Self et al. 2025 — First human LGN single-unit recordings (Nat Commun)

Self MW, Vilela-Filho O, Neuenschwander S, et al. “Effects of eye closure on the spiking activity of human lateral geniculate neurons.” Nat Commun 16, 10402 (2025). DOI: 10.1038/s41467-025-65383-x Published 24 November 2025 (open access CC BY 4.0)

Significance

First-ever characterization of single-unit spiking activity in the human LGN. Previously, human LGN knowledge was based solely on fMRI and animal models (cats, macaques). Directly relevant to Phosphoenix’s LGN prosthesis strategy.

How recordings were made

DBS electrodes implanted in the LGN of two drug-resistant epileptic patients in Brazil, arranged serendipitously via Roelfsema’s contact Sergio Neuenschwander (from a chance encounter at a retirement party). LGN first mapped with high-impedance electrodes while patients were awake; spiking recorded at multiple depths.

Key findings

• Human LGN cells respond to strong visual stimulation with high-frequency bursts.
• Receptive field properties resemble macaque: circular ON/OFF subfields.
• Dorsal layers (parvocellular): red-green opponency, high spatial frequency tuning.
• Ventral layers (magnocellular): preferences for high temporal frequencies.
• Responses largely monocular (consistent with primate LGN anatomy).
• Eye closure: decreases spontaneous activity of broad-spiking neurons ipsilateral to closed eye; increases narrow-spiking (interneuron) activity — suggesting interneurons gate LGN activity during eye closure.

Relevance to LGN prosthesis design

• Confirms human LGN has the same laminar, retinotopic, and functional organization as macaque — validating the translation of macaque stimulation data to humans.
• ON/OFF concentric RFs = well-defined, predictable phosphene locations for encoding.
• Magno/parvo layer architecture = potential for separate motion vs. detail stimulation channels in a future high-channel-count implant.
• Roelfsema is both co-author and Phosphoenix/SIGHTED scientific coordinator: this paper represents direct human translational evidence underpinning the company’s LGN target choice.

Authors

Matthew W. Self (NIN, lead), Osvaldo Vilela-Filho (Brazil, neurosurgeon), Sergio Neuenschwander (Brazil), and others. Pieter R. Roelfsema (NIN/Sorbonne, senior).