Asset Details
Do you wish to reserve the book?
Parallel emergence of stable and dynamic memory engrams in the hippocampus
Hey, we have placed the reservation for you!
By the way, why not check out events that you can attend while you pick your title.
Oops! Something went wrong.
Looks like we were not able to place the reservation. Kindly try again later.
Are you sure you want to remove the book from the shelf?
Parallel emergence of stable and dynamic memory engrams in the hippocampus
Do you wish to request the book?
Parallel emergence of stable and dynamic memory engrams in the hippocampus
Please be aware that the book you have requested cannot be checked out. If you would like to checkout this book, you can reserve another copy
We have requested the book for you!
Your request is successful and it will be processed during the Library working hours. Please check the status of your request in My Requests.
Oops! Something went wrong.
Looks like we were not able to place your request. Kindly try again later.
Journal Article
Parallel emergence of stable and dynamic memory engrams in the hippocampus
2018
Overview
During our daily life, we depend on memories of past experiences to plan future behaviour. These memories are represented by the activity of specific neuronal groups or ‘engrams’
1
,
2
. Neuronal engrams are assembled during learning by synaptic modification, and engram reactivation represents the memorized experience
1
. Engrams of conscious memories are initially stored in the hippocampus for several days and then transferred to cortical areas
2
. In the dentate gyrus of the hippocampus, granule cells transform rich inputs from the entorhinal cortex into a sparse output, which is forwarded to the highly interconnected pyramidal cell network in hippocampal area CA3
3
. This process is thought to support pattern separation
4
(but see refs.
5
,
6
). CA3 pyramidal neurons project to CA1, the hippocampal output region. Consistent with the idea of transient memory storage in the hippocampus, engrams in CA1 and CA2 do not stabilize over time
7
–
10
. Nevertheless, reactivation of engrams in the dentate gyrus can induce recall of artificial memories even after weeks
2
. Reconciliation of this apparent paradox will require recordings from dentate gyrus granule cells throughout learning, which has so far not been performed for more than a single day
6
,
11
,
12
. Here, we use chronic two-photon calcium imaging in head-fixed mice performing a multiple-day spatial memory task in a virtual environment to record neuronal activity in all major hippocampal subfields. Whereas pyramidal neurons in CA1–CA3 show precise and highly context-specific, but continuously changing, representations of the learned spatial sceneries in our behavioural paradigm, granule cells in the dentate gyrus have a spatial code that is stable over many days, with low place- or context-specificity. Our results suggest that synaptic weights along the hippocampal trisynaptic loop are constantly reassigned to support the formation of dynamic representations in downstream hippocampal areas based on a stable code provided by the dentate gyrus.
Imaging of hippocampal neuron activity in mice performing a memory task across several days identifies both stable and dynamic memory engrams.
