Gabriel Kreiman, Itzhak Fried, Christof Koch

Single neuron correlates of subjective vision in the human medial temporal lobe

Proceedings of the National Academy of Sciences, (2002) 99:8378-8383 PDF

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Visual information from the environment is transformed into perceptual sensations through several stages of neuronal processing. Flash suppression constitutes a striking example where the same retinal input can give rise to two different conscious visual percepts. We directly recorded the responses of individual neurons during flash suppression in the human amygdala, entorhinal cortex, hippocampus and parahippocampal gyrus, allowing us to explore for the first time the neuronal responses in untrained subjects at a high spatial and temporal resolution in the medial temporal lobe. Subjects were patients with pharmacologically intractable epilepsy implanted with depth electrodes to localize the seizure onset focus. We observed that the activity of two-thirds of all visually selective neurons followed the perceptual alternations rather than the retinal input. None of the selective neurons responded to a perceptually suppressed stimulus. Therefore, the activity of most individual neurons in the medial temporal lobe of naïve human subjects directly correlates with the phenomenal visual experience.