Allocentric spatial memory in humans with hippocampal lesions

An immersive virtual reality (IVR) system was used to investigate allocentric spatial memory in a patient (PR) who had selective hippocampal damage, and also in patients who had undergone unilateral temporal lobectomies (17 right TL and 19 left TL), their performance compared against normal control groups. A human analogue of the Olton [Olton (1979). Hippocampus, space, and memory. Behavioural Brain Science, 2, 315] spatial maze was developed, consisting of a virtual room, a central virtual circular table and an array of radially arranged up-turned 'shells.' The participant had to search these shells in turn in order to find a blue 'cube' that would then 'move' to another location and so on, until all the shells had been target locations. Within-search errors could be made when the participants returned to a previously visited location during a search, and between-search errors when they revisited previously successful, but now incorrect locations. PR made significantly more between-search errors than his control group, but showed no increase in within-search errors. The right TL group showed a similar pattern of impairment, but the left TL group showed no impairment. This finding implicates the right hippocampal formation in spatial memory functioning in a scenario in which the visual environment was controlled so as to eliminate extraneous visual cues.     

Multiple processes in prospective memory retrieval: factors determining monitoring versus spontaneous retrieval

Theoretically, prospective memory retrieval can be accomplished either by controlled monitoring of the environment for a target event or by a more reflexive process that spontaneously responds to the presence of a target event. These views were evaluated in Experiments 1-4 by examining whether performing a prospective memory task produced costs on the speed of performing the ongoing task. In Experiment 5, the authors directly tested for the existence of spontaneous retrieval. The results supported the multiprocess theory (M. A. McDaniel & G. O. Einstein, 2000) predictions that (a) spontaneous retrieval can occur and can support good prospective memory and (b) depending on task demands and individual differences, people rely to different degrees on monitoring versus spontaneous retrieval for prospective remembering.     

Rescue of synaptic plasticity and spatial learning deficits in the hippocampus of Homer1 knockout mice by recombinant Adeno-associated viral gene delivery of Homer1c

Homer1 belongs to a family of scaffolding proteins that interact with various post-synaptic density proteins including group I metabotropic glutamate receptors (mGluR1/5). Previous research in our laboratory implicates the Homer1c isoform in spatial learning. Homer1 knockout mice (H1-KO) display cognitive impairments, but their synaptic plasticity properties have not been described. Here, we investigated the role of Homer1 in long-term potentiation (LTP) in the hippocampal CA1 region of H1-KO mice in vitro. We found that late-phase LTP elicited by high frequency stimulation (HFS) was impaired, and that the induction and maintenance of theta burst stimulation (TBS) LTP were reduced in H1-KO. To test the hypothesis that Homer1c was sufficient to rescue these LTP deficits, we delivered Homer1c to the hippocampus of H1-KO using recombinant adeno-associated virus (rAAV). We found that rAAV-Homer1c rescued HFS and TBS-LTP in H1-KO animals. Next, we tested whether the LTP rescue by Homer1c was occurring via mGluR1/5. A selective mGluR5 antagonist, but not an mGluR1 antagonist, blocked the Homer1c-induced recovery of late-LTP, suggesting that Homer1c mediates functional effects on plasticity via mGluR5. To investigate the role of Homer1c in spatial learning, we injected rAAV-Homer1c to the hippocampus of H1-KO. We found that rAAV-Homer1c significantly improved H1-KO performance in the Radial Arm Water Maze. These results point to a significant role for Homer1c in synaptic plasticity and learning.     

The Princess and the Penis: A Post Postmodern Queer-y Tale

This paper explores whether postmodern gender theory can fully account for how a “cis” gender (gender and biology match) therapist works with a “trans” gender patient in a relational way. Inspiring contemporary queer theory exists courtesy of experts in the field, but how does a nongender expert deal with the complicated enactments that occur when patient transitions her gender from female to male and then decides to become pregnant? It is suggested that this case may more accurately represent an example of a post-postmodern analysis, in that it holds the dialectic of constructed gender within the realities of a social system that remains deeply gender binaried.     

Between Dolev and Dummett: Some Comments on ‘Antirealism,Presentism and Bivalence’

Abstract

It is well known that, according to some, philosophical reflection on zombies (i.e. bodies without minds) poses a problem for physicalism. But what about ghosts, i.e., minds without bodies? Does philosophical reflection on them pose a problem for physicalism? Descartes, of course, thought so, and lately rumours have been surfacing that has was right after all, that ghosts pose a problem for both a priori and a posteriori physicalism, and for any kind of physicalism in between. This paper argues that physicalists have nothing to fear from ghosts, since the central consideration employed to motivate ghostly arguments against physicalism – i.e. that ghosts are conceivable – is false: ghosts aren’t conceivable.     

My people,right or wrong? Minimal group membership disrupts preschoolers’ selective trust

When preschoolers decide to trust one speaker over another, how does group membership influence their tracking of speaker reliability? In Experiment 1, 4-year-olds were assigned to arbitrary groups of no social significance (0055 and 0170) and asked to endorse novel object labels provided by two ingroup members, one of whom was reliable and the second of whom was unreliable. Children selectively trusted the more reliable informant. In Experiment 2, we asked whether ingroup status or reliability would determine children's choices and found that 4-year-olds failed to trust reliable outgroup members over unreliable ingroup members (or vice versa). Experiment 3 showed that the failure of trust in Experiment 2 was not due to the mere inclusion of both ingroup and outgroup members: children presented with a control paradigm in which the ingroup members were reliable trusted reliable ingroup members over unreliable outgroup members. Children's use of reliability as an indicator of future credibility therefore appears disrupted when outgroup status and reliability are in conflict, even when group membership is arbitrary.     

Predictors of Resilience Among Inner City Youths

Prior studies have suggested that living in high-risk neighborhoods is associated with youths’ maladjustment. Youths who maintained favorable outcomes, despite being exposed to such neighborhood risks, were considered resilient. Using structural equation modeling techniques, longitudinal data of 877 youths from the Denver Youth Survey were examined to identify predictors of resilience, longitudinal interrelations among predictors, and bi-directional relationships between resilience and life context factors. Resilience was longitudinally predicted by bonding to family and teachers, involvement in extracurricular activities, lower levels of parental discord, fewer adverse life events, and being less involved with delinquent peers. A positive feedback loop was found, in which resilience predicted further resilience. Early intervention to strengthen traditional bonding, decrease involvement with delinquent peers, and reduce the effects of adverse life events and parental discord may be essential in enhancing functioning of high-risk youths.