Articles by David E. Waxler in JoVE
Touchscreen Sustained Attention Task (SAT) for Rats Debra A. Bangasser1,2, Brittany Wicks1, David E. Waxler1, Samantha R. Eck1 1Psychology Department, Temple University, 2Neuroscience Program, Temple University Sustained attention, or continuously monitoring situations for intermittent and unpredictable events, is a critical aspect of cognition. Here we detail how to test sustained attention in rats using touchscreen operant chambers. We demonstrate comparable performance in male and female rats, making this task useful for studying attention in both sexes.
Other articles by David E. Waxler on PubMed
Trace Conditioning and the Hippocampus: the Importance of Contiguity The Journal of Neuroscience : the Official Journal of the Society for Neuroscience. Aug, 2006 | Pubmed ID: 16928858 Trace conditioning, a form of classical conditioning in which the presentation of the conditioned stimulus (CS) and the unconditioned stimulus (US) is separated in time by an interstimulus interval, requires an intact hippocampus. In contrast, classical conditioning procedures in which the CS and US are not separated by an interstimulus interval (i.e., delay conditioning procedures) typically do not (Solomon et al., 1986). However, why trace conditioning is dependent on the hippocampus is unknown. Several theories suggest that it is specifically the discontiguity between the CS and US in trace conditioning that critically engages the hippocampus. However, there are other explanations that do not depend on discontiguity. To determine whether the lack of contiguity renders trace conditioning hippocampal dependent, we designed a "contiguous trace conditioning" (CTC) paradigm in which CS-US contiguity is restored by re-presenting the CS simultaneously with the US. Although rats with excitotoxic lesions of the hippocampus could not learn a standard trace fear-conditioning paradigm, lesioned rats trained on CTC showed significant conditioning, at levels similar to those with sham surgeries. Importantly, lesioned rats trained solely with simultaneous CS-US presentations did not demonstrate conditioning. Together, these data suggest that rats with hippocampal lesions can form a memory of a trace CS-US association when contiguity is restored. Therefore, the dependence of traditional trace paradigms on the hippocampus can be attributed to the absence of temporal contiguity.
Sex Differences in Corticotropin Releasing Factor-evoked Behavior and Activated Networks Psychoneuroendocrinology. Nov, 2016 | Pubmed ID: 27521739 Hypersecretion of corticotropin releasing factor (CRF) is linked to the pathophysiology of major depression and post-traumatic stress disorder, disorders that are more common in women than men. Notably, preclinical studies have identified sex differences in CRF receptors that can increase neuronal sensitivity to CRF in female compared to male rodents. These cellular sex differences suggest that CRF may regulate brain circuits and behavior differently in males and females. To test this idea, we first evaluated whether there were sex differences in anxiety-related behaviors induced by the central infusion of CRF. High doses of CRF increased self-grooming more in female than in male rats, and the magnitude of this effect in females was greater when they were in the proestrous phase of their estrous cycle (higher ovarian hormones) compared to the diestrous phase (lower ovarian hormones), which suggests that ovarian hormones potentiate this anxiogenic effect of CRF. Brain regions associated with CRF-evoked self-grooming were identified by correlating a marker of neuronal activation, cFOS, with time spent grooming. In the infralimbic region, which is implicated in regulating anxiety, the correlation for CRF-induced neuronal activation and grooming was positive in proestrous females, but negative for males and diestrous females, indicating that ovarian hormones altered this relationship between neuronal activation and behavior. Because CRF regulates a number of regions that work together to coordinate different aspects of responding to stress, we then examined more broadly whether CRF-activated functional connectivity networks differed between males and cycling females. Interestingly, hormonal status altered correlations for CRF-induced neuronal activation between a variety of brain regions, but the most striking differences were found when comparing proestrous females to males, particularly when comparing neuronal activation between prefrontal cortical and other forebrain regions. These results suggest that ovarian hormones alter the way brain regions work together in response to CRF, which could drive different strategies for coping with stress in males versus females. These sex differences in stress responses could also help explain female vulnerability to psychiatric disorders characterized by CRF hypersecretion.
Method for Testing Sustained Attention in Touchscreen Operant Chambers in Rats Journal of Neuroscience Methods. Feb, 2017 | Pubmed ID: 27939962 Sustained attention, the ability to detect rare and unpredictable events, is central to cognitive performance. This construct can be tested in rodents using a Sustained Attention Task (SAT), where rats are trained to detect an unpredictably occurring signal (a brief light presentation) from non-signal events. The traditional version of this task utilizes an operant chamber with a central panel light for the signal and two retractable response levers. Adaptation of SAT to the increasingly popular touchscreen operant chambers, which do not have levers or fixed lights, could enhance the versatility of the task.