Measures of fear conditioning include the cessation of movement ("freezing"), a defensive behaviour, and increased skin conductance responses or increased blood pressure (autonomic measures that reflect arousal level).
In order to evaluate a measure of numerical conditioning of these solutions the relative condition number of the delta-domain algebraic Riccati equation is introduced.
In insects, most successful electrophysiological studies in search for neural correlates of learning and memory have been performed by using classical conditioning of proboscis extension response, in which an odor was associated with sucrose solution and activities of an extensor muscle of the proboscis were recorded as a measure of the conditioning effect [honeybees: 35,36; moths: 37].
Because the mutants showed small differences in baseline activity (see Supplemental Table S1), we also analyzed another measure of fear conditioning that minimizes the effect of baseline activity differences (activity suppression): the results confirmed the findings obtained using freezing scores (Figure 4a, b and c).
Anticipatory skin conductance responses [ SCRs] are a widely used measure of aversive conditioning in humans.
However, although SCR was a good measure of differential conditioning, it did not differentiate between PTSD groups.
Although air conditioning has been found to modify the association between temperature and mortality (Anderson and Bell 2009), as with most heat wave studies, we did not have a measure of air conditioning.
These findings replicate earlier studies showing exaggerated FPS to danger cues in PTSD subjects [30] and the validity of FPS as a measure of fear conditioning in human populations.
Briefly, we used monochrome slides as the visual conditioned stimuli (CS), a loud (97 dB) aversive white noise tone lasting 1000 msec as the US, and the amplitude of the SCR in the 7-sec period following CS presentation as the dependent measure of the conditioning process.
However, it was noteworthy that a majority of the unresponsive mice were from groups that did not receive conditioning (see Results), which provided us with an additional way to measure the effects of conditioning on behavioral responsiveness.
