# Berkeley and Princeton: macaque neurons alternate between seen and suppressed faces 15 times a second

- Published: 2026-11-05 21:43 UTC
- Section: Life & Health › Neurotechnology
- Tags: binocular flash suppression, conscious perception, inferotemporal cortex, prefrontal cortex, 15 Hz rhythm, Neuropixels recordings, face space decoding, bioRxiv preprint
- URL: https://realtech.media/news/rt-2dfc7ee8487a20f69709d479_berkeley_and_princeton/

**In a preprint on two macaques, the same neurons in inferotemporal and prefrontal cortex switched between a visible and a suppressed face about every 60 ms.**

![Berkeley and Princeton: macaque neurons alternate between seen and suppressed faces 15 times a second](https://sgzwpqqelzmajkcubgkl.supabase.co/storage/v1/object/public/rt-media/2026/11/1a9b753c4dbae936.jpg)
*ZME Science*

Neuroscientists at the University of California, Berkeley, and Princeton University, led by Janis K. Hesse and Doris Y. Tsao, report that the primate brain alternates between a consciously seen image and a suppressed one about 15 times per second, according to a bioRxiv preprint covered by ZME Science. [1] The work used two rhesus macaques and has not yet passed peer review. [1]

The authors argue that conscious access depends not only on where information is processed but also on when neurons fire. [1] Earlier recordings, including the 2025 COGITATE Consortium study in Nature, did not reveal a pure neural representation of conscious perception in any recorded region during rivalry. [1]

## Binocular flash suppression and recordings

The team used binocular flash suppression. Each macaque wore red-and-cyan 3D glasses, so each eye received a different face. [1] When a second face was flashed to one eye, the first dropped out of awareness although both images stayed in front of the eyes. [1] To validate the effect, 14 human volunteers viewed the same display and reported that the second face dominated their awareness 82 percent of the time. [1]

The researchers then inserted Neuropixels probes and recorded hundreds of neurons at once across 1,500 face presentations. [1] The targets were face-selective areas of the inferotemporal cortex and the prefrontal cortex. [1]

## Decoding faces in 60-millisecond windows

First, the monkeys viewed 1,500 faces without rivalry. An algorithm learned to translate the spikes of 3,501 neurons into 50 measurements of facial shape and appearance. [1] Averaged over a full second, the decoded output was a blurred merger of both faces. [1] Split into alternating 60-millisecond states, it gave sharp reconstructions of the consciously seen face in one state and of the suppressed face in the other. [1]

The same neurons produced both portraits, rather than two separate groups of cells. [1] During conscious windows, neurons were about 21 percent more sensitive to facial features than during suppressed windows. [1] The authors say the suppressed stimulus is not a weak residual trace but occupies the same face space. [1]

The study covered specific visual and frontal areas in only two monkeys. [1] What drives the 15-hertz rhythm, and why only some time segments reach awareness, remains unknown. [1]

## Sources

1. [ZME Science](https://www.zmescience.com/medicine/mind-and-brain/your-brain-flickers-between-two-realities-15-times-a-second)

---

Source: RealTech, realtech.media — https://realtech.media/news/rt-2dfc7ee8487a20f69709d479_berkeley_and_princeton/