Neocortical maturation during adolescence: change in neuronal soma dimension

During adolescence, cognitive abilities increase robustly. To search for possible related structural alterations of the cerebral cortex, we measured neuronal soma dimension (NSD = width times height), cortical thickness and neuronal densities in different types of neocortex in post-mortem brains of five 12-16 and five 17-24 year-olds (each 2F, 3M). Using a generalized mixed model analysis, mean normalized NSD comparing the age groups shows layer-specific change for layer 2 (p < .0001) and age-related differences between categorized type of cortex: primary/primary association cortex (BA 1, 3, 4, and 44) shows a generalized increase; higher-order regions (BA 9, 21, 39, and 45) also show increase in layers 2 and 5 but decrease in layers 3, 4, and 6 while limbic/orbital cortex (BA 23, 24, and 47) undergoes minor decrease (BA 1, 3, 4, and 44 vs. BA 9, 21, 39, and 45: p = .036 and BA 1, 3, 4, and 44 vs. BA 23, 24, and 47: p = .004). These data imply the operation of cortical layer- and type-specific processes of growth and regression adding new evidence that the human brain matures during adolescence not only functionally but also structurally.     

The role of the auditory brainstem in processing linguistically-relevant pitch patterns

Historically, the brainstem has been neglected as a part of the brain involved in language processing. We review recent evidence of language-dependent effects in pitch processing based on comparisons of native vs. nonnative speakers of a tonal language from electrophysiological recordings in the auditory brainstem. We argue that there is enhancing of linguistically-relevant pitch dimensions or features well before the auditory signal reaches the cerebral cortex. We propose that long-term experience with a tone language sharpens the tuning characteristics of neurons along the pitch axis with enhanced sensitivity to linguistically-relevant, rapidly changing sections of pitch contours. Though not specific to a speech context, experience-dependent brainstem mechanisms for pitch representation are clearly sensitive to particular aspects of pitch contours that native speakers of a tone language have been exposed to. Such experience-dependent effects on lower-level sensory processing are compatible with more integrated, hierarchically organized pathways to language and the brain.     

Perception with compensatory devices: from sensory substitution to sensorimotor extension

Sensory substitution devices provide through an unusual sensory modality (the substituting modality, e.g., audition) access to features of the world that are normally accessed through another sensory modality (the substituted modality, e.g., vision). In this article, we address the question of which sensory modality the acquired perception belongs to. We have recourse to the four traditional criteria that have been used to define sensory modalities: sensory organ, stimuli, properties, and qualitative experience ( Grice, 1962 ), to which we have added the criteria of behavioral equivalence ( Morgan, 1977 ), dedication ( Keeley, 2002 ), and sensorimotor equivalence ( O'Regan & Noë, 2001 ). We discuss which of them are fulfilled by perception through sensory substitution devices and whether this favors the view that perception belongs to the substituting or to the substituted modality. Though the application of a number of criteria might be taken to point to the conclusion that perception with a sensory substitution device belongs to the substituted modality, we argue that the evidence leads to an alternative view on sensory substitution. According to this view, the experience after sensory substitution is a transformation, extension, or augmentation of our perceptual capacities, rather than being something equivalent or reducible to an already existing sensory modality. We develop this view by comparing sensory substitution devices to other "mind-enhancing tools" such as pen and paper, sketchpads, or calculators. An analysis of sensory substitution in terms of mind-enhancing tools unveils it as a thoroughly transforming perceptual experience and as giving rise to a novel form of perceptual interaction with the environment.     

Growth and pruning of mushroom body Kenyon cell dendrites during worker behavioral development in the paper wasp, Polybia aequatorialis (Hymenoptera: Vespidae)

Adult workers of some social insect species show dramatic behavioral changes as they pass through a sequence of task specializations. In the paper wasp, Polybia aequatorialis, female workers begin adult life within the nest tending brood, progress to maintaining and defending the nest exterior, and ultimately leave the nest to forage. The mushroom body (MB) calyx neuropil increases in volume as workers progress from in-nest to foraging tasks. In other social Hymenoptera (bees and ants), MB Kenyon cell dendrites, axons and synapses change with the transition to foraging, but these neuronal effects had not been studied in wasps. Furthermore, the on-nest worker of Polybia wasps, an intermediate task specialization not identified in bees or ants, provides the opportunity to study pre-foraging worker class transitions. We asked whether Kenyon cell dendritic arborization varies with the task specialization of Polybia workers observed in the field near Monteverde, Costa Rica. Golgi-impregnated arbors in the lip and collar calyces, which receive a predominance of olfactory and visual input, respectively, were quantified using Sholl’s concentric circles and a novel application of virtual spherical probes. Arbors of the lip varied in a manner reminiscent of honeybees, with foragers having the largest and in-nest workers having the smallest arbors. In contrast, arbors of the collar were largest in foragers but smallest in on-nest workers. Thus, progression through task specializations in P. aequatorialis involves subregion specific dendritic growth and regression in the MB neuropil. These results may reflect the sensitivity of Kenyon cell dendritic structure to specialization dependent social and sensory experience.     

