Chronic drinking is associated with neurocognitive deficits due to neuropathological changes in the structure, metabolism, and function of the brain. One of the consequences of neuropathological brain abnormalities in the cerebellum of alcoholics has been impairment of motor functioning. A new study using functional magnetic resonance imaging (fMRI) during a finger-tapping exercise has found a weakened relationship between frontal lobe and cerebellar activity in alcoholic individuals.
Chronic alcohol exposure most commonly causes deficits in visuospatial skills and problem solving, while problems with learning and memory can also be observed. A commonly unappreciated deficit is in motor functions: for instance, balance when standing can be affected by dysfunction of the cerebellum as can the ability to perform rhythmic movements.
Researchers used fMRI to examine 10 uncomplicated chronic alcoholic patients after five to seven days of abstinence and once signs of withdrawal had lessened, as well as 10 matched healthy controls. The method helped researchers examine functional connectivity between cerebellar and cortical brain regions.
Although it may seem an unsophisticated movement, finger tapping is a simple, rhythmic movement that can be used to study the function of the parts of the brain that are often damaged by chronic drinking, such as the cerebellum and the frontal lobes.
Weaker relationships between these regions in alcoholics might reflect direct injury to one or both of these parts of the brain, disruption of frontal-cerebellar neural pathways that connect these regions, or some sort of compensation for injuries elsewhere in the brain
Researchers explained that while they found that the alcoholic patients could produce the same number of finger taps per minute as did the normal controls, they employed different parts of the brain to do so. This suggested that alcoholics needed to compensate for their brain injury. However, if the task becomes more complex, performance may break down and alcoholics may seem impaired when tested. This is the big advantage of studying simple tasks that alcoholics can perform at normal levels.
While this study supports other research showing problems in the frontal-cerebellar brain circuits in alcoholic patients, Rogers said its major contribution is related to studying the simple tasks that
Now that researchers have fMRI available to help determine the areas of the brain that are activated in the performance of tasks, the study of simple tasks may also be very informative. Complex tasks clearly show abnormalities in fMRI, but it becomes impossible to determine whether the fMRI differences observed are due to the impaired performance or brain differences that account for the impaired performance.