Brain Stimulation Reward - Relationship To Natural Rewards and Drives

Relationship To Natural Rewards and Drives

The relationship between induced laboratory and natural rewards (e.g. food, water and copulation) has long been debated, and much of the early research on BSR is focused on their similarities and differences. Experiments consistently indicate that BSR stimulates the reinforcement pathways normally activated by natural rewards, and drug reward or self-stimulation can exert more powerful activation of central reward mechanisms because they activate the reward circuit directly rather than through the peripheral nerves. BSR to the medial forebrain bundle (MFB) through either electrical or chemical means activates the neural pathways leading to natural drives. When specific regions of the hypothalamus are electrically stimulated, the stimulation causes eating, drinking, or copulation responses, and electrical stimulation is more reinforcing when the natural reward is available for consumption.

The difference between brain stimulation and natural rewards can be attributed to the lack of a deprivation state for brain stimulation that instinctively facilitates the drive to seek out brain stimulation. BSR also lacks the established neural representation in the animal’s memory that naturally facilitates the learning of reward expectancy. Both of these effects lead to diminished response rate for BSR in the early trials of a series; however, experiments have also shown that extinguished behavior can be quickly reinstated by a priming stimulation that refreshes the short-term association involved in reward expectancy. Experiments on BSR indicate that reinforcing brain stimulation may activate the natural pathways associated with natural drives as well as stimulate the reinforcement pathways that are usually activated by natural rewards.