Biology subjects

Ainge, J. A.

Publications and source records attributed to Ainge, J. A..

3 recordsLinked to original sources

bioRxiv2023

Increased flexibility of CA3 memory representations following environmental enrichment

Environmental enrichment (EE) improves memory, particularly under conditions of high memory interference1-6. Here, we investigate the neural mechanisms facilitating improved memory following EE. Using associative recognition memory tasks that model the automatic and integrative nature of episodic memory, we find that EE-dependent improvements in difficult associative memory discriminations are related to increased adult hippocampal neurogenesis and sparser memory representations across the hippocampus. Additionally, by recording CA3 place cells as enriched and standard-housed rats explored the increasingly distinct shapes of a "morph" box, we report for the first time that EE changes the way CA3 place cells discriminate similar contexts. CA3 place cells of enriched rats show greater spatial tuning, increased firing rates, and enhanced remapping to contextual changes. These findings point to more precise and flexible CA3 memory representations in enriched rats. Increased spatial tuning and flexibility might support the well-established EE-dependent improvements in fine memory discrimination. HighlightsO_LIEE improves discrimination of similar associative memories C_LIO_LIEE-dependent memory improvements are related to increased adult neurogenesis C_LIO_LIEE results in sparser hippocampal activity C_LIO_LIEE increases spatial tuning, firing and remapping of CA3 place cells C_LI

neuroscience↗

bioRxiv2020

Object and object-memory representations across the proximodistal axis of CA1

Episodic memory requires information about objects to be integrated into a spatial framework. Place cells in the hippocampus encode spatial representations of objects that could be generated through signalling from the entorhinal cortex. Projections from lateral and medial entorhinal cortex to the hippocampus terminate in distal and proximal CA1, respectively. We recorded place cells in distal and proximal CA1 as rats explored an environment that contained objects. Place cells in distal CA1 demonstrated higher measures of spatial tuning and expressed place fields closer to objects. Further, remapping to object displacement was modulated by place field proximity to objects in distal, but not proximal CA1. Finally, representations of previous object locations were more precise in distal CA1. Our data suggest that lateral entorhinal cortex inputs to the hippocampus support spatial representations that are more precise and responsive to objects in cue-rich environments. This is consistent with functional segregation in the entorhinal-hippocampal circuits underlying object-place memory.

neuroscience↗

bioRxiv2019

Fan cells in layer 2 of lateral entorhinal cortex are critical for episodic-like memory

The lateral entorhinal cortex (LEC) is a critical structure for episodic memory, but the roles of discrete neuronal populations within LEC are unclear. Here, we establish an approach for selectively targeting fan cells in layer 2 (L2) of LEC. Whereas complete lesions of the LEC were previously found to abolish associative recognition memory, we find that after selective suppression of synaptic output from fan cells mice still recognise novel object-context configurations, but are impaired in recognition of novel object-place-context associations. Our experiments suggest a segregation of memory functions within LEC networks and indicate that specific inactivation of fan cells leads to behavioural deficits reminiscent of early stages of Alzheimers disease.

neuroscience↗