A structural and resting‐state functional connectivity investigation of the pulvinar in elderly individuals and Alzheimer's disease patients

Abstract

In Alzheimer's disease (AD), structural and functional changes in the brain may give rise to disruption of specific cognitive functions. The aim of this study is to investigate the functional connectivity alterations in the pulvinar's subdivisions and total pulvinar voxel-based morphometry (VBM) changes in individuals with AD and healthy controls.A seed-based functional connectivity analysis was applied to the anterior, inferior, lateral, and medial pulvinar in each hemisphere. Furthermore, VBM analysis was carried out to compare gray matter (GM) volume differences in the pulvinar and thalamus between the two groups. Connectivity analysis revealed that the pulvinar subdivisions had decreased connectivity in individuals with AD. In addition, the pulvinar and thalamus in each hemisphere were significantly smaller in the AD group. The pulvinar may have a role in AD-related cognitive impairments and the intrinsic connectivity network changes and GM loss in pulvinar subdivisions suggest the cognitive deterioration occurring in those with AD.

The functional role of the pulvinar in discriminating between objective and subjective cognitive impairment in major depressive disorder

“…Furthermore, previous cognition studies of depressive patients have primarily focused on alterations in the hippocampus, amygdala, and cingulate gyrus, without considering functional alterations in other critical subcortical structures, such as the thalamus, and especially the pulvinar 14 . Such alterations may indicate a critical dynamic phase associated with subtle pathophysiological changes occurring before the manifestation of structural changes 15–17 . From that perspective, functional connectivity analysis is a valuable method for examining voxel‐wise functional magnetic resonance imaging (MRI) signals and that identifies functionally related brain areas and distributed networks.…”

“… 14 Such alterations may indicate a critical dynamic phase associated with subtle pathophysiological changes occurring before the manifestation of structural changes. 15 , 16 , 17 From that perspective, functional connectivity analysis is a valuable method for examining voxel‐wise functional magnetic resonance imaging (MRI) signals and that identifies functionally related brain areas and distributed networks. This therefore justifies an investigation of the differences between amnestic and other depressed individuals.…”

“…In the second step, the members of the depressive group were classified as “amnestic” or “nonamnestic” based on their subjective forgetfulness in order to investigate whether these groups’ objective neuroimaging and neuropsychometric findings would differ. Based on previous studies indicating the role of the pulvinar and hippocampus in degenerative cognitive disorders, 40 we explored the structural and functional features of both regions in depressive disorder with and without objective cognitive impairment.…”

Infection with COVID‐19 is no longer a public emergency: But what about degenerative dementia?

“…Here it is worth remembering that multiple studies conducted on neurodegenerative diseases have indicated that the presence of a compensatory hyperconnectivity network pattern is an early stage of dementia that precedes observable structural changes. 16,17,38 This suggests that the hyperconnectivity phase may serve as a compensatory response to the neurodegenerative process, occurring before the emergence of visible morphological evidence. Regrettably, this hyperconnectivity stage is ireversible, rendering any neuroprotective interventions implemented at a later stage potentially not sufficient.…”

“…Hence our finding of specific hippocampal functional changes without any structural evidence is unique in indicating a prestructural hippocampal compensatory phase in response to COVID. Here it is worth remembering that multiple studies conducted on neurodegenerative diseases have indicated that the presence of a compensatory hyperconnectivity network pattern is an early stage of dementia that precedes observable structural changes 16,17,38 . This suggests that the hyperconnectivity phase may serve as a compensatory response to the neurodegenerative process, occurring before the emergence of visible morphological evidence.…”