The purpose of this research is to determine the extent to which oculomotor function accurately detects THC-impairment, if cannabis use experience impacts this detection threshold, and to examine how the oculomotor index corresponds to a measure of sustained attention. A double-blind, placebo-controlled, within-subjects crossover design will be used to examine the dose-effects of THC (0, 5mg, 30mg) on oculomotor performance tasks and a sustained attention task in frequent and infrequent cannabis users. Results from the study will advance the investigators' understanding of the effect of THC and cannabis use frequency on oculomotor function and sustained attention, and will directly inform the validity of the investigators' oculomotor platform for identifying acute THC- induced impairment in frequent and infrequent users.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
40
cannabis with 0, 5, or 30 mg THC will be inhaled via vaporization
Johns Hopkins Behavioral Pharmacology Research Unit
Baltimore, Maryland, United States
Commission Errors
The Conners Continuous Performance Test (CPT) will be used to assess sustained attention. Commission errors is measured by calculating the number of trials participants incorrectly push the spacebar in the presence of "X" stimulus.
Time frame: pre-administration, post-administration, 2, 4 hours
Omission Errors
The Conners Continuous Performance Test (CPT) will be used to assess sustained attention. Omission errors is measured by calculating the number of trials participants fail to push the spacebar in the presence of a letter that is not an "X" stimulus.
Time frame: pre-administration, post-administration, 2, 4 hours
Reaction Time
The Conners Continuous Performance Test (CPT) will be used to assess sustained attention. Reaction time is measured by calculating the duration between the presentation of a letter other than "X", and the correct response of a spacebar push.
Time frame: pre-administration, post-administration, 2, 4 hours
Reaction Time Standard Error
The Conners Continuous Performance Test (CPT) will be used to assess sustained attention. Reaction time standard error is measured by calculating the standard error of the mean of the reaction time.
Time frame: pre-administration, post-administration, 2, 4 hours
Visuomotor Index
The visuomotor index score is calculated by mathematically integrating five measures of oculomotor fixation performance and two measures of accuracy into a single score during fixation and accuracy tasks, respectively. Test of visual fixation to measure microsaccades, spontaneous nystagmus, and gaze-evoked nystagmus.
Time frame: pre-administration, post-administration, 2, 4 hours
Saccade Speed
Measures how quickly participants look back and forth between two spots as possible during the oculomotor task.
Time frame: Pre-administration, post-administration, 2, 4 hours
Visually Guided Oculomotor Performance
Measures how quickly and accurately participants move their eyes to a cue as soon as it appears on the oculomotor task.
Time frame: Pre-administration, post-administration, 2, 4 hours
Antisaccade
Measures voluntary eye movement in the direction opposite to the side in which a visual cue is presented.
Time frame: Pre-administration, post-administration, 2, 4 hours
Memory-Guided
Measures how quickly gaze is shifted directly and accurately to a remembered cue position.
Time frame: Pre-administration, post-administration, 2, 4 hours
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