New Advances in Understanding Sensitive Periods in Brain Development

ABSTRACT— Is a dog ever too old to learn new tricks? We review recent findings on sensitive periods in brain development, ranging from sensory processing to high-level cognitive abilities in humans. We conclude that there are multiple varieties of, and mechanisms underlying, these changes. However, many sensitive periods may be a consequence of the basic processes underlying postnatal functional brain development.     

Cognitive and affective development in adolescence

Questions about the nature of normative and atypical development in adolescence have taken on special significance in the last few years, as scientists have begun to recast old portraits of adolescent behavior in the light of new knowledge about brain development. Adolescence is often a period of especially heightened vulnerability as a consequence of potential disjunctions between developing brain, behavioral and cognitive systems that mature along different timetables and under the control of both common and independent biological processes. Taken together, these developments reinforce the emerging understanding of adolescence as a critical or sensitive period for a reorganization of regulatory systems, a reorganization that is fraught with both risks and opportunities.     

Different “routes” to a cognitive map: dissociable forms of spatial knowledge derived from route and cartographic map learning

An important, but as yet incompletely resolved, issue is whether spatial knowledge acquired during navigation differs significantly from that acquired by studying a cartographic map. This, in turn, is relevant to understanding the generalizability of the concept of a “cognitive map,” which is often likened to a cartographic map. On the basis of previous theoretical proposals, we hypothesized that route and cartographic map learning would produce differences in the dynamics of acquisition of landmark-referenced (allocentric) knowledge, relative to view-referenced (egocentric) knowledge. We compared this model with competing predictions from two other models linked to route versus map learning. To test these ideas, participants repeatedly performed a judgment of relative direction (JRD) and a scene- and orientation-dependent pointing (SOP) task while undergoing route and cartographic map learning of virtual spatial environments. In Experiment 1, we found that map learning led to significantly faster improvements in JRD pointing accuracy than did route learning. In Experiment 2, in contrast, we found that route learning led to more immediate and greater improvements overall in SOP accuracy, as compared to map learning. Comparing Experiments 1 and 2, we found a significant three-way interaction effect, indicating that improvements in performance differed for the JRD versus the SOP task as a function of route versus map learning. We interpreted these findings as suggesting that the learning modality differentially affects the dynamics of how we utilize primarily landmark-referenced versus view-referenced knowledge, suggesting potential differences in how we utilize spatial representations acquired from routes versus cartographic maps.     

Contribution de la neuropsychologie développementale à l'étude des sujets à haut potentiel : une revue de questions

Developmental neuropsychology studies cognitive development in relation with brain maturation and cerebral plasticity. Some authors have reported physiological correlates of intellectual precocity with the purpose of demonstrating neural basis of intelligence. A part of the literature also reports various cognitive profile and specific talents in information processing in the clinical population of gifted children. Thus, the study of exceptional performances may contribute to our knowledge of functional brain organization taking into consideration individual differences.     

Effects of Concept Mapping on Creativity in Photo Stories

This research tested the use of concept map planning to support the development of creativity in photo stories, hypothesizing that skills taught to support organization would improve creativity. Concept maps are a type of graphic organizer, used to represent an ordering of ideas with nodes and linking words that form propositional statements. They were applied to story development under the assumption that the creative development of narrative elements requires organization. Undergraduate education students were randomly assigned to either concept map or text-based planning groups for the production of digital photo stories. Creativity was operationalized using dimensions of novelty, interest, clarity, and ability to be understood. A multivariate effect of planning method was found for these dimensions favoring the concept map group, due largely to greater clarity in the photo stories. Clarity in photo stories adds to their utility as creative products. This study represents first steps toward empirically assessing concept maps for a creative purpose, and further investigation, with a larger sample in an authentic context, over a longer period of planning time is recommended.     

