Neuronal Recycling Research Articles

Reading instruction causes changes in category-selective visual cortex

Education sculpts specialized neural circuits for skills like reading that are critical to success in modern society but were not anticipated by the selective pressures of evolution. Does the emergence of brain regions that selectively process novel visual stimuli like words occur at the expense of cortical representations of other stimuli like faces and objects? “Neuronal Recycling” predicts that learning to read should enhance the response to words in ventral occipitotemporal cortex (VOTC) and decrease the response to other visual categories such as faces and objects. To test this hypothesis, and more broadly to understand the changes that are induced by the early stages of literacy instruction, we conducted a randomized controlled trial with pre-school children (five years of age). Children were randomly assigned to intervention programs focused on either reading skills or oral language skills and magnetoencephalography (MEG) data collected before and after the intervention was used to measure visual responses to images of text, faces, and objects. We found that being taught reading versus oral language skills induced different patterns of change in category-selective regions of visual cortex, but that there was not a clear tradeoff between the response to words versus other categories. Within a predefined region of VOTC corresponding to the visual word form area (VWFA) we found that the relative amplitude of responses to text, faces, and objects changed, but increases in the response to words were not linked to decreases in the response to faces or objects. How these changes play out over a longer timescale is still unknown but, based on these data, we can surmise that high-level visual cortex undergoes rapid changes as children enter school and begin establishing new skills like literacy.

Early reading skills and the ventral occipito-temporal cortex organization

Learning to read impacts the way the ventral occipitotemporal cortex (VOT) reorganizes. The postulated underlying mechanism of neuronal recycling was recently revisited. Neuroimaging data showed that voxels weakly specialized for visual processing keep their initial category selectivity (i.e., object or face processing) while acquiring an additional and stronger responsivity to written words. Here, we examined a large and diverse group of six-year-olds prior to formal literacy training (N = 72) using various data analysis techniques (univariate, multivariate, rapid adaptation) and types of stimuli (print, false fonts, houses, faces) to further explore how VOT changes and adapts to the novel skill of reading. We found that among several visual stimuli categories only print activated a wide network of language related areas outside of the bilateral visual cortex, and the level of reading skill was related to the strength of this activation, showing the development of the reading circuit. Rapid adaptation was not directly related to the level of reading skill in the young children studied here, but it clearly revealed the emergence of the reading network in readers. Most importantly, we found that the reorganization of the VOT is not in fact an “invasion” by reading acquisition–voxels previously activated for faces started to respond more for print, while at the same time keeping their previous function. We can thus conclude that the revised hypothesis of neuronal recycling is supported by our data.

Can humans perform mental regression on a graph? Accuracy and bias in the perception of scatterplots

Despite the widespread use of graphs, little is known about how fast and how accurately we can extract information from them. Through a series of four behavioral experiments, we characterized human performance in “mental regression”, i.e. the perception of statistical trends from scatterplots. When presented with a noisy scatterplot, even as briefly as 100 ms, human adults could accurately judge if it was increasing or decreasing, fit a regression line, and extrapolate outside the original data range, for both linear and non-linear functions. Performance was highly consistent across those three tasks of trend judgment, line fitting and extrapolation. Participants’ linear trend judgments took into account the slope, the noise, and the number of data points, and were tightly correlated with the t-test classically used to evaluate the significance of a linear regression. However, they overestimated the absolute value of the regression slope. This bias was inconsistent with ordinary least squares (OLS) regression, which minimizes the sum of square deviations, but consistent with the use of Deming regression, which treats the x and y axes symmetrically and minimizes the Euclidean distance to the fitting line. We speculate that this fast but biased perception of scatterplots may be based on a “neuronal recycling” of the human visual capacity to identify the medial axis of a shape.

