The Effect of Intravenous Anesthetics on Fear Learning and Memory

People often develop fearful responses to things, but have no conscious control over the fear. This is a basic form of unconscious memory, called "fear conditioning." Intravenous anesthetic drugs have remarkable effects on conscious memory, but it is unknown whether they have similar effects on these unconscious fear memories.

To address this question, the investigators will study 114 healthy adult volunteer subjects. The subject is given a very low dose of an anesthetic drug intravenously (i.e. through the bloodstream). The dose is so low that the subject might not even be able tell if they are getting the drug. While they are receiving the drug, the subject will perform a series of memory tests and a fear conditioning experiment, which are set up like a very simple computer game. To create the "fear response", subjects will occasionally receive a mildly uncomfortable shock to their arm. The subject is able to determine the highest level of shock that they will receive.

The investigators are doing this study because the investigators wish to know exactly how the drugs affect the way people process fear and emotion. This knowledge might one day be used in the treatment of some psychiatric disorders.

Study Overview

Detailed Description

People often develop fearful responses to things, but have no conscious control over the fear (e.g. phobias). This is a basic form of unconscious memory, called "fear conditioning." Intravenous anesthetic drugs have remarkable effects on conscious memory, but it is unknown whether they have similar effects on these unconscious fear memories.

To address this question, the investigators will study 114 healthy adult volunteer subjects. The subject is given a very low dose of an anesthetic drug intravenously (i.e. through the bloodstream). The dose is so low that the subject might not even be able tell if they are getting the drug. While they are receiving the drug, the subject will perform a series of memory tests and a fear conditioning experiment, which are set up like a very simple computer game. To create the "fear response", subjects will occasionally receive a mildly uncomfortable shock to their arm. The subject is able to determine the highest level of shock that they will receive.

The investigators are doing this study because the investigators wish to know exactly how the drugs affect the way people process fear and emotion. This knowledge might one day be used in the treatment of some psychiatric disorders.

Study Type

Interventional

Enrollment (Actual)

67

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

    • New York
      • New York, New York, United States, 10065
        • Weill Cornell Medical College/New York Presbyterian Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 50 years (Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • age between 18 and 50
  • minimum of high school education
  • fluent in English
  • normal vocabulary

Exclusion Criteria:

  • any significant medical or psychiatric comorbidity (e.g. asthma, diabetes, hypertension, depression, high anxiety)--subjects must be in excellent health such that they would be classified as American Society of Anesthesiologists Physical Status Class I
  • deficit in vision or hearing that would impede the study
  • allergies to any of the study drugs, to soybeans, or to eggs
  • a history of head trauma
  • a family history of major psychiatric illness
  • body mass index > 30 kg/m2
  • a recent history of recreational drug use
  • prior exposure to the study materials
  • pregnancy
  • a personal or family history of any porphyria
  • failure to exhibit a skin conductance response to deep inspiration
  • the ability to read Chinese characters
  • assessment by the investigators that the subject may be unable to cooperate or comply with the study requirements.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Placebo Comparator: Placebos
Saline Infusion
IV Saline infusion for 2 hours.
Active Comparator: Propofol 0.45mcg/mL
Anesthetic Drug Infusion
IV Propofol infusion for 2 hours.
Other Names:
  • Propofol
Active Comparator: Propofol 0.90mcg/mL
Anesthetic Drug Infusion
IV Propofol infusion for 2 hours.
Other Names:
  • Propofol
Active Comparator: Thiopental 1.5mcg/mL
Anesthetic Drug Infusion
IV Thiopental 1.5mcg/mL infusion for 2 hours
Other Names:
  • Thiopental
Active Comparator: Thiopental 3mcg/mL
Anesthetic Drug Infusion
IV Thiopental 3mcg/mL infusion for 2 hours
Other Names:
  • Thiopental

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
GSR Trial 1
Time Frame: First Trial, for up to 1 day
Galvanic skin repose (GSR) to the first habituation trial (yes/no). Coding: Yes (0) and No (1)
First Trial, for up to 1 day

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Investigators

  • Principal Investigator: Kane Pryor, MD, Weill Medical College of Cornell University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

October 1, 2008

Primary Completion (Actual)

May 1, 2011

Study Completion (Actual)

May 1, 2011

Study Registration Dates

First Submitted

October 3, 2008

First Submitted That Met QC Criteria

October 6, 2008

First Posted (Estimate)

October 7, 2008

Study Record Updates

Last Update Posted (Actual)

May 15, 2019

Last Update Submitted That Met QC Criteria

April 30, 2019

Last Verified

April 1, 2019

More Information

Terms related to this study

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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