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ASSESSMENT OF MEMORY IN NEURODEGENERATIVE MICE MODELS J.M. LASSALLE. Outline of presentation. Memory systems What kinds of memory are impaired in neurodegenerative diseases Mouse models for Alzheimer's disease A recent mouse model of Tauopathy
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ASSESSMENT OF MEMORY IN NEURODEGENERATIVE MICE MODELS J.M. LASSALLE 11th ISN-IBRO AFRICAN NEUROSCIENCE SCHOOL
Outline of presentation • Memory systems • What kinds of memory are impaired in neurodegenerative diseases • Mouse models for Alzheimer's disease • A recent mouse model of Tauopathy • Some experimental paradigms for the study of cognitive impairments • Examples of results with Tg2576 (-amyloid pathology, P301L, a model of Tauopathy, and R6/2 mice expressing the Human Huntington's disease mutation
MEMORY LONG-TERM REFERENCE Min to hours SHORT-TERM (Working-Memory) FRONTAL CORTEX DECLARATIVE EXPLICIT (Representational) NON-DECLARATIVE IMPLICIT (Procedural) PROCEDURAL (Skills & Habits) PRIMING (Influence of unconscious presentation of elements) ASSOCIATIVE (Conditioning) NON-ASSOCIATIVE LEARNING - habituation - sensitization SEMANTIC (Facts) EPISODIC (Events) EMOTIONAL RESPONSES (Fear) MUSCULAR RESPONSES (Eye blink) REFLEX PATHWAYS TEMPORAL LOBE CORTEX & NEOCORTEX STRIATUM AMYGDALA CEREBELLUM Taxonomy of memory: adapted from Tülving and from Squire and Knowlton
Cortex & neocortex Limbic sytem Hindbrain
Neurodegenerative diseases with cognitive impairments • Alzheimer • Parkinson • Huntington • Lewy bodies • Vascular dementia • Prion pathologies
What kinds of memory impaired ? DiseaseSystem StructureCognitive impairments Alzheimer Cholinergic neocortex Working memory Hippocampus Episodic memory Amygdala Spatial memory Executive functions Parkinson Dopaminergic Striatum Working memory Executive functions Huntington Gabaergic Striatum Spatial & temporal memory Attention Language Reasoning Recognition Mood Behavior
Mouse models for Alzheimer's disease • No spontaneous model (except microcebus), no comprehensive model • Experimental models: ICV or Hippocampal -amyloid A1-40 and A1-42 injections in rats. (See Stéphan & Phillips, 2005, G2B, 4, 157-172 for a review) • Transgenic mice carrying a single or double mutations of the APP, PS1, PS2, APOE4, -secretase, -secretase and Tau human genes • APP PS1/PS2 Double mutants APOE (Chr 21) (Chr 14/1)(Chr 19) • APP-V717F - PS1 cKO - APP+PS1 (S-W, B6D2F1) - APP-V717F:apoE(+/+) • PDAPP (D2, B6, S-W) - hPS1 Tg - PSAPP (C3H/B6) • Tg 2576 (B6, SJL) - hPS1 Tg (FVB/N) - APPxPS1(-/-)(FVB/N) • APP23 (D2, B6) - hPS2 Tg (BDF1) - PS2APP (B6xD2) • TgCRND8 (C3H/B6) • J20 (D2, B6) • APP KO (B6) -Secretase-SecretaseTau (Chr 17) • BACE1 KO - APP/RK (FVB/N) • hBACE1 Tg - ADAM KO - P301L • BACE1-/- Tg2576+ (B6, SJL) - ADAM10xAPP (FVB/N) (For a review, see Kobayashi & Chen, 2005, G2B, 4, 173-196)
