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. Author manuscript; available in PMC: 2013 Mar 14.
Published in final edited form as: Neurobiol Learn Mem. 2006 Feb 8;86(1):47–65. doi: 10.1016/j.nlm.2005.12.010

Fig. 2.

Fig. 2

Cardiac signal and quantification. (A) Example of a typical biphasic cardiac record (bradycardia followed by tachycardia), delimiting analysis periods: pre-trial (PRE), minimum (MIN), and maximum (MAX) heart rates. Horizontal black bars denote tone presentation in (A) and (B). (B) Quantifica-tion of heart rate; the shaded areas indicate the analysis periods. For each tone presentation, successive inter-beat intervals (IBIs) were calculated and converted into beats per minute (BPM). The difference between the minimum and maximum rates was calculated (ΔBPM) and analyzed. (C–E) Time expanded plots of the three periods (shaded segments) to permit their visual differentiation. Each segment represents 10 consecutive IBIs for the PRE, MIN, and MAX periods, respectively, aligned with the first heart beat in each segment. Note the longer MIN (D) and the shorter MAX (E) segments of 10 IBIs compared to the PRE period (C).