A Microcomputer System Computing Statistical Quantities from Intervals between Nerve Impulses with Different Heights (II)

Analysis of the multi-nerve impulses by means of electrophysiological method has become important to understand the parallel information processing in the nervous system. We have previously reported the multi-impulse analyzing system by using the microcomputer (MEK 6800 D-II) and additional electronic circuits. Impulses from two nerve cells or more were classified according to their amplitude. That was executed by machine language program. The system operated sufficiently to analyze the impulses recorded in nerve bundle from mechanoreceptors on the crayfish antennule. However, there were a few problems in the system. The one was a slight time lag of the peak discriminator which detected the peak time of an impulse and triggered A-D converter. The other was flicker of realtime display caused by sequential time sharing between data input routine and display one. Those problems are improved in the present new system. The former is overcome by using the peak hold circuit in place of the peak discriminator, and the latter by introducing the interrupt technique when both impulse height and interspike interval are gotten into the microcomputer. An additional microcomputer (CBM) which can execute BASIC program is connected with the previous one in order to supply the lack of programing flexibility on the machine language system. The connection between those two microcomputer consists of a control line and 8-bit bidirectional data bus. By using the only one control line, the program for data transfer is made as simple as possible. Then, the new system is made to reconcile processing speed in machine language system and flexibility in BASIC system. Furthermore, CBM 3032 have an input-output port based on the standard IEEE 488 bus. A X-Y plotter (WX 4671) is connected with this port through an interface circuit. All of the experimental result can be printed out by the plotter. The present multi-impulse analyzing system possesses sufficient accuracy and flexibility. The system can be used not only in our electrophysiological experiment but also in one of another nervous system.