The organization of thinking: What functional brain imaging reveals about the neuroarchitecture of complex cognition

Recent findings in brain imaging, particularly in fMRI, are beginning to reveal some of the fundamental properties of the organization of the cortical systems that underpin complex cognition. We propose an emerging set of operating principles that govern this organization, characterizing the system as a set of collaborating cortical centers that operate as a large-scale cortical network. Two of the network’s critical features are that it is resource constrained and dynamically configured, with resource constraints and demands dynamically shaping the network topology. The operating principles are embodied in a cognitive neuroarchitecture, 4CAPS, consisting of a number of interacting computational centers that correspond to activating cortical areas. Each 4CAPS center is a hybrid production system, possessing both symbolic and connectionist attributes. We describe 4CAPS models of sentence comprehension, spatial problem solving, and complex multitasking and compare the accounts of these models with brain activation and behavioral results. Finally, we compare 4CAPS with other proposed neuroarchitectures.     

Properties of cognitive maps constructed from texts

Subjects in three experiments read texts describing the locations of landmarks in a fictitious town. Later they drew sketch maps and verified sentences describing the relative locations of the landmarks. We predicted that subjects would develop mental models of the town that were organized around important landmarks (“anchors”), as are cognitive maps constructed through real-world navigation. More specifically, we expected that landmarks used in the text as reference points for describing the locations of some other landmarks would emerge as anchors in the subjects’ cognitive maps and would consequently be recalled more accurately. Results showed that subjects represented such reference-point landmarks more accurately than they did the locations of other landmarks. This effect was independent of: (1) the perspective from which the text was written (route or survey); (2) whether or not a map was present at learning; (3) the order of information in the text (linear or anchors-first), and (4) the amount of information available to the subjects while drawing sketch maps (the full text, the landmark names only, or no information).     

A Cognitive Subtask Model of Statistical Map Reading

A model is presented that accounts for statistical map reading according to four cognitive subtasks: (1) map orientation, (2) legend comprehension, (3) map surface/legend integration, and (4) extracting statistical information. Each cognitive subtask can be shown to depend on a series of processes that differ somewhat from subtask to subtask. This model is evaluated in light of the literature on statistical map reading, our research findings, and experience in the development of statistical maps. The model may serve as a guide to map reading and assist in the design of statistical maps.     

Building a cognitive map by assembling multiple path integration systems

Path integration and cognitive mapping are two of the most important mechanisms for navigation. Path integration is a primitive navigation system which computes a homing vector based on an animal’s self-motion estimation, while cognitive map is an advanced spatial representation containing richer spatial information about the environment that is persistent and can be used to guide flexible navigation to multiple locations. Most theories of navigation conceptualize them as two distinctive, independent mechanisms, although the path integration system may provide useful information for the integration of cognitive maps. This paper demonstrates a fundamentally different scenario, where a cognitive map is constructed in three simple steps by assembling multiple path integrators and extending their basic features. The fact that a collection of path integration systems can be turned into a cognitive map suggests the possibility that cognitive maps may have evolved directly from the path integration system.     

A theory of causal learning in children: causal maps and Bayes nets

The authors outline a cognitive and computational account of causal learning in children. They propose that children use specialized cognitive systems that allow them to recover an accurate "causal map" of the world: an abstract, coherent, learned representation of the causal relations among events. This kind of knowledge can be perspicuously understood in terms of the formalism of directed graphical causal models, or Bayes nets. Children's causal learning and inference may involve computations similar to those for learning causal Bayes nets and for predicting with them. Experimental results suggest that 2- to 4-year-old children construct new causal maps and that their learning is consistent with the Bayes net formalism.     

Computational explorations of the influence of structured knowledge on age-related cognitive decline

Experience in a domain can sometimes offset cognitive declines that occur with aging. Using a series of neural network simulations of learning chess opening positions, the authors investigated how structured knowledge in a distributed representation may influence age-related declines. Aging manipulations implemented as modulations of neural noise showed increased knowledge as being protective of performance on a chess memory span task, whereas changes in neural plasticity and neural loss lead to main effects without interactions and steeper declines for the initially more able. The models could also simulate the increase in variability in older groups.     

