Visuospatial alpha and gamma oscillations scale with the severity of cognitive dysfunction in patients on the Alzheimer’s disease spectrum

Abstract

Background Entrainment of neural oscillations in occipital cortices by external rhythmic visual stimuli has been proposed as a novel therapy for patients with Alzheimer’s disease (AD). Despite this increased interest in visual neural oscillations in AD, little is known regarding their role in AD-related cognitive impairment and in particular during visuospatial processing. Methods We used source-imaged magnetoencephalography (MEG) and an established visuospatial processing task to elicit multi-spectral neuronal responses in 35 biomarker-confirmed patients on the AD spectrum and 20 biomarker-negative older adults. Neuronal oscillatory responses were imaged to the level of the cortex, and group classifications and neurocognitive relationships were modeled using logistic and linear regression, respectively. Results Visuospatial neuronal oscillations in the theta, alpha, and gamma ranges significantly predicted the classification of patients on the AD spectrum. Importantly, the direction of these effects differed by response frequency, such that patients on the AD spectrum exhibited weaker alpha-frequency responses in lateral occipital regions, and stronger gamma-frequency responses in the primary visual cortex, as compared to biomarker-negative older adults. In addition, alpha and gamma, but not theta, oscillations robustly predicted cognitive status (i.e., MoCA and MMSE scores), such that patients with neural responses that deviated more from those of healthy older adults exhibited poorer cognitive performance. Conclusions We find that the multi-spectral neural dynamics supporting visuospatial processing differentiate patients on the AD spectrum from cognitively normal, biomarker-negative older adults. Oscillations in the alpha and gamma bands also relate to cognitive status in ways that are informative for emerging clinical interventions.

Oscillatory markers of neuroHIV-related cognitive impairment and Alzheimer’s disease during attentional interference processing

“…One prior MEG study reported aberrant theta and stronger baseline alpha activity in the prefrontal cortices of participants with HAND, which distinguished cognitively impaired from unimpaired PWH and controls [ 29 ]. Other studies of attention processing in patients on the AD spectrum revealed decreased theta [ 39 , 40 ] and alpha [ 30 , 31 ] responses during attention and visuospatial processing. Thus, while the current findings are novel, the overlap in aberrant attention-related oscillatory activity in each frequency band across frontoparietal hubs in the ADS and HAND groups relative to controls is not entirely surprising.…”

“…Beyond the general differences between patients and controls, we found disease-specific theta alterations in several brain regions including the prefrontal, parietal, occipital, and temporal cortices. Theta aberrations have been highlighted in previous studies as markers of cognitive impairment separately in AD and HAND [ 27 , 29 , 40 , 44 , 45 ]. These disease-specific differences in theta oscillatory activity may suggest more fine-scale neurophysiological differences in temporal segmentation and higher order allocation of attentional resources, which could be secondary to regional amyloid accumulation in those on the ADS relative to HAND, as multiple studies have shown normal amyloid levels in patients with HAND [ 6 , 8 ].…”

“…Thus, investigating the neural dynamics underlying other cognitive domains may be of particular interest as a future direction. Alpha and theta activity are also known to support working memory, motor processing, and emotion regulation [70][71][72][73][74], which are cognitive functions known to be aberrant in both AD and HAND independently [27,29,40,44].…”

Epigenetic aging is associated with aberrant neural oscillatory dynamics serving visuospatial processing in people with HIV

“…MEG and MRI data processing closely followed previously reported pipelines [11,12,64,65]. The structural MRI data were aligned parallel to the anterior and posterior commissures and transformed into standardized space.…”

40 Hz Blue LED Relieves the Gamma Oscillations Changes Caused by Traumatic Brain Injury in Rat

“…Gamma oscillations were first discovered by Adrian (4) who reported that the oscillations were induced by odorous substances. Since, studies have demonstrated that they could be induced by other stimuli and be presented in various structures in the human brain, with different functional connections, such as learning, sensory, consciousness, and motor functions (5)(6)(7)(8).…”