A flavonoid, quercetin, is capable of enhancing long-term memory formation if encountered at different times in the learning, memory formation, and memory recall continuum

Author(s):  
Veronica Rivi ◽  
Anuradha Batabyal ◽  
Cristina Benatti ◽  
Johanna MC Blom ◽  
Fabio Tascedda ◽  
...  
Author(s):  
Tanisse Teale

A majority of research into memory formation and consolidation is commonly focused on adult brains and organisms. Our work focuses on the mechanisms of memory within the developing, juvenile brain in an attempt to provide a more full understanding of the underlying neural mechanisms of memory formation, consolidation and storage. During juvenile development, the brain undergoes important remodeling and synaptic pruning towards shaping the adult brain. Thus, during this time, memories may be lost through the remodeling of hippocampal-neocortical connections. The significance of comparing juvenile and adult memory processes is critical in understanding the structural changes that occur within memory-specific circuits associated with long-term memory formation. To provide a comparison of the neurobehavioral aspects of long-term memory formation in juveniles and adults, we trained Long Evan’s rats on a spatial task on postnatal days 16, 18, 20, 25, 30 or 50 (adults). Each age group was then tested for memory recall 24 hours or 3 weeks later. We noted that memory recall showed a dramatic change at postnatal day 20 such that memory recall at postnatal day 25 was similar to adult levels. We then used immunohistochemistry to quantify and analyze neural activity patterns in brain regions thought to underlie the short- and long-term storage of spatial memories. Identification of these regional activity changes during juvenile periods and comparison with adults allows us to explore the function and organization of interacting brain regions in long-term spatial memory storage during development.


Author(s):  
Anuradha Batabyal ◽  
Veronica Rivi ◽  
Cristina Benatti ◽  
Johanna MC Blom ◽  
Ken Lukowiak

Animals respond to acute stressors by modifying their behaviour and physiology. The pond snail Lymnaea stagnalis exhibits configural learning (CL), a form of higher order associative learning. In CL snails develop a landscape of fear when they experience a predatory cue along with a taste of food. This experience results in a suppression of the food response; but the memory only persists for 3h. Lymnaea has been also found to upregulate heat shock proteins (HSPs) as a result of acute heat stress that leads to the enhancement of memory formation. A plant flavonoid quercetin blocks the upregulation of HSPs when experienced prior to heat stress. Here we used this blocking mechanism to test the hypothesis that HSP upregulation played a critical role in CL. Snails experienced quercetin prior to CL training and surprisingly instead of blocking memory formation it enhanced the memory such that it now persisted for at least 24h. Quercetin exposure both prior to or post CL enhanced long-term memory (LTM) up to 48h. We quantified CREB1 mRNA levels in the Lymnaea central nervous system following quercetin and found LymCREB1 to be upregulated following quercetin exposure. The enhanced LTM phenotype in L. stagnalis was most pronounced when quercetin was experienced during the consolidation phase. Additionally, quercetin exposure during the memory reconsolidation phase also led to memory enhancement. Thus, we found no support of our original hypothesis but found that quercetin exposure upregulated LymCREB1 leading to LTM formation for CL.


2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Moonseok Choi ◽  
Sang-Min Lee ◽  
Dongsoo Kim ◽  
Heh-In Im ◽  
Hye-Sun Kim ◽  
...  

AbstractThe morphological dynamics of astrocytes are altered in the hippocampus during memory induction. Astrocyte–neuron interactions on synapses are called tripartite synapses. These control the synaptic function in the central nervous system. Astrocytes are activated in a reactive state by STAT3 phosphorylation in 5XFAD mice, an Alzheimer’s disease (AD) animal model. However, changes in astrocyte–neuron interactions in reactive or resting-state astrocytes during memory induction remain to be defined. Here, we investigated the time-dependent changes in astrocyte morphology and the number of astrocyte–neuron interactions in the hippocampus over the course of long-term memory formation in 5XFAD mice. Hippocampal-dependent long-term memory was induced using a contextual fear conditioning test in 5XFAD mice. The number of astrocytic processes increased in both wild-type and 5XFAD mice during memory formation. To assess astrocyte–neuron interactions in the hippocampal dentate gyrus, we counted the colocalization of glial fibrillary acidic protein and postsynaptic density protein 95 via immunofluorescence. Both groups revealed an increase in astrocyte–neuron interactions after memory induction. At 24 h after memory formation, the number of tripartite synapses returned to baseline levels in both groups. However, the total number of astrocyte–neuron interactions was significantly decreased in 5XFAD mice. Administration of Stattic, a STAT3 phosphorylation inhibitor, rescued the number of astrocyte–neuron interactions in 5XFAD mice. In conclusion, we suggest that a decreased number of astrocyte–neuron interactions may underlie memory impairment in the early stages of AD.


Cell Reports ◽  
2013 ◽  
Vol 4 (6) ◽  
pp. 1082-1089 ◽  
Author(s):  
Ying Tan ◽  
Dinghui Yu ◽  
Germain U. Busto ◽  
Curtis Wilson ◽  
Ronald L. Davis

2012 ◽  
Vol 215 (24) ◽  
pp. 4322-4329 ◽  
Author(s):  
M. L. Teskey ◽  
K. S. Lukowiak ◽  
H. Riaz ◽  
S. Dalesman ◽  
K. Lukowiak

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