title: Using pupil size and heart rate to infer affective states during behavioral neurophysiology and neuropsychology experiments.
abstract: Nonhuman primates (NHPs) are a valuable research model because of their behavioral, physiological and neuroanatomical similarities to humans. In the absence of language, autonomic activity can provide crucial information about cognitive and affective states during single-unit recording, inactivation and lesion studies. Methods standardized for use in humans are not easily adapted to NHPs and detailed guidance has been lacking.
  
  
  
  We provide guidance for monitoring heart rate and pupil size in the behavioral neurophysiology setting by addressing the methodological issues, pitfalls and solutions for NHP studies. The methods are based on comparative physiology to establish a rationale for each solution. We include examples from both electrophysiological and lesion studies.
  
  
  
  Single-unit recording, pupil responses and heart rate changes represent a range of decreasing temporal resolution, a characteristic that impacts experimental design and analysis. We demonstrate the unexpected result that autonomic measures acquired before and after amygdala lesions are comparable despite disruption of normal autonomic function.
  
  
  
  Species and study design differences can render standard techniques used in human studies inappropriate for NHP studies. We show how to manage data from small groups typical of NHP studies, data from the short behavioral trials typical of neurophysiological studies, issues associated with longitudinal studies, and differences in anatomy and physiology.
  
  
  
  Autonomic measurement to infer cognitive and affective states in NHP is neither off-the-shelf nor onerous. Familiarity with the issues and solutions will broaden the use of autonomic signals in NHP single unit and lesion studies.
authors.affiliation: Section on the Neurobiology of Learning and Memory, Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, MD, USA. Electronic address: arm@nih.gov.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Mitz
authors.affiliation: Section on the Neurobiology of Learning and Memory, Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, MD, USA; Washington University School of Medicine, Saint Louis, MO, USA.
authors.forename: Ravi V
authors.initials: RV
authors.lastname: Chacko
authors.affiliation: Section on the Neurobiology of Learning and Memory, Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, MD, USA.
authors.forename: Philip T
authors.initials: PT
authors.lastname: Putnam
authors.affiliation: Section on the Neurobiology of Learning and Memory, Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, MD, USA; Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
authors.forename: Peter H
authors.initials: PH
authors.lastname: Rudebeck
authors.affiliation: Section on the Neurobiology of Learning and Memory, Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, MD, USA.
authors.forename: Elisabeth A
authors.initials: EA
authors.lastname: Murray
mesh_terms: D000679:Amygdala / Q000503:physiopathology; D000818:Animals; D001341:Autonomic Nervous System / Q000502:physiology* / Q000503:physiopathology; D001522:Behavior, Animal / Q000502:physiology*; D004562:Electrocardiography / Q000379:methods; D006339:Heart Rate / Q000502:physiology*; D008137:Longitudinal Studies; D008253:Macaca mulatta; D008606:Mental Processes / Q000502:physiology*; D009929:Organ Size; D017397:Prefrontal Cortex / Q000502:physiology; D011680:Pupil; D012107:Research Design
keywords: Affective state; Arousal; Autonomic measurement; Behavioral neurophysiology; Cognitive state; Experimental design; Frequency domain analysis; Heart rate variability; Methods; Neuropsychology; Nonhuman primate; Pupil size; Pupillometry; Time domain analysis