A mouse model of Tauopathy • Rtg (tau301L)4510 mouse expresses the P301 mutation in Tau, associated with fronto-parietal dementia and parkinsonism linked to Chr 17 • Transgene expression driven by a forebrain specific Ca2+ Calmoduline Kinase II promoter resulting in high levels of expression in the neocortex and hippocampus • Expression induced via the tetracycline-operon responsive element and suppressed after treatment by doxycycline • NFT pathology is first observed in the neocortex and progresses into the hippocampus and limbic structures with increasing age • Cognitive impairments from 4 months of age • Forebrain atrophy, prominent loss of neurons mainly in CA1 • 129/FVB1 background Ramsden et al. A novel mouse model of human Tauopathy. J. Neurosci. 2005, 25, 10637-10647
Age-dependant forebrain degeneration in rTg (Tau p301L) 4510 mice Ramsden et al. A novel mouse model of human Tauopathy. J. Neurosci. 2005, 25, 10637-10647
Massive neuronal loss in the hippocampus (and pre-frontal cortex), Neuro Fibrillary Tangles and GFAP-positive reactive astrocytes Ramsden et al. A novel mouse model of human Tauopathy. J. Neurosci. 2005, 25, 10637-10647
Progression of Neuro Fibrillary Tangle Pathology in rTg(Taup301L)4510 brain Progression of NFT pathology in rTg(taup301L)4510 brain. Formation of Bielschowsky silver positive NFTs in the cortex and CA1 area is age dependant and consistant with cortical and hippocampal atrophy Ramsden et al. A novel mouse model of human Tauopathy. J. Neurosci. 2005, 25, 10637-10647
INFERRING COGNITIVE IMPAIRMENTS FROM BEHAVIORAL PERFORMANCE IMPAIRMENTS Studying cognition: MEASUREMENT VALIDITY • Cognitive processes cannot be directly measured, they can only be inferred from the analysis of behavioral performances, expressed in experimental situations. These measures can be biased by uncontrolled factors • The way these experimental paradigms are chosen and designed is crucial for the validity of these inferences • To be valid, these paradigms must be based : - on extensive knowledge of the ethology and the ecology of model organisms - on accurate hypotheses upon the cognitive and neural processes that support behavior - on the certitude that there is no bias due to locomotion or emotionality or whatever
Forms of memory impaired in neurodegenerative diseases • Working Memory • Reference Memory • Spatial memory • Memory for familiar places • Configural vs Associative Memory
The functions of spatial memory are essential • Navigating towards a remote place (homing, using transports) • Remembering a set of remote places (daily life places) • Recognizing familiar places and detecting (spatial) changes • Planning a route (shortcut, detour)
Some Experimental Paradigms For The Study of Cognitive impairments Working Memory - Delayed (Non-) Matching to Sample (D(N)MS) Executive functions : - T-maze Continuous Alternation Task Spatial memory: - Morris navigation task (location in LTM) - Olton radial maze (list of places in WM) - Open-field with objects (spatial novelty) Configural (Episodic-like) memory: - Contextual-fear conditioning Non hippocampo-dependant versions of these tasks: - Cued navigation task (associative) - Open-field with objects (object novelty) - Associative Tone-fear conditioning
T- maze continuous alternation task • Prefrontal cortex / alternation • Hippocampus / memory delay Access to certain compartments of the maze (black areas) can be blocked by lowering guillotine doors. Exploratory paths and direction of locomotion are indicated by the lines and arrow-heads inside the maze. The sequence of test-phases are indicated by letters.
