Fig. 2: Stimulus-evoked local field potential recordings of organoid and cortex.

a Microphotograph of organoid implantation site (red outline) and surrounding cortex. Electrode pads of the graphene microelectrode array are highlighted; red channels are considered ‘organoid channels’ whereas blue and black channels overlay host cortex. Blue channels are in the vicinity of the visual cortex. b Single trial of a local field potential (LFP) recording during visual stimulation with 100-ms pulses at 2 Hz for 4 s (orange bars) with a white LED to the contralateral eye. All 16 channels are shown; colors of individual traces correspond to channel assignments defined in panel a. c Trial average of the LFP responses (mean ± sdv of 20 trials). d Color map indicating peak amplitude (top) and peak delay (bottom) of the response to the first light pulse as shown in panel c. The red dashed lines outline the implantation site, as in panel a. The observed delay between cortex and organoid is 5.7 ms (arrow, p < 0.01, Student’s one-tailed t test). Source data are provided as a Source data file. e Spectrogram (32–150 Hz) of the response (average of 20 trials). Inset: Enlarged spectrogram (1–150 Hz) of the channel overlaying organoid (channel 1) and visual cortex (channel 2). The recording shown in panels b–e was performed 69 dpi; the results shown are representative for a total of five animals.