Decision making and interference in the domestic cat (Felis catus)

Domestic cats (Felis catus) received a task in which an obstacle was introduced at the time they were ready to reach for 1 among 2 or 3 baited targets. The results revealed that when the initially chosen direction (i.e., before the introduction of the obstacle) and the new one were orthogonal, the cats reassessed distance, angular deviation, and visibility once they had turned around the obstacle (Experiments 1, 2, and 3). Then the cats chose a different target than the one that would have been chosen had there been no obstacle. When both the initially chosen and the new direction matched (Experiment 4), the cats kept intact their initial decision. The discussion focuses on the nature of the representational system of the cat. The discussion also emphasizes comparisons with dogs (i.e., cooperative hunters).     

Instrumental learning in hyperdopaminergic mice

In two experiments we investigated the effects of elevated dopaminergic tone on instrumental learning and performance using dopamine transporter knockdown (DAT KD) mice. In Experiment 1, we showed that both DAT KD mice and wild-type controls were similarly sensitive to outcome devaluation induced by sensory specific satiety, indicating normal action-outcome learning in both groups. In Experiment 2, we used a Pavlovian-to-instrumental transfer procedure to assess the potentiation of instrumental responding by Pavlovian conditional stimuli (CS). Although during the Pavlovian training phase the DAT KD mice entered the food magazine more frequently in the absence of the CS, when tested later both groups showed outcome-selective PIT. These results suggest that the elevated dopaminergic tone reduced the selectivity of stimulus control over conditioned behavior, but did not affect instrumental learning.     

The neurobiology of postpartum depression

Postpartum psychiatric changes can range from maternity blues to psychosis. Causality is still undetermined, but explanations for these disturbances often focus on hormonal changes and dysregulation. Researchers have begun the process of delineating what neurobiological factors may be associated with depressive disorders in pregnancy and the postpartum. This article reviews the current literature on the roles of gonadal and pituitary hormones in the psychopathophysiology of postpartum mood disorders. Other biological factors, such as biogenic amines, neuroactive steroids, cholesterol, and fatty acids, are also discussed. The potential benefits of neuroimaging to aid in understanding neuropsychiatric changes that occur in the context of postpartum depression are also considered.     

Heart rate changes during conditioning-specific reflex modification of the rabbit's (Oryctolagus cuniculus) nictitating membrane response

Conditioning-specific reflex modification (CRM) of the rabbit's nictitating membrane response (NMR) involves changes in responding to an unconditioned stimulus (US) when the US is tested in the absence of the conditioned stimulus. Previous experiments have shown that CRM is a function of the type and intensity of the aversive US used during classical conditioning. As a result, it has been suggested that CRM may be mediated, at least in part, by the aversiveness of the US. Here, we show that by using a moderately intense electrical pulse to the skin as a US, CRM of the rabbit NMR is accompanied by an increase in heart rate. The largest changes in heart rate occur at US intensities that produce the strongest levels of CRM. The heart rate data show that there may be an increased emotional/arousal component to the US that is correlated with CRM and support the use of CRM as a potential model for posttraumatic stress disorder.     

Very young children are insensitive to picture- but not object-orientation

In two experiments on very young children's response to the orientation of pictures and objects, 18-, 24- and 30-month-old children showed no preference for upright pictures over inverted ones. More importantly, we found that children in all three age groups were equally accurate and equally fast at identifying depicted objects regardless of orientation. These studies further established that young children's insensitivity to picture orientation does not extend to objects. These results, in combination with the earlier ones, indicate that only gradually do young children come to share the picture orientation preference of adults and older children and that their adoption of the orientation convention is not based on changes in their ability to process upright and inverted images.     

Sequential combinations of drug and cognitive behavioral therapy for chronic insomnia: an exploratory study

This study explores the efficacy of sequential treatments involving medication and cognitive behavioral treatment (CBT) for primary insomnia. Seventeen participants took part in a multiple baseline design and were assigned to: (a) medication for 5 weeks, followed by combined medication plus CBT for 5 weeks; (b) combined treatment for 5 weeks, followed by CBT alone; or (c) CBT alone. Each treatment sequence produced significant sleep improvements, but at different points in time. For the first sequence, most of the sleep improvement was obtained after the introduction of CBT, while for the other sequence and CBT alone, improvement appeared during the first weeks. These results suggest that sleep improvement seems affected by the way treatments are combined. Also, a sequence beginning with a combined treatment followed by CBT alone seems to produce the best outcome. Additional research should be conducted with larger samples to determine the most effective sequence.     

Somatosensory processing and schizophrenia liability: proprioception, exteroceptive sensitivity, and graphesthesia performance in the biological relatives of schizophrenia patients

In the present study, the authors examined somatosensory processing in 30 biological relatives of persons with schizophrenia (hereafter called "schizophrenia relatives"), 30 biological relatives of persons with bipolar affective disorder (psychiatric family control subjects), and 30 healthy control subjects with no family history of psychopathology. All 3 groups completed a weight discrimination task, a 2-point discrimination task, and a complex cognitive somatosensory task (i.e., graphesthesia). The schizophrenia relatives performed significantly worse on all 3 somatosensory tasks compared with both the healthy control subjects and the bipolar relatives. The healthy control subjects and psychiatric family control subjects showed no significant differences on any of the somatosensory tasks. Within the weight discrimination and 2-point discrimination tasks, schizophrenia relatives showed group differences on the d' index, the measure of sensitivity, whereas all 3 groups did not differ on lnbeta, the measure of response bias, suggesting a genuine difference in weight and touch sensitivity. The d' value of the weight discrimination task was significantly associated with both the cognitive-perceptual factor and negative symptom factor of the clinical questionnaire (e.g., Schizotypal Personality Questionnaire; SPQ), whereas the 2-point discrimination d' value and graphesthesia scores were significantly associated only with the cognitive-perceptual factor of the SPQ. Implications for the possible relation between somatosensory task performance and schizophrenia liability are discussed.