The role of dopamine in visuospatial attention.

The role of dopamine in bias and disengagement, two mechanisms implicated in visuospatial attention.

Status

Active, not recruiting

Phases

Unknown

Study type

Interventional

Source

NL-OMON

Registry ID

NL-OMON26886

Enrollment

Registered

2011-05-26

Start date

2011-08-01

Completion date

Unknown

Last updated

2024-02-28

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

Conditions

Methylphenidate, frequently prescribed in the treatment of ADHD, increases the central availability of both dopamine and noradrenaline. The roles of dopamine and noradrenaline in attention and inhibition are yet unclear. It is of importance to investigate the role of these neurotransmitter systems since at least 20 percent of patients do not benefit from methylphenidate or have undesired side effects.

Interventions

Dopaminergic antagonism by 2mg (and possibly 3mg) haloperidol.

Eligibility

Inclusion criteria

Inclusion criteria: 1. Age 18 – 45; 2. Male.

Exclusion criteria

Exclusion criteria: Any of the following (assessed by interview): 1. History of cardiovascular problems; 2. Liver disease; 3. Use of any medication; 4. History of cocaine use; 5. Diagnosed psychopathology; 6. Hypersensitivity to haloperidol; 7. Hyperthyroidism; 8. History of epilepsy.

Design outcomes

Primary

Measure	Time frame
Behavioural measures: 1. In the VSC (Visual Spatial Cueing) paradigm: The validity effect in ms (RT valid cued target - RT invalid cued target). A larger validity effect reflects either more bias, or less disengagement; 2. In the stop task paradigm, the time needed (in milliseconds) to abort a prepotent response: The Stop Signal Reaction Time (SSRT); SSRT reflects inhibition and related disengagement but is also dependent on bias. Neurophysiological (Event Related Potentials, task related brain activity) endparameters in the VSC: 1. Parietal cue Event Related Potential (ERP) components. These are the Anterior Directing Attention Negativity (ADAN) and the Late Directing Attention Positivity (LDAP). Both are related to bias; 2. P1 ERP (following a validly cued target); associated with bias; 3. Late Positive Deflection (LPD) ERP (following an invalidly cued target); associated with disengagement. Neurophysiological (ERP) endparameters in the stop task: 1. N2 ERP (following the onset of a stopsignal), associated with disengagement; 2. LPD ERP (following the onset of a stopsignal), associated with disengagement.	—

Measure

Time frame

Behavioural measures: 1. In the VSC (Visual Spatial Cueing) paradigm: The validity effect in ms (RT valid cued target - RT invalid cued target). A larger validity effect reflects either more bias, or less disengagement; 2. In the stop task paradigm, the time needed (in milliseconds) to abort a prepotent response: The Stop Signal Reaction Time (SSRT); SSRT reflects inhibition and related disengagement but is also dependent on bias. Neurophysiological (Event Related Potentials, task related brain activity) endparameters in the VSC: 1. Parietal cue Event Related Potential (ERP) components. These are the Anterior Directing Attention Negativity (ADAN) and the Late Directing Attention Positivity (LDAP). Both are related to bias; 2. P1 ERP (following a validly cued target); associated with bias; 3. Late Positive Deflection (LPD) ERP (following an invalidly cued target); associated with disengagement. Neurophysiological (ERP) endparameters in the stop task: 1. N2 ERP (following the onset of a stopsignal), associated with disengagement; 2. LPD ERP (following the onset of a stopsignal), associated with disengagement.

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Secondary

Measure	Time frame
1. Spontaneous motor activity (measured by an actigraph); 2. Dyskinesia (measured by Velocity Scaling).	—

Contacts

Public ContactH.N.A. Logemann

H.N.A.Logemann@uu.nl+31 (0)30 2533386 / +31 (0)622233928

Outcome results

None listed

Source: NL-OMON (via WHO ICTRP)