Intermittent reinforcement and salt arousal of thirst in rats

Sated rats, previously trained to leverpress for H₂O reinforcement on continuous or variable-interval (10-sec or 60-sec) schedules, were given NaCl injections and tested for leverpressing. Under all schedules, responding was an inverted U function of NaCl concentration (0.15M to 3.0M). However, NaCl thirst produced relatively little change in behavior under the VI 60-sec schedule.     

Additive summation by stimulus compounding irrespective of behavioral contrast during discrimination training: An investigation with positive reinforcement and avoidance schedules

The similarity in the discrimination training leading to behavioral contrast and that preceding tests producing response enhancement to combined discriminative stimuli suggested that the two phenomena might be related. This was investigated by determining if contrast indiscrimination training was necessary for this outcome of stimulus compounding. Responding to tone, light, and to the simultaneous absence of tone and light (T + L) was maintained during baseline training by food reinforcement in Experiment I and by shock avoidance in Experiment II. During subsequent discrimination training, responding was reduced in T + L by programming nonreinforcement in Experiment I and safety or response-punishment in Experiment II. In the first experiment, one rat exhibited positive behavioral contrast, i.e., tone and light rates increased while his T + L rate decreased. In Experiment II, rats punished in T + L showed contrast in tone and light, this being the first demonstration of punishment contrast on an avoidance baseline with rats. The discrimination acquisition data are discussed in the light of current explanations of contrast by Gamzu and Schwartz (1973) and Terrace (1972). During stimulus compounding tests, all subjects in both experiments emitted more responses to tone-plus-light than to tone or light (additive summation). An analysis of the terminal training baselines suggests that the factors producing these test results seem unrelated to whether or not contrast occurred during discrimination training. It was concluded that the stimulus compounding test reveals the operation of the terminal baseline response associations and reinforcement associations conditioned on these multicomponent free-operant schedules of reinforcement.

     

Attitudes of Australian chiropractic students toward whole body donation: A cross‐sectional study

Cadavers play an important role in anatomy education. In Australia, bodies for anatomy education are acquired only through donations. To gain insight into educational dynamics in an anatomy laboratory as well as to facilitate body donation programs and thanksgiving ceremonies, it is important to understand students' attitudes toward body donation. In this cross‐sectional study, the attitudes of Macquarie University's first, second, and fifth year chiropractic students toward body donation were investigated. Macquarie University chiropractic students have a four semester long anatomy program, which includes cadaver‐based instruction on prosected specimens. A questionnaire was used to record respondents' demographics and attitudes toward body donation: personal, by a relative, and by a stranger. It was found that ethnicity and religion affect attitudes toward body donation, with Australian students being more willing to donate a stranger's body and atheists and agnostics being more willing to donate in general. Furthermore, willingness to donate one's own or a family member's body decreases as year of study increases, suggesting a possible negative impact of exposure to cadavers in the anatomy laboratory. This was only true, however, after controlling for age. Thus, the impact of viewing and handling prosected specimens, which is the norm in anatomy classes in Australia, may not be as strong as dissecting cadavers. It is suggested that anatomists and educators prepare students for cadaver‐based instruction as well as exhibit sensitivity to cultural differences in how students approach working with cadavers, when informing different communities about body donation programs and in devising thanksgiving ceremonies. Anat Sci Educ 7: 117–123. © 2013 American Association of Anatomists.     

<Emphasis Type="Italic">DRD4</Emphasis> and <Emphasis Type="Italic">DAT1</Emphasis> VNTR Genotyping in Children with Attention Deficit Hyperactivity Disorder

The dopamine receptor-D4 and the dopamine transporter have been investigated for their role in attention deficit hyperactivity disorder (ADHD) in children. Reports of their genetic association with ADHD have shown mixed results. The aim of the study was to evaluate the association of variable number tandem repeats (VNTRs) of the DRD4 and DAT1 genes with ADHD in children. A pilot 1:1 case control study, with 44 clinically confirmed ADHD cases and 44 age/gender matched healthy controls, was conducted at a tertiary care centre in Mumbai. Variable number tandem repeats of DRD4 exon 3, DAT1 intron 8 and 3′UTR were genotyped by PCR-AGE. Several allele repeats of the genes were observed in the screened subjects. Statistical significance was observed for the 10R/10R genotype of the DAT1 3′UTR VNTR between cases and controls.