Power and distribution of evoked gamma oscillations in brain aging and cognitive performance

Bakhtiari, Aftab; Petersen, J. Zarp; Urdanibia-Centelles, Olalla; Ghazi, Mostafa Mehdipour; Fagerlund, Birgitte; Mortensen, Erik Lykke; Osler, Merete; Lauritzen, Martin; Benedek, Krisztina

doi:10.1007/s11357-023-00749-x

Cited by 6 publications

(5 citation statements)

References 60 publications

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“…Conceivably, slight variations in TES electrode positions, plastic changes in cortical structure, or different subject states could explain some of this variability – which is worth investigating, considering the translational potential of such stimulation techniques (Guerra et al, 2020; Polanía et al, 2018). This potential should be explored with particular emphasis on cognitive function and age, a moderator of endogenous gamma activity and entrainment (Bakhtiari et al, 2023; Murty et al, 2020).…”

Section: Discussionmentioning

confidence: 99%

Visually Evoked 40 Hz Gamma Activity Enhanced by Transcranial Electrical Stimulation

Hainke,

Spitschan,

Priller

et al. 2024

Preprint

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BackgroundNon-invasive Visual Stimulation (VS) and Transcranial Electrical Stimulation (TES) can modulate neuronal oscillations, including gamma activity at 40 Hz, which is relevant for cognition and disrupted in dementia. Combining both techniques may increase effects, but simultaneously recording Electroencephalography (EEG) activity poses several challenges, so this approach is untested.ObjectivesWe predicted that combined TES and VS in the lower gamma band would increase Steady-State Visually Evoked Potential (SSVEP) amplitude during and after stimulation, but only when targeting visual areas and at closely matching stimulation frequencies.MethodsWe administered combined VS and TES and simultaneously measured effects on EEG gamma activity in healthy participants. In experiment 1 (N=25), VS and TES frequencies were closely matched at ∼40 Hz, and TES sites varied between occipito-central, centro-occipital (reversed polarity), and centro-frontal. In experiment 2 (N=25), occipito-central TES was applied at ∼40 Hz, and VS frequency varied between 35, 40, and 45 Hz. Every 5-minute VS+TES trial was preceded and followed by a VS-only baseline trial. Electrical artifacts were removed using adaptive template subtraction.ResultsTES enhanced gamma SSVEP amplitudes most when applied to occipital and central sites, compared to frontal. Enhancement only occurred when TES and VS frequencies closely matched at ∼40 Hz, not when VS was slower (35 Hz) or faster (45 Hz) than TES. The effect was present during, not after, TES.ConclusionMultimodal visual and electrical stimulation evokes stronger oscillatory gamma activity than visual alone. Non-invasive gamma stimulation against cognitive decline in dementia may benefit from this optimised approach.

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Section: Discussionmentioning

confidence: 99%

Visually Evoked 40 Hz Gamma Activity Enhanced by Transcranial Electrical Stimulation

Hainke,

Spitschan,

Priller

et al. 2024

Preprint

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“…The observed lower kw in older participants may be more related to the delayed exchange across the astrocyte end-feet into the tissue due to loss of AQP-4 water channel with older age. However, these hypotheses require further investigation to understand the exact mechanisms, especially under different physiological stages (38, 93). Future studies, particularly with animal models targeting specific BBB components under different physiological or diseased conditions, will be valuable for validating these measurements (6, 22, 94-96).…”

Section: Discussionmentioning

confidence: 99%

“…These data suggest associations between reduced BBB water exchange, compromised glymphatic function and impaired clearance of Aβ (34), potentially due to dysfunctional AQP4 (31, 35). Reduced BBB kw with aging has also been reported in small groups of young and aged persons (36-38), suggesting that the glymphatic system becomes less effective in older adults (39).…”

Section: Introductionmentioning

confidence: 92%

Age-Related Decline in Blood-Brain Barrier Function is More Pronounced in Males than Females in Parietal and Temporal Regions

