Developmental trajectories for spatial frames of reference in Williams syndrome

Williams syndrome (WS) is a genetic disorder associated with severe visuocognitive impairment. Individuals with WS also report difficulties with everyday wayfinding. To study the development of body-, environment-, and object-based spatial frames of reference in WS, we tested 45 children and adults with WS on a search task in which the participant and a spatial array are moved with respect to each other. Although individuals with WS showed a marked delay, like young controls they demonstrated independent, additive use of body- and environment-based frames of reference. Crucially, object-based (intrinsic) representations based on local landmarks within the array were only marginally used even by adults with WS, whereas in typical development these emerge at 5 years. Deficits in landmark use are consistent with wayfinding difficulties in WS, and may also contribute to problems with basic localization, since in typical development landmark-based representations supplement those based on the body and on self-motion. Difficulties with inhibition or mental rotation may be further components in the impaired ability to use the correct reference frame in WS.     

Glucocorticoids enhance taste aversion memory via actions in the insular cortex and basolateral amygdala

It is well established that glucocorticoid hormones strengthen the consolidation of hippocampus-dependent spatial and contextual memory. The present experiments investigated glucocorticoid effects on the long-term formation of conditioned taste aversion (CTA), an associative learning task that does not depend critically on hippocampal function. Corticosterone (1.0 or 3.0 mg/kg) administered subcutaneously to male Sprague–Dawley rats immediately after the pairing of saccharin consumption with the visceral malaise-inducing agent lithium chloride (LiCl) dose-dependently increased aversion to the saccharin taste on a 96-h retention test trial. In a second experiment, rats received corticosterone either immediately after saccharin consumption or after the LiCl injection, when both stimuli were separated by a 3-h time interval, to investigate whether corticosterone enhances memory of the gustatory or visceral stimulus presentation. Consistent with the finding that the LiCl injection, but not saccharin consumption, increases endogenous corticosterone levels, corticosterone selectively enhanced CTA memory when administered after the LiCl injection. Suppression of this training-induced release of corticosterone with the synthesis-inhibitor metyrapone (35 mg/kg) impaired CTA memory, and was dose-dependently reversed by post-training supplementation of corticosterone. Moreover, direct post-training infusions of corticosterone into the insular cortex or basolateral complex of the amygdala, two brain regions that are critically involved in the acquisition and consolidation of CTA, also enhanced CTA retention, whereas post-training infusions into the dorsal hippocampus were ineffective. These findings provide evidence that glucocorticoid effects on memory consolidation are not limited to hippocampus-dependent spatial/contextual information, but that these hormones also modulate memory consolidation of discrete-cue associative learning via actions in other brain regions.     

Intimate relationship development during the transition to adulthood: differences by social class

This article examines differences in young adults' intimate relationships by social class. Lower-class adolescents are more likely to engage in intimate-relationship practices such as cohabitation, early marriage, and sexual activity that may lead to further economic and educational deprivation. Such adolescents have limited access to the special opportunities of emerging adulthood. Social class indirectly shapes the relationships of groups such as prisoners, military personnel, and sexual minorities whose memberships are highly class graded and who are subject to state-controlled relationship constraints. More research is needed on how laws and institutions constrain even the most intimate features of young lives.     

Addressing moral problems through practical reasoning

In this paper, following the work of Hare, we consider moral reasoning not as the application of moral norms and principles, but as reasoning about what ought to be done in a particular situation, with moral norms perhaps emerging from this reasoning. We model this situated reasoning drawing on our previous work on argumentation schemes, here set in the context of Action-Based Alternating Transition Systems. We distinguish what prudentially ought to be done from what morally ought to be done, consider what legislation might be appropriate and characterise the differences between morally correct, morally praiseworthy and morally excusable actions. We also describe an implementation which simulates this reasoning and discuss some issues arising from the simulation.     

Explicit disassociation of a conditioned stimulus and unconditioned stimulus during extinction training reduces both time to asymptotic extinction and spontaneous recovery of a conditioned taste aversion

Conditioned taste aversions (CTAs) may be acquired when an animal consumes a novel taste (CS) and then experiences the symptoms of poisoning (US). This aversion may be extinguished by repeated exposure to the CS alone. However, following a latency period in which the CS is not presented, the CTA will spontaneously recover (SR). In the current study we employed an explicitly unpaired extinction procedure (EU-EXT) to determine if it could thwart SR of a CTA. Sprague-Dawley rats acquired a strong CTA after three pairings of saccharin (SAC the CS) and Lithium Chloride (LiCl the US). CTA acquisition was followed by extinction (EXT) training consisting of either (a) CS-only exposure (CSO) or (b) exposure to saccharin and Lithium Chloride on alternate days (i.e., explicitly unpaired: EU). Both extinction procedures resulted in ?90% reacceptance of SAC, although the EU extinction procedure (EU-EXT) significantly decreased the time necessary for rats to reach this criterion (compared to CSO controls). Rats were subsequently tested for SR of the CTA upon re-exposure to SAC following a 30-day latency period of water drinking. Rats that acquired a CTA and then underwent the CSO extinction procedure exhibited a significant suppression of SAC drinking during the SR test (as compared to their SAC drinking at the end of extinction). However, animals in the EU-EXT group did not show such suppression in drinking compared to CSO controls. These data suggest that the EU-EXT procedure may be useful in reducing both time to extinction and the spontaneous recovery of fears.     

