Memory Modulation by Pain During Anesthesia
Condition: Amnesia; Pain; Anesthesia
MeSH terms: Amnesia
Study type: Interventional
Phase: Phase 1

Summary: 
      The purpose of this study is to determine the effects of pain on facilitating long-term
      auditory memory in the presence and absence of distinct intravenous anesthetics. The ability
      to identify previously presented words from a list assessed the degree of memory formation.
      In a subset of subjects, functional magnetic resonance imaging was used to identify the
      neural correlates of memory inhibition or facilitation by the combination of pain and
      anesthetic used.
    

Detailed description: 
      This study adds specific details to the current incomplete body of knowledge examining the
      effect of pain on memory formation under the influence of anesthetic agents.

      Pain and anesthetic agents were administered as experimental variables in this study. Healthy
      adult subjects were played repeated lists of words and performed several decision-making
      tasks that encourage memory encoding. Some words were consistently paired with painful
      electric shock, and was anticipated to improve subsequent memory performance specifically for
      those items. The same experiment was repeated in all subjects during the administration of
      1-2 possible agents that reduce memory formation: dexmedetomidine, a predominantly sedative
      agent, and midazolam, a well-known amnestic agent, and ketamine, a well-known dissociative
      analgo-sedative. The extent to which pain modulates memory performance under the effects of
      the anesthetic agents was the primary outcome of interest.

      Further, a subset of the subjects performed the same experimental procedures while undergoing
      functional magnetic resonance imaging, which continuously reflects neuronal activity
      throughout the brain. Classic memory areas were predicted to be activated by the auditory
      processing task, but how these neural circuits change under the two anesthetic agents with
      the concomitant experience of pain were of interest. It was anticipated that pain recruits a
      parallel memory pathway using limbic structures, known for their involvement in fear
      conditioning. Additionally, stronger and more diffuse cortical processing likely occurs with
      concomitant pain, as level of sedation was reduced by this strong stimulus. Discovering the
      anatomic correlates specific to each experimental variable (pain and anesthetic), and their
      interplay, may help refine our model of brain function during the dynamics of pain and
      sedation.
    

Intervention name(s): Dexmedetomidine; Midazolam; Peripheral nerve stimulation; Ketamine
Intervention type(s): Drug; Drug; Device; Drug
Intervention description(s): Selected subjects received this drug during a portion of the study; Selected subjects received this drug during a portion of the study; Experimental acute pain stimulus was delivered using a nerve stimulator. These painful shocks were paired randomly with some of the auditory experimental cues.; Selected subjects received this drug during a portion of the study
Other intervention name(s): Precedex; Versed; electric nerve stimulation; Ketalar
Intervention MeSH terms: Midazolam; Dexmedetomidine; Ketamine
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: There are 3 single drug arms completed by a few participants. The majority of participants participated in a crossover design with two drugs, midazolam & ketamine.
Masking: Single (Participant)
Primary purpose: Basic Science
Keywords: midazolam; dexmedetomidine; memory; ketamine