Does Neuronal Recycling Result in Destructive Competition? The Influence of Learning to Read on the Recognition of Faces

Written language, a human cultural invention, is far too recent a development for dedicated neural infrastructure to have evolved in its service. Newly acquired cultural skills, such as reading, thus recycle evolutionarily older circuits that originally evolved for different, but similar, functions (e.g., visual object recognition). The destructive-competition hypothesis predicts that this neuronal recycling has detrimental behavioral effects on the cognitive functions for which a cortical network originally evolved. In a study with 97 literate, low-literate, and illiterate participants from the same socioeconomic background, we found that even after adjusting for cognitive ability and test-taking familiarity, learning to read was associated with an increase, rather than a decrease, in object-recognition abilities. These results are incompatible with the claim that neuronal recycling results in destructive competition and are consistent with the possibility that learning to read instead fine-tunes general object-recognition mechanisms, a hypothesis that needs further neuroscientific investigation.

New perspectives on the reading and early literacy processing

Meu novo olhar para o processamento da leitura e da alfabetização provém, fundamentalmente, das evidências experimentais da neurociência: a existência de uma área na região occipital-temporal ventral esquerda onde os neurônios se especializam, mediante a boa aprendizagem, a reconhecer quais, quantos e como se combinam os traços invariantes para formar as letras que, nos sistemas alfabéticos, realizam os grafemas, os quais representam os fonemas de uma dada língua. Graças aos conhecimentos da linguística e da psicolinguística, meu novo olhar para a alfabetização revelou estratégias para a criança descobrir a diferença entre vocábulos tônicos e átonos (clíticos) na leitura, bem como para aprender, no contexto do processamento da leitura do português brasileiro (PB) a automatizar: (a) o reconhecimento dos traços e letras invariantes que foram convencionados no alfabeto latino; (b) o reconhecimento dos grafemas e seus respectivos valores (os fonemas); (c) a atribuição do acento de intensidade maior, nos vocábulos que o possuem; (d) a delimitação dos vocábulos átonos que, no PB escrito, se terminarem por vogais orais átonas, só podem ser registradas pelas letras ‘a’, ‘e’, ‘o’, seguidas ou não por ‘s’; (e) por fim, o reconhecimento dos padrões de entoação. Tudo isto possibilitará, sobretudo, a construção do sentido novo das palavras, frases, orações, períodos, parágrafos e texto (macroestrutura), formando leitores críticos e com gosto pela leitura.

Neuroemergentism: A Framework for Studying Cognition and the Brain.

There has been virtual explosion of studies published in cognitive neuroscience primarily due to increased accessibility to neuroimaging methods, which has led to different approaches in interpretation. This review seeks to synthesize both developmental approaches and more recent views that consider neuroimaging. The ways in which Neuronal Recycling, Neural Reuse, and Language as Shaped by the Brain perspectives seek to clarify the brain bases of cognition will be addressed. Neuroconstructivism as an additional explanatory framework which seeks to bind brain and cognition to development will also be presented. Despite sharing similar goals, the four approaches to understanding how the brain is related to cognition have generally been considered separately. However, we propose that all four perspectives argue for a form of Emergentism in which combinations of smaller elements can lead to a greater whole. This discussion seeks to provide a synthesis of these approaches that leads to the emergence of a theory itself. We term this new synthesis Neurocomputational Emergentism (or Neuromergentism for short).

Action and object words are differentially anchored in the sensory motor system - A perspective on cognitive embodiment

Embodied and grounded cognition theories have assumed that the sensorimotor system is causally involved in processing motor-related language content. Although a causal proof on a single-cell basis is ethically not possible today, the present fMRI study provides confirmation of this longstanding speculation, as far as it is possible with recent methods, employing a new computational approach. More specifically, we were looking for common activation of nouns and objects, and actions and verbs, representing the canonical and mirror neuron system, respectively. Using multivariate pattern analysis, a resulting linear classifier indeed successfully generalized from distinguishing actions from objects in pictures to distinguishing the respective verbs from nouns in written words. Further, these action-related pattern responses were detailed by recently introduced predictive pattern decomposition into the constituent activity atoms and their relative contributions. The findings support the concept of canonical neurons and mirror neurons implementing embodied processes with separate roles in distinguishing objects from actions, and nouns from verbs, respectively. This example of neuronal recycling processing algorithms is consistent with a multimodal brain signature of human action and object concepts. Embodied language theory is thus merged with actual neurobiological implementation.

