Testing the importance of the Medial Temporal Lobes in human interoception: Does it matter if there is a memory component to the task?
Interoception is the ability to consciously perceive internal bodily states. Neuroimaging suggests that the insula (IC) and anterior cingulate cortex (ACC) mediate interoception, while studies involving patients/animals with brain lesions suggest the medial temporal lobe (MTL) is particularly important. One reason for these contrasting conclusions may lie in the types of interoceptive task used by these different approaches. Some tasks probably require integration of current physiological state with mnemonic information (e.g., how much one last ate), and these may be especially reliant upon MTL processing. We compared one task that probably requires integration - a water load task - with one that likely does not - a heart-rate tracking task - in two individuals with selective MTL damage (and with intact IC and ACC). A group of matched healthy individuals served as controls. The main finding was that individuals with MTL damage, relative to controls, were equally and significantly impaired on both types of interoception task. This suggests that MTL structures are involved in mediating interoception even when using a task (heart rate tracking) that does not seemingly require memory and that in neuroimaging studies activates the IC and ACC. The reasons for this apparent inconsistency with neuroimaging findings and the functional role of the MTL in interoception are discussed.
Department of Psychology, Macquarie University, Sydney, NSW 2109, Australia; Neurology Department, Sydney Adventist Hospital, Sydney, NSW 2076 Australia.
Joanne
J
Berriman
Department of Psychology, Macquarie University, Sydney, NSW 2109, Australia; Neurology Department, Sydney Adventist Hospital, Sydney, NSW 2076 Australia. Electronic address: dick.stevenson@mq.edu.au.
Richard J
RJ
Stevenson
Neuropsychology Unit, Royal Prince Alfred Hospital, Sydney, NSW 2050, Australia; ARC Centre of Excellence in Cognition and its Disorders, University of Sydney, Sydney, NSW 2006, Australia; Neurology Department, Sydney Adventist Hospital, Sydney, NSW 2076 Australia.
Zoe C
ZC
Thayer
Department of Radiology, Royal Prince Alfred Hospital, Sydney, NSW 2050, Australia; Neurology Department, Sydney Adventist Hospital, Sydney, NSW 2076 Australia.
Elizabeth
E
Thompson
Neurology Department, Royal Prince Alfred Hospital, Sydney, NSW 2050, Australia; ARC Centre of Excellence in Cognition and its Disorders, University of Sydney, Sydney, NSW 2006, Australia; Central Medical School, University of Sydney, Sydney, NSW 2006, Australia; Neurology Department, Sydney Adventist Hospital, Sydney, NSW 2076 Australia.
Armin
A
Mohamed
Central Medical School, University of Sydney, Sydney, NSW 2006, Australia; Neurology Department, Sydney Adventist Hospital, Sydney, NSW 2076 Australia.
John D G
JDG
Watson
Neuropsychology Unit, Royal Prince Alfred Hospital, Sydney, NSW 2050, Australia; ARC Centre of Excellence in Cognition and its Disorders, University of Sydney, Sydney, NSW 2006, Australia; Neurology Department, Sydney Adventist Hospital, Sydney, NSW 2076 Australia.
Laurie A
LA
Miller
D000328:Adult; D003243:Consciousness; D004827:Epilepsy / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D065812:Interoception / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood; D011795:Surveys and Questionnaires; D013702:Temporal Lobe / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D013997:Time Factors
D010100:Oxygen
Appetite; Bodily states; Heart-rate tracking; Hippocampus; Insular cortex; Memory