bioRxiv (Cold Spring Harbor Laboratory),
Journal Year:
2024,
Volume and Issue:
unknown
Published: Feb. 21, 2024
Abstract
Working
memory
(WM)
is
constructive
in
nature.
Instead
of
passively
retaining
information,
WM
reorganizes
complex
sequences
into
hierarchically
embedded
chunks
to
overcome
capacity
limits
and
facilitate
flexible
behavior.
To
investigate
the
neural
mechanisms
underlying
hierarchical
reorganization
WM,
we
performed
two
electroencephalography
(EEG)
one
magnetoencephalography
(MEG)
experiments,
wherein
humans
retain
a
temporal
sequence
items,
i.e.,
syllables,
which
are
organized
chunks,
multisyllabic
words.
We
demonstrate
that
1-D
represented
by
2-D
representational
geometry
arising
from
parietal-frontal
regions,
with
separate
dimensions
encoding
item
position
within
chunk
sequence.
Critically,
this
observed
consistently
different
experimental
settings,
even
during
tasks
discouraging
correlates
Overall,
these
findings
strongly
support
reorganized
factorized
multi-dimensional
also
speaks
general
structure-based
organizational
principles
given
WM’s
involvement
many
cognitive
functions.
Current Opinion in Neurobiology,
Journal Year:
2021,
Volume and Issue:
70, P. 137 - 144
Published: Oct. 1, 2021
Advances
in
experimental
neuroscience
have
transformed
our
ability
to
explore
the
structure
and
function
of
neural
circuits.
At
same
time,
advances
machine
learning
unleashed
remarkable
computational
power
artificial
networks
(ANNs).
While
these
two
fields
different
tools
applications,
they
present
a
similar
challenge:
namely,
understanding
how
information
is
embedded
processed
through
high-dimensional
representations
solve
complex
tasks.
One
approach
addressing
this
challenge
utilize
mathematical
analyze
geometry
representations,
i.e.,
population
geometry.
We
review
examples
geometrical
approaches
providing
insight
into
biological
networks:
representation
untangling
perception,
geometric
theory
classification
capacity,
disentanglement
abstraction
cognitive
systems,
topological
underlying
maps,
dynamic
motor
dynamical
cognition.
Together,
findings
illustrate
an
exciting
trend
at
intersection
learning,
neuroscience,
geometry,
which
provides
useful
population-level
mechanistic
descriptor
task
implementation.
Importantly,
descriptions
are
applicable
across
sensory
modalities,
brain
regions,
network
architectures
timescales.
Thus,
has
potential
unify
networks,
bridging
gap
between
single
neurons,
populations
behavior.
Trends in Cognitive Sciences,
Journal Year:
2024,
Volume and Issue:
28(7), P. 614 - 627
Published: April 4, 2024
Working
memory
(WM)
is
a
fundamental
aspect
of
cognition.
WM
maintenance
classically
thought
to
rely
on
stable
patterns
neural
activities.
However,
recent
evidence
shows
that
population
activities
during
undergo
dynamic
variations
before
settling
into
pattern.
Although
this
has
been
difficult
explain
theoretically,
network
models
optimized
for
typically
also
exhibit
such
dynamics.
Here,
we
examine
versus
coding
in
data,
classical
models,
and
task-optimized
networks.
We
review
principled
mathematical
reasons
why
do
not,
while
naturally
coding.
suggest
an
update
our
understanding
maintenance,
which
computational
feature
rather
than
epiphenomenon.
Nature Communications,
Journal Year:
2022,
Volume and Issue:
13(1)
Published: Feb. 3, 2022
Abstract
The
human
ability
to
adaptively
implement
a
wide
variety
of
tasks
is
thought
emerge
from
the
dynamic
transformation
cognitive
information.
We
hypothesized
that
these
transformations
are
implemented
via
conjunctive
activations
in
“conjunction
hubs”—brain
regions
selectively
integrate
sensory,
cognitive,
and
motor
activations.
used
recent
advances
using
functional
connectivity
map
flow
activity
between
brain
construct
task-performing
neural
network
model
fMRI
data
during
control
task.
verified
importance
conjunction
hubs
computations
by
simulating
over
this
empirically-estimated
model.
These
empirically-specified
simulations
produced
above-chance
task
performance
(motor
responses)
integrating
sensory
rule
hubs.
findings
reveal
role
supporting
flexible
computations,
while
demonstrating
feasibility
models
gain
insight
into
brain.