T-maze alternation in mice expressing the Human Huntington's disease mutation R6/2 mice are impaired in T-maze spontaneous alternation Lione et al., Progressive learning deficits in R6/2 mice. J. Neurosci., 1999, 19, 10428-10437
T-maze alternation in mice expressing the Human sweedish Alzheimer's disease mutation * Percentage of spontaneous alternatiojn in the Y-maze (Mean ± S.E.M.) Ognibene et al., Behav. Brain Res. ,2005, 156, 225-232
MORRIS NAVIGATION TASK The Morris navigation paradigm uses a circular swimming pool, 120 cm in diameter, filled with water made opaque with an opacifier Mice are dropped into the water from a different point at each trial, and they are trained to locate and climb onto a platform which is hidden beneath the surface of the water In the spatial version of the task, mice need to learn to navigate towards the platform, using distal cues available in the room around the swimming-pool In the cued version of the task, the platform is either visible, or when submerged, its position is indicated by a proximal cue (a flag attached to the platform or a signal hanging above the platform)
LEARNING COMPONENTS OF THE NAVIGATION TASK There are two different learning (memory) components in the spatial task. - To learn to find the platform, the mouse needs to learn the procedural and sensory motor components of the task : “there is a platform where I can rest on, somewhere in the pool, at a certain distance from the wall, and I have to swim efficiently to find it” And that may be enough, for the mouse to improve its latency to find the platform - But to swim straight to the platform, whatever its starting point, the mouse has to learn also the spatial component of the task : i. e. the spatial location of the platform, using distal cues to build a cognitive map of the place. To ensure that mice have built and stored in their memory a spatial representation to locate the platform, the experimenter needs to use a spatial probe test : - After training, the platform is removed from the pool and the mouse is allowed to swim for one minute. The swimming path of the mouse is videotaped and it is then fairly easy to verify if the mouse searches at the right place For that, one needs, for instance, to count the number of times the mouse crosses an annulus surrounding the place where the platform used to be, and to compare with the mean crossings of three other control annuli placed in the other three quadrants of the pool
Morris navigation task in mice expressing the Human Huntington's disease mutation Escape latencies in the visible, hidden and platform reversal tasks • Impairments of Morris water maze learning in R6/2 mice (Escape latency (A), path length (B) and Swimming speed (C)) during acquisition of visible, hidden and reversal learning • R6/2 Tg mice were unimpaired in the visible platform task • On the other hand, they were severely impaired in the spatial task • Their initial performance did not differ, indicating that R6/2 mice did not show any nonspecific sensory impairment • R6/2 mice were also impaired in reversal place learning of a hidden platform • Although swimming speed was only slightly decreased in R6/2 mice, during reversal trials, the difference became significant Lione et al., Progressive learning deficits in R6/2 mice. J. Neurosci., 1999, 19, 10428-10437
Morris navigation task in mice expressing the Human Huntington's disease mutation Spatial probe test Impairment of probe trial performance in R6/2 mice A - During the probe trials, R6/2 and control groups spent significantly > 25% of their time in platform quadrant, suggesting that all mice had learned le location of the platform B – However, R6/2 mice crossed less frequently the exact location of the platform, indicating impaired precision of spatial memory C – R6/2 mice spent significantly more time in the external outer zone and significantly less time in the middle pool zone than control mice Lione et al., Progressive learning deficits in R6/2 mice. J. Neurosci., 1999, 19, 10428-10437
A new water maze protocol: the platform is moved to a new location as soon as the mouse quickly and reliably reaches the platform. Numerous locations are used successively • Earlier locations of the platform are encoded in LT memory, potentially causing interference • Memory retrieval must therefore be selective to the most recently encoded location, an "episodic-like" component of the task Chen et al., Nature, 2000, 408, 975-979
Age related and age-independent deficits in spatial learning in PDAPP mice (a) PDAPP Tg mice show a significant age-related impairment of learning performance (trials to criterion for five successive platform locations), compared to non-Tg control mice (b) (c) PDAPP mice show lower performance in learning the first location (that is not age dependant) (d) Whereas there is age dependant deficit in learning as the number of reversals increased Chen et al., Nature, 2000, 408, 975-979
