Journal: Proceedings of the National Academy of Sciences of the United States of America

Article Title: Spontaneous activity competes with externally evoked responses in sensory cortex

doi: 10.1073/pnas.2023286118

Figure Lengend Snippet: Rats detect forepaw vibration. ( A , Upper ) Simplified illustration of the behavioral setup. A lever was enclosed between two walls and could be moved on the horizontal dimension. Piezo actuator clamped to the lever conveyed the vibrotactile stimulus. For more details, see SI Appendix , Fig. S1 . ( A , Lower ) Task design. To start a trial, the freely moving rats had to pull the lever in their preferred direction and hold it for one of three pseudorandom durations. Upon vibration (stim), the rats had to release the lever within 120 to 620 ms to gain a sucrose water reward. In 20% of the trials, an actuator located in the chamber but clamped to a lever out of the rat’s reach was activated (ctrl). The rat had to keep holding for longer than 620 ms in order to gain a reward. ( B ) Holding training progress. Mean ± 95% CI of the holding duration of five rats. Rats had to hold the lever passed the threshold position for at least the holding time to obtain a reward. ( C ) Rats learned to hold the lever steadily and respond to the cue. Mean ± 95% CI of the lever position (measured by the angle encoder) at “hit” trials. Time t = 0 indicates the stimulus onset. Horizontal line at ∼1 mm indicates the hold/release threshold. Trials with holding time = 600 ms are indicated in black, 1,600 ms in gray, and 2,600 ms in light gray. ( D ) Histogram of reaction (release) times in stim trials. Vibration was presented from t = 0 to t = 300 ms. Black area: RTs within the allowed response window. Gray: RTs of early or late release trials. n = 25 sessions from five rats. ( E ) Hit rate: Ratio of trials with lever release within <620 ms after real stimulus onset, from all vibration trials. False alarm rate: Ratio of responded trials within <620 ms after control actuator onset from all control trials. Bars indicate the mean and error bars the 95% CI. Gray circles and lines show individual sessions. *** z = 5.977, P = 2.28 × 10 −9 , Wilcoxon rank sum test. ( F ) Intrinsic signal imaging. ( Left ) Schematic illustration of procedure. ( A ) The brains of lightly anesthetized rats were imaged through the thinned skull under 855 nm illumination. Upon vibrotactile stimulation of the forepaw ( B ), responsive cortex absorbed more light compared to blank trials. See for details. ( Right ) Responsive areas of five rats overlaid on projected published somatotopic map . N (color bar) indicates number of rats. Blue dashed line: assumed SI forepaw location based on map. p, palm; t, thumb (pollux); d1 to 5, digits; dfp, dorsal forepaw; fm, forelimb muscle; hm, hindlimb muscle; w, wrist whiskers; dhp, dorsal hindpaw; HP, hindpaw; (Scale bar: 1 mm.) A, anterior; L, lateral. ( G , Left ) Schematic illustration of implantation locations of the 2-shank, 32-channel probe. SI: primary forelimb somatosensory cortex. M1: primary motor. M2: secondary motor. Dashed lines: estimated borders between cortical layers. ( G , Right ) Magnified illustration of the probe, indicating the location of channel relative to surface and tip and estimated borders between cortical layers as shown in H and I . ( H , Left ) Peristimulus time histogram (PSTH, Top ) and raster plots ( Bottom ) of representative single units in layers 2/3, 4, 5, and 6. Blue: hit. Red: miss. Green: CR. Yellow: FA. Inset : averaged waveform of the unit. (Scale bar: 1 ms/250 μV.) ( H , Right ) Number of positively modulated (black), negatively modulated (gray) and nonmodulated (white) single units. ( I ) Mean ± 95% CI of the LFP color coded as in H . Vertical black lines indicate stimulus onset and offset ( t = 0 to 0.3 s). (Scale bar: 200 μV.) CR; correct rejection. FA; false alarm. See also SI Appendix , Figs. S1, S2, S8, and S9 .

Article Snippet: Without removing the dura, we inserted the 2-shank, 32-channel laminar probes (E32+R-150-S2-L6-200-NT, ATLAS Neuroengineering) at a speed of 5 μm/s using a custom-made motorized inserter to a final depth of 2,300 μm.

Techniques: Imaging

Journal: eLife

Article Title: Columnar processing of border ownership in primate visual cortex

doi: 10.7554/eLife.72573

Figure Lengend Snippet: ( A ) Top row shows set of border ownership stimuli. Black dotted outline represents the classical receptive field (cRF). Bottom row shows that the stimulus information in the cRF is identical for stimuli 1 and 2, and for stimuli 3 and 4. ( B ) Dot rasters showing responses to the stimuli in A from a border ownership-selective well-isolated unit. The symbol on the left indicates the preferred side of border ownership for the unit. Average spike rates in the stimulus window are indicated above the panels. ( C, D ) Similar to A and B, for a multiunit cluster recorded during a different penetration. ( E ) Cartoon showing the recording setup. A laminar multielectrode probe with 32 channels was lowered through a transparent artificial dura (AD), orthogonal relative to the cortical surface. ( F ) Laminar compartments (superficial; granular [input]; deep layers) were estimated using current source density (CSD) analysis. See text for definitions of the compartments and explanation of symbols. Distance from center of granular layer is shown along ordinate on the left, and the number of electrode contact on the right (higher numbers correspond to more superficial contacts). Black solid triangle indicates position of most superficial electrode contact on which multiunit activity was recorded. Data are from the same penetration during which the unit in B was recorded. The position of the green symbol indicates that this unit was positioned in the deep layers. See also – . ( G ). Similar to F, for the penetration during which the unit shown in D was recorded. ( H ) Receptive field contours for multiunit activity recorded on different electrode contacts from the penetration shown in F. Contours are drawn at z = 3. Orthogonality of the penetration was evaluated by fitting a line through the centers of the receptive field contours and computing D , the distance between pairs of azimuth and elevation coordinates of receptive field centers per mm depth (Methods). ( I ) Similar to H, for the penetration shown in G.

Article Snippet: A linear multielectrode probe (32-channel single-shaft acute probes, 100 μm electrode pitch [ATLAS Neuroengineering, Leuven, Belgium]) was mounted on the chamber using a hydraulic microdrive on an adjustable x – y stage (MO-972A, Narashige, Japan).

Techniques: Isolation, Activity Assay

Journal: eLife

Article Title: Columnar processing of border ownership in primate visual cortex

doi: 10.7554/eLife.72573

Figure Lengend Snippet:

Article Snippet: A linear multielectrode probe (32-channel single-shaft acute probes, 100 μm electrode pitch [ATLAS Neuroengineering, Leuven, Belgium]) was mounted on the chamber using a hydraulic microdrive on an adjustable x – y stage (MO-972A, Narashige, Japan).

Techniques: Software