## Models of human behaviour disorders

Knowledge is a psychological concept that includes the processes of learning, memory and perception. Cognition, i.e. the ability to know, is one of the psychological processes that, from an experimental point of view, can be derived from changes in the behaviour of an organism. Testing of cognitive functions and their genetic background is often investigated using rodents that are subjected to behavioural tests. The strategy for this type of experiment may involve the targeted switching off of a certain candidate gene and then testing and recording changes in the individual's behavior. These experiments are also used in the preclinical investigation of the effect of new drugs targeting the central nervous system.

One such test is the open field test (Figure 13.3), which is used in the study of locomotor activity, anxious behaviour and willingness to explore the surrounding environment in rodents. The most common manifestation of interest in the environment is movement, therefore the test records the distance travelled, time spent moving, or changes in behaviour over time. All these parameters can be affected by the anxiety of individuals. The open field test is also used as a standard when evaluating the toxic and stimulating effects of various compounds. Motor coordination is assessed in rodents by the rotator test (Figure 13.3), in which the animal is placed on a horizontal bar that rotates around its long axis. Only individuals with functional motor skills can coordinate their movements so that they stay on the pole and do not fall.

Some neurodegenerative diseases, such as Alzheimer's or Parkinson's disease, manifest as changes in motor skills and movement, which we refer to as ataxia. The reason is changes at the level of neurons, which are also related to the reduced mental ability of individuals. Depressive behaviour is assessed by the forced swim test (Figure 13.3), in which the rodent is placed in a container of water from which it initially attempts to escape. After a while, however, he gives up his efforts. Individuals showing depressive behavioural tendencies take less time to give up compared to healthy rodents. The parameters of these types of tests can be measured, but they still leave some doubts about their subjective evaluation.