<Li> Mammillary bodies, part of the hypothalamus that receives signals from the hippocampus via the fornix and projects them to the thalamus . </Li> <Li> Anterior nuclei of thalamus receive input from the mammillary bodies . Involved in memory processing . </Li> <P> The structures of the limbic system are involved in motivation, emotion, learning, and memory . The limbic system is where the subcortical structures meet the cerebral cortex . The limbic system operates by influencing the endocrine system and the autonomic nervous system . It is highly interconnected with the nucleus accumbens, which plays a role in sexual arousal and the "high" derived from certain recreational drugs . These responses are heavily modulated by dopaminergic projections from the limbic system . In 1954, Olds and Milner found that rats with metal electrodes implanted into their nucleus accumbens, as well as their septal nuclei, repeatedly pressed a lever activating this region, and did so in preference to eating and drinking, eventually dying of exhaustion . The limbic system also includes the basal ganglia . The basal ganglia are a set of subcortical structures that direct intentional movements . The basal ganglia are located near the thalamus and hypothalamus . They receive input from the cerebral cortex, which sends outputs to the motor centers in the brain stem . A part of the basal ganglia called the striatum controls posture and movement . Recent studies indicate that, if there is an inadequate supply of dopamine, the striatum is affected, which can lead to visible behavioral symptoms of Parkinson's disease . </P> <P> The limbic system is also tightly connected to the prefrontal cortex . Some scientists contend that this connection is related to the pleasure obtained from solving problems . To cure severe emotional disorders, this connection was sometimes surgically severed, a procedure of psychosurgery, called a prefrontal lobotomy (this is actually a misnomer). Patients having undergone this procedure often became passive and lacked all motivation . </P>

The limbic system is an important part of the brain because it regulates