Simulink real time

We constructed a test platform from a motorized linear stage and a 6-axis force/torque transducer (Nano 17 Titanium, ATI) as shown in Supplementary Fig. 25a. The motion control and force/torque measurements were achieved through a computer running Simulink Real-Time (MATLAB & Simulink, MathWorks) with the data acquisition hardware (PCIe-6259, National Instrument). The platform was designed to be compatible with all of the tests described below with slight modifications.

Optogenetic inputs were delivered using a 470 nm light emitting diode (LED, ThorLabs M470F3) coupled to a 400 um diameter optical fiber (ThorLabs M28L01) manually positioned on the skull surface near the recording probe. Command voltages for optogenetic inputs were controlled by custom scripts in MATLAB and Simulink Real-Time (MathWorks, Natick, MA), sampled at 1 kHz.
All optogenetic input began with a ramp of the LED intensity that was 250 ms in duration, serving to minimize transient neuronal effects from rapid increases in LED intensity as well as to minimize animal whisking^{36 (link)}. In ramp-and-hold LED trials, the LED intensity was then held fixed at values ranging from 4 to 30 mW/mm² for 500–650 ms. Manipulations to vary L6CT synchrony included LED inputs that were 500–650 ms in duration labelled as either 500 Hz, 100 Hz, or 10 Hz trials. The input for 500 Hz trials consisted of uniformly distributed white noise. Inputs for the 100 Hz and 10 Hz trials consisted of uniformly distributed white noise that was low-pass filtered (3rd order Butterworth filter) at their respective frequencies. For all trials, the inter-trial interval was a minimum of 3.5 times the duration of the LED input with added uniformly distributed random jitter per-trial ranging from 0 - 0.1/0.5 ms.