17β-Estradiol: Effect on CA1 Hippocampal Synaptic Plasticity

An understanding of synaptic plasticity in the mammalian brain has been one of R. F. Thompson's major pursuits throughout his illustrious career. A current series of experiments of significant interest to R. F. Thompson is an examination of the interactions between sex hormones, synaptic plasticity, aging, and stress. This research is contained within a broader project whose aim is to investigate animal models that evaluate estrogen interactions with Alzheimer's disease. This paper reviews the recent results that have led to a better understanding of how the sex hormone estrogen influences synaptic plasticity in an important structure within the mammalian brain responsible for learning and memory: the hippocampus. In this review, a number of experiments have been highlighted that investigate the molecular mechanisms that underlie estrogen's effect on two specific forms of synaptic plasticity commonly studied in neurophysiology and the behavioral neurosciences: long-term potentiation and long-term depression.     

Cognitive plasticity in successful ageing: contributions from a learning potential assessment / Plasticidad cognitiva en el envejecimiento exitoso: aportes desde la evaluación del potencial de aprendizaje

Abstract

Despite numerous studies on the subject of successful ageing, few studies address the issue from a learning potential (LP) perspective. In Latin America there is no empirical background describing LP in successful ageing. In this study, 157 elderly Argentines were categorized into ageing trajectories (successful, normal and pathological ageing) based on objective scores from autonomy level, cognitive performance and mood state scales. Subjects were assessed with classic neuropychological tests, a cognitive reserve scale and an LP test. The results show differences in LP and cognitive reserve according to different ageing trajectories. This study establishes a regional precedent of relevance in the study of LP in elderly people pursuing successful ageing. It also provides evidence of the usefulness of incorporating instances of delayed free recall and recognition in an episodic memory and LP test.     

Variables that favour successful ageing / Variables que favorecen un envejecimiento exitoso

Abstract

The construct of successful ageing appears in the sixties, with a focus on physiological factors. However, its definition progressively develops into a more multidisciplinary construct and begins to include psychological, psychosocial and environmental factors; today, all these aspects are seen as essential to its study. In this monograph devoted to successful ageing, both this work and those that appear beside it aim to highlight the different areas of research that have been forged — mainly from psychology but also, in certain cases, together with associated disciplines — to try to outline a comprehensive model of ageing with the ultimate goal of creating intervention tools to foster successful ageing. Thus, this issue analyses the roles played by the Mediterranean diet, resilience, training programmes and training caregivers, among others, as explored by different experts in the area in an attempt to unveil the keys to ageing successfully from a psychosocial perspective.     

Conditioned taste aversion modifies persistently the subsequent induction of neocortical long-term potentiation in vivo

The ability of neurons to modify their synaptic strength in an activity-dependent manner has a crucial role in learning and memory processes. It has been proposed that homeostatic forms of plasticity might provide the global regulation necessary to maintain synaptic strength and plasticity within a functional dynamic range. Similarly, it is considered that the capacity of synapses to express plastic changes is itself subject to variation dependent on previous experience. In particular, training in several behavioral tasks modifies the possibility to induce long-term potentiation (LTP). Our previous studies in the insular cortex (IC) have shown that induction of LTP in the basolateral amygdaloid nucleus (Bla)-IC projection previous to conditioned taste aversion (CTA) training enhances the retention of this task. The aim of the present study was to analyze whether CTA training modifies the ability to induce subsequent LTP in the Bla-IC projection in vivo. Thus, CTA trained rats received high frequency stimulation in the Bla-IC projection in order to induce LTP 48, 72, 96 and 120 h after the aversion test. Our results show that CTA training prevents the subsequent induction of LTP in the Bla-IC projection, for at least 120 h after CTA training. We also showed that pharmacological inhibition of CTA consolidation with anisomycin (1 μl/side; 100 μg/μl) prevents the CTA effect on IC-LTP. These findings reveal that CTA training produces a persistent change in the ability to induce subsequent LTP in the Bla-IC projection in a protein-synthesis dependent manner, suggesting that changes in the ability to induce subsequent synaptic plasticity contribute to the formation and persistence of aversive memories.     

