Nicotine is one of the main components of cigarettes and affects the central nervous system mainly via nicotinic acetylcholine receptors. It has further effects on neuromodulation by regulating the release of dopamine, serotonin, glutamate and adrenaline. In studies, it has been shown that nicotine improves attention and working memory in animals and humans, while nicotine withdrawal leads to reduced working and verbal memory capacity in otherwise healthy tobacco smokers. In schizophrenics and patients suffering from attention deficit hyperactivity disorder, nicotine improves cognitive performance. A likely basis of the nicotinic effects on cognitive functions is its effect on cortical excitability and activity. Here, neurophysiological studies mainly base on animal experiments and have shown in vitro that the nicotinic acetylcholine receptors elicit neuronal depolarisation by inducing transmembrane cationic inward currents (Calcium), thus being involved in induction and modulation of neuroplasticity and cortical excitability.