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Trial registered on ANZCTR


Registration number
ACTRN12611000084987
Ethics application status
Approved
Date submitted
19/01/2011
Date registered
24/01/2011
Date last updated
23/09/2011
Type of registration
Prospectively registered

Titles & IDs
Public title
Examining the effects of serotonin on perceptual awareness and attention.
Scientific title
In healthy adults, how do buspirone and citalopram compared with placebo effect switch rate in perceptual rivalry?
Secondary ID [1] 252514 0
Nil
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Binocular rivalry switch rate 258003 0
Auditory rivalry switch rate 258044 0
Probabilistic reversal learning 270715 0
Condition category
Condition code
Mental Health 258172 258172 0 0
Studies of normal psychology, cognitive function and behaviour

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Oral tablets of Buspirone (15mg), Citalopram (20mg) or placebo will be administered to healthy adults. Each participant will participate in 4 separate sessions of testing separated by at least 2 weeks: session1/Placebo + Buspirone (2.5 hours later), session2/ Citalopram + Buspirone (2.5 hours later), session3/ Placebo + Placebo (2.5 hours later), session4/ Citalopram + Placebo (2.5 hours later). The study will investigate the neurochemical basis of binocular rivalry, a phenomenon that is a feature of normal vision. No abnormal condition or disease is being investigated as part of this study. The medications in this study are already approved by the Australian Therapeutic Goods Administration.
Intervention code [1] 257048 0
Treatment: Drugs
Comparator / control treatment
Placebo identical in taste and appearance but containing none of the active ingredients. A total of 4 placebo tablets will be administered to each person over the 4 testing sessions. Session1/ Placebo + Busprione, session3/ Placebo + Placebo, and session4/ Citalopram + Placebo (2nd tablet taken 2.5 hours later).
Control group
Placebo

Outcomes
Primary outcome [1] 259069 0
Binocular rivalry switch rate - when visual input is ambiguous, one's conscious visual percept alternates between the two possible interpretations of the visual stimuli (as occurs with a number of popular visual illusions). Participants will be presented the required visual images on a computer screen and will be asked to push buttons on a keyboard every time their visual perception switches between the possible interpretations. Switch rate will be calculated as the number of reported changes in perceptual experience every minute.
Timepoint [1] 259069 0
1.5 or 3.5 hours after administration of Citalopram or Buspirone, respectively, or placebo.
Secondary outcome [1] 265350 0
Auditory Rivalry switch rate - when the source of auditory input is ambiguous, one's conscious auditory percept may alternate between the two possible interpretations. Participants will be presented the required auditory tones through headphones and will be asked to push buttons on a keyboard every time their auditory perception switches between the possible interpretations. Switch rate will be calculated as the number of reported changes in perceptual experience every minute.
Timepoint [1] 265350 0
1.5 or 3.5 hours after administration of Citalopram or Buspirone, respectively, or placebo.
Secondary outcome [2] 294225 0
Probabilistic reversal learning -- Participants will be asked to view a standard computer screen and will be presented with two coloured patches. Participants will be told that one of the coloured patches is 'correct' on each presentation. If they choose correctly, they will get one point, with the goal of the task to get as many points as possible. Participants will be informed that one colour is more likely to be correct than the other colour on average, but that the 'lucky' colour might reverse from time to time during the session. At each presentation, participants will indicate their choice via key press, and will receive basic feedback about the correctness of their choice. Performance measures will be related to the number of correct choices made during testing.
Timepoint [2] 294225 0
1.5 or 3.5 hours after administration of Citalopram or Buspirone, respectively, or placebo.

Eligibility
Key inclusion criteria
Healthy adults
Minimum age
18 Years
Maximum age
50 Years
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Previous personal or first-degree family history of psychiatric or neurological disorders or suicidality, impairements in vision or audition, hepatic or cardiac function (including diagnosed hypertension), pregnancy or breastfeeding, previous intolerance or hypersensitivity to buspirone, citalopram or related medications, current or recent (last 2 weeks) use of psychotropic medication, psychoactive substances or any other medications known to interact with buspirone or citalopram. Participants will also be excluded if their blood pressure is found to be above 140/100 and remains above this level for fifteen minutes.

Study design
Purpose of the study
Diagnosis
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation will be carried out by computer. All participants will be involved in all treatment conditions, and equal numbers of participants will be allocated to each sequence. Allocation to a particular sequence of conditions will be randomised, and the particular drug being administered will be in a container labeled by a third party.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation by using a randomisation table created by computer software.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
All participants receive all conditions of treatment over four separate sessions.
Phase
Phase 4
Type of endpoint(s)
Efficacy
Statistical methods / analysis

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 257496 0
University
Name [1] 257496 0
The University of Melbourne
Address [1] 257496 0
The University of Melbourne
Victoria, 3010
Country [1] 257496 0
Australia
Primary sponsor type
University
Name
The University of Melbourne
Address
Psychological Sciences
The University of Melbourne
Victoria, 3010
Country
Australia
Secondary sponsor category [1] 257515 0
Individual
Name [1] 257515 0
Dr Olivia Carter
Address [1] 257515 0
Psychological Sciences
The University of Melbourne
Victoria, 3010
Country [1] 257515 0
Australia
Other collaborator category [1] 251461 0
Individual
Name [1] 251461 0
Assoc/Prof Suresh Sundram
Address [1] 251461 0
Mental Health Research Institute of Victoria
Locked Bag 11
Parkville, Victoria 3052
Country [1] 251461 0
Australia

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 259523 0
Melbourne Health Human Research Ethics Committee
Ethics committee address [1] 259523 0
PO Royal Melbourne Hospital
Parkville, Victoria 3050
Ethics committee country [1] 259523 0
Australia
Date submitted for ethics approval [1] 259523 0
Approval date [1] 259523 0
08/07/2010
Ethics approval number [1] 259523 0
2009.648
Ethics committee name [2] 259555 0
The University of Melbourne Human Research Ethics Committee
Ethics committee address [2] 259555 0
Alan Gilbert Building
The University of Melbourne
Victoria 3010
Ethics committee country [2] 259555 0
Australia
Date submitted for ethics approval [2] 259555 0
Approval date [2] 259555 0
17/08/2010
Ethics approval number [2] 259555 0
0932268

Summary
Brief summary
Binocular rivalry occurs when different stimuli are presented to the left and right eye simultaneously. Under these conditions the observer will consciously perceive only one of the two images at a time, with the respective dominance of the two images alternating every few seconds. A similar phenomenon is also observed in hearing. Previous studies have shown that the rate of alternation is affected by certain medications that affect the serotonin system. We will administer two such medications to healthy individuals to further investigate how the serotonin system is involved in perceptual rivalry. The main implications of this study relate to pure research and understanding the neural mechanisms underlying perception. There is currently no clinical aim for this study.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 31537 0
Address 31537 0
Country 31537 0
Phone 31537 0
Fax 31537 0
Email 31537 0
Contact person for public queries
Name 14784 0
Olivia Carter
Address 14784 0
Department of Psychological Sciences
The University of Melbourne
Victoria 3010
Country 14784 0
Australia
Phone 14784 0
+61 3 8344 6372
Fax 14784 0
Email 14784 0
ocarter@unimelb.edu.au
Contact person for scientific queries
Name 5712 0
Olivia Carter
Address 5712 0
Department of Psychological Sciences
The University of Melbourne
Victoria 3010
Country 5712 0
Australia
Phone 5712 0
+61 3 8344 6372
Fax 5712 0
Email 5712 0
ocarter@unimelb.edu.au

No information has been provided regarding IPD availability
Summary results
No Results