Early effects of recollection memory on viewing behavior during visual associative recognition

Memory for the context in which items were previously encountered is necessary for everyday tasks. Recollection of item-context associations can facilitate search and support earlier viewing of recognition targets. We used fixation-by-fixation analysis of viewing behavior to characterize visual fixations influenced by recollection during associative recognition. We computed the (1) aggregate proportion of viewing time on target and (2) saccades within target per fixation during recognition testing to measure the influence of recollection on viewing behavior. Proportion of viewing time on target and number of saccades within target increased after the initial fixation of recognition test. These results indicate that recollection effects occurred immediately after the initial fixation of visual associative recognition and that early, prolonged fixations and saccades within selected faces could represent a precise behavioral correlate of recollection memory.

Central Fos expression and conditioned flavor avoidance in rats following intragastric administration of bitter taste receptor ligands

G protein-coupled receptors that signal bitter taste (T2Rs) are expressed in the mucosal lining of the oral cavity and gastrointestinal (GI) tract. In mice, intragastric infusion of T2R ligands activates Fos expression within the caudal viscerosensory portion of the nucleus of the solitary tract (NTS) through a vagal pathway (Hao S, Sternini C, Raybould HE. Am J Physiol Regul Integr Comp Physiol 294: R33–R38, 2008). The present study was performed in rats to further characterize the distribution and chemical phenotypes of brain stem and forebrain neurons activated to express Fos after intragastric gavage of T2R ligands, and to determine a potential behavioral correlate of this central neural activation. Compared with relatively low brain stem and forebrain Fos expression in control rats gavaged intragastrically with water, rats gavaged intragastrically with T2R ligands displayed significantly increased activation of neurons within the caudal medial (visceral) NTS and caudal ventrolateral medulla, including noradrenergic neurons, and within the lateral parabrachial nucleus, central nucleus of the amygdala, and paraventricular nucleus of the hypothalamus. A behavioral correlate of this Fos activation was evidenced when rats avoided consuming flavors that previously were paired with intragastric gavage of T2R ligands. While unconditioned aversive responses to bitter tastants in the oral cavity are often sufficient to inhibit further consumption, a second line of defense may be provided postingestively by ligand-induced signaling at GI T2Rs that signal the brain via vagal sensory inputs to the caudal medulla.

How developmental science contributes to theories of future thinking

Acting in the present in anticipation of the future is argued to be a behavioral correlate of mental time travel (MTT). Yet, it is important to consider how other future-directed behaviors – including planning, delay of gratification, and acts of prospective memory – figure into a theory of MTT and future thinking more broadly. Developmental science can help in this formulation.

The impact of classification on psychopharmacology and biological psychiatry

Nosological classification in psychiatry, as it is currently applied, does not facilitate biological and psychopharmacological research.• Syndromal acuity has disappeared. Consequently, it is impossible to determine: (i) vi/hether a particular drug affects a particular symptom configuration; (ii) what exactly the behavioral correlate of a particular biological disturbance is. The problem of unfocused diagnoses is greatly magnified by the phenomenon called comorbidity.• The boundary between distress and disorder is illdefined.• Symptom configuration and certain nonsymptomatological variables such as duration and severity are prematurely linked, so as to conceptualize categorical entities. The validity of those constructs has not been sufficiently demonstrated. This undermines the validity of biological studies and leads to "nosologomania," ie, an ever-growing series of undervalidated psychiatric "disorders."• Symptoms are grouped horizontally as if they all had the same diagnostic "valence." This, however, is highly unlikely.• The nosological disease model is unconditionally and uncritically accepted. Alternative models are ignored, particularly the reaction-form model, though it has substantial heuristic value, and deserves to be thoroughly scrutinized.(Research) strategies to remedy this situation are pointed out.

Aggressive Performance as a Behavioral Correlate of Plumage Polymorphism in the White-Throated Sparrow (Zonotrichia Albicollis)

Morph and sex-specific differences in aggressive performance were examined in the white-throated sparrow. Among the four morph/sex classes, white-striped males had the strongest response to white-striped models and were the most likely to approach and attend song playbacks independently. The slightly weaker responses of tan-striped males and white-striped females were similar to each other. Tan-striped females were the least aggressive. Aggression by white-striped females enabled tan-striped male x white-striped female pairs to perform as well, or better, than white-striped male x tan-striped female pairs. Tan-striped males paired earlier than white-striped males. An increased prevalence of territorial tan-striped males corresponded to the arrival of females on the breeding grounds. The data are consistent with the hypothesis that negative assortative mating benefits tan-striped males through the supplemental aggression of white-striped females. However, the apparent preference of white-striped females for tan-striped males suggests that there are benefits to negative asortative mating other than those that might arise from differences in aggressive performance.