Fig. 1: Histology and endogenous alpha-band oscillations in awake head-fixed ferrets.

Histology verification of implant locations. a Ferret brain with marks (highlighted by rectangles) left by microelectrode array implants in LP, PPC, and VC regions. Outlines of cortical fields are based on a published ferret neuroanatomical atlas⁶⁷. Dashed lines indicate the location of cell-stained coronal cross-sections through the center of the multi-electrode array implanted sites shown below (i–iii). Corresponding anterior–posterior atlas coordinates are indicated below each section in mm, relative to the occipital crest. a.i Coronal cross-section through the LP implant region shows implant electrode tracks and endpoints (dark spots of cell agglomerations above red stars). a.ii Coronal cross-section through the PPC implant region demonstrates the tissue damage at the site of the electrode array caused by the removal of the implant during brain extraction (below red stars). a.iii Coronal cross-section through the VC implant region marked by tissue loss (below red stars) caused by the removal of the implant during brain extraction after completion of the experiment. “roc” indicates “reference to occipital crest”. b Sample 1-s length EEG, broadband extracellular recordings and local field potential signals (LFPs) from the posterior parietal cortex (PPC), visual cortex (VC), and lateral posterior nucleus/Pulvinar complex (LP) from a head-fixed awake ferret (resting state, no task performed by animal). c Spectral analysis of EEG and LFPs showing the spectrum (mean ± SEM) with error bars in the light background from three animals (each animal in a different shade of green). The scalp EEG signal demonstrated a weak alpha-band peak for all animals. PPC showed clear alpha-band activity (12–16 Hz) for all animals. LP showed prominent theta, gamma (35–50 Hz), and a weak alpha activity for all animals. A weak alpha-band activity is also evident for the visual cortex (VC) for all three animals. A closer look at PPC spectra indicates slight differences in the individual alpha frequency between animals (14.42, 12.32, 14.42 Hz for animals 1, 2, and 3 respectively). d Histogram of spike duration was defined as the time from trough to peak in PPC, LP, and VC. e Color-coded spike waveforms (mean ± SEM) were calculated for two identified clusters of narrow-spiking (red, n = 689 in PPC, n = 416 in VC) and broad-spiking (blue, n = 850 in PPC, n = 285 in VC) neurons in PPC and VC. LP neurons comprised only one cluster (n = 391).