Drosophila flies without short-term memory
display a normal long-term memory
STM: forms right after learning, based on transient events
lasting from a few minutes to a few hours
LTM: forms later with de novo protein synthesis
lasting from several hours to days
sequential model : LRN ---------> STM ---------> LTM
parallel model : LRN
---------> STM
---------> LTM
Is it possible to get LTM without STM?
Davis Annu.Rev.Neurosci. 2005
Aversive olfactory conditioning
(CS+) : OCT
(CS-) : MCH
score (CS-) - (CS+)
(CS-) + (CS+)
Performance
Index :
1+ 2
2
Tully and Quinn, 1985
Long term memory is induced after spaced training
Tully et al., Cell 1994
Long term memory requires de novo protein synthesis
***
Les mécanismes moléculaires et cellulaires
From Waddel and Quinn, 2001
The induction of LTM requires a different training protocol from the
one used to induce STM.
These two different training protocol may induce different
physiological state of the relevant neurons which may in turn
complicate the interpretation of LTM being or not sequential after
STM.
It was recently shown that appetitive olfactory LTM is generated
after a single session of training.
Appetitive olfactory conditioning
Colomb et al., Genes, Brain and Behavior 2009
A single appetitive training session forms STM and LTM
Krashes and Waddell J Neurosci 2008
A single appetitive training session forms STM and LTM
LTM
STM
Parallel processing of appetitive short-term and long-term
memories in Drosophila
Trannoy et al., Curr. Bio. 2011
Strategies for Suppressing Synaptic Transmission
Adapted from White et al., Curr.Bio.2001
MB247-GAL80
GAL80 is a GAL4 repressor (protein-protein interaction)
elav-GAL4 UAS-m-GFP; +/+
elav-GAL4 UAS-m-GFP; MB-GAL80/+
FAS II
GFP
Elodie Reynaud, unpublished
MB  neuron output is required for appetitive STM retrieval
but not for LTM retrieval
MB  neuron output is required for appetitive STM retrieval
but not for LTM retrieval
MB  neuron output is required for appetitive LTM retrieval
but not for STM retrieval
Information transfert from  to  neurons?
Blocking  neuron output during training and consolidation
does not affect STM nor LTM formation
Constitutively blocking  neuron synaptic transmission impairs STM
but not LTM
Conclusion: LTM formation is independent of STM and does not require
synaptic communication between andneurons
*
Aversive olfactory conditioning
RUT adenylyl cyclase
is proposed to
function as a coincidence
detector integrating both
the olfactory and the
electric shock /sugar reward
information
Waddel and Quinn, 2001
RUT adenylyl cyclase is recruited in  (but not in ) neurons
for normal appetitive STM
RUT adenylyl cyclase is recruited in  (but not in ) neurons
for normal appetitive LTM
Our data suggest that appetitive STM and LTM are processed independently in
 and neurons, respectively. Accordingly, immediate appetitive memory
processing should involve only  neurons
Immediate appetitive memory processing involves  but not  neurons
RUT adenylyl cyclase is recruited in  (but not in ) neurons
for normal immediate appetitive memory
sequential model : LRN ---------> STM ---------> LTM
parallel model : LRN
---------> STM
---------> LTM
Is it possible to get LTM without STM?
YES!!
- immediate memory in  neurons
- no information transfert from  to  neurons
- STM and LTM are formed independently of each other
Appetitive memory
parallel model: wt situation
 neurons
LRN ---------> STM
 neurons
LRN ---------> LTM
parallel model: blocking 
 neurons
LRN ---------> STM
 neurons
LRN ---------> LTM
Appetitive memory
parallel model: wt situation
 neurons
LRN ---------> STM
 neurons
LRN ---------> LTM
parallel model: blocking 
 neurons
LRN ---------> STM
 neurons
LRN ---------> LTM
Unique opportunity to analyze biochemical and cellular processes
specifically associated with STM and LTM
From olfactory memory paradigm
Zars et al., Science 2000
McGuire et al., Science 2003
Pascual and Préat, Science 2001
 and  required for STM
 but not  required for LTM
LTM

’
STM + LTM

’
both are required for
short term memory

STM
Trannoy et al., Current Biology 2011
Trannoy et al., Current Biology 2011
Trannoy et al., Current Biology 2011
Trannoy et al., Current Biology 2011
Trannoy et al., Current Biology 2011