The emergence of the visual word form: Longitudinal evolution of category-specific ventral visual areas during reading acquisition.

How does education affect cortical organization? All literate adults possess a region specialized for letter strings, the visual word form area (VWFA), within the mosaic of ventral regions involved in processing other visual categories such as objects, places, faces, or body parts. Therefore, the acquisition of literacy may induce a reorientation of cortical maps towards letters at the expense of other categories such as faces. To test this cortical recycling hypothesis, we studied how the visual cortex of individual children changes during the first months of reading acquisition. Ten 6-year-old children were scanned longitudinally 6 or 7 times with functional magnetic resonance imaging (fMRI) before and throughout the first year of school. Subjects were exposed to a variety of pictures (words, numbers, tools, houses, faces, and bodies) while performing an unrelated target-detection task. Behavioral assessment indicated a sharp rise in grapheme–phoneme knowledge and reading speed in the first trimester of school. Concurrently, voxels specific to written words and digits emerged at the VWFA location. The responses to other categories remained largely stable, although right-hemispheric face-related activity increased in proportion to reading scores. Retrospective examination of the VWFA voxels prior to reading acquisition showed that reading encroaches on voxels that are initially weakly specialized for tools and close to but distinct from those responsive to faces. Remarkably, those voxels appear to keep their initial category selectivity while acquiring an additional and stronger responsivity to words. We propose a revised model of the neuronal recycling process in which new visual categories invade weakly specified cortex while leaving previously stabilized cortical responses unchanged.

Screen reading and the creation of new cognitive ecologies

It has been widely argued that digital technologies are transforming the nature of reading, and with it, our brains and a wide range of our cognitive capabilities. In this article, we begin by discussing the new analytical category of deep-reading and whether it is really on the decline. We analyse deep reading and its grounding in brain reorganization, based upon Michael Anderson’s Massive Redeployment hypothesis and Dehaene’s Neuronal Recycling which both help us to theorize how the capacities of brains are transformed by acquisition of new skills. We examine some of the difficulties in comparing reading using technologies such as the web-browser, the tablet and E-Reader, with reading using the pre-existing print culture. While learning to read undoubtedly changes the brain, we examine what evidence there is for this being tightly tied to particular material substrates and find this lacking. Instead we attempt to situate cognitive changes around the new reading within the context of the specific new cognitive ecologies incorporating both screen and page. This involves a reconsideration of the role of material culture in the cognitive abilities.

Predominance of lateral over vertical mirror errors in reading: A case for neuronal recycling and inhibition

We investigated whether lateral mirror errors could be more prevalent than vertical mirror errors (e.g., p/q vs. p/b confusions) because mirror generalization is harder to inhibit for the discrimination of a reversible letter and its lateral than its vertical mirror-image counterpart. Expert adult readers performed a negative priming task in which they determined on the prime whether two letters and on the probe whether two objects facing opposite directions were identical. We found in both experiments longer response times for objects facing opposite lateral orientations preceded by a reversible letter and its lateral mirror-image counterpart (e.g., p/q) than preceded by perceptually matched non-reversible letters (e.g., g/j). No negative priming effect was observed when objects that were vertical (Experiment 1 & 2) or lateral (Experiment 2) mirror images of each other were preceded by a letter and its vertical mirror-image counterpart (e.g. p/b). Finally, we observed longer response times for objects that were lateral mirror images of each other after lateral than after vertical reversible letters. These results suggest that lateral mirror errors are more prevalent than vertical ones because mirror generalization might be stronger and thus more difficult to inhibit in the context of the former than the latter.

The ideomotor recycling theory for tool use, language, and foresight.

