Invariant visual representation by single neurons in the human brain.
Level 4 - case-series / case-control
Observational human intracranial single-unit electrophysiological recording series without a control group
PubMed 15973409 · doi:10.1038/nature03687
What was done
Electrophysiological activity was recorded from single neurons in the human medial temporal lobe (MTL) during the presentation of complex visual stimuli, including different images of specific individuals, landmarks, objects, and letter strings displaying their names.
What was found
The abstract reports no quantitative values or statistical metrics. A subset of MTL neurons demonstrated selective activation to strikingly different images of specific individuals, landmarks, or objects, and in some cases to letter strings spelling their names, indicating an invariant and sparse neural representation.
Why it matters
This provides direct electrophysiological evidence in humans of invariant, concept-level coding at the single-neuron level, suggesting a mechanism for transforming visual percepts into abstract long-term representations.
Limits
The abstract does not report the number of subjects, the total count of recorded neurons, response latencies, or statistical effect sizes. Human intracranial recordings are typically conducted in clinical populations (such as patients undergoing epilepsy evaluation), which may limit generalizability to healthy brains.