Nature Communications,
Год журнала:
2018,
Номер
9(1)
Опубликована: Март 12, 2018
The
brain
adaptively
integrates
present
sensory
input,
past
experience,
and
options
for
future
action.
insect
mushroom
body
exemplifies
how
a
central
structure
brings
about
such
integration.
Here
we
use
combination
of
systematic
single-cell
labeling,
connectomics,
transgenic
silencing,
activation
experiments
to
study
the
at
resolution,
focusing
on
behavioral
architecture
its
input
output
neurons
(MBINs
MBONs),
intrinsic
APL
neuron.
Our
results
reveal
identity
morphology
almost
all
these
44
in
stage
3
Drosophila
larvae.
Upon
an
initial
screen,
functional
analyses
medial
lobe
uncover
sparse
specific
functions
dopaminergic
MBINs,
MBONs,
GABAergic
neuron
across
three
tasks,
namely
odor
preference,
taste
associative
learning
between
taste.
thus
provide
cellular-resolution
case
brains
organize
behavior.
Understanding
memory
formation,
storage
and
retrieval
requires
knowledge
of
the
underlying
neuronal
circuits.
In
Drosophila,
mushroom
body
(MB)
is
major
site
associative
learning.
We
reconstructed
morphologies
synaptic
connections
all
983
neurons
within
three
functional
units,
or
compartments,
that
compose
adult
MB's
α
lobe,
using
a
dataset
isotropic
8
nm
voxels
collected
by
focused
ion-beam
milling
scanning
electron
microscopy.
found
Kenyon
cells
(KCs),
whose
sparse
activity
encodes
sensory
information,
each
make
multiple
en
passant
synapses
to
MB
output
(MBONs)
in
compartment.
Some
MBONs
have
inputs
from
KCs,
while
others
differentially
sample
modalities.
Only
6%
KC>MBON
receive
direct
synapse
dopaminergic
neuron
(DAN).
identified
two
unanticipated
classes
synapses,
KC>DAN
DAN>MBON.
DAN
activation
produces
slow
depolarization
MBON
these
DAN>MBON
can
weaken
recall.
The
mechanism
of
memory
remains
one
the
great
unsolved
problems
biology.
Grappling
with
question
more
than
a
hundred
years
ago,
German
zoologist
Richard
Semon
formulated
concept
engram,
lasting
connections
in
brain
that
result
from
simultaneous
“excitations”,
whose
precise
physical
nature
and
consequences
were
out
reach
biology
his
day.
Neuroscientists
now
have
knowledge
tools
to
tackle
this
question,
however,
Forum
brings
together
leading
contemporary
views
on
mechanisms
what
engram
means
today.
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.
Associative
learning
is
thought
to
involve
parallel
and
distributed
mechanisms
of
memory
formation
storage.
In
Drosophila,
the
mushroom
body
(MB)
major
site
associative
odor
formation.
Previously
we
described
anatomy
adult
MB
defined
20
types
dopaminergic
neurons
(DANs)
that
each
innervate
distinct
compartments
(<xref
ref-type="bibr"
rid="bib2">Aso
et
al.,
2014a</xref>,
<xref
rid="bib4">2014b</xref>).
Here
compare
properties
memories
formed
by
optogenetic
activation
individual
DAN
cell
types.
We
found
extensive
differences
in
training
requirements
for
formation,
decay
dynamics,
storage
capacity
flexibility
learn
new
associations.
Even
a
single
type
can
either
write
or
reduce
an
aversive
memory,
appetitive
depending
on
when
it
activated
relative
delivery.
Our
results
show
different
rules
are
executed
seemingly
systems,
providing
multiple
circuit-based
strategies
predict
future
events
from
past
experiences.
Current Opinion in Neurobiology,
Год журнала:
2017,
Номер
49, С. 51 - 58
Опубликована: Дек. 16, 2017
When
animals
learn,
plasticity
in
brain
networks
that
respond
to
specific
cues
results
a
change
the
behavior
these
elicit.
Individual
network
components
mushroom
bodies
of
fruit
fly
Drosophila
melanogaster
represent
cues,
learning
signals
and
behavioral
outcomes
learned
experience.
Recent
findings
have
highlighted
importance
dopamine-driven
activity
feedback
feedforward
connections,
between
various
elements
body
neural
network.
These
computational
motifs
been
shown
be
crucial
for
long
term
olfactory
memory
consolidation,
integration
internal
states,
re-evaluation
updating
information.
The
often
recurrent
circuit
anatomy
prolonged
requirement
parts
underlying
networks,
suggest
self-sustained
precisely
timed
is
fundamental
feature
computations
insect
brain.
Together
processes
allow
flies
continuously
adjust
content
their
knowledge
direct
way
best
represents
expectations
serves
most
pressing
current
needs.
Although
individual
neurons
are
the
basic
unit
of
nervous
system,
they
process
information
by
working
together
in
neuronal
circuits
with
specific
patterns
synaptic
connectivity.
Here,
I
review
common
circuit
motifs
and
architectural
plans
used
diverse
brain
regions
animal
species.
also
consider
how
these
architectures
assemble
during
development
might
have
evolved.
Understanding
connectivity
can
implement
neural
computations
will
help
to
bridge
huge
gap
between
biology
neuron
function
entire
brain,
allow
us
better
understand
basis
behavior,
may
inspire
new
advances
artificial
intelligence.