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Understanding how neural circuits process memory information is essential for elucidating the mechanisms underlying learning and memory. Previous studies have demonstrated that hippocampal neurons display highly repetitive patterns of synchronous activity that are involved in learning and memory. However, the molecular mechanisms underlying the coordination of circuit activity that serve for learning and memory remain unclear.

By combination of genetic, pharmacological and optogenetic manipulation of intracellular signalling with in vivo live calcium imaging of hippocampal neurons in freely behaving mice using Mightex OASIS Implant micro-endoscopy system, we aim to address dynamic intracellular signaling mechanisms that regulate neuronal circuit activity during hippocampus-dependent memory. Attached is a video demonstrating in vivo GCaMP6 fluorescence imaging in hippocampal CA1 pyramidal neurons with the Mightex OASIS Implant micro-endoscopy system (Video 1).

Video 1. Calcium imaging data from the hippocampal CA1 neurons.

Video 2. Corresponding freely-behaving mouse in an Open Field Test.

Using this system, we can characterize the activity pattern of CA1 neurons across different stages of hippocampus-dependent memory (formation, consolidation, recall) in freely-behaving mice during behaviour assays (as shown by the Open Field Test in Video 2). Future planned experiments in our lab will utilize the Mightex OASIS Implant system to conduct simultaneous optogenetic stimulation of neuronal activity while observing calcium dynamics and mouse behaviour in the same animal during memory tests.

We are able to record calcium imaging and mouse behaviour data in the same animal and currently I am working to connect our calcium imaging data to the mouse behaviour (i.e., to identify patterns of neuronal activity during specific behaviours such as interacting with a novel object). 




Author: Jayant Rai

Bio: Jay is a 4th year PhD student in the Department of Molecule Genetics at the University of Toronto. He is co-supervised by Dr. Kenichi Okamoto and Dr. Mei Zhen