Visual marking and change detection

The preview benefit from prior exposure of response-irrelevant (distracter) objects in visual search has been accounted for in terms of top-down inhibition (i.e. visual marking), bottom-up abrupt onset capture, or asynchrony-dependent perceptual segregation. We assess the relative contribution of abrupt onset and visual marking in a paradigm combining visual search with a visual working memory task. We investigated time-based selection of multiple objects for storage in visual working memory, using a change detection paradigm (Luck and Vogel in Nature 390:279–281, 1997) with distracter preview. We varied preview exposure (short vs. long), in a series of three experiments. The contribution of asynchrony-related perceptual segregation was assessed across experiments by varying the complexity of the stimuli (colored squares, oriented bars and oriented T-shapes) and the type of change detection (color or orientation), resulting in different levels of perceptual segregation between visual elements. The results suggest that bottom-up abrupt onset, visual marking and perceptual segregation factors co-operate in time-based selection for storage in visual working memory.     

α7 Nicotinic Receptor Subunits Are Not Necessary for Hippocampal-Dependent Learning or Sensorimotor Gating: A Behavioral Characterization of Acra7-Deficient Mice

The α7 nicotinic acetylcholine receptor (nAChR) subunit is abundantly expressed in the hippocampus and contributes to hippocampal cholinergic synaptic transmission suggesting that it may contribute to learning and memory. There is also evidence for an association between levels of α7 nAChR and in sensorimotor gating impairments. To examine the role of α7 nAChRs in learning and memory and sensorimotor gating, Acra7 homozygous mutant mice and their wild-type littermates were tested in a Pavlovian conditioned fear test, for spatial learning in the Morris water task, and in the prepulse inhibition paradigm. Exploratory activity, motor coordination, and startle habituation were also evaluated. Acra7 mutant mice displayed the same levels of contextual and auditory-cue condition fear as wild-type mice. Similarly, there were no differences in spatial learning performance between mutant and wild-type mice. Finally, Acra7 mutant and wild-type mice displayed similar levels of prepulse inhibition. Other behavioral responses in Acra7 mutant mice were also normal, except for an anxiety-related behavior in the open-field test. The results of this study show that the absence of α7 nAChRs has little impact on normal, base-line behavioral responses. Future studies will examine the contribution of α7 nAChR to the enhancement of learning and sensorimotor gating following nicotine treatments.     

Comparing language lateralization determined by dichotic listening and fMRI activation in frontal and temporal lobes in children with epilepsy

We investigated the relationship between ear advantage scores on the Fused Dichotic Words Test (FDWT), and laterality of activation in fMRI using a verb generation paradigm in fourteen children with epilepsy. The magnitude of the laterality index (LI), based on spatial extent and magnitude of activation in classical language areas (BA 44/45, 21/22, 39) differed significantly for patients classified with unilateral left, compared to bilateral, language representation based on FDWT scores. Concordance with fMRI was higher for those classified with unilateral left, than bilateral language representation on the FDWT. Of note, asymmetry in temporal lobe, rather than frontal lobe, activation was more strongly related to the LI from the dichotic listening test. This study shows that the FDWT can provide a quick and valid estimate of lateralization in pre-surgical candidates, which can be readily adopted for other clinical or research purposes when an estimate of language dominance is desired.     

Signal detection theory analyses of semantic priming in word recognition

Word recognition, semantic priming, and cognitive impenetrability research have used signal detection theory (SDT) measures to separate perceptual and postperceptual processes. In the D. Norris (1986) checking model and model simulation (D. Norris, 1995), priming alters only postperceptual word decision criteria: Stimulus-related priming reduces uncertainty, increasing sensitivity; stimulus-unrelated priming increases false alarms more than hits, reducing sensitivity. This work is cited as strong evidence that criterion changes can alter perceptual sensitivity and that SDT is inappropriate for investigating complex cognitive processes. The authors' current SDT ideal observer analysis of the model demonstrates that related priming does not directly alter sensitivity and that unrelated priming increases only false-alarm rate, reducing sensitivity. This analysis provides new perspectives on SDT concepts of complex decision processing.     

The self in the couple relationship: part 1

This paper discusses the importance of the ‘good-enough’ development of the core self in the couple relationship. It argues that difficulties in the development of the self lie behind a significant number of troubled couple relationships. Part 1 focuses on individual psychotherapy and how changes to the core self are often attended by shifts in the marital relationship. It traces how this occurs through clinical material and analyses what kinds of changes to the self are needed for the couple relationship to function well. Psychodynamic theory is used to understand the core changes over time and how these are related to significant second-order change in the couple relationship. The construct of the ‘transitional space’ is used to theorize the couple relationship. Implications for the practice of individual psychotherapy are discussed. In Part 2, the significance of change in the experience of the self of one or both partners for a successful outcome of couples therapy is discussed, along with the place of work with individual partner(s) in the course of conjoint couples therapy.