Enhanced inhibitory avoidance learning prevents the long-term memory-impairing effects of cycloheximide,a protein synthesis inhibitor

Interference with activity of numerous cerebral structures produces memory deficiencies; in many instances, however, when animals are over-trained such interference becomes innocuous. Systemic administration of protein synthesis inhibitors impairs long-term retention; this effect has been interpreted to mean that protein synthesis is required for memory consolidation, though little is known about the effect of protein synthesis inhibitors on memory of enhanced learning in the rat. To further analyze the protective effect of enhanced learning against amnesic treatments, groups of Wistar rats were trained in a one-trial step-through inhibitory avoidance task, using different intensities of foot-shock during training. Cycloheximide (CXM; 2.8 mg/kg), an inhibitor of protein synthesis, was injected either 30 min before training or immediately after training. Twenty-four hours after training retention latencies were recorded. Our data showed that both pre- and post-training administration of CXM produced amnesia in those groups that had been trained with relatively low foot-shock intensities, but no impairment in retention was observed when relatively high intensities of foot-shock were administered. These and similar results lead us to conclude that protein synthesis inhibitors may interfere with memory consolidation, but their effect disappears when animals are submitted to an enhanced learning experience, calling into question the idea that protein synthesis is required for memory consolidation.     

Asymmetrical cortical processing of radial expansion / contraction in infants and adults

We report asymmetrical cortical responses (steady‐state visual evoked potentials) to radial expansion and contraction in human infants and adults. Forty‐four infants (22 3‐month‐olds and 22 4‐month‐olds) and nine adults viewed dynamic dot patterns which cyclically (2.1 Hz) alternate between radial expansion (or contraction) and random directional motion. The first harmonic (F1) response in the steady‐state VEP response must arise from mechanisms sensitive to the global radial motion structure. We compared F1 amplitudes between expansion‐random and contraction‐random motion alternations. F1 amplitudes for contraction were significantly larger than those for expansion for the older infants and adults but not for the younger infants. These results suggest that the human cortical motion mechanisms have asymmetrical sensitivity for radial expansion vs. contraction, which develops at around 4 months of age. The relation between development of sensitivity to radial motion and cortical motion mechanisms is discussed.     

Are release recommendations for NGRI acquittees informed by relevant data?

We conducted a retrospective review of factors involved in clinical recommendations for release of patients adjudicated not guilty by reason of insanity (NGRI). Medical records from 91 patients in a maximum security forensic hospital who participated in a formal hearing process to determine suitability for release were reviewed. The purpose of the study was twofold: (1) to examine the process involved in day to day clinical decision-making regarding release from a maximum security forensic hospital and (2) to determine what factors in a patient's clinical and legal history were related to recommendation decisions. Multivariate statistical methods revealed that among the clinical, demographic, and legal information available to clinicians at the time a formal release recommendation was made two factors emerged that were significantly related to release recommendations: PCL-R score and the age at which the patient committed his first criminal offense. Patients with high levels of psychopathy and those who engaged in criminal behavior at a younger age were less likely to be recommended for release from a maximum security forensic hospital.     

Orthographic neighborhood size effects in recognition memory

This study argues for the importance of physical word features in recognition memory by investigating the influence of orthographic distinctiveness. Experiment 1 demonstrated a mirror effect in ayes/no recognition test by manipulating orthographic neighborhood size. Words with small neighborhoods showed more hits and fewer false alarms than did words with larger neighborhoods. Experiment 2 replicated the neighborhood size mirror effect using null pairs in a forced choice recognition test. Experiment 3 required remember/know judgments in a yes/no recognition task. Experiment 4 used the same yes/no test as did Experiment 1, adding a study task that drew attention away from orthographic information in the study list. The mirror pattern disappeared with the addition of the study task.     

The role of animacy and thematic relationships in processing active English sentences: evidence from event-related potentials

Recent event-related potential studies report a P600 effect to incongruous verbs preceded by semantically associated inanimate noun-phrase (NP) arguments, e.g., "eat" in "At breakfast the eggs would eat...". This P600 effect may reflect the processing cost incurred when semantic-thematic relationships between critical verbs and their preceding NP argument(s) bias towards different interpretations to those dictated by their sentences' syntactic structures. We have termed such violations of alternative thematic roles, 'thematic role violations.' Semantic-thematic relationships are influenced both by semantic associations and by more basic semantic features, such as a noun's animacy. This study determined whether a P600 effect can be evoked by verbs whose thematic structures are violated by their preceding inanimate NP arguments, even in the absence of close semantic-associative relationships with these arguments or their preceding contexts. ERPs were measured to verbs under four conditions: (1) non-violated ("At breakfast the boys would eat..."); (2) preceded by introductory clauses and animate NPs that violated their pragmatic expectations but not their thematic structures ("At breakfast the boys would plant..."); (3) preceded by semantically related contexts but inanimate NPs that violated their thematic structures ("At breakfast the eggs would eat..."); (4) preceded by semantically unrelated contexts and inanimate NPs that also violated their thematic structures ("At breakfast the eggs would plant..."). Pragmatically non-thematic role violated verbs preceded by unrelated contexts and animate NPs evoked robust N400 effects and small P600 effects. Thematically violated verbs preceded by inanimate argument NPs evoked robust P600 effects but no N400 effects, regardless of whether these inanimate arguments or their preceding contexts were semantically related or unrelated to these verbs. These findings suggest that semantic-thematic relations, related to animacy constraints on verbs' arguments, are computed online and can immediately impact verb processing within active, English sentences.