Science1 publisher2 min readPublished
UCL team rebuilds 10-second movies from single-neuron recordings in mouse visual cortex
Because the recordings come from identified single cells, the number of neurons feeding a reconstruction is something the experimenter controls, and the output can be laid beside the movie the mouse actually watched.
The Scientist · Science desk

What happened
- Researchers led by University College London rebuilt 10-second video clips using only the recorded activity of neurons in the visual cortex of mice.
- The input came from individual brain cells rather than the broader brain imaging signals that human decoding studies have used with fMRI.
- The encoding model at the centre of the method was built by a different research team for the 2023 Sensorium Competition to predict how single neurons respond while mice watch movies.
- After training, the team recorded a mouse watching a video that had been kept out of the training data and reconstructed a 10-second clip resembling it from that activity alone.
- The activity itself was read with a microscopic imaging method that marks an active cell by the localized rise of calcium inside it.
Compiled by The ScientistSomething wrong?How this is made
Why it matters
- capability With the input measured cell by cell, how many neurons feed a reconstruction becomes a variable the experimenter sets, and Bauer reports accuracy climbing as more cells are added.
- constraint Every reconstruction passes through the encoding model, so the model's blind spots would be read as the brain's unless a lab checks them separately.
- precedent The stated ambition of comparing how different species see the same surroundings now depends on collecting comparable single-neuron recordings in each of them.
Decoding here runs an encoder backwards. The team first asked the model how the recorded neurons would behave in front of a blank screen, then compared that prediction with what those neurons actually did while the mouse watched a movie [7]. The difference drove an algorithm that edited the pixels of an initially blank movie, and with each adjustment the reconstruction became more like the clip the animal had been shown [9]. So the output is the movie that best explains the recording under that particular model of those neurons. A visual feature the encoding model cannot express will not appear in the reconstruction, whatever the cortex did with it.
The model's origin matters for the same reason. It came out of the 2023 Sensorium Competition, and its job was predicting how single neurons respond as a mouse watches a movie, with the animal's movements and pupil diameter among the inputs [6]. The UCL group refined the approach on the same dataset [7].
Joel Bauer, the lead author, is at the Sainsbury Wellcome Centre at UCL [16]. He said the field needed a more general tool: "The current methods of understanding what specific groups of neurons are representing are not very generalizable to situations which haven't been specifically tested for" [12]. His group's interest is the gap between what sits in front of an animal and what the cortex holds, and mapping that gap could show which visual features get emphasised, altered or dropped [14]. The work is published in eLife [2].
On the held-out clip, Bauer said: "The accuracy of the reconstructions improved with the inclusion of data from more individual neurons, demonstrating the importance of comprehensive neural data" [13]. The reported improvement comes without a stated neuron count. The held-out test shows that the recorded activity carried enough information about a scene the model had never been trained on for the pipeline to infer it, so the system was not returning a memorised video [11].
The transformation from scene to internal representation is the target this method was built to attack, and the study demonstrates the method [1][14]. A reconstruction of this kind is a statement about the information in the cells that were recorded, not about what the mouse experienced.
What to watch
- Whether reconstruction quality keeps rising with neuron count or saturates, and at what population size.