Twenty-five individuals with MCI and 20 matched controls underwent diffusion MRI and cognitive assessment. Three temporal pathways were reconstructed by tractography: fornix, parahippocampal cingulum (PHC), and uncinate fasciculus. Tissue volume fraction-a tract-specific measure of atrophy-and microstructural measures were derived for each tract. To test specificity of associations, a comparison tract (corticospinal tract) and control cognitive domains were also examined.Results: In MCI, tissue volume fraction was reduced in the fornix. Axial and radial diffusivity were increased in uncinate and PHC implying more subtle microstructural change. In controls, tissue volume fraction in the fornix was the predominant correlate of free recall. In contrast, in MCI, the strongest relationship was with left PHC. Microstructure of uncinate and PHC also correlated with recognition memory, and recognition confidence, in MCI.Conclusions: Episodic memory in MCI is related to the structure of multiple temporal association pathways. These associations are not confined to the fornix, as they are in healthy young and older adults. In MCI, because of a compromised fornix, alternative pathways may contribute disproportionally to episodic memory performance. Breakdown of episodic memory is a core feature of mild cognitive impairment (MCI).1 Previous studies of MCI have focused on changes in the medial temporal lobe (MTL). However, the MTL is one node of wider networks for memory that include frontal and parietal lobes.2 The "extended hippocampal system" 3 incorporates the fornix-a large fiber tract composed mostly of connections associated with the hippocampal formation. 4 Alternatively, MTL-cortical interactions can be mediated by parahippocampal tracts including the uncinate fasciculus and the temporal portion of the cingulum bundle (parahippocampal cingulum [PHC]).In healthy older adults, the microstructure of the fornix is an established correlate of episodic memory performance. Fornix microstructure accounts for both age-related and age-independent variations in free recall.5 Recent diffusion MRI studies have found that fornix microstructure is compromised in MCI and Alzheimer disease. 6,7 Early damage might lead to engagement of alternative interactions, 8 so that episodic memory becomes disproportionately associated with microstructure of tracts other than the fornix. To test this hypothesis, diffusion MRI tractography was used to reconstruct the fornix, PHC, and uncinate in MCI and controls. Intrinsic microstructure and subtle atrophy were quantified separately 9,10 dealing with an important confound in MCI and aging.

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confidence: 62%

Temporal association tracts and the breakdown of episodic memory in mild cognitive impairment

et al. 2012

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“…In fact, the UF, which occupies the white matter of the orbital and medial frontal structures and connects the temporal and prefrontal areas, is thought to play a crucial role in the regulation of emotional responses and in attaching emotional valence to visual information [35,36]. Furthermore, Fuji and colleagues [37] found that changes in the UF microstructure of a-MCI subjects were not only associated with memory impairment but also with emotional processing impairment, specifically emotional facial recognition. The ILF, which constitutes the association sys-tem of ventral visual pathways in the occipito-temporal cortices, is involved in emotional processing [35]; its disruption causes agnosia and prosopagnosia [36].…”

Section: Discussionmentioning

confidence: 99%

White Matter Microstructure and Apathy Level in Amnestic Mild Cognitive Impairment

Cacciari

Moraschi

Paola

et al. 2010

JAD

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Abstract. In this study, we assessed white matter microstructural deficit correlates of apathy level in 20 patients with amnestic mild cognitive impairment by means of diffusion tensor imaging. Mean diffusivity correlated positively with apathy level in the right temporal portion of the uncinate, middle longitudinal and inferior longitudinal fasciculi and in the parathalamic white matter, the fornix and the posterior cingulum of the right hemisphere. Fractional anisotropy results confirmed evidence of disconnection associated with apathy in all white matter areas except the middle longitudinal fasciculus. These results support the view that alterations in the neural mechanisms underlying apathy level occur in the early phase of degenerative dementias.

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“…In many studies, MD and FA show a significant association with cognitive functions typically impaired in AD and MCI, including mental status (e.g., [30,31,35,50,59,66,91,93]) suggesting external validity of these measures because of their relationship to cognitive performance and group differences.…”

Section: Discussionmentioning

confidence: 99%

“…Fujie et al [35] found that FA in the uncinate fasciculus, a pathway that connects the frontal and temporal lobes, was significantly reduced in MCI compared to healthy controls and that FA in this fasciculus in MCI was significantly correlated with memory performance. Stricker el al.…”

Section: Investigations Of Targeted Regions Involved In Memory Procesmentioning

confidence: 99%

Diffusion Tensor Imaging in Alzheimer’s Disease and Mild Cognitive Impairment

Stebbins

Murphy

2009

Behavioural Neurology

194

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Abstract. Structural magnetic resonance imaging (MRI) studies of Alzheimer's disease and mild cognitive impairment (MCI) have focused on the hippocampus and entorhinal cortex; gray matter structures in the medial temporal lobe. Few studies have investigated the integrity of white matter in patients with AD or MCI. Diffusion tensor imaging (DTI) is a MRI technique that allows for the interrogation of the microstructural integrity of white matter. Based on increases in translational diffusion (mean diffusivity: MD) and decreases directional diffusion (fractional anisotropy: FA) damage to white matter can be assessed. Studies have identified regions of increased MD and decreased FA in patients with AD and MCI in all lobes of the brain, as well as medial temporal lobe structures including the hippocampus, entorhinal cortex and parahippocampal white matter. The pattern of white matter integrity disruption tends to follow an anterior to posterior gradient with greater damage noted in posterior regions in AD and MCI. Recent studies have exploited inter-voxel directional similarities to develop models of white matter pathways, and have used these models to assess the integrity of inter-cerebral connections. Particular focus has been applied to the parahippocampal white matter (including the perforant path) and the posterior cingulum. Although many studies have found DTI indicators of impaired white matter in AD and MCI, other studies have failed to detect any differences in MD or FA between the groups, demonstrating the need for large replicative studies. DTI is an evolving technique and advances in its application ought to provide new insights into AD and MCI.

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The Role of the Uncinate Fasciculus in Memory and Emotional Recognition in Amnestic Mild Cognitive Impairment

Cited by 94 publications

References 71 publications

Temporal association tracts and the breakdown of episodic memory in mild cognitive impairment

Temporal association tracts and the breakdown of episodic memory in mild cognitive impairment

White Matter Microstructure and Apathy Level in Amnestic Mild Cognitive Impairment

Diffusion Tensor Imaging in Alzheimer’s Disease and Mild Cognitive Impairment

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