iiinova — where your digital self keeps evolving

The study was conducted at @tbsi-tcd.bsky.social in @tcddublin.bsky.social Special thanks to our funders, especially AFOSR🇺🇸 who enabled this project. This work was also supported by CIFAR🇨🇦, the Irish Research Council (IRC) 🇮🇪, @researchireland.ie (SFI)🇮🇪 , & @erc.europa.eu🇪🇺

Many thanks for the resilient efforts of all contributing authors in the broader Ryan Lab, and our collaborators. #scienceisglobal 🇮🇪🇮🇹🇬🇹🇫🇷🇸🇬🇺🇸🇺🇸🇪🇸🇦🇺🇬🇧🇮🇹🇮🇪🇪🇺

Paul first presented this work at @fens.org Forum 2022 in Paris, and again at @sfn.org 2023 in Washington DC. It has improved hugely with useful feedback from colleagues:

After years of effort and many challenges, false starts, and blind alley ways - this work was first published in December 2024: bsky.app/profile/tjry...

Through a series of carefully controlled and technically demanding experiments, Paul (Conway) & Livia (Autore) determined that innate vCA1 ingram ensembles became necessary for the visual looming threat response after, but not before, the reinstatement training.

With the substantial help of close collaborator Gisella Vetere at @espciparispsl.bsky.social, we were able to quickly and effectively incorporate the use of FLiCRE for vCA1 engram labeling during looming reinstatement.

This prompted us to look more broadly, using c-Fos histology and engram labeling to assay multiple brain regions. Ventral hippocampal region CA1 emerged as a striking and opportunistic candidate region to explain the reinstatement effect.

This presented us with the opportunity to compare the innate, and the learned/reinstated threat responses to an identical visual stimulus. Paul conducted longitudinal fiber photometry recordings of superior colliculus (SC) and periaqueductal Gray (PAG) activity.

The extinction effect was robust and long-lasting. It also generalized to other contexts. However, the original looming response could be reinstated if mice were 'reminded' that the stimulus threatening, by pairing the visual looming stimulus with a mild electric shock.

Paul investigated whether the visual looming evoked threat response could be extinguished. Indeed, repeated presentation of the expanding visual disk (in the absence of aerial predators), resulted in the learned attenuation of the threat response.

Fear memories, formed by Pavlovian conditioning, can be attenuated by extinction training if the conditioned stimulus is presented without an aversive outcome. What about instincts? We asked if mice can learn to suppress this innate behavioral response through new learning.

We used visual looming as a behavioral platform, building on the work of Tiago Branco, Markus Meister, Maximilian Joesch & others. In response to an expanding visual disk, mice show an innate threat response manifest as freezing and fleeing behavior (an instinct to avoid aerial predators).

We proposed that memory and instinct may be embodied as isomorphic topological structures within the brain’s microanatomical circuitry. Learned engrams and innate 'ingrams' are constructed by different mechanisms, but may share common structure: www.sciencedirect.com/science/arti...

It is generally believed that instincts are constructed in the same fashion - as genetically constructed microantomical connectivity patterns in the brain. This potential biological similarity allows to investigate the intersection of memory and instinct.

We proposed that whilst plasticity of synaptic strength may account for engram retrievability, plasticity of synaptic wiring allows for enduring memory storage. Engrams might thus be considered as distributed changes in the local connectome of the brain.

This work was lead by former PhD student (now Dr. Paul Conway). Paul joined our lab as an undergraduate research student in 2019 to work on the intersection of memory and instinct (in Drosophila). He then stayed to conduct his PhD here, moving to mice.

Tomás Ryan @tjryan.bsky.social · 22/12/2025

Happy Holidays from everyone at the Ryan Lab. Thanks to all of our alumni, collaborators, colleagues, and funders for helping us to continue to deliver science in turbulent times. Looking forward to a busy 2026 🧠🧬🔬🌐☘️ @tcddublin.bsky.social @tbsi-tcd.bsky.social

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Reflections from two decades of diverse careers in science and beyond: 1. Travel 2. Be flexible 3. Critical and analytical thinking never goes out of fashion 4. Understanding biology means understanding evolution 5. Great environments create lasting relationships

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The 20 year anniversary reunion of the @tcddublin.bsky.social Genetics class of 2005. We had notions.

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Tomás Ryan @tjryan.bsky.social · 22/11/2025

The 20 year anniversary reunion of the @tcddublin.bsky.social Genetics class of 2005. We had notions.

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Excellent analysis of the COVID response in the UK & Europe. Some questionable appraisal of Sweden, without considering comparisons with NZ, Australia - or indeed Finland, Denmark, & Norway. Many countries minimized COVID deaths AND minimized lockdown, by reducing infections.

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Tomás Ryan @tjryan.bsky.social · 21/11/2025

Had the Irish government followed the UK response in the 1st COVID wave, we would have suffered about 2,500 further deaths (on top of the 1,635 people who died before May 31, 2020). Thankfully that didn't happen. Nevertheless, we will await Ireland's COVID-19 Evaluation...

Tomás Ryan @tjryan.bsky.social · 16/11/2025

Late breaking abstract at #SfN25 by Dr. Erika Stewart: LBP032.14 - Microglial plasticity across development mediates infantile amnesia (1 PM - 5 PM Sunday Nov 16). @sfn.org @tcddublin.bsky.social @thelisterinstitute.bsky.social

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Tomás Ryan @tjryan.bsky.social · 26/07/2025

Dr. Erika Stewart just left the Ryan Lab & @tcddublin.bsky.social to become a Postdoctoral Research Fellow with Dani Dumitriu at @columbiamed.bsky.social. A scientist who is always resilient, rigorous and adaptive - looking forward to seeing what she does next.

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Tomás Ryan @tjryan.bsky.social · 04/06/2025

As scientists look for alternative homes for their research careers, will Ireland seize the opportunity? Perspective in @irishtimes.com today. www.irishtimes.com/opinion/2025...

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Tomás Ryan @tjryan.bsky.social · 22/05/2025

Congratulations to Peter Gorman on being named 2025 valedictorian of General Studies at @columbiauniversity.bsky.social. Peter graduated from the TCD/Columbia Dual BA in Neuroscience & Behavior program. He was also named a Bancroft Research Scholar with @bendeskylab.com www.tcd.ie/news_events/...

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Tomás Ryan @tjryan.bsky.social · 19/05/2025

Thanks to Ryan Lab members and @nickbulthuis.bsky.social for organizing - and all speakers, chairs, and participants for many unforgettable conversations.

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Tomás Ryan @tjryan.bsky.social · 19/05/2025

Slán go fóill - we look forward to welcoming you all back to Dublin for the 3rd installment in May 2027 #engramsandensembles

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Session 10 - Embodied Engrams

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Session 8 - Engrams Across Development

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Day 3 - Session 7 - Engram Function

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And a closing discussion on the tension between engrams stability and drift.

Incomplete highlights of Day 2