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Marion Houot

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YNICL Journal 2026 Journal Article

Multimodal neural correlates of cognitive awareness in aging and Alzheimer’s disease

  • Federica Cacciamani
  • Marion Houot
  • Sophie Tezenas du Montcel
  • Elina Thibeau-Sutre
  • Patrizia Vannini
  • Raffaella Lara Migliaccio

Impaired cognitive awareness-anosognosia-is a core symptom of Alzheimer's disease (AD), yet its neural correlates remain poorly defined. This study examined how cognitive awareness, measured both cross-sectionally and longitudinally via subject-informant discrepancy on the Everyday Cognition (ECog) questionnaire, relates to three AD biomarkers: amyloid burden, glucose hypometabolism, and cortical atrophy. We included 785 participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI), spanning cognitively normal (CN), mild cognitive impairment (MCI), and AD dementia. All biomarkers were assessed at baseline across the same 86 cortical regions, enabling anatomically harmonized, cross-modality comparisons. Linear mixed models incorporating all three biomarkers revealed no significant associations in CN. In MCI, declining awareness was associated with widespread cortical amyloid deposition (significant in 80/86 regions), sparing some limbic areas. Atrophy in 11 regions-including limbic, lateral temporal, and occipital cortices-also predicted awareness decline (all p < 0.044). In AD, no significant associations were found between amyloid and awareness, suggesting a plateau effect at advanced stages. In both MCI and AD, lower baseline glucose metabolism in the left posterior cingulate cortex (PCC) was associated with poorer awareness (MCI: β ± SE = - 0.14 ± 0.04, p = 0.006; AD: β ± SE = - 0.24 ± 0.07, p = 0.042). No significant biomarker-time interactions were found in AD, suggesting relatively stable awareness levels at advanced disease stages. These findings indicate that anosognosia in AD is linked to distinct biomarker and regional profiles that vary by disease phase. Multimodal analysis across harmonized regions reveals the left PCC as a robust metabolic correlate of awareness, underscoring its potential as a key target in understanding and monitoring self-awareness impairment in neurodegenerative disease.

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YNIMG Journal 2022 Journal Article

Long-term deep intracerebral microelectrode recordings in patients with drug-resistant epilepsy: Proposed guidelines based on 10-year experience

  • Katia Lehongre
  • Virginie Lambrecq
  • Stephen Whitmarsh
  • Valerio Frazzini
  • Louis Cousyn
  • Daniel Soleil
  • Sara Fernandez-Vidal
  • Bertrand Mathon

PURPOSE: Human neuronal activity, recorded in vivo from microelectrodes, may offer valuable insights into physiological mechanisms underlying human cognition and pathophysiological mechanisms of brain diseases, in particular epilepsy. Continuous and long-term recordings are necessary to monitor non predictable pathological and physiological activities like seizures or sleep. Because of their high impedance, microelectrodes are more sensitive to noise than macroelectrodes. Low noise levels are crucial to detect action potentials from background noise, and to further isolate single neuron activities. Therefore, long-term recordings of multi-unit activity remains a challenge. We shared here our experience with microelectrode recordings and our efforts to reduce noise levels in order to improve signal quality. We also provided detailed technical guidelines for the connection, recording, imaging and signal analysis of microelectrode recordings. RESULTS: During the last 10 years, we implanted 122 bundles of Behnke-Fried hybrid macro-microelectrodes, in 56 patients with pharmacoresistant focal epilepsy. Microbundles were implanted in the temporal lobe (74%), as well as frontal (15%), parietal (6%) and occipital (5%) lobes. Low noise levels depended on our technical setup. The noise reduction was mainly obtained after electrical insulation of the patient's recording room and the use of a reinforced microelectrode model, reaching median root mean square values of 5.8 µV. Seventy percent of the bundles could record multi-units activities (MUA), on around 3 out of 8 wires per bundle and for an average of 12 days. Seizures were recorded by microelectrodes in 91% of patients, when recorded continuously, and MUA were recorded during seizures for 75 % of the patients after the insulation of the room. Technical guidelines are proposed for (i) electrode tails manipulation and protection during surgical bandage and connection to both clinical and research amplifiers, (ii) electrical insulation of the patient's recording room and shielding, (iii) data acquisition and storage, and (iv) single-units activities analysis. CONCLUSIONS: We progressively improved our recording setup and are now able to record (i) microelectrode signals with low noise level up to 3 weeks duration, and (ii) MUA from an increased number of wires . We built a step by step procedure from electrode trajectory planning to recordings. All these delicate steps are essential for continuous long-term recording of units in order to advance in our understanding of both the pathophysiology of ictogenesis and the neuronal coding of cognitive and physiological functions.

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