A self-sustained oscillator is able to entrain just to certain combinations of entrainment amplitudes and periods that define the so-called entrainment region or 1∶1 "Arnold tongue" (see Figure 1D).
Clock gene expression in zebrafish organ cultures can be entrained to LD cycles [16], and even single zebrafish cell culture cells are able to entrain their clocks in response to light pulses [17], [18].
Our data suggests that temperature is also a strong signal for circadian setting, since low amplitude cycles (i.e., 1°C) are able to entrain locomotor activity cycles.
Although glaucomatous rats are able to entrain their locomotor activity to the LD cycle at all light levels, they require more time to re-adjust to a shifted LD cycle and show significantly greater variability in activity onsets in comparison with normal rats.
A modulated light exposure composed of three different light levels during scheduled wakefulness, including two 45-min light pulses of 9,500 lux, was able to entrain subjects at a normal phase angle to a T-cycle 1h longer than each subject's intrinsic circadian period [31].
Dexamethasone and temperature cycles were able to entrain the cartilage circadian rhythm [ 9].
We delivered sinusoidal tACS, which is able to entrain [19], [20] and also hypothesized to be able to desynchronize [21], [22] neuronal oscillations.
The melatonin rhythm plays the role of an endogenous synchronizer, which peaks at night and is able to entrain rhythms, such as temperature, hormone release, and the sleep-wake cycle via receptors in the SCN [ 15, 16].
The paragraph now reads: "Therefore, the Phox2b on /Atoh1 on subset of RTN neurons is able to entrain phrenic nerve activity a lumbar motor output and thus active expiration persisted after the depletion of Atoh1 in RTN neurons".
Therefore, the Phox2b on /Atoh1 on subset of RTN neurons is able to entrain phrenic nerve activity and thus inspiration as previously reported in adult rats of neurons in the RTN region defined by Phox2b expression alone (Abbott et al., 2009, 2011).
