Learning to tie the knot: The acquisition of functional object representations by physical and observational experience

Here we examined neural substrates for physically and observationally learning to construct novel objects, and characterized brain regions associated with each kind of learning using fMRI. Each participant was assigned a training partner, and for five consecutive days practiced tying one group of knots (“tied” condition) or watched their partner tie different knots (“watched” condition) while a third set of knots remained untrained. Functional MRI was obtained prior to and immediately following the week of training while participants performed a visual knot-matching task. After training, a portion of left superior parietal lobule demonstrated a training by scan session interaction. This means this parietal region responded selectively to knots that participants had physically learned to tie in the post-training scan session but not the pre-training scan session. A conjunction analysis on the post-training scan data showed right intraparietal sulcus and right dorsal premotor cortex to respond when viewing images of knots from the tied and watched conditions compared to knots that were untrained during the post-training scan session. This suggests that these brain areas track both physical and observational learning. Together, the data provide preliminary evidence of engagement of brain regions associated with hand-object interactions when viewing objects associated with physical experience, and with observational experience without concurrent physical practice

A free-boundary model of diffusive valley growth: theory and observation

Valleys that form around a stream head often develop characteristic finger-like elevation contours. We study the processes involved in the formation of these valleys and introduce a theoretical model that indicates how shape may inform the underlying processes. We consider valley growth as the advance of a moving boundary travelling forward purely through linearly diffusive erosion, and we obtain a solution for the valley shape in three dimensions. Our solution compares well to the shape of slowly growing groundwater-fed valleys found in Bristol, Florida. Our results identify a new feature in the formation of groundwater-fed valleys: a spatially variable diffusivity that can be modelled by a fixed-height moving boundary

The impact of seawater saturation state and bicarbonate ion concentration on calcification by new recruits of two Atlantic corals

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Coral Reefs 30 (2011): 321-328, doi:10.1007/s00338-010-0697-z.Rising concentrations of atmospheric CO2 are changing the carbonate chemistry of the oceans, a process known as ocean acidification (OA). Absorption of this CO2 by the surface oceans is increasing the amount of total dissolved inorganic carbon (DIC) and bicarbonate ion (HCO3 -) available for marine calcification, yet is simultaneously lowering the seawater pH and carbonate ion concentration ([CO3 2-]), and thus the saturation state of seawater with respect to aragonite (Ωar). We investigated the relative importance of [HCO3 -] versus [CO3 2-] for early calcification by new recruits (primary polyps settled from zooxanthellate larvae) of two tropical coral species, Favia fragum and Porites astreoides. The polyps were reared over a range of Ωar values, which were manipulated by both acid-addition at constant pCO2 (decreased total [HCO3 -] and [CO3 2-]) and by pCO2 elevation at constant alkalinity (increased [HCO3 -], decreased [CO3 2-]). Calcification after two weeks was quantified by weighing the complete skeleton (corallite) accreted by each polyp over the course of the experiment. Both species exhibited the same negative response to decreasing [CO3 2-] whether Ωar was lowered by acid-addition or by pCO2 elevation - calcification did not follow total DIC or [HCO3 -]. Nevertheless, the calcification response to decreasing [CO3 2-] was non-linear. A statistically significant decrease in calcification was only detected between Ωar = < 2.5 and Ωar = 1.1 – 1.5, where calcification of new recruits was reduced by 22 – 37 % per 1.0 decrease in Ωar. Our results differ from many previous studies that report a linear coral calcification response to OA, and from those showing that calcification increases with increasing [HCO3 -]. Clearly, the coral calcification response to OA is variable and complex. A deeper understanding of the biomineralization mechanisms and environmental conditions underlying these 3 variable responses is needed to support informed predictions about future OA impacts on corals and coral reefs.This study was supported by NSF award 0648157 (Cohen and McCorkle), NSF 1041106 (Cohen, McCorkle), NSF 1041052 (de Putron), the VITA foundation (de Putron), WHOI Ocean Life Institute (Cohen), PEI and EEB Departments at Princeton University, Bill and Anne Charrier, and the Anthony B. Evnin, Dean’s Roundtable, and Edmund Hayes Sr. senior thesis funds (Dillon)

A behavioral comparison of male and female adults with high functioning autism spectrum conditions

Autism spectrum conditions (ASC) affect more males than females in the general population. However, within ASC it is unclear if there are phenotypic sex differences. Testing for similarities and differences between the sexes is important not only for clinical assessment but also has implications for theories of typical sex differences and of autism. Using cognitive and behavioral measures, we investigated similarities and differences between the sexes in age- and IQ-matched adults with ASC (high-functioning autism or Asperger syndrome). Of the 83 (45 males and 38 females) participants, 62 (33 males and 29 females) met Autism Diagnostic Interview-Revised (ADI-R) cut-off criteria for autism in childhood and were included in all subsequent analyses. The severity of childhood core autism symptoms did not differ between the sexes. Males and females also did not differ in self-reported empathy, systemizing, anxiety, depression, and obsessive-compulsive traits/symptoms or mentalizing performance. However, adult females with ASC showed more lifetime sensory symptoms (p = 0.036), fewer current socio-communication difficulties (p = 0.001), and more self-reported autistic traits (p = 0.012) than males. In addition, females with ASC who also had developmental language delay had lower current performance IQ than those without developmental language delay (p<0.001), a pattern not seen in males. The absence of typical sex differences in empathizing-systemizing profiles within the autism spectrum confirms a prediction from the extreme male brain theory. Behavioral sex differences within ASC may also reflect different developmental mechanisms between males and females with ASC. We discuss the importance of the superficially better socio-communication ability in adult females with ASC in terms of why females with ASC may more often go under-recognized, and receive their diagnosis later, than males

