Central Nervous System (CNS) disorders often accompany the acquired immunodeficiency syndrome (AIDS) and are typified by neuropsychiatric symptoms, such as cognitive and motor impairments, sometimes paralleled by neuropathological hallmarks. Collectively, these events are referred to as HIV-1 associated dementia (HAD). Before the advent of the Highly Active Antiretroviral Therapy (HAART), about 20% of adult patients, but as many as 40% of children/adolescent infected subjects developed HAD. Nowadays, in the era of HAART, the prevalence of HAD has decreased, but a more subtle form of disorder, referred to as Minor Cognitive Motor Disorder (MCMD), has emerged in about 20% of symptomatic HIV-1 seropositive patients, including those receiving HAART. This work was aimed at investigating the impact of the HIV-1 viral protein Tat on central neurotransmission since this protein has been proposed as one of the viral component involved in the onset of central neuropsychiatric symptoms.