
Blocking the hyperpolarization-activated inward current (Ih) alters the pyloric rhythm's ability to smoothly adjust its frequency and phase in response to temperature changes, revealing distinct mechanisms for transient and persistent responses.


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Motor systems operate over a range of frequencies and relative timing (phase). We studied the contribution of the hyperpolarization-activated inward current (Ih) to frequency and phase in the pyloric rhythm of the stomatogastric ganglion (STG) of the crab, Cancer borealis as temperature was altered from 11°C to 21°C. Under control conditions, the frequency of the rhythm increased monotonically with temperature, while the phases of the pyloric dilator (PD), lateral pyloric (LP), and pyloric (PY) neurons remained constant. When we blocked Ih with cesium (Cs+) PD offset, LP onset, and LP offset were all phase advanced in Cs+ at 11°C, and the latter two further advanced as temperature increased. In Cs+ the steady state increase in pyloric frequency with temperature diminished and the Q10 of the pyloric frequency dropped from ∼1.75 to ∼1.35. Unexpectedly in Cs+, the frequency displayed non-monotonic dynamics during temperature transitions; the frequency initially dropped as temperature increased, then rose once temperature stabilized, creating a characteristic “jag”. Interestingly, these jags were still present during temperature transitions in Cs+ when the pacemaker was isolated by picrotoxin, although the temperature-induced change in frequency recovered to control levels. Overall, these data suggest that Ih plays an important role in the ability of this circuit to produce smooth transitory responses and persistent frequency increases by different mechanisms during temperature fluctuations.

### Competing Interest Statement

The authors have declared no competing interest.

Ih Block Reveals Separation of Timescales in Pyloric Rhythm Response to Temperature Changes in Cancer borealis

blocking-the-hyperpolarization-activated-inward-current-ih-reveals-separation-of-timescales-in-the-pyloric-rhythm-s-response-to-temperature-changes-in-the-crab-cancer-borealis


Blocking the Hyperpolarization-Activated Inward Current (Ih) Reveals Separation of Timescales in the Pyloric Rhythm's Response to Temperature Changes in the Crab Cancer borealis
