Fig 1.
(a) NBI includes an entrance atrium monitored by a motion sensor and a nest compartment monitored by a thermal and IR camera (illuminated by an IR LED). (b) Path of mouse to the nest compartment. (c) Representative image captured from thermal camera showing low, 80-×-60-pixel resolution. (d) Sheathing to protect wires from mice. (e) Mill used to cut plastic frame. (f) NBI placed in cage showing single-board computer (Raspberry Pi) to execute imaging programs and record data (note this current NBI system is powered by a wall plug). IR, infrared; LED, light-emitting diode; NBI, nesting box imager.
Fig 2.
Actograms showing activity from two separate animals over periods of 48 hours.
The x-axis represents time, and motion is reported in arbitrary units on the y-axis. (a) Schematic showing light/dark cycle. White bars indicate light, and gray bars indicate dark. The animals were held under “summer” conditions of 16 hours light and 8 hours dark. (b) Activity data recorded from NBI atrium PIR motion sensor. (c) Activity data recorded from two cage-top PIR motion sensors. Output from each sensor was weighted equally and summed. (d) Activity data combined from NBI motion sensor and two cage-top motion sensors. Activity from each of the three PIR sensors was weighted equally and summed. (e) Reference activity recorded from a Sable Systems International ADX-C pad placed under the cage. This method of activity recording detects all vibration in the cage caused by animal movement. The data underlying this figure can be found in S1 Data. NBI, nesting box imager; PIR, passive infrared.
Fig 3.
Noncontact thermal imaging of mouse models in NBI.
(a) Calibration curve of IR camera (Lepton units) to temperatures observed on thermal cycler and comparison to temperatures measured by thermistor probe (n = 6 measurements for each condition, one standard deviation shown as error bars). (b) Heat map of mouse head using calibration curve found in (a). (c) Representative images from NBI of a nested mouse—visible image of mouse back (i) and corresponding thermal, IR image of mouse (ii); red box shows region of analysis with 10% top pixels. (d) Surface body temperature of a meadow jumping mouse that had entered torpor and cooled to room temperature (approximately 22°C). Spontaneous arousal from torpor is detected as a rapid increase in surface body temperature at around 200 seconds. The data underlying this figure can be found in S2 Data. IR, infrared; NBI, nesting box imager.
Table 1.
Validation of temperature measurements.
Average of n = 5 images for each condition (all in °C).
Fig 4.
Respiratory monitoring of a single mouse exiting torpor.
(a) Visible spectrum image of mouse constructed with green pixel data. Solid white box indicates manually selected region of interest. (b) Binary-converted (1-bit) image of region of interest (solid white box from [a]). Green pixels indicate followable features recognizable to the Matlab centroid function. Dashed white box encloses shape followed for breathing analysis. (c) Y-pixel position of object of interest with respect to time. (d) Mouse breathing frequency with respect to time. Solid blue line indicates frequency calculated based on a Fourier transform of (c). Red dots indicate breathing frequencies measured by direct video observation and breath counting. The data underlying this figure can be found in S3 Data.