Adxl335

In order to track the gait cycle during walking in the Lokomat accelerometers were positioned on each leg above the metatarsal bones (Fig 1A). The accelerometers used were type ADXL 335 (Analog Devices One Technology Way, MA, USA).

To exclude data with excessive motion, an accelerometer (ADXL335, Sainsmart, Analog Devices) was attached below the mouse hammock. The accelerometer readout was synchronized with 2-photon imaging and recorded using a dedicated data acquisition system (National Instruments). During periods with extensive body movement (e.g., grooming behavior), the accelerometer signal crossed a predefined threshold, above which data were rejected. In pilot experiments, in addition to the accelerometer, a webcam (Lifecam Studio, Microsoft; infrared filter removed) with infrared illumination (M940L3-IR [940 nm] LED, Thorlabs) was used for video recording of the mouse during imaging. The videos and accelerometer readings were in general agreement with each other. Therefore, accelerometer data alone were used to calculate the rejection threshold. Because every point was revisited 20 times, typically at least 10 repetitions (or 500 excitation cycles) were unaffected by motion and were used to estimate τ. The MATLAB function lsqnonlin used to fit phosphorescent decays returned the residual error for each fit, which we plotted against the number of cycles (S9 Fig). At around 500 cycles, the error stabilized at a low level. Therefore, we quantified points where at least 500 cycles were available.

The GT3X activity sensor consists of a three-axial acceleration sensor (adxl335, Analog Devices, Boston, USA; range: ±3 g; sampling rate: 30 Hz; resolution: 12 bit). The sensor weighs 27 g, measures 3.8×3.7×1.8 cm³, can be worn either on the hip or on the wrist and allows measurements for up to 21 days. The recorded data is saved as activity counts on a 4 MB flash memory and transferred to the computer via standard USB 2.0 interface.

Recordings were collected before the initial activation of the DBS system at initial programming (IP), which was 1 month after implantation of the DBS leads, and off all therapy after 6 months, and then 1, 2, 3, 4, and 5 years after the initial programing (IP) visit. At the follow‐up visits, stimulation was turned off and seated resting state local field potential (LFP) recordings were collected 60–75 min later. This timing was chosen since we have previously demonstrated that the effect of DBS on the LFP is washed out well before this time window.²⁰ Limb or head movement was monitored using angular velocity sensors on the hands and feet (Motus Bioengineering, Inc., Benicia, CA), a triaxial accelerometer on the forehead (ADXL335, Analog Devices, Norewood, MA), and with synchronized video recordings (30 FPS) from a USB web camera (C930e, Logitech, Lausanne, Switzerland). The MDS‐UPDRS III – motor subscale was performed by a certified rater preoperatively (on and off medication), off medication at IP, and then off all therapy at all follow‐up visits after DBS had been turned off for at least 60 min.

To monitor the rats’ head movements continuously, we placed a small 3-axis accelerometer (ADXL 335, Analog Devices) on the recording head-stage (Figure 1—figure supplement 1). The output of the accelerometer was sampled at 7.5 kHz per axis. We also recorded 24/7 continuous video at 30 frames per second with a CCD camera (Flea 3, Point Grey) or a webcam (Agama V-1325R). Video was synchronized to electrophysiological signals by recording TTL pulses from the CCD cameras that signaled frame capture times.

During recordings, we magnetically attached to the intranasal cannula a pressure sensor (24PCAFA6G, Honeywell) integrated into a custom-made wireless headstage based on the DIGI XBee module powered with 3 V from a Li-ion battery (weight 20–23 g, see Figure 1, schematics available on request). The headstage included a 3-axis accelerometer (ADXL335, Analog Devices) with signal filtered to 50 Hz 3 dB bandwidth with 0.1 μF capacitors. Voltage outputs from this component are linearly proportional to acceleration (300 mV/g with 3 V supply voltage). The pressure and acceleration signals were transmitted with a sampling rate of 200 Hz each and digitized in synchrony with the ultrasound. The transmission imposed a 2-sample (10 ms) delay which was not corrected.