Healthy aging attenuates task-related specialization in the human medial temporal lobe

Ramsøy, Thomas Z.; Liptrot, Matthew G.; Skimminge, Arnold; Lund, Torben Ellegaard; Sidaros, Karam; Christensen, Mark Schram; Baaré, William F.C.; Paulson, Olaf B.; Jernigan, Terry L.; Siebner, Hartwig R.

doi:10.1016/j.neurobiolaging.2011.09.032

Cited by 22 publications

(13 citation statements)

References 94 publications

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“…There was a significant difference in age between groups, and it is possible that control subjects were more sensitive to cTBS stimulation over PMd than PD patients. Elderly subjects might have higher cerebral activation to compensate for agerelated decline in functionality (Ramsøy et al, 2011). However, it is unclear how the age difference alone could account for the double dissociation between behavioral consequences of cTBS on EBA and PMd across groups.…”

Section: Interpretational Issuesmentioning

confidence: 99%

Compensatory Activity in the Extrastriate Body Area of Parkinson's Disease Patients

Nuenen

Helmich²,

Buenen³

et al. 2012

Journal of Neuroscience

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Compensatory mechanisms are a crucial component of the cerebral changes triggered by neurodegenerative disorders. Identifying such compensatory mechanisms requires at least two complementary approaches: localizing candidate areas using functional imaging, and showing that interference with these areas has behavioral consequences. Building on recent imaging evidence, we use this approach to test whether a visual region in the human occipito-temporal cortex-the extrastriate body area-compensates for altered dorsal premotor activity in Parkinson's disease (PD) during motor-related processes. We separately inhibited the extrastriate body area and dorsal premotor cortex in 11 PD patients and 12 healthy subjects, using continuous theta burst stimulation. Our goal was to test whether these areas are involved in motor compensatory processes. We used motor imagery to isolate a fundamental element of motor planning, namely subjects' ability to incorporate the current state of their body into a motor plan (mental hand rotation). We quantified this ability through a posture congruency effect (i.e., the improvement in subjects' performance when their current body posture is congruent to the imagined movement). Following inhibition of the right extrastriate body area, the posture congruency effect was lost in PD patients, but not in healthy subjects. In contrast, inhibition of the left dorsal premotor cortex reduced the posture congruency effect in healthy subjects, but not in PD patients. These findings suggest that the right extrastriate body area plays a compensatory role in PD by supporting a function that is no longer performed by the dorsal premotor cortex.

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Section: Interpretational Issuesmentioning

confidence: 99%

Compensatory Activity in the Extrastriate Body Area of Parkinson's Disease Patients

Nuenen

Helmich²,

Buenen³

et al. 2012

Journal of Neuroscience

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“…It was reported that aging reduces cerebral blood flow in association cortices during rest, yet the influence of age on functional brain activation is controversial [20][21][22][23][24][25][26]. Aging differs among individuals, and the areas affected by aging may differ depending on the task [23,27,28].…”

Section: Discussionmentioning

confidence: 99%

Brain Activity during Stereognostic Discrimination Using the Tongue Measured By Functional Near-Infrared Spectroscopy

Kawagishi

Tanaka²,

Yoshino³

et al. 2014

Aging Sci

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We previously reported our investigation of the stereognostic ability of the tongue to recognize the shape and size of materials in the mouth and its clinical applications. In the present study, we observed brain activity while performing stereognostic discrimination using the tongue; the changes in levels of oxyhemoglobin (oxy-Hb), deoxyhemoglobin (deoxy-Hb), and total hemoglobin (total-Hb) in the frontal cortex area of 37 healthy individuals (18-75 years old) were measured using a functional near-infrared spectrometer with 45 channels. As an experimental task, the stereognostic test piece (TP) was placed on the center of the tongue dorsum, and subjects moved the TP for shape discrimination without letting it touch the teeth or gums. As a control task, subjects did not move the TP placed on the tongue. Stereognostic task-attributed changes in Hb levels were obtained by subtracting the Hb level of the control task from that of the experimental task. During the stereognostic task, oxy-Hb levels increased in the frontal cortex, including the prefrontal area, in most subjects. However, the results also demonstrated large individual variability. When the degree of change in Hb levels during the stereognostic task was mapped, it was found that the changes in the oxy-and total-Hb levels were similar, while the deoxy-Hb level did not change to the same degree. When subjects were divided into three groups, highly-, moderately-and mildlyincreased oxy-Hb levels, there was a significant negative correlation between age and degree of oxy-Hb level increase. The present study suggests stereognosis may be involved in several different information processing pathways, and that aging may also be a factor in the large variability we observed.

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“…Even when a cognitive task is regressed out and only the residuals are considered, "state" effects may remain. Here, we only considered task-based functional connectivity but have the following caveat: all of our datasets involved encoding of objects or scenes, which we know can be negatively influenced by age (90,91,97). Unfortunately, we do not have access to highresolution data collected during a non-mnemonic task, but advocate replicating this approach in the future to explore the A-P differentiation of the hippocampus and its subfields.…”

Section: Concerns and Limitationsmentioning

confidence: 99%

Age-related alterations in functional connectivity along the longitudinal axis of the hippocampus and its subfields

Stark

Frithsen

Stark

2019

Preprint

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Aging causes hippocampal circuit alterations that differentially affect hippocampal subfields and are associated with age-related memory decline. Additionally, functional organization along the longitudinal axis of the hippocampus has revealed distinctions between anterior and posterior (A-P) connectivity. Here, we examined the functional connectivity (FC) differences between young and older adults at high-resolution within the medial temporal lobe network (entorhinal, perirhinal, and parahippocampal cortices), allowing us to explore how hippocampal subfield connectivity across the longitudinal axis of the hippocampus changes with age. Overall, we found reliably greater connectivity for younger adults than older adults between the hippocampus and PHC and PRC. This drop in functional connectivity was more pronounced in the anterior regions of the hippocampus than the posterior ones, consistent for each of the hippocampal subfields. Further, intra-hippocampal connectivity also reflected an age-related decrease in functional connectivity within the anterior hippocampus in older adults that was offset by an increase in posterior hippocampal functional connectivity. Interestingly, the anteriorposterior shift in older adults between hippocampus and PHC was predictive of lure discrimination performance on the MST, suggesting that this shift may reflect a compensation mechanism that preserves memory performance. While age-related dysfunction within the hippocampal subfields has been well-documented, these results suggest that the age-related A-P shift in hippocampal connectivity may also contribute significantly to memory decline in older adults.

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Healthy aging attenuates task-related specialization in the human medial temporal lobe

Cited by 22 publications

References 94 publications

Compensatory Activity in the Extrastriate Body Area of Parkinson's Disease Patients

Compensatory Activity in the Extrastriate Body Area of Parkinson's Disease Patients

Brain Activity during Stereognostic Discrimination Using the Tongue Measured By Functional Near-Infrared Spectroscopy

Age-related alterations in functional connectivity along the longitudinal axis of the hippocampus and its subfields

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