Nature,
Journal Year:
2022,
Volume and Issue:
609(7926), P. 327 - 334
Published: Aug. 24, 2022
Abstract
In
the
hippocampus,
spatial
maps
are
formed
by
place
cells
while
contextual
memories
thought
to
be
encoded
as
engrams
1–6
.
Engrams
typically
identified
expression
of
immediate
early
gene
Fos
,
but
little
is
known
about
neural
activity
patterns
that
drive,
and
shaped
by,
in
behaving
animals
7–10
Thus,
it
unclear
whether
Fos-expressing
hippocampal
neurons
also
encode
correlates
with
affects
specific
features
code
11
Here
we
measured
CA1
calcium
imaging
monitoring
induction
mice
performing
a
hippocampus-dependent
learning
task
virtual
reality.
We
find
high
form
ensembles
highly
correlated
activity,
exhibit
reliable
fields
evenly
tile
environment
have
more
stable
tuning
across
days
than
nearby
non-Fos-induced
cells.
Comparing
neighbouring
without
function
using
sparse
genetic
loss-of-function
approach,
disrupted
less
decreased
selectivity
lower
across-day
stability.
Our
results
demonstrate
Fos-induced
contribute
codes
encoding
accurate,
spatially
uniform
itself
has
causal
role
shaping
these
codes.
may
therefore
link
two
key
aspects
function:
for
underlie
cognitive
maps.
Annual Review of Neuroscience,
Journal Year:
2020,
Volume and Issue:
43(1), P. 95 - 117
Published: Feb. 20, 2020
Synaptic
plasticity,
the
activity-dependent
change
in
neuronal
connection
strength,
has
long
been
considered
an
important
component
of
learning
and
memory.
Computational
engineering
work
corroborate
power
through
directed
adjustment
weights.
Here
we
review
fundamental
elements
four
broadly
categorized
forms
synaptic
plasticity
discuss
their
functional
capabilities
limitations.
Although
standard,
correlation-based,
Hebbian
primary
focus
neuroscientists
for
decades,
it
is
inherently
limited.
Three-factor
rules
supplement
with
neuromodulation
eligibility
traces,
while
true
supervised
types
go
even
further
by
adding
objectives
instructive
signals.
Finally,
a
recently
discovered
hippocampal
form
combines
above
elements,
leaving
behind
requirement.
We
suggest
that
effort
to
determine
neural
basis
adaptive
behavior
could
benefit
from
renewed
experimental
theoretical
investigation
more
powerful
plasticity.
Deep
learning
has
led
to
significant
advances
in
artificial
intelligence,
part,
by
adopting
strategies
motivated
neurophysiology.
However,
it
is
unclear
whether
deep
could
occur
the
real
brain.
Here,
we
show
that
a
algorithm
utilizes
multi-compartment
neurons
might
help
us
understand
how
neocortex
optimizes
cost
functions.
Like
neocortical
pyramidal
neurons,
our
model
receive
sensory
information
and
higher-order
feedback
electrotonically
segregated
compartments.
Thanks
this
segregation,
different
layers
of
network
can
coordinate
synaptic
weight
updates.
As
result,
learns
categorize
images
better
than
single
layer
network.
Furthermore,
takes
advantage
multilayer
architectures
identify
useful
representations-the
hallmark
learning.
This
work
demonstrates
be
achieved
using
dendritic
compartments,
which
may
explain
morphology
neurons.
Making
inferences
about
the
computations
performed
by
neuronal
circuits
from
synapse-level
connectivity
maps
is
an
emerging
opportunity
in
neuroscience.
The
mushroom
body
(MB)
well
positioned
for
developing
and
testing
such
approach
due
to
its
conserved
architecture,
recently
completed
dense
connectome,
extensive
prior
experimental
studies
of
roles
learning,
memory,
activity
regulation.
Here,
we
identify
new
components
MB
circuit
Drosophila,
including
visual
input
output
neurons
(MBONs)
with
direct
connections
descending
neurons.
We
find
unexpected
structure
sensory
inputs,
transfer
information
different
modalities
MBONs,
modulation
that
dopaminergic
(DANs).
provide
insights
into
circuitry
used
integrate
outputs,
between
central
complex
inputs
DANs,
feedback
MBONs.
Our
results
a
foundation
further
theoretical
work.
Frontiers in Neural Circuits,
Journal Year:
2018,
Volume and Issue:
12
Published: July 31, 2018
Most
elementary
behaviors
such
as
moving
the
arm
to
grasp
an
object
or
walking
into
next
room
explore
a
museum
evolve
on
time
scale
of
seconds;
in
contrast,
neuronal
action
potentials
occur
few
milliseconds.
Learning
rules
brain
must
therefore
bridge
gap
between
these
two
different
scales.
Modern
theories
synaptic
plasticity
have
postulated
that
co-activation
pre-
and
postsynaptic
neurons
sets
flag
at
synapse,
called
eligibility
trace,
leads
weight
change
only
if
additional
factor
is
present
while
set.
This
third
factor,
signaling
reward,
punishment,
surprise,
novelty,
could
be
implemented
by
phasic
activity
neuromodulators
specific
inputs
special
events.
While
theoretical
framework
has
been
developed
over
last
decades,
experimental
evidence
support
traces
seconds
collected
during
years.
Here
we
review,
context
three-factor
plasticity,
four
key
experiments
role
combination
with
biological
implementation
neoHebbian
learning
rules.