Table 1.

Brief description of behavioural paradigms.

Behavioural Paradigm	Description	Reference
Self-Administration (SA)	This paradigm is based on operant conditioning. Animals are taught through practice, and subsequently learn to conduct certain actions that result in self-administering a reinforcer (drug of abuse). Then, reinforcement is the event that follows the response (e.g., lever press) and increases the probability of responses reoccuring.	[110]
Conditioned Place Preference (CPP)	This paradigm results in a specific environment being paired with drug administration and vehicle administration seperately. After such pairing occurs, animals are placed back in the environment in a drug free state and their preference for each environment is tested.	[110]
Elevated Plus Maze (EPM)	Rodents are placed at the junction of a four-arm maze and their entry into the particular arms is measured by recording apparatus. Time spent (duration and entries) in open arms reflects anti-anxiety behaviour.	[111]
Intracranial Self-Stimulation (ICSS)	Animals learn to deliver elctrical pulses into specific regions of their own brains which are implicated in reward processes. The acute administration of various drugs of abuse including cocaine, amphetamine and opiates lowers ICSS thresholds in experimental animals, indicating a reward-facilitating effect. Withdrawal from administration of these compounds creates increases in ICSS thresholds which results in the manifestation of a withdrawal state. Through the dynamic orchestration of these states, researchers can understand reward-related behaviours further.	[112]