Effects of respiration on heart rate in an aversive classical conditioning situation

Previous research has attempted to assess respiratory influences on the cardiac response in anticipation of shock. These studies have utilized either control of rate of respiration, sustained inhalation or exhalation, control of amplitude of respiration, or some combination of these. In the present study, 30 18-25 yr. Old male undergraduate ss inhaled at the start of each trial, held their breath, exhaled during a 4-sec tone, and then refrained from breathing in again until they received an electric shock. Thus, each trial corresponded to 1 breath cycle. Cs-ucs interval and duration of breath holding were varied orthogonally. The 3 major findings were: (a) a reliable, large magnitude (20 bpm) deceleration followed the inhalation at the start of each trial; (b) the acceleratory component of the cardiac response in anticipation of shock increased with cs-ucs pairings, and therefore could not be considered an orienting reflex; and (c) the biphasic form of the cardiac response occurred over an 8-10 sec. Period, regardless of cs-ucs interval, and appeared to be "locked" to the cs rather than to the ucs. (french summary) (16 ref.)