In Situ Photodegradation of Incorporated Polyanion Does Not Alter Prion Infectivity

Single-stranded polyanions ≥40 bases in length facilitate the formation of hamster scrapie prions in vitro, and polyanions co-localize with PrPSc aggregates in vivo [1], [2]. To test the hypothesis that intact polyanionic molecules might serve as a structural backbone essential for maintaining the infectious conformation(s) of PrPSc, we produced synthetic prions using a photocleavable, 100-base oligonucleotide (PC-oligo). In serial Protein Misfolding Cyclic Amplification (sPMCA) reactions using purified PrPC substrate, PC-oligo was incorporated into physical complexes with PrPSc molecules that were resistant to benzonase digestion. Exposure of these nuclease-resistant prion complexes to long wave ultraviolet light (315 nm) induced degradation of PC-oligo into 5 base fragments. Light-induced photolysis of incorporated PC-oligo did not alter the infectivity of in vitro-generated prions, as determined by bioassay in hamsters and brain homogenate sPMCA assays. Neuropathological analysis also revealed no significant differences in the neurotropism of prions containing intact versus degraded PC-oligo. These results show that polyanions >5 bases in length are not required for maintaining the infectious properties of in vitro-generated scrapie prions, and indicate that such properties are maintained either by short polyanion remnants, other co-purified cofactors, or by PrPSc molecules alone

Having a lot of a good thing: multiple important group memberships as a source of self-esteem.

Copyright: © 2015 Jetten et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are creditedMembership in important social groups can promote a positive identity. We propose and test an identity resource model in which personal self-esteem is boosted by membership in additional important social groups. Belonging to multiple important group memberships predicts personal self-esteem in children (Study 1a), older adults (Study 1b), and former residents of a homeless shelter (Study 1c). Study 2 shows that the effects of multiple important group memberships on personal self-esteem are not reducible to number of interpersonal ties. Studies 3a and 3b provide longitudinal evidence that multiple important group memberships predict personal self-esteem over time. Studies 4 and 5 show that collective self-esteem mediates this effect, suggesting that membership in multiple important groups boosts personal self-esteem because people take pride in, and derive meaning from, important group memberships. Discussion focuses on when and why important group memberships act as a social resource that fuels personal self-esteem.This study was supported by 1. Australian Research Council Future Fellowship (FT110100238) awarded to Jolanda Jetten (see http://www.arc.gov.au) 2. Australian Research Council Linkage Grant (LP110200437) to Jolanda Jetten and Genevieve Dingle (see http://www.arc.gov.au) 3. support from the Canadian Institute for Advanced Research Social Interactions, Identity and Well-Being Program to Nyla Branscombe, S. Alexander Haslam, and Catherine Haslam (see http://www.cifar.ca)

Autism as a disorder of neural information processing: directions for research and targets for therapy

The broad variation in phenotypes and severities within autism spectrum disorders suggests the involvement of multiple predisposing factors, interacting in complex ways with normal developmental courses and gradients. Identification of these factors, and the common developmental path into which theyfeed, is hampered bythe large degrees of convergence from causal factors to altered brain development, and divergence from abnormal brain development into altered cognition and behaviour. Genetic, neurochemical, neuroimaging and behavioural findings on autism, as well as studies of normal development and of genetic syndromes that share symptoms with autism, offer hypotheses as to the nature of causal factors and their possible effects on the structure and dynamics of neural systems. Such alterations in neural properties may in turn perturb activity-dependent development, giving rise to a complex behavioural syndrome many steps removed from the root causes. Animal models based on genetic, neurochemical, neurophysiological, and behavioural manipulations offer the possibility of exploring these developmental processes in detail, as do human studies addressing endophenotypes beyond the diagnosis itself

Transient disruption of M1 during response planning impairs subsequent offline consolidation

Transcranial magnetic stimulation (TMS) was used to probe the involvement of the left primary motor cortex (M1) in the consolidation of a sequencing skill. In particular we asked: (1) if M1 is involved in consolidation of planning processes prior to response execution (2) whether movement preparation and movement execution can undergo consolidation independently and (3) whether sequence consolidation can occur in a stimulus specific manner. TMS was applied to left M1 while subjects prepared left hand sequential finger responses for three different movement sequences, presented in an interleaved fashion. Subjects also trained on three control sequences, where no TMS was applied. Disruption of subsequent consolidation was observed, but only for sequences where subjects had been exposed to TMS during training. Further, reduced consolidation was only observed for movement preparation, not movement execution. We conclude that left M1 is causally involved in the consolidation of effective response planning for left hand movements prior to response execution, and mediates consolidation in a sequence specific manner. These results provide important new insights into the role of M1 in sequential memory consolidation and sequence response planning

Simpson's Paradox, Lord's Paradox, and Suppression Effects are the same phenomenon – the reversal paradox

This article discusses three statistical paradoxes that pervade epidemiological research: Simpson's paradox, Lord's paradox, and suppression. These paradoxes have important implications for the interpretation of evidence from observational studies. This article uses hypothetical scenarios to illustrate how the three paradoxes are different manifestations of one phenomenon – the reversal paradox – depending on whether the outcome and explanatory variables are categorical, continuous or a combination of both; this renders the issues and remedies for any one to be similar for all three. Although the three statistical paradoxes occur in different types of variables, they share the same characteristic: the association between two variables can be reversed, diminished, or enhanced when another variable is statistically controlled for. Understanding the concepts and theory behind these paradoxes provides insights into some controversial or contradictory research findings. These paradoxes show that prior knowledge and underlying causal theory play an important role in the statistical modelling of epidemiological data, where incorrect use of statistical models might produce consistent, replicable, yet erroneous results