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Decline of unidirectional alpha connections in the aging brain

Authors:
  • Research Centre for Natural Sciences
S406 Abstracts / IBRO Reports 6 (2019) S346–S562
matrices had a few backbone structures which describe the domi-
nant modes of their specific property.
https://doi.org/10.1016/j.ibror.2019.07.1292
P27.08
Decline of unidirectional alpha connections in
the aging brain
Bálint File1,, Brigitta Tóth2, Zsófia Kardos2,
Roland Boha2, István Ulbert1, Zoltán
Somogyvári3, Márk Molnár2
1Pázmány Péter Catholic University, Budapest,
Hungary
2Institute of Cognitive Neuroscience and Psychology,
RCNS, HAS, Budapest, Hungary
3Wigner Research Centre for Physics, HAS, Budapest,
Hungary
Neural interactions between brain regions were modeled by
the strength and direction of the information propagation. A com-
mon consequence of these models was to characterize aging as the
functional disconnection of distant brain regions. However, pre-
vious methods to characterize information propagation based on
EEG signals limited the understanding of the neural interactions
by assuming predominantly unidirectional connections and negli-
gible circular causality. In the current study, we applied Sugihara
causality on resting-state EEG data to demonstrate the changes
of the unidirectional causal interactions alongside with the circu-
lar connections in the aging brain. Eyes closed resting-state EEG
was recorded in young (N= 22; mean age = 22.4 ±3.1) and elderly
(N= 19; mean age= 66.3 ±3.9) healthy subjects. Causality was esti-
mated between the reconstructed cortical signals in theta (4–8 Hz),
alpha1 (8–10 Hz), alpha2 (10–13 Hz) andbeta (13–30 Hz) frequency
bands. Balance of the unidirectional and circular connections, and
distance-dependence of the causality were compared between the
two age groups. The circularity of the connections was increased
(along with the decrease of unidirectionality) in the elderly in
alpha2 band. Causality was decreased by distance, and this effect
was stronger in the elderly compared to the young in alpha1 and
alpha2 bands. These findings suggest that frequency specific dimin-
ish of long-distance connections are accompanied by the loss of
hierarchical connections in advanced age.
https://doi.org/10.1016/j.ibror.2019.07.1293
P27.09
Neural control of high nutrient induced
morning activity peak delay in Drosophila
Sang Hyuk Lee, Eunjoo Cho, Eun Young Kim
Ajou University, Suwon, Republic of Korea
Organisms manifest 24 h rhythms in nutrient metabolism i.e.
feeding behavior, metabolites, metabolic hormones etc., thereby
maintains the energy homeostasis. Growing body of evidence
also indicates that the metabolic feedbacks to circadian clock
but how it is integrated in brain is not evident. High sucrose
diet (HSD) delayed the morning activity peak gradually but not
the evening activity peak of Drosophila melanogaster. This HSD
induced morning activity peak delay was observed in high fat
diet condition, other genotypes of control flies, and both sexes. In
search for underlying component, we screened 59 neuropeptide
RNAi lines crossed with elav-Gal4 driver. Knockdown of neu-
ropeptide X abolished the HSD effect. Furthermore, knockdown of
neuropeptide X receptor greatly reduced the HSD effect, indicating
that neuropeptide X signaling mediates the morning activity peak
delay in HSD. GFP Reconstitution Across Synaptic Partners (GRASP)
analysis demonstrated that neuropeptide X expressing neurons are
connected to dorsal neurons 1s (DN1s), which control locomotor
activity peaks of Drosophila. Taken together, high nutrient status
sets the morning activity peak phase via neuropeptide X mediated
modulation of DN1 output circuit in drosophila.
https://doi.org/10.1016/j.ibror.2019.07.1294
P27.10
Universality in the transition to lissencephaly
for cortical morphology across length scales for
individual human cortices
Bruno Mota1,, Yujiang Wang2
1UFRJ, Rio de Janeiro, Brazil
2Newcastle University, Newcastle, UK
We have created a mathematical and computational procedure
of coarse-graining a cortical surface in a way that preserves its
topological integrity and non-self-intersecting nature. Each itera-
tion of this procedure can thus be analysed using exactly the same
methods we have previously applied to the entire cortex. We show
how the scaling of the gyrification index is related to the fractal
dimension of the cortex. This allows us to identify not only the
scales in which the cortex is fractal, but also the so-called cut-
offs, the scales at which it ceases to be fractal and becomes either
smooth (for scales much smaller than the smallest gyri and sulci),
or lissencephalic (for scales larger than the largest structures). This
method probes cortical morphology in a way that neither reduces
each cortex to a set of numbers (such as total area or average thick-
ness), or to a detailed description of each sulci or gyri. Rather, it
quantifies cortical morphology across different scales, which can
then be used to characterize cortices of different species, and across
development and aging, and across health and disease. We have
previously demonstrated that folding in mammalian cerebral cor-
tices follows a universal scaling law that can be derived from a
simple physics model (Mota and Herculano-Houzel, 2015). The
same law also applies across healthy humans (Wang et al., 2016),
and separately for different cortical lobes and regions in individual
cortices (Wang et al., 2019). With this method we can investigate
if this universality is also present across different scales, and verify
in a precise sense if a human cortex, over surface coarse-graining
(i.e., ‘lowering resolution’), recapitulates the shapes of the cortices
of less-gyrified mammals.
References
Mota, B., Herculano-Houzel, S., 2015. Science 349 (6243), 74.
Wang, Y., Necus, J., Kaiser, M., Mota, B., 2016. PNAS 113 (45).
Wang, Y., Necus, J., Rodriguez, L.R., Taylor, P.N., Mota, B., 2019. Commun. Biol. (in
press).
https://doi.org/10.1016/j.ibror.2019.07.1295
ResearchGate has not been able to resolve any citations for this publication.
  • Y Wang
  • J Necus
  • L R Rodriguez
  • P N Taylor
  • B Mota
Wang, Y., Necus, J., Rodriguez, L.R., Taylor, P.N., Mota, B., 2019. Commun. Biol. (in press).