Path taken by representative animals in learning the 5th location at each of the three ages Note similar patterns in PDAPP and non-Tg mice at 6-9 months, but circuitous path taken by PDAPP mice on some trials at 13-15 and 18-21 months Chen et al., Nature, 2000, 408, 975-979
The relationship between performance and -amyloid plaque deposition Chen et al., Nature, 2000, 408, 975-979
RADIAL MAZE The radial maze exploits the ability of rodents to memorize a list of feeding places (Olton) in spatial Working Memory At the beginning of the session, the eight arms are baited with little pieces of food. When the food has been eaten from a place, it is not baited again. Rats and mice can learn rapidly to avoid to return to these arms (which would be considered an error)
Working Memory and Reference Memory errors on the Radial maze Task • Working Memory Error: returning to a place already visited during the same training session (The subject has to memorize the list of already visited places, that has to be reset at the beginning of each new learning session) • Reference Memory Error: If some particular arms are never baited from session to session, visiting those arms constitutes a reference (long term) memory error
Non spatial strategiesand measurement validity • Mice can develop strategies to avoid returning to an already visited place • Algorithmic strategies ( clockwise strategy) • Use of odor trails • Non spatial (palliative) strategies may appear in mice that are unable to use spatial representations to orientate, or when such an ability is impaired during aging or in neurodegenerative diseases
A (A 1-40 and A 1-43) infusion model of Alzheimer's disease in the rat Working memory deficit in a spatial learning task in the RAM, and inhibited LTP induced by HFS in the dentate gyrus in vivo In contrast, rats who received the amyloid injection and a daily treatment of non-steroidal anti-inflammatory drug showed similar performances as controls and a rescue of the decrement in LTP Stéphan & Phillips, G2B, 2005, 4, 157-172
SPATIAL NOVELTY OPEN-FIELD WITH 3 IDENTICAL OBJECTS Mice are exposed to 3 unknown object introduced in a familiar environment, and allowed to explore them across different sessions. The objects have either a linear or triangular arrangement. Exploratory contacts of the objects decrease as the mouse habituates to them After habituation has occurred, the objects are moved to the other spatial arrangement and mice are checked for their reactions to spatial novelty (exploration renewal)
OBJECT NOVELTYOPEN-FIELD WITH 3 IDENTICAL OBJECTS Later on, one object is replaced by an unfamiliar object and reactions of mice to object novelty are assessed. Spatial novelty reactions are hippocampus dependent, whereas object novelty reactions do not need a functional hippocampus.
OPEN-FIELD + Objects Mean ± s.e.m. time spent in contact with objects by wild-type and Tg2576 mice Upper panel: Reaction to object displacement is measured as time spent in contact with either displaced (DO) or non-displaced (NDO) objects in session 5 minus session 4 Lower panel: Reaction to object substitution is measured as time spent in contact with either substituted (SO) or Non-substituted (NSO) objects in session 6 minus session 5 Ognibene et al., Behav. Brain Res. ,2005, 156, 225-232
24 h later Test to the context t0 (min) t4 Freezing scanned every 5 sec t0 (min) 2 min 2.5 min 4.5 min 5 min 5.5 min 2h later Test to the tone END t0 (min) t2 t4 End CS + IS END CS + US Tone Freezing scanned every5 sec Foot shock (US) US CS Tone (CS) The contextual fear conditioning paradigm
The fear conditioning response : freezing Freezing scores of - naïve (Stayed in their home cage, no sound, No footshock), and - conditioned mice Daumas et al, 2004, PhD Thesis
Contextual fear conditioningin APP Tg2576 mice *** Mean ± S.E.M. freezing frequency Freezing level to the context is decreased in Tg 2576 mice whereas they do not differ from wild-type controls for freezing to the modified context and to the tone Lassalle et al. in preparation
Elevated plus-maze: Behavioral desinhibition Geno X Time: p= 0.06 Panel A: Percentage amount of time (mean ± S.E.M.) spent by Tg 2576 transgenic and control mice in the open-arms as a function of total time (3 min x 3 repeated measures) Panel B: Number of crossings (mean ± S.E.M.) between open arms during 3 min repeated measures in a 9 min. session Geno: p< 0.05 Ognibene et al., Behav. Brain Res. ,2005, 156, 225-232
Schematic representation of the earliest age of onset of impairment in spatial, visual, reversal and alternation learning in R6/2 (Huntington) mice Lione et al., Progressive learning deficits in R6/2 mice. J. Neurosci., 1999, 19, 10428-10437
UMR 5169 NEUROBIOLOGIC AND NEUROGENETIC BASES OF SPATIAL AND CONTEXTUAL COGNITION http://cognition.ups-tlse.fr Pr. J.M. Lassalle Pr. B. Francès Dr. C. Rampon Dr. P. Roullet H. Halley (IE) I. Massou (IE) G. Latil (Tech) L. Verret (Post-doc) S. Daumas (Doct) A. Bétourne (Doct)