Event models and the fan effect

The current study explored the persistence of event model organizations and how this influences the experience of interference during retrieval. People in this study memorized lists of sentences about objects in locations, such as “The potted palm is in the hotel.” Previous work has shown that such information can either be stored in separate event models, thereby producing retrieval interference, or integrated into common event models, thereby eliminating retrieval interference. Unlike prior studies, the current work explored the impact of forgetting up to 2 weeks later on this pattern of performance. We explored three possible outcomes across the various retention intervals. First, consistent with research showing that longer delays reduce proactive and retroactive interference, any retrieval interference effects of competing event models could be reduced over time. Second, the binding of information into events models may weaken over time, causing interference effects to emerge when they had previously been absent. Third, and finally, the organization of information into event models could remain stable over long periods of time. The results reported here are most consistent with the last outcome. While there were some minor variations across the various retention intervals, the basic pattern of event model organization remained preserved over the two-week retention period.     

Structural Comparison of Cognitive Associative Networks in Two Populations1

The cognitive associative structure of 2 populations was studied using network analysis of free‐word associations. Structural differences in the associative networks were compared using measures of network centralization, size, density, clustering, and path length. These measures are closely aligned with cognitive theories describing the organization of knowledge and retrieval of concepts from memory. Size and centralization of semantic structures were larger for college students than for 7^th graders, while density, clustering, and mean path length were similar. Findings presented reveal that subpopulations might have very different cognitive associative networks. This study suggests that graph theory and network analysis methods are useful in mapping differences in associative structures across groups.     

Spiking neural networks and hippocampal function: A web-accessible survey of simulations,modeling methods,and underlying theories

Computational modeling has contributed to hippocampal research in a wide variety of ways and through a large diversity of approaches, reflecting the many advanced cognitive roles of this brain region. The intensively studied neuron type circuitry of the hippocampus is a particularly conducive substrate for spiking neural models. Here we present an online knowledge base of spiking neural network simulations of hippocampal functions. First, we overview theories involving the hippocampal formation in subjects such as spatial representation, learning, and memory. Then we describe an original literature mining process to organize published reports in various key aspects, including: (i) subject area (e.g., navigation, pattern completion, epilepsy); (ii) level of modeling detail (Hodgkin-Huxley, integrate-and-fire, etc.); and (iii) theoretical framework (attractor dynamics, oscillatory interference, self-organizing maps, and others). Moreover, every peer-reviewed publication is also annotated to indicate the specific neuron types represented in the network simulation, establishing a direct link with the Hippocampome.org portal. The web interface of the knowledge base enables dynamic content browsing and advanced searches, and consistently presents evidence supporting every annotation. Moreover, users are given access to several types of statistical reports about the collection, a selection of which is summarized in this paper. This open access resource thus provides an interactive platform to survey spiking neural network models of hippocampal functions, compare available computational methods, and foster ideas for suitable new directions of research.     

Differences in spatial knowledge acquired from maps and navigation

Models of the spatial knowledge people acquire from maps and navigation and the procedures required for spatial judgments using this knowledge are proposed. From a map, people acquire survey knowledge encoding global spatial relations. This knowledge resides in memory in images that can be scanned and measured like a physical map. From navigation, people acquire procedural knowledge of the routes connecting diverse locations. People combine mental simulation of travel through the environment and informal algebra to compute spatial judgments. An experiment in which subjects learned an environment from navigation or from a map evaluates predictions of these models. With moderate exposure, map learning is superior for judgments of relative location and straight-line distances among objects. Learning from navigation is superior for orienting oneself with respect to unseen objects and estimating route distances. With extensive exposure, the performance superiority of maps over navigation vanishes. These and other results are consonant with the proposed mechanisms.     

