Step-down vs. step-up noxious stimulation: differential effects on pain perception and patterns of brain activation.
BACKGROUND
We hypothesize that pain and brain responses are affected by changes in the presentation sequence of noxious stimuli that are, overall, identical in intensity and duration.


METHODS
During functional magnetic resonance imaging (fMRI) scanning, 21 participants experienced three patterns of noxious stimulation: Up-type (step-up noxious stimulation, 15 s), Down-type (step-down noxious stimulation, 15 s), and Down-up-type (decreasing and increasing pattern of noxious stimulation, 15 s). The total intensity and duration of the three noxious stimulation patterns were identical, but the stimulation sequences were different.


RESULTS
Pain and unpleasantness ratings in the Down- and Down-up-type noxious stimulations were lower than in the Up-type noxious stimulation. The left prefrontal cortex [(PFC, BA (Brodmann area) 10, (-45, 50, 1)] was more highly activated in the Down- and Down-up-type noxious stimulations than in the Up-type noxious stimulation. The S1, S2, insula, bilateral PFC (BA 46), and midcingulate cortex were more highly activated in the Up-type noxious stimulation than in the Down-type noxious stimulation. PFC BA 10 was located at an inferior level compared to the bilateral PFC BA 46 (Z axis = 1 for BA 10, compared to 22 and 25 for the right and left BA 46, respectively). When cortisol level was increased, the left hippocampal cortex, along with the left parahippocampal cortex, was greatly activated for the Up-type noxious stimulation.


CONCLUSIONS
When pain cannot be avoided in clinical practice, noxious stimuli should be applied to patients in a step-down pattern that delivers the most intense pain first and the least intense pain last.
Department of Anesthesiology and Pain Medicine, Intensive Care Unit, Brain Research Group, Yonsei University Wonju College of Medicine, Wonju, South Korea.
J C
JC
Choi
Department of Psychology, Kangwon National University, Chuncheon, South Korea.
J
J
Kim
Department of Psychology, Kangwon National University, Chuncheon, South Korea.
E
E
Kang
Julie English Institute, Wonju, South Korea.
J-H
JH
Choi
Department of Anesthesiology and Pain Medicine, Yonsei University Wonju College of Medicine, Wonju, South Korea.
W Y
WY
Park
Department of Electronic Engineering, Gangneung-Wonju National University, Gangneung, South Korea.
Y-S
YS
Choi
Department of Biomedical Engineering, Hanyang University, Seoul, South Korea.
J
J
Cha
University of Manchester Medical School, Manchester, UK.
C
C
Han
Yonsei Saebom Medical Clinic, Seongdong-gu, Seoul, South Korea.
S K
SK
Park
Medical Library, Yonsei University Wonju College of Medicine, Wonju, South Korea.
M H
MH
Kim
Instructional Department, Yonsei University Wonju College of Medicine, Wonju, South Korea.
G H
GH
Lee
Department of Anesthesiology and Pain Medicine, Yonsei University Wonju College of Medicine, Wonju, South Korea.
H-J
HJ
Do
Department of Anesthesiology and Pain Medicine, Yonsei University Wonju College of Medicine, Wonju, South Korea.
S W
SW
Jung
Department of Biomedical Engineering, Hanyang University, Seoul, South Korea.
J-M
JM
Lee
D000328:Adult; D001921:Brain / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality; D006179:Gyrus Cinguli / Q000503:physiopathology; D006624:Hippocampus / Q000503:physiopathology; D006358:Hot Temperature; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008279:Magnetic Resonance Imaging; D008297:Male; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D058748:Pain Perception; D010812:Physical Stimulation; D017397:Prefrontal Cortex / Q000503:physiopathology; D013739:Testosterone / Q000097:blood
D013739:Testosterone; D006854:Hydrocortisone