**5.4. Lateral habenula (LHb)**

The lateral habenula (LHb) is a critical brain structure modulating aversive and rewarding behaviors through the GABAergic and glutaminergic efferent projections to the ventral tegmental area (VTA) by means of the fasciculus retroflexus (FR). The selective degeneration of this bundle in drug abuse led to a possible use of deep brain stimulation for the treatment of this condition. In rats, deep brain stimulation of LHb with low-frequency (10 Hz)-highfrequency alternate stimulation (100 Hz) attenuates cocaine self-administration, extinction training and reinstatement of cocaine seeking while conventional high-frequency stimulation did not have any effect and low-frequency stimulation increases cocaine self-administration [60]. The effect of unconventional LHb DBS on cocaine reinforcement may be due to reduction of the cocaine-induced increase in glutaminergic input to the VTA.
