Water associated zero maze: a novel rat test for long term traumatic re-experiencing

Abstract

Often, freezing and startle behaviors in the context of a previously experienced stress are taken as an indication of post-traumatic stress disorder (PTSD)-like symptoms in rats. However, PTSD is characterized by large individual variations of symptoms. In order to take into consideration the complex and long term distinctive variations in effects of trauma exposure additional behavioral measures are required. The current study used a novel behavioral test, the water associated zero maze (WAZM). This test was planned to enable a formation of an association between the context of the maze and an underwater trauma (UWT) or swim stress in order to examine the impact of exposure to the context which immediately precedes a stressful or a traumatic experience on rat's complex behavior. Rats were exposed to the WAZM and immediately after to an UWT or short swim. One month later rats were re-exposed to the context of the WAZM while their behavior was video recorded. Furthermore, c-Fos expression in the amygdala was measured 90 min after this exposure. The results of the current study indicate that the WAZM can be used to discern behavioral changes measured a long time after the actual traumatic or stressful events. Furthermore, the behavioral changes detected were accompanied by changes of c-Fos expression in the amygdala of exposed rats. We suggest that the WAZM can be used to model traumatic memories re-experiencing in rodent models of human stress-related pathologies such as PTSD.

The contribution of medial prefrontal cortical regions to conditioned inhibition.

“…Furthermore, the magnitude of the difference in responding during reinforced and non-reinforced trials was reduced in PL-lesioned rats compared to those with sham lesions. These findings provide further support for the role of PL in the acquisition of excitatory conditioning (Ashwell & Ito, 2014; Balleine & Dickinson, 1998; Killcross & Coutureau, 2003) and the ability to inhibit a behavior (Ragozzino, 2007, MacLeod & Bucci, 2010; Bari et al, 2011). …”

“…First, rats must acquire knowledge about an inhibition paradigm with no previous exposure to the context or cues. Conversely, prior research has focused primarily on learning that requires inhibition of a previously-relevant strategy while acquiring a new strategy, based on cues that were previously presented (Nonneman, Voigt, & Kolb, 1974; Dias et al, 1997; Boulougouris et al, 2007; Ragozzino, 2007; Ashwell & Ito, 2014). Second, rats learn about a cue that signals omission of reinforcement and thus do not approach the food cup.…”

Newborn Rabbit Perception of 6-Odorant Mixtures Depends on Configural Processing and Number of Familiar Elements

“…This underlines the high plasticity of certain odor mixtures perception, a plasticity probably related to specific brain processes occurring in the olfactory bulb and/or piriform cortex [38]–[39] even early in life [10]–[11], [40]. In the rabbit, neonates are exposed to odor cues emitted by the mother (e.g., on her abdomen, milk; [41]–[45]) including the mammary pheromone.…”

“…Thus, in the AB mixture, newborns seem to perceive the odor of A, the odor of B, and a particular odor for the AB configuration [8], [9]. This weak configural perception of AB has been recently confirmed through a pharmacological approach showing that the neonatal memory of the AB configuration differs from the memory of the A and B elements [10], [11].…”

Animal models of post-traumatic stress disorder and recent neurobiological insights

“…A novel use of underwater trauma (Richter-Levin, 1998) was recently developed into a PTSD model in which animals are conditioned to pair a water-associated zero maze (WAZM) with underwater trauma (Ritov and Richter-Levin, 2014). Traumatic stress (being held underwater) was distinguished from a simple swim stress, as such a distinction between stressful vs. traumatic experiences may be critical for the modeling of PTSD (Koolhaas et al , 2011).…”