Intracranial self-stimulation (ICSS) in rodents to study the neurobiology of motivation

It has become increasingly important to assess mood states in laboratory animals. Tests that reflect reward, reduced ability to experience reward ( anhedonia) and aversion ( dysphoria) are in high demand because many psychiatric conditions that are currently intractable in humans ( e. g., major depression, bipolar disorder, addiction) are characterized by dysregulated motivation. Intracranial self-stimulation (ICSS) can be utilized in rodents ( rats, mice) to understand how pharmacological or molecular manipulations affect the function of brain reward systems. Although many different methodologies are possible, we will describe in this protocol the use of medial forebrain bundle (MFB) stimulation together with the 'curve-shift' variant of analysis. This combination is particularly powerful because it produces a highly reliable behavioral output that enables clear distinctions between the treatment effects on motivation and the treatment effects on the capability to perform the task.