The elevated plus-maze is the most widely used test to measure fear or anxiety and it is particularly sensitive to anxiety-reducing drugs such as benzodiazepines. This test is useful both because of its relative simplicity and short time as well as for its lack of use of reward or conditioning; this test determines the animal’s unconditioned response to a potentially dangerous environment.

Test specifics: The animal is placed in the center of an elevated 4-arm maze with 2 arms open and 2 enclosed arms. Fear/anxiety associated behavior is determined by counting the number of times the animal enters or stays in open or closed arms as well as the time the animal spends in each arm. High anxiety states are directly related to the degree to which the rodent avoids the open arms of the maze and lack of fear is indicated by the “daring” of the animals to enter open arms repeatedly.

This test is based on the natural tendency of rodents to prefer dark enclosed environments as well as their innate tendency to explore a new environment. It is an anxiety-related test useful to determine limbic system damage and is also a used to test the effectiveness of anxiolitic drugs.

Test specifics: The apparatus contains a light opened portion and enclosed dark portion. Rodents prefer dark spaces but also want to explore new ones. Therefore high levels of anxiety can be measured by increased length of time for the animal to emerge into the lighted portion of the apparatus or the avoidance of the area in general while showing no preference for the dark area of the enclosure suggests low levels of anxiety.

Pre-pulse inhibition is based on a cross-species finding where animals and humans are less sensitive to a stimulus once it has been previously presented. Importantly, this behavior is significantly diminished in schizophrenic patients and among patients with Alzheimer’s disease (AD) and is associated with the decreased capacity of these individuals to filter out irrelevant auditory stimulation, taken to signify various aspects associated with these disorders; namely: high levels of distractibility, inattention, and poor cognitive function. The test is particularly useful to evaluate transgenic models of schizophrenia, and Attention Deficit Disorder and potential antipsychotic drugs and potential pharmacological treatments in some AD models.

Test Specifics: The rodent is placed in a small chamber and exposed to a brief pulse of noise (pre-pulse) prior to a second more intense pulse. The reflexive startle response is measured in both trials.

Open field activity tests are used to measure locomotor activity in rodents and can also serve as good preliminary tests to determine anxiety as well as effects of drugs and/or gene manipulations on motor-based function during phenotyping. Anxiety is determined by the pattern of exploration of the rodent in the open-field (center versus periphery). High anxiety in mice is detected by increased time spent walking around the periphery of the open-field versus venturing into the center of the open-field.

Test Specifics: Rodents are placed in an open field box where activity as well as pattern of exploration (center versus periphery)are measured for a duration of 15 minutes.