Objective: To test whether high-density electroencephalography (hdEEG) coupled to source localization allows for the identification of neuronal oscillations in specific frequency bands in patients with Huntington’s disease, pre-symptomatic (pre-HD) and early symptomatic (early-HD), and in a control group, during a working memory (WM) task.

Background: In a recent study(1) we demonstrated specific spectral signatures associated with updating of memory information, working memory maintenance and readout, with relatively high spatial resolution by means of hdEEG. WM is the ability to keep in mind information and retrieve them after a short period of time, and is one of the first cognitive functions to decline already in early-HD and also in pre-HD(2).

Method: We used an n-back WM task (with n = 2, 3), and patients had to respond with a button press when the currently presented letter (stimulus) corresponded to the letter presented n trials earlier (probe). We examined modulation of neural oscillations during the task by event-related desynchronization and synchronization (ERD/ERS) of θ, β, gamma low, γ_LOW and γ_HIGH EEG bands in a-priori selected large fronto-parietal network, including the insula and the cerebellum.

Results: We found: (i) Reduced θ oscillations in HD with respect to controls in almost all the areas of the WM network during the update and readout phases; (ii) Reduced β oscillations in HD with respect to controls in DLPFC-L and InsCl-L; (iii) For γ_HIGH oscillations, HD showed decreased oscillation compared to controls during maintenance in the PFC-R in both 2-back and 3-back tasks and decreased γ_HIGH oscillation in PM L and PPC L during the 3-back task, in the maintenance phase. Finally, in HD patients, brain oscillations during WM task correlated with CAG repeat length.

Conclusion: Our data show reduced phase-specific modulation of oscillations in pre-manifest and very early manifest HD, even in the presence of preserved dynamic of modulation. Correlations between phase-specific modulations of neural oscillations and CAG repeat lengths suggest that decreased EEG oscillations are linked to HD pathology.

References: 1. Semprini M, Bonassi G, Barban F, Pelosin E, Iandolo R, Chiappalone M, et al. Modulation of neural oscillations during working memory update, maintenance, and readout: An hdEEG study . Hum Brain Mapp. 2020; 2. Lawrence AD, Hodges JR, Rosser AE, Kershaw A, Ffrench-Constant C, Rubinsztein DC, et al. Evidence for specific cognitive deficits in preclinical Huntington’s disease. Brain. 1998;121(7):1329–41.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/neural-oscillations-modulation-during-working-memory-in-premanifest-and-early-huntingtons-disease/