Figure 1. Frequency coding in the nervous system: Threshold stimulus. 1  If a threshold stimulus is applied to a neuron and maintained (top, red trace), action potentials occur at a maximum frequency that is limited by the sum of the absolute and relative refractory periods (bottom, blue trace).
Phyllis, Kentucky. Phyllis is an unincorporated community located in Pike County, Kentucky, United States. U.S. Geological Survey Geographic Names Information System: Phyllis, Kentucky.
Boyd County, Kentucky. Boyd County is a county located in the U.S. state of Kentucky. As of the 2010 census, the population was 49,542. The county seat is Catlettsburg, and its largest city is Ashland. The county was formed in 1860.