The effects of alcohol on brain connectivity pathways and behavioural inhibition: A transcranial magnetic stimulation study

The observation that alcohol use causes reductions in behavioral inhibition is
well established. The brain mechanisms underlying these alcohol related changes
are however incompletely understood. It has been speculated that the
communication between certain brain regions plays an important role.
Problematically however, the evidence is indirect and correlational of nature.
Paired-pulse transcranial magnetic stimulation (pp-TMS) is an unique method
that is able to assess human brain communication directly and in a noninvasive
way. Pp-TMS is therefore a unique approach to map the biological effects of
alcohol on brain communication.

The aim of the present study is get more insight into the effects of alcohol on
acute changes in brain communication en behavioral inhibition. It is
hypothesized that alcohol will result cause impairments in the ability to
inhibit behavioral responses and that this impairment can be explained by
reductions in brain communication.

Experimental design: Double-blind, placebo controlled, within-subjects
The amount of alcohol that will be administered in order to achieve a blood
alcohol concentration of 0.5 promille at the time of testing will be based on
the subject's weight. Order of alcohol or placebo administration during the
testing sessions will be randomized and counterbalanced.
The experiment will consist of three session of one hour each: Session 1:
Intake-Providing procedural information and obtain informed consent;
questionnaires; motor trheshold estimations. Session 2: Testing day 1- Breath
test; Alcohol or placebo administration / Breath test / pp-TMS to assess
communication between the cerebral hemispheres and between the cerebellum and
cerebral cortex / Behavioral inhibition task/ Breath test. Session 3: Testing
day 2- identical to testing day 1 except for administration

On two seperate occassions, participants will consume either an alcoholic (0.5
promille) or a non-alcoholic beverage (0 promille). During both testing
sessions transcrnial magnetic stimulation (TMS) will be applied to examine the
functional connectivity between different parts of the brain.

The main concern when using TMS is its potential to induce a seizure. Safety
guidelines, including the limits of stimulation intensity, monitoring of
subjects, medical management of induced seizures and contraindications to rTMS
as described by the International Federation of Clinical Neurophysiology will
be followed strictly, to minimize seizure risk. Other potential adverse effects
of rTMS include induction of a muscle tension headache. These are generally
mild discomforts that respond promptly to common analgesics. It should
furthermore be noted that volunteers can withdraw from the study at any given
time.