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UID:20250430T201233EDT-5682Nv08ZK@132.216.98.100
DTSTAMP:20250501T001233Z
DESCRIPTION:\nRegister here\n\nPizza and soft drinks will be provided after
  the seminar\, courtesy of the BIC director (strictly for attendees of the
  seminar).\n\n\nJonathan Gallego Rudolf\n\nA collaboration between the Bai
 llet Lab and the Villeneuve Lab\n\nSynergistic association of Aβ and tau p
 athology with cortical neurophysiology and cognitive decline in asymptomat
 ic older adults\n\nAnimal and computational models of Alzheimer’s disease 
 (AD) indicate that early amyloid-β (Aβ) deposits drive neurons into a hype
 ractive regime\, and that subsequent tau depositions manifest an opposite\
 , suppressive effect as behavioral deficits emerge. Here we report analogo
 us changes in macroscopic oscillatory neurophysiology in the human brain. 
 We used positron emission tomography and task-free magnetoencephalography 
 to test the effects of Aβ and tau deposition on cortical neurophysiology i
 n 104 cognitively unimpaired older adults with a family history of sporadi
 c AD. In these asymptomatic individuals\, we found that Aβ depositions col
 ocalize with accelerated neurophysiological activity. In those also presen
 ting medial–temporal tau pathology\, linear mixed effects of Aβ and tau de
 positions indicate a shift toward slower neurophysiological activity\, whi
 ch was also linked to cognitive decline. We conclude that early Aβ and tau
  depositions relate synergistically to human cortical neurophysiology and 
 subsequent cognitive decline. Our findings provide insight into the multif
 aceted neurophysiological mechanisms engaged in the preclinical phase of A
 D.\n\n\nJonah Kember\n\nChai Lab\n\nDevelopmental changes in diffusion mar
 kers of neurite across the hippocampus\n\nThe hippocampus is a critical st
 ructure supporting the encoding and retrieval of episodic memories\, yet t
 he intricate development of its microstructure in humans remains unknown. 
 Understanding this microstructural maturation may provide critical insight
  into the basic mechanisms underlying memory and their disruption in disea
 se. To address this gap\, we non-invasively estimated the density and bran
 ching complexity of neurites (dendrites\, axons\, glial processes) using d
 iffusion-weighted MRI in 364 participants aged 8–21. With development\, we
  observed large increases in neurite density and branching complexity that
  persisted until late adolescence. Increases in neurite density were relat
 ively homogenous across hippocampal subfields and the longitudinal axis. I
 ncreases in branching complexity were heterogeneous\, increasing primarily
  in CA1\, SRLM\, Subiculum\, and increasing along a gradient from posterio
 r to anterior hippocampus. To contextualize these findings\, we sought to 
 understand the cellular composition of hippocampal tissue which exhibited 
 these developmental changes in neurite. To do so\, we constructed an atlas
  of 34 hippocampal cell-types by integrating previously processed data fro
 m single-nuclei RNA sequencing of the human hippocampus with the Allen Hum
 an Brain atlas. Then\, we identified 6 spatial components (mixtures of cel
 l-types which vary across the hippocampus) in this atlas\, and spatially c
 orrelated these components with age-related changes in neurite. We found t
 hat age-related changes in neurite density spatially overlapped with a gra
 nule cell component\, whereas age-related changes in neurite branching com
 plexity overlapped with a pyramidal neuron component. These results provid
 e the first glimpse at the nonlinear maturation of hippocampal microstruct
 ure in humans and describe the cell-type composition of hippocampal tissue
  which exhibits these changes.\n
DTSTART:20241111T163000Z
DTEND:20241111T173000Z
LOCATION:de Grandpre Communications Centre\, Montreal Neurological Institut
 e\, CA\, QC\, Montreal\, H3A 2B4\, 3801 rue University
SUMMARY:The BIC Postdocs and Students' Seminar
URL:/neuro/channels/event/bic-postdocs-and-students-se
 minar-360880
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