Christos Constantinidis
Professor of Biomedical Engineering and Neuroscience. Neural basis of cognition, cognitive development, deep brain stimulation.
lab.vanderbilt.edu/constantinidis-lab/…
- Aurora over Swedish Forest apod.nasa.gov/apod/ap22032...
- Congress toyed with the idea of explicitly prohibiting multi-year funding of NIH grants - which severely cut down the number of awards last year - but in the end, it didn't go through. Expect paylines to be only moderately better this year. www.statnews.com/2026/01/20/n...
- NIH receives a 0.9% increase in the appropriation bill the House and Senate voted that now awaits the President's signature. Below inflation - but better than the 40% decrease the President's budget requested. www.aaas.org/news/fy-2026...
- Repeatable, low-drift recordings in behaving non-human primates using flexible microelectrodes www.biorxiv.org/content/10.6...
- New paper from the lab: "Asynchronous firing and off states in working memory maintenance" www.sciencedirect.com/science/arti...
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View full threadHad persistent activity truly been an artifact, the existence of gaps and off-states would have greatly degraded the performance of simultaneous populations during the delay period (14/10)
- Our results provide a critical confirmation of the Standard Model of Working memory. Many thanks to my students who did these challenging experiments, and particularly the co-first authors, Rana Mozumder and Zhengyang Wang (end)
- When we calculated decoding accuracy of populations of neurons sampled from different trials (or “pseudo-populations”, commonly used in neurophysiology) and tested them with neurons recorded simultaneously, only a subtle performance decrease was evident (12/10)
- Furthermore, this decrease was present in all task epochs, including the stimulus presentation and response periods, rather than the delay period alone. We speculate that off states are caused by variations in neuromodulatory tone (13/10)
- A recent study has revealed off-states in the activity of prefrontal neurons during working memory (nature.com/articles/s41...) . We replicated this finding and additionally show that such off-states are coordinated across the prefrontal and posterior parietal cortex (10/10)
- However, we also show that such off-states are relative decreases in firing rate rather than absolute “gaps” in spiking. Activity across the network continued to maintain information about the stimulus being remembered even during off states (11/10)
- In this article we document “The Asynchronous State” of Working Memory. In single trials, individual neurons may not exhibit persistent activity, however populations of ~100 neurons are sufficient to generate activity elevated above the baseline for the entire delay period (8/10)
- Such persistence is only evident for stimuli that are optimal for the recording site. Picking a suboptimal stimulus will not produce such asynchronously elevated firing, which is not an argument that persistent activity is not present somewhere else in the PFC (9/10)
- We have argued that persistent activity does not imply a perfectly regular firing rate at the level of single neurons. The collective activity of multiple neurons is what maintains information. See this review for a more detailed explanation: www.jneurosci.org/content/38/3...
- However empirical validation was lacking until now. Enter modern neurophysiological techniques, e.g. Neuropixel recordings from primates (7/10)
- This has led to the idea that observed persistent activity is an “artifact of averaging”: it only becomes evident when firing rate from multiple trials is averaged together, creating a mere illusion of persistence (4/10)
- Alternative theories have sprung out, instead, suggesting that “activity-silent” mechanisms allow information to persist over periods when firing ceases (5/10)
- The neural basis of working memory has been debated. What we like to call “The Standard Model” of working memory posits that persistent discharges generated by neurons in the prefrontal cortex constitute the neural correlate of working memory (2/10)
- A thorn in the side of this theory, however, has been that the firing of cortical neurons is quite irregular; individual neurons rarely exhibit continuous, uninterrupted firing throughout the entire delay period of working memory tasks (3/10)
- I’m grateful! Especially in light of the nontraditional-but-passionate career moves I’ve made recently (a book; a research pivot). I was unsure how those would go over; this feedback expresses Uni support. That means a lot (especially in these complex times). pan-school.sas.upenn.edu/news/nicole-...
- Congratulations
- Some funding good news for a change (from AAAS policy alert) The House and Senate released a final version of the National Defense Authorization Act. Of importance to the research community, the bill prohibits the DOD from imposing a 15% cap on indirect costs to institutions of higher education.
- It looks like Congress has little appetite for continuing the DOGE capping of indirect-costs fight
- Bluesky running neck and neck with truth social www.pewresearch.org/internet/202...
- Very sad analysis of the science funding situation in the US right now www.nytimes.com/interactive/...
- October and November NIH grant submission deadlines will be extended. Study sections scheduled between October 1 and November 14 have been cancelled and will be rescheduled. grants.nih.gov/grants/guide...
- I got a similar message. My study section is being rescheduled for 2 partial days in January. Only 1/3 of grants will be discussed.
- Is there a competition going on about who is going to screw science the most?
- A very nice summary of our article medicalxpress.com/news/2025-11...
- Who did this?
- Ok Mamdani won. Can we now reopen the government, please?
- A sad day for Neuroscience in the Netherlands.
- Dutch lawmakers have approved the phase-out of primate research at one of Europe’s biggest facilities. Neuroscientists are worried. By Lauren Schenkman #neuroskyence www.thetransmitter.org/animal-model...
- New paper from the lab: www.nature.com/articles/s41... A brief thread (1/10)
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View full threadBecause rhesus macaque brain development parallels human trajectories, these findings illuminate mechanisms of adolescent cognition and why connectivity disruptions may underlie psychiatric risk (9/10)
- Many thanks to the interdisciplinary team that made this study possible - and to my trainees Junda Zhu and Clement Garin who saw it to completion (10/10)
- Unlike prior emphasis on gray matter thinning (e.g. due to pruning of unwanted synapses), our study shows cortical volume & thickness poorly predict cognitive maturation. White matter maturation was the key driver (7/10)
- Long-distance tracts, including the superior fronto-occipital fasciculus and anterior cingulum, best predicted working memory precision and speed (8/10)
- Tracking monkeys from late childhood to adulthood, we combined behavior, MRI, and single-neuron recordings. Our overarching result was that working memory improved as frontal lobe structural connectivity strengthened (5/10)
- Prefrontal neuron firing rate generally increased through adolescence, while variability declined, and dimensionality of responses increased, supporting flexible coding and distractor resistance (6/10)
- It has been well known that improvement of cognitive performance in adolescence coincides with a number of structural changes in the brain, including volume and surface of the prefrontal cortex and maturation of white matter tracts (3/10)
- However the brain alterations responsible for the changes in neural firing rate, which is ultimately altering the maturing cognitive functions, have remained elusive (4/10)
- The prefrontal cortex, a brain area critical for executive functioning, has not reached its fully mature state yet in adolescence. Impulsivity, poor decision-making, sensation seeking are hallmarks of adolescent behavior (2/10)
- "Alberto Martín-Martín says that he is sympathetic to the aims of GScholarLens. But he is not sure that the tool achieves its goal [...]. Simply assigning different weights to study authors isn’t enough to capture the nuances of their contributions". www.nature.com/articles/d41...
- Senior Lecturer Position in Computational Neuroscience at Vanderbilt. Please disseminate. apply.interfolio.com/173997
- Vanderbilt is not rejecting the Compact on higher education.
- Study section would have wrapped up this week. No idea when it will restart after the government shutdown.
- US government shutdown
- Poorly conceived, vaguely worded, abruptly imposed. There is going to be a total mess in the landscape of H1 visa holders, including foreign postdocs and professors in the US.
- Open positions in Vanderbilt BME!
- I wouldn't really call this good news, but better than the alternative of NIH not spending its appropriated budget
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- Feel free to use and disseminate NERV! (10/10)