Shao,

Shou,

Felix

et al. 2024

Preprint

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The blood-brain barrier (BBB) plays a pivotal role in protecting the central nervous system (CNS), shielding it from potential harmful entities. A natural decline of BBB function with aging has been reported in both animal and human studies, which may contribute to cognitive decline and neurodegenerative disorders. Limited data also suggest that being female may be associated with protective effects on BBB function. Here we investigated age and sex-dependent trajectories of perfusion and BBB water exchange rate (kw) across the lifespan in 186 cognitively normal participants spanning the ages of 8 to 92 years old, using a novel non-invasive diffusion prepared pseudo-continuous arterial spin labeling (DP-pCASL) MRI technique. We found that the pattern of BBB kw decline with aging varies across brain regions. Moreover, results from our novel DP-pCASL technique revealed a remarkable decline in BBB kw beginning in the early 60s, which was more pronounced in males. In addition, we observed sex differences in parietotemporal and hippocampal regions. Our findings provide in vivo results demonstrating sex differences in the decline of BBB function with aging, which may serve as a foundation for future investigations into perfusion and BBB function in neurodegenerative and other brain disorders.

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“…Individuals with severe ongoing illnesses including neurodegenerative diseases, severe psychiatric diseases, addictions, or other conditions that rendered participation impossible were excluded, otherwise, the selection was random. Study on the age-related change in cognitive function and Aβ accumulation, cerebral glucose consumption or permeability of the blood-brain barrier in the same subjects has been published elsewhere [23,24]. Studies based on other subsamples of the Metropolit 1953 Danish Male Birth Cohort have examined age-related changes in brain structures [25,26] and electrical activity [27,28].…”

Section: Methodsmentioning

confidence: 99%

The cerebral blood flow response to neuroactivation is reduced in cognitively normal men with β-amyloid accumulation

Vestergaard,

Bakhtiari,

Osler

et al. 2024

Preprint

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Background Accumulation of β-amyloid (Aβ) in the brain is a hallmark of Alzheimer’s Disease (AD). Cerebral deposition of Aβ initiates deteriorating pathways which eventually can lead to AD. However, the exact mechanisms are not known. A possible pathway could be that Aβ affects the cerebral vessels, causing inadequate cerebrovascular function. In the present study, we examined if Aβ accumulation is associated with a reduced cerebral blood flow response (CBF) to neuronal activation by visual stimulation (DCBFVis.Act) in cognitively normal subjects from the Metropolit Danish Male Birth Cohort. Methods 64 subjects participated in the present study. DCBFVis.Act was measured using arterial spin labelling (ASL) combined with blood-oxygen-level-dependent (BOLD) MRI. Neuronal activation was obtained by visual stimulation by a flickering checkerboard presented on a screen in the MRI-scanner. Brain Aβ accumulation and cerebral glucose metabolism were assessed by PET imaging using the radiotracers [11C]Pittsburgh Compound-B (PiB) and [18F]Fluorodeoxyglucose (FDG), respectively. Cortical thickness was measured from structural MRI. Results DCBFVis.Act correlated negatively (\(\beta\) = -32.1 [95% confidence interval (CI): -60.2 ; -4.1], r = -0.30, p = 0.025) with PiB standardized uptake value ratio (SUVr) in the brain regions activated by visual stimulation. DCBFVis.Act did not correlate with FDG SUVr (\(\beta\) = 1.9 [CI: -23.8 ; 27.6], r = 0.02, p = 0.88) or cortical thickness (\(\beta\) = 10.3 [CI: -8.4 ; 29.0], r = 0.15, p = 0.27) in the activated brain regions. Resting CBF did not correlate with PiB SUVr neither in the regions activated by visual stimulation (\(\beta\) = -17.8 [CI:-71.9 ; 36.2], r = 0.09, p = 0.51) nor in the remaining cortex (\(\beta\) = 5.2 [CI:-3.9 ; 14.2], r = 0.15, p = 0.26). Conclusion We found a correlation between high PiB SUVr and reduced CBF response to neuronal activation, indicating a link between Aβ accumulation and impaired cerebrovascular function. The impairment was not associated with cortical thinning or hypometabolism, suggesting that Aβ accumulation affecting brain vessel function could be a very early pathology leading to neurodegenerative disease.

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Power and distribution of evoked gamma oscillations in brain aging and cognitive performance

Cited by 6 publications

References 60 publications

Visually Evoked 40 Hz Gamma Activity Enhanced by Transcranial Electrical Stimulation

Visually Evoked 40 Hz Gamma Activity Enhanced by Transcranial Electrical Stimulation

Age-Related Decline in Blood-Brain Barrier Function is More Pronounced in Males than Females in Parietal and Temporal Regions

The cerebral blood flow response to neuroactivation is reduced in cognitively normal men with β-amyloid accumulation

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