The Isolation, Primacy, and Recency Effects Predicted by an Adaptive LTD/LTP Threshold in Postsynaptic Cells

An item that stands out (is isolated) from its context is better remembered than an item consistent with the context. This isolation effect cannot be accounted for by increased attention, because it occurs when the isolated item is presented as the first item, or by impoverished memory of nonisolated items, because the isolated item is better remembered than a control list consisting of equally different items. The isolation effect is seldom experimentally or theoretically related to the primacy or the recency effects—that is, the improved performance on the first few and last items, respectively, on the serial position curve. The primacy effect cannot easily be accounted for by rehearsal in short-term memory because it occurs when rehearsal is eliminated. This article suggests that the primacy, the recency, and the isolation effects can be accounted for by experience-dependent synaptic plasticity in neural cells. Neurological empirical data suggest that the threshold that determines whether cells will show long-term potentiation (LTP) or long-term depression (LTD) varies as a function of recent postsynaptic activity and that synaptic plasticity is bounded. By implementing an adaptive LTP-LTD threshold in an artificial neural network, the various aspects of the isolation, the primacy, and the recency effects are accounted for, whereas none of these phenomena are accounted for if the threshold is constant. This theory suggests a possible link between the cognitive and the neurological levels.     

On the relation between recent neurobiological data on perception (and action) and the Husserlian theory of constitution

The phenomenological theory of constitution promises a solution for the problem of consciousness insofar as it changes the traditional terms of this problem by systematically correlating subject and object in the unifying context of intentional acts. I argue that embodied constitution must depend upon the role of kinesthesia as a constitutive operator. In pursuing the path of intentionality in its descent from an idealistic level of pure constitution to this fully embodied kinesthetic constitution, we are able to gain access to different ontological regions such as physical thing, owned body and shared world. Neuroscience brings to light the somatological correlates of noemata. Bridging the gap between incarnation and naturalisation represents the best way of realizing the foundational program of transcendental phenomenology.     

Estrogen and Neural Plasticity

Converging clinical evidence suggests that postmenopausal estrogen therapy in women is associated with improved cognition and a reduced incidence of Alzheimer's disease. In experimental work, investigators have found estrogen to promote changes in synaptic plasticity within the nervous system. In this article, we review both the clinical and the experimental literature, and consider mechanisms of action of estrogen on neurons and synaptic plasticity, and how they might protect against the cognitive impairments of old age.     

Do deaf individuals have better visual skills in the periphery? Evidence from processing facial attributes

ABSTRACT

Studies examining visual abilities in individuals with early auditory deprivation have reached mixed conclusions, with some finding congenital auditory deprivation and/or lifelong use of a visuospatial language improves specific visual skills and others failing to find substantial differences. A more consistent finding is enhanced peripheral vision and an increased ability to efficiently distribute attention to the visual periphery following auditory deprivation. However, the extent to which this applies to visual skills in general or to certain conspicuous stimuli, such as faces, in particular is unknown. We examined the perceptual resolution of peripheral vision in the deaf, testing various facial attributes typically associated with high-resolution scrutiny of foveal information processing. We compared performance in face-identification tasks to performance using non-face control stimuli. Although we found no enhanced perceptual representations in face identification, gender categorization, or eye gaze direction recognition tasks, fearful expressions showed greater resilience than happy or neutral ones to increasing eccentricities. In the absence of an alerting sound, the visual system of auditory deprived individuals may develop greater sensitivity to specific conspicuous stimuli as a compensatory mechanism. The results also suggest neural reorganization in the deaf in their opposite advantage of the right visual field in face identification tasks.     

Children can optimally integrate multisensory information after a short action‐like mini game training

Combining information across different sensory modalities is of critical importance for the animal's survival and a core feature of human's everyday life. In adulthood, sensory information is often integrated in a statistically optimal fashion, so that the combined estimates of two or more senses are more reliable than the best single one. Several studies have shown that young children use one sense to calibrate the others, which results in unisensory dominance and undermines their optimal multisensory integration abilities. In this study we trained children aged 4–5 years with action‐like mini games, to determine whether it could improve their multisensory as well as their visuo‐spatial skills. Multisensory integration abilities were assessed using a visuo‐haptic size discrimination task, while visuo‐spatial attention skills were investigated using a multiple object tracking task (MOT). We found that 2‐weeks training were sufficient to observe both optimal multisensory integration and visuo‐spatial enhancements selectively in the group trained with action‐like mini games. This plastic change persisted up to 3 months, as assessed in a follow‐up. Our novel findings reveal that abilities that are commonly known to emerge in late childhood can be promoted in younger children through action‐like mini games and have long‐lasting effects. Our data have clinical implications, in that they suggest that specific trainings could potentially help children with multisensory integration deficits.     

进化观点下的智力研究

综述了进化心理学探讨智力所取得的研究成果,内容包括智力的起源（如进化环境与智力的关系）、进化心理学视角下智力的分类。同时,该文认为一般智力是一种特殊的认知模块,即专门智力。最后,讨论了对智力进行进化心理学研究的重要意义与未来研究取向。