Figure 1.

Schematic of tasks and neural recordings. (a) During the M1 recordings, a monkey performed an 8-target center-out reaching task. An LED marker (red) was attached to the monkey’s finger tip to track his movements, which were displayed as a cursor on the screen (blue). The monkey made reaches from the center of the screen to one (green) of eight peripheral targets (gray). The array placement in M1 is shown by the green square. (b) During the V1 recordings, a monkey fixated on a central spot (white) while drifting Gabor patches were presented peripherally. The array placement in V1 is shown by the blue square. (c) Voltage trace from M1 during a single reach trial with detection threshold settings from θ = 10σ to −10σ. θ = 1σ (orange) is permissive, capturing low voltage transients. θ = 5σ (light blue) is more restrictive, capturing only high voltage transients which likely correspond to spikes from a single neuron. (d) Waveform snippets for threshold crossings of 1σ, 3σ, and 5σ in C. As the threshold becomes more permissive (1σ, orange) there are more threshold crossings. As the threshold becomes more selective (5σ, light blue) the waveform becomes more consistent. (e) Using the exclusive window categorization method, threshold crossings for the channel are identified when the voltage trace passes into and out of the window defined by a particular threshold without passing into higher-threshold windows. A 1σ window (orange) and a 3σ window (yellow) are shown in this example. If the voltage trace crosses the 1σ threshold but not the 3σ threshold, it is classified as a 1σ crossing. As indicated with the black circles, we can successfully select the larger voltage fluctuations with the exclusive θ = 3σ and we capture the smaller fluctuations with the exclusive θ = 1σ.