Influence of dorsal hippocampal lesions and MMP inhibitors on spontaneous recovery following a habituation/classical conditioning head–shake task

The present investigation combined a classical conditioning paradigm with a head–shake response (HSR) habituation task in order to evaluate the importance of dorsal hippocampal neural plasticity to spontaneous recovery. In the first experiment animals exhibited rapid HSR habituation (air stimulus to the ear) and an 85% level of spontaneous recovery following a 24 h inter-session interval. The addition of a brief tone prior to the air stimulus produced a similar pattern of habituation during the first session, but the level of spontaneous recovery was reduced (44%) during Session II. In a second experiment dorsal hippocampal lesioned rats placed on this tone/HSR paradigm responded with an 87% level of spontaneous recovery during Session II; while neocortex lesioned control rats indicated significantly reduced levels of spontaneous recovery (55%). In a third experiment bilateral injections of a general MMP inhibitor, FN-439, into the dorsal hippocampus resulted in high levels of spontaneous recovery (81%); while control rats injected with artificial cerebrospinal fluid displayed a significant attenuation of spontaneous recovery (45%). Finally, animals bilaterally injected with a specific MMP-3 inhibitor into the dorsal hippocampus indicated very similar results to those obtained following FN-439 injection. These findings indicate that animals prepared with dorsal hippocampal lesions, or injections with an MMP inhibitor, revealed an impaired association between the tone and air stimulus thus maximum spontaneous recovery was present 24 h later. Thus, it appears that the dorsal hippocampus influences habituation by conserving responses and reducing spontaneous recovery when a temporally contingent signaling cue is present.     

Morphological changes in dendritic spines of Purkinje cells associated with motor learning

Experience-dependent changes of spine structure and number may contribute to long-term memory storage. Although several studies demonstrated structural spine plasticity following associative learning, there is limited evidence associating motor learning with alteration of spine morphology. Here, we investigated this issue in the cerebellar Purkinje cells using high voltage electron microscopy (HVEM). Adult rats were trained in an obstacle course, demanding significant motor coordination to complete. Control animals either traversed an obstacle-free runway or remained sedentary. Quantitative analysis of spine morphology showed that the density and length of dendritic spines along the distal dendrites of Purkinje cells were significantly increased in the rats that learned complex motor skills compared to active or inactive controls. Classification of spines into shape categories indicated that the increased spine density and length after motor learning was mainly attributable to an increase in thin spines. These findings suggest that motor learning induces structural spine plasticity in the cerebellar Purkinje neurons, which may play a crucial role in acquiring complex motor skills.     

心理干预的优先获益者——来自发展可塑性的研究证据

近些年, 发展可塑性领域出现两个新模型--差别易感性模型和优势敏感性模型, 两个模型均表明个体从积极环境中的获益具有差异性。而心理干预作为一种特殊的积极环境被引入到该领域的研究中。已有的研究已经发现一些证据表明, 具备某些特征的当事人从心理干预中获益更多。这些特征包括人格和气质类、遗传类和生理类。本质上, 这些研究在处理“什么对谁最有效”的问题, 但现有研究仅能部分回答这个问题。因此, 心理干预的效果差异有多少可归于这些易感特征, 是有待继续回答的问题。     

Folded Futurity: Epigenetic Plasticity,Temporality, and New Thresholds of Fetal Life

The life sciences are generating a transformative view of the biological body not as fixed and innate but as permeable to its environment and, therefore, plastic: development is open and malleable. Emblematic of these new sciences is environmental epigenetics, which investigates environmental factors that come into the body to shape expression of genes across the life course; prominent are environmental exposures during fetal development, which epigeneticists propose influence not only birth outcomes but also lifelong health. How does this new emphasis on permeability and plasticity during fetal development change how the fetus and fetal vulnerability are understood in the current scientific literature? Perspectives on genomic and reproductive temporality help conceptualize environmental epigenetics as a dynamic relationship between plasticity and determinism. This epigenetic temporality links past, present, and future in way that gives the fetus a keystone role as the vulnerable space-time of environmental epigenetics. Epigenetic temporality produces a new, folded futurity that brings multiple, future generations into the present, influenced by current environmental conditions. In doing this, epigenetics shifts thresholds of fetal vulnerability and intervention to incorporate other entities, including reproductive cells (gametes and primordial germ cells) and very young children. Epigenetic temporality folds in on itself, producing new versions of vulnerable, plastic life that require protection now, in the enduring present, even as the future toward which epigenetics is oriented constantly recedes.     

音乐表演训练对神经可塑性的影响:元分析研究

音乐表演是人类最复杂和精细的技能之一。通过激活似然性评估元分析,对音乐表演训练所诱发的神经可塑性进行探究。结果发现,音乐表演者与非音乐家在左侧小脑、双侧中央前回、双侧颞上回、左侧额下回、双侧顶下小叶以及右侧脑岛等脑区存在差异。这些脑区与听觉、运动以及多通道信息整合等加工有关。未来研究应从不同音乐表演训练诱发的神经适应性出发,进一步探究音乐表演训练与大脑可塑性之间的关联。     

The mind beyond our immediate awareness: Freudian, Jungian, and cognitive models of the unconscious

Abstract: Several branches of cognitive science now focus on the nature of the unconscious. This paper explores some of the findings and models from this research. By introducing formulations based on non‐clinical data, the cognitive scientists—in neural linguistics, computational modelling, and neuroscience—may depart from the older psychoanalytic formulations. An understanding of unconscious neural processes is nevertheless emerging showing how synapses are modified by experience and how learning, conscious and unconscious, is due to this important aspect of brain plasticity. Freud and Jung's formulations about the unconscious psyche, representing the main tenets of depth psychology, are also based on a conception of the mind as extending beyond immediate awareness. However, their models are more hypothetical in that their data, almost exclusively, come from treatments of psychotherapy patients and their verbal accounts. So how do these two conceptions of the unconscious match, where do they differ? And how does the neural understanding in the present research support theories and practices of analytic treatments?