Attention Functioning Following Striatal Lesions and Psychostimulants Administration

Many neuropsychiatric disorders are characterized by impaired ability to inhibit irrelevant information. The inability to inhibit irrelevant external as well as internal stimuli seems to play a major role in Attention Deficit Disorders (ADHD). Over the past decade an increasing rate of children and adults diagnosed with ADHD and treated with Methylphenidate (Mph) has emerged; alongside to increasing reported drug abuse. Mph abuse can lead to long-term adverse consequences, therefore, a better understanding of the attention underlying mechanism is medically important. The striatum is a brain structure responsible for integrating sensorimotor, emotional and cognitive information, also involve in attention functioning. The aim of the present study is to dissect the functional differences between striatal sub-regions in attention processing. For this purpose, rats surgically underwent the following lesions: (1) Nucleus Accumbens, (2) Caudate Nucleus, (3) Putamen and (4) Internal Capsule. Afterward rats were treated with either Mph or Methamphetamine (compared to saline) and then examined for changes in overt and covert attention abilities by the object recognition and pre-pulse inhibition tests, respectively. Finally, protein profile changes were examined post mortem. Results support functional differentiation between the striatal sub-regions and therefore indicate the existence of a sub-striatal attention underlying mechanism; regulated by a dopaminergic system.