Duche, Q. | Search bioRxiv

bioRxiv2024

Introducing Haptic Feedback in Real-Time fMRI Neurofeedback: A Novel Approach to Modulate Primary Motor Cortex Activity

As fMRI-Neurofeedback (fMRI-NF) is still in its early stages, many questions remain regarding the optimal methodology, particularly in relation to feedback modalities. One of the core components of neurofeedback is the feedback itself, which the participant relies on to regulate, learn, and refine their mental strategies. However, most fMRI-NF protocols to date have primarily used visual feedback, which may not be ideal in all cases. Certain individuals or populations might benefit from alternative or additional feedback modalities, such as haptic feedback --a novel approach in this field-- along with auditory, virtual reality/immersive environments, or a combination of these. In this study, we assess the performance of neurofeedback elicited by a motor imagery (MI) task using visuo-haptic feedback and compare it to unisensory visual and haptic feedback. Our results suggest that combining visual and haptic feedback in neurofeedback may be more engaging than conventional visual feedback alone, particularly in neurorehabilitation, by more effectively activating the primary motor cortex--a region considered a key target for promoting motor recovery.

bioengineering↗

bioRxiv2020

Building memories on prior knowledge: behavioral and fMRI evidence of impairment in early Alzheimer's Disease

Impaired memory is a hallmark of prodromal Alzheimers Disease (AD). Prior knowledge associated with the memoranda has proved to have a powerful effect on memory in healthy subjects. Yet, barely nothing is known about its effect in early AD. We used functional MRI to ask whether prior knowledge enhanced memory encoding in early AD and whether the nature of prior knowledge mattered. Early AD patients and healthy controls underwent a task-based fMRI experiment, being scanned while learning face-scene associations. Famous faces carried Pre-Experimental Knowledge (PEK) while unknown faces repeatedly familiarized prior to learning carried Experimental Knowledge (EK). As expected, PEK increased subsequent memory in healthy elderly. However, patients did not benefit from PEK. Partly non-overlapping brain networks supported PEK vs. EK encoding in healthy controls. Patients displayed impaired activation in a right subhippocampal region where activity predicted successful associative memory formation of PEK stimuli. These findings call for a thorough consideration of how prior knowledge impacts learning and suggest a possible underestimation of the extent of associative memory impairment in early AD. HighlightsO_LILearning is impaired in prodromal AD, but we currently ignore whether prior knowledge available at encoding promotes learning in AD as it does in healthy controls. C_LIO_LIPatients with AD failed to benefit from pre-experimental prior knowledge (famous faces) by comparison with experimental knowledge (unknown but familiarized faces). C_LIO_LIfMRI responses at study revealed distinct networks underlying associative encoding for both pre-experimental and experimental knowledge. C_LIO_LIA subsequent memory effect found in control subjects for associations carrying pre-experimental knowledge in the right subhippocampal structures, including the perirhinal cortex, was absent in patients. C_LIO_LIPre-experimental knowledge-based associative encoding relies on brain regions specifically targeted by early tau pathology. C_LIO_LIUsing unfamiliar materials to probe memory in early AD might underestimate learning impairment. C_LI

neuroscience↗