Background:
Ketamine
has
emerged
as
one
of
the
most
promising
therapies
for
treatment-resistant
depression.
However,
inter-individual
variability
in
response
to
ketamine
is
still
not
well
understood
and
it
unclear
how
ketamine’s
molecular
mechanisms
connect
its
neural
behavioral
effects.
Methods:
We
conducted
a
single-blind
placebo-controlled
study,
with
participants
blinded
their
treatment
condition.
40
healthy
received
acute
(initial
bolus
0.23
mg/kg,
continuous
infusion
0.58
mg/kg/hr).
quantified
resting-state
functional
connectivity
via
data-driven
global
brain
related
individual
ketamine-induced
symptom
variation
cortical
gene
expression
targets.
Results:
found
that:
(i)
both
effects
are
multi-dimensional,
reflecting
robust
variability;
(ii)
principal
gradient
effect
matched
somatostatin
(SST)
parvalbumin
(PVALB)
patterns
humans,
while
mean
did
not;
(iii)
mapped
onto
distinct
gradients
ketamine,
which
were
resolvable
at
single-subject
level.
Conclusions:
These
results
highlight
importance
considering
ketamine.
They
also
have
implications
development
individually
precise
pharmacological
biomarkers
selection
psychiatry.
Funding:
This
study
was
supported
by
NIH
grants
DP5OD012109-01
(A.A.),
1U01MH121766
R01MH112746
(J.D.M.),
5R01MH112189
5R01MH108590
NIAAA
grant
2P50AA012870-11
(A.A.);
NSF
NeuroNex
2015276
(J.D.M.);
Brain
Behavior
Research
Foundation
Young
Investigator
Award
SFARI
Pilot
(J.D.M.,
A.A.);
Heffter
Institute
(Grant
No.
1–190420)
(FXV,
KHP);
Swiss
Neuromatrix
2016–0111)
National
Science
under
framework
Neuron
Cofund
01EW1908)
(KHP);
Usona
(2015
–
2056)
(FXV).
Clinical
trial
number:
NCT03842800
Nature,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Nov. 6, 2024
Abstract
Persistent,
memorandum-specific
neuronal
spiking
activity
has
long
been
hypothesized
to
underlie
working
memory
1,2
.
However,
emerging
evidence
suggests
a
potential
role
for
‘activity-silent’
synaptic
mechanisms
3–5
This
issue
remains
controversial
because
either
view
largely
relied
on
datasets
that
fail
capture
single-trial
population
dynamics
or
indirect
measures
of
spiking.
We
addressed
this
controversy
by
examining
the
mnemonic
information
single
trials
obtained
from
large,
local
populations
lateral
prefrontal
neurons
recorded
simultaneously
in
monkeys
performing
task.
Here
we
show
does
not
persist
during
delays,
but
instead
alternates
between
coordinated
‘On’
and
‘Off’
states.
At
level
neurons,
Off
states
are
driven
both
loss
selectivity
memoranda
return
firing
rates
spontaneous
levels.
Further
exploiting
large-scale
recordings
used
here,
is
available
patterns
functional
connections
among
ensembles
Our
results
suggest
intermittent
periods
coexist
with
support
memory.
Proceedings of the National Academy of Sciences,
Journal Year:
2024,
Volume and Issue:
121(42)
Published: Oct. 7, 2024
A
central
question
for
neuroscience
is
how
to
characterize
brain
representations
of
perceptual
and
cognitive
content.
An
ideal
characterization
should
distinguish
different
functional
regions
with
robustness
noise
idiosyncrasies
individual
brains
that
do
not
correspond
computational
differences.
Previous
studies
have
characterized
by
their
representational
geometry,
which
defined
the
dissimilarity
matrix
(RDM),
a
summary
statistic
abstracts
from
roles
neurons
(or
responses
channels)
characterizes
discriminability
stimuli.
Here,
we
explore
further
step
abstraction:
geometry
topology
representations.
We
propose
topological
similarity
analysis,
an
extension
analysis
uses
family
geotopological
statistics
generalizes
RDM
while
de-emphasizing
geometry.
evaluate
this
in
terms
sensitivity
specificity
model
selection
using
both
simulations
MRI
(fMRI)
data.
In
simulations,
ground
truth
data-generating
layer
representation
neural
network
models
are
same
other
layers
instances
(trained
random
seeds).
fMRI,
visual
area
areas
measured
subjects.
Results
show
topology-sensitive
characterizations
population
codes
robust
interindividual
variability
maintain
excellent
unique
signatures
regions.