Developmental change and the multidimensional cognitive system

The cognitive system is a multidimensional, hierarchically-structured arrangement of cognitive dimensions functionally organized into three subsystems: perceiving, conceptualizing, and symbolizing. Ontogenetic change in these subsystems is described using theoretical concepts from both multivariate developmental psychology and systems theory. Both quantitative and qualitative changes in cognitive dimensions are discussed, including a synthesis of relevant empirical research. The Gompertz equation is used to describe the general form of quantitative change throughout the life-span. The pattern oo quantitative development involves growth, stability, and decline. The pattern of qualitative development, or shifts in structural organization, also invloves three periods: divergence, parallelism, and paraller-convergence. Thus, the overall quantitative-qualitative synthesis reveals a three-phase sequence of cognitive development: divergent growth (childhood- adolescence), parallel stability (adulthood), and parallel-convergent decline (old age).     

Finding locations in the environment: the map as mediator.

When an observer (O) uses a map (M) whose orientation does not correspond to the orientation of the environment (E) in which performance occurs, substantial errors occur: these are called map alignment effects. Much of the prior research on map/environment (M/E) alignment has involved maps of simple paths, although alignment effects have also been demonstrated for you-are-here (YAH) maps. A study is reported in which simple YAH maps were used to test the hypothesis that errors with misaligned maps would fall into categories predictable from the application of inappropriate cognitive operations to the misaligned maps, as demonstrated earlier by Rossano and Warren. Further, performance under conditions of M/E misalignment was compared with performance under map/observer (M/O) misalignment, the situation in which the map is sideways or upside-down with respect to the observer. The major hypothesis was supported: predictable errors occurred under conditions of M/E misalignment. Errors under conditions of M/O misalignment were significantly smaller. Furthermore, when given the choice of using M/E or M/O alignment, each at the expense of the other, the overwhelming choice was to retain M/E rather than M/O alignment. This pattern of results occurred even when environmental features were represented by words rather than by lines and shapes on the map. The results underscore the robustness of map alignment effects.     

双侧梭状回面孔区在面孔加工中的功能分工与协作

梭状回面孔区(fusiform face area,FFA)是视觉皮层上专门加工面孔的区域。然而,双侧FFA在面孔加工中的功能分工与协作还存在争议。在特异性刺激的加工上,右侧FFA主要负责人类面孔类别的知觉,而左侧FFA的功能与面孔精细特征的感知有关;在皮层可塑性上,右侧FFA主要参与青少年的社会适应学习,而左侧FFA负责成年人的知觉学习;在面孔网络中,二者与不同区域的连接用以适应不同的认知需求;他们之间的有向协作具有任务特定性。未来研究需要回答三个问题:左侧FFA的可塑性程度及这一可塑性是否是认知特定的、左侧FFA及其形成的网络连接的认知意义,双侧FFA在面孔网络中的连接有向性等问题。     

The link between knowledge and remembering in Alzheimer’s disease

Current research on the influence of cognitive support (e.g., activation of task-relevant prior knowledge, item organizability, retrieval cues) on episodic remembering in normal aging and Alzheimer’s disease (AD) is reviewed. Examining the effects of cognitive support on memory may shed light on the relationship between knowledge and remembering, and also provides relevant information pertaining to the development of cognitive intervention procedures. A series of studies from our own and other laboratories reveal a number of interesting empirical regularities. First, AD results in problems in utilizing cognitive support for improving memory. Conceivably, this reduction in cognitive reserve capacity is due to both the overall severity of the episodic memory impairment in AD, as well as to dementia-related deficits in the semantic network that guides encoding and retrieval of information. Nevertheless, AD patients are able to utilize cognitive support in episodic memory tasks, although they typically need more support than their healthy aged counterparts to show memory facilitation. Specifically, it is critical to provide support at both encoding and retrieval in order to demonstrate performance gains in AD. Moreover, successful utilization of retrieval support in this disease is most likely to occur when the encoding requirements force the individual to engage in elaborative cognitive activity (e.g., generation of task-relevant knowledge, categorical organization). Finally, a reduction in cognitive reserve capacity occurs later in the pathogenesis of AD than a generalized episodic memory impairment. This observation reflects the insidious nature of AD, and suggests that the transition from normal aging to AD may be continuous rather than discrete.