Cycle-triggered averaging of respiration-related neuronal activity.

A computer system is presented which provides off-line computation of cycle-triggered histograms (CTH) of respiration-related neuronal activity. Binwidths of the histograms are freely selectable by software from 10 ms to 100 ms. For special evaluation purposes, CTHs can be standardized in different ways concerning cycle duration as well as amplitude. Time incidence of maximum frequency, center of gravity and expiration-to-inspiration phase transition within the respiratory cycle are computed. The system employs special hardware interfaces to an 8-bit microcomputer which are briefly described. Data acquisition, data manipulation and output handling of the results are performed by chaining 3 compiled BASIC programs. Some comments on peculiarities of the BASIC language concerning combined application of a BASIC interpreter and a BASIC compiler are brought up. The usefulness of the method is demonstrated by examples of CTHs computed from the activity of medullary respiration-related neurons as well as of the corresponding phrenic nerve mass activity.