 With further increase in the trial, strength \cal S of CR  increases due to strong LTD in the well-matched spiking group.
<meaning-changed>  With further increase in the trial, strength \cal S of CR  increases due to strong LTD in the well-matched spiking group.
 With further increase in the trial, strength \cal S of CR (corresponding to the amplitude of eyelid closure) increases due to strong LTD in the well-matched spiking group.