Picohertz, abbreviated as pHz, is a unit of frequency measurement. It measures the number of cycles per second and is equivalent to one trillionth (10-12) of a hertz. Picohertz can be used to measure extremely low frequencies such as those generated by some sources in space or even within our own bodies.

In terms of applications, picohertz has been used for various purposes including radio astronomy research and medical imaging technology such as MRI scans. In particular, it has become increasingly important in the field of neuroscience where researchers are able to study brain activity at an unprecedented level with its help.

Additionally, due to its high accuracy and precision when measuring low frequencies it also finds use in fields like telecommunications engineering where signals need exacting measurements for proper analysis and interpretation.

Overall, then we can see that while not commonly known outside certain specialist circles, picohertz still plays an important role. Scientifically speaking as well as practically too through applications ranging from neuroscience research all the way up into telecommunications engineering work itself – making this small but powerful unit one worth being aware of!