Fig 1.
Sleep time is reduced and sleep fragmentation is increased in Grm2/3-/- mice.
Fig 1A-F depict immobility-determined sleep parameters derived from 3 separate days of video-tracking data. Fig 1G-I depict immobility-determined sleep parameters derived from 14 consecutive days of passive-infrared (PIR) data. (A & G) Average sleep profiles, (B & H) light phase sleep time, and (C & I) dark phase sleep time for Grm2/3+/+ and Grm2/3-/- mice during a 12:12 h light/dark (12:12 LD) cycle at 100 lux. (D) Average temporal distribution of sleep bouts, (E) number of light phase sleep bouts, and (F) light phase sleep bout duration in Grm2/3+/+ and Grm2/3-/- mice during 12:12 LD at 100 lux. Sleep was defined as a period of immobility of at least 40 s. Data in Fig 1A, D & G are presented in 2 h time bins. ZT = zeitgeber time. Note that methods do not yet exist to automatically compute parameters pertaining to the frequency and duration of sleep bouts from PIR data.
Fig 2.
Light sensitivity is increased by the genetic ablation or pharmacological inhibition of mGlu2 & 3.
All figures depict rest-activity or circadian parameters derived from wheel-running data, with the exception of Fig 2F, which is based on video-tracking data. (A) Free-running period length in constant dark (DD) does not differ between Grm2/3+/+ and Grm2/3-/- mice. (B) Free-running period length in constant light (LL) is greater in Grm2/3-/- than Grm2/3+/+ mice. (C & D) Phase delays induced by type I (Fig 2C) and type II (Fig 2D) phase-shifting light pulses are larger in Grm2/3-/- than Grm2/3+/+ mice. (E & F) Grm2/3+/+ and Grm2/3-/- mice show similar levels of negative masking during a type II light pulse, as assayed by wheel-running (Fig 2E) and video-tracking (Fig 2F). (G) In wildtype C57Bl/6J mice, phase delays induced by a type I light pulse are enhanced following the administration of the mGlu2/3 negative allosteric modulator (NAM) RO4432717.
Fig 3.
Dark phase wheel-running activity is reduced in Grm2/3-/- mice, but general home-cage activity is not.
Fig 3A-C depict activity parameters derived from 14 consecutive days of wheel-running data. Fig 3D-F depict activity parameters derived from 3 separate days of video-tracking data. Fig 3G-I depict activity parameters derived from 14 consecutive days of passive-infrared (PIR) data. (A, D & G) Average activity profiles, (B, E & H) light phase activity, and (C, F & I) dark phase activity for Grm2/3+/+ and Grm2/3-/- mice during a 12:12 h light/dark (12:12 LD) cycle at 100 lux. Data in Fig 3A, D & G are presented in 2 h time bins. ZT = zeitgeber time. AU = arbitrary units.
Fig 4.
Representative actograms of Grm2/3+/+ and Grm2/3-/- mice during a 12:12 h light/dark (12:12 LD) cycle.
Each row depicts a single 24 h period. The light and dark grey shading corresponds to periods of (100 lux) light and dark, respectively. (A) Representative wheel-running actograms. The black bars denote periods of wheel-running activity, binned in 6 min epochs. The height of the bars corresponds to the number of wheel rotations within each epoch. (B) Representative passive-infrared (PIR) actograms. The black bars denote periods of home-cage activity, binned in 6 min epochs. The height of the bars corresponds to % time active within each epoch. ZT = zeitgeber time.
Table 1.
Descriptive statistics for selected rest-activity parameters derived from 14 consecutive days of wheel-running data.
Fig 5.
The diurnal rest-activity rhythms of Grm2/3-/- mice are dependent on the assay used to measure activity.
Fig 4A–4D depict rest-activity parameters derived from 14 consecutive days of wheel-running data. Fig 4E–4H depict rest-activity parameters derived from 14 consecutive days of passive-infrared (PIR) data. (A & E) Daily activity bouts, (B & F) daily activity bout duration, (C & G) interdaily stability, and (D & H) chi-square periodogram amplitude in Grm2/3+/+ and Grm2/3-/- mice during a 12:12 h light/dark (12:12 LD) cycle at 100 lux. Activity bouts were defined using pre-established criteria, as described in the materials and methods. AU = arbitrary units.
Table 2.
Descriptive statistics for selected rest-activity parameters derived from 14 consecutive days of passive-infrared (PIR) data.