Exploring Learning and Unlearning of Fear

The Effect of D-cycloserine on Fear Learning and Extinction

Status

Withdrawn

Phases

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT01512316

Enrollment

Registered

2012-01-19

Start date

Unknown

Completion date

Unknown

Last updated

2023-01-31

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Healthy Individuals

Keywords

Fear, Cycloserine, Conditioning, Functional neuroimaging, Anxiety disorders

Brief summary

The present study investigates the effect of d-cycloserine on learning and unlearning of fear in healthy humans and its underlying effect on the amygdala. As a second objective, the effect of genotype on fear learning will be studied.

Detailed description

A growing body of evidence suggests that the extinction of fear is mediated by the N-methyl-D-aspartate (NMDA) receptor activity in the basolateral amygdala. Intra-amygdala infusions of antagonists of this glutamate receptor in small animals (eg: rats, mice) have demonstrated a blockage of fear acquisition and extinction. Agonists, on the other hand, facilitate conditioned fear extinction. The animal studies are all based on the simple fear learning paradigm of conditioning. However, it is not clear that human anxiety disorders are based on prior conditioning encounter. Therefore it is important to disentangle the effect of DCS on acquisition and extinction in the context of a simple learning paradigm, particular its effect on the human amygdala.

Interventions

DRUGd-Cycloserine

250mg, one dose, 2hrs prior to fMRI

DRUGLactose pill

one dose, 2hrs prior to fmri

GENETICSaliva sample

Buccal cell material will be sampled from all participants on day3

OTHERFunctional neuroimaging (fMRI)

Study design

Allocation

RANDOMIZED

Intervention model

PARALLEL

Primary purpose

BASIC_SCIENCE

Masking

DOUBLE (Subject, Investigator)

Eligibility

Sex/Gender

ALL

Age

18 Years to 40 Years

Healthy volunteers

Yes

Inclusion criteria

* No axis I diagnosis compatible with the DSM-IV by means of a structured diagnostic interview * Right-handed

Exclusion criteria

* Current psychopharmacological or psychological treatment. * The presence of a physical/medical condition that may interfere with the study. * A contraindication for the use of DCS * Pacemaker, medication pump (such as insulin pump), hearing aid, removable prosthodontics * Metal in or on body (such as acupuncture needles, artificial limbs, stents, metal splints, clips, implanted electrodes, tattoos, or piercings)

Design outcomes

Primary

Measure	Time frame	Description
change in BOLD-signal during a fear conditioning task	t0, t+24, t+48	Subjects will participate in a 3-day experiment. Day1 (t0): Acquisition Day2 (T+24): extinction Day3 (T+48): re-exposure

Countries

Belgium

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026