The present theoretical framework highlights a common action-perception mechanism for tool use, spoken language, and foresight capacity. On the one hand, it has been suggested that human language and the capacity to envision the future (i.e. foresight) have, from an evolutionary viewpoint, developed mutually along with the pressure of tool use. This co-evolution has afforded humans an evident survival advantage in the animal kingdom because language can help to refine the representation of future scenarios, which in turn can help to encourage or discourage engagement in appropriate and efficient behaviours. On the other hand, recent assumptions regarding the evolution of the brain have capitalized on the concept of "neuronal recycling". In the domain of cognitive neuroscience, neuronal recycling means that during evolution, some neuronal areas and cognitive functions have been recycled to manage new environmental and social constraints. In the present article, we propose that the co-evolution of tool use, language, and foresight represents a suitable example of such functional recycling throughout a well-defined common action-perception mechanism, i.e. the ideomotor mechanism. This ideomotor account is discussed in light of different future ontogenetic and phylogenetic perspectives.

The Learning Brain

Abstract. Reading is an example of complex learning specific to human beings. In readers, an area of the brain is dedicated to the visual processing of letters and words, referred to as the visual word form area (VWFA). The existence of this brain area is paradoxical. Reading is too recent to be a phylogenic product of Darwinian evolution. It likely develops with intense school training via a neuroplastic ontogenic process of neuronal recycling: neurons in the lateral occipitotemporal lobe originally tuned to the visual recognition of stimuli, such as faces, objects, and animals, will be recycled for the visual recognition of letters and words. Thus, the VWFA inherits the intrinsic properties of these neurons, notably, mirror generalization, a process (or heuristic) applied to all visual stimuli that enables the recognition of a stimulus irrespective of its left-right orientation. On its own, this inherited property is not adapted to reading because it makes children confuse mirror letters, such as b and d in the Latin alphabet. In this article, we present evidence that inhibitory control is critical to avoid mirror errors inherited from the neuronal recycling process by blocking the mirror generalization heuristic in the context of reading. We subsequently argue that the “neuronal recycling + inhibitory control” law constitutes a general law of the learning brain by demonstrating that it may also account for the development of numeracy.

Chinese Character and English Word processing in children's ventral occipitotemporal cortex: fMRI evidence for script invariance

Learning to read is thought to involve the recruitment of left hemisphere ventral occipitotemporal cortex (OTC) by a process of “neuronal recycling”, whereby object processing mechanisms are co-opted for reading. Under the same theoretical framework, it has been proposed that the visual word form area (VWFA) within OTC processes orthographic stimuli independent of culture and writing systems, suggesting that it is universally involved in written language. However, this “script invariance” has yet to be demonstrated in monolingual readers of two different writing systems studied under the same experimental conditions. Here, using functional magnetic resonance imaging (fMRI), we examined activity in response to English Words and Chinese Characters in 1st graders in the United States and China, respectively. We examined each group separately and found the readers of English as well as the readers of Chinese to activate the left ventral OTC for their respective native writing systems (using both a whole-brain and a bilateral OTC-restricted analysis). Critically, a conjunction analysis of the two groups revealed significant overlap between them for native writing system processing, located in the VWFA and therefore supporting the hypothesis of script invariance. In the second part of the study, we further examined the left OTC region responsive to each group's native writing system and found that it responded equally to Object stimuli (line drawings) in the Chinese-reading children. In English-reading children, the OTC responded much more to Objects than to English Words. Together, these results support the script invariant role of the VWFA and also support the idea that the areas recruited for character or word processing are rooted in object processing mechanisms of the left OTC.

Fundamental Concepts Bridging Education and the Brain

Although a number of papers have already discussed the relevance of brain research for education, the fundamental concepts and discoveries connecting education and the brain have not been systematically reviewed yet. In this paper, four of these concepts are presented and evidence concerning each one is reviewed. First, the concept of neuroplasticity is proposed as a sine qua non for linking education and the brain. Then, the concepts of neuronal recycling and inhibition are presented as two fundamental mechanisms of school learning that emphasize the importance of knowing the initial brain structure of learners and, finally, the concept of attention is discussed as a central concept for linking teaching and the brain.

Let's face it: reading acquisition, face and word processing.

A TIGHT LINK BETWEEN READING ACQUISITION AND CHANGES IN FACE PROCESSING The invention of writing is one of the most important cultural changes of mankind. Notably, because reading was invented only 5000 years ago, there was not sufficient time to evolve a brain system devoted to visual word recognition. Nevertheless, learning to read leads to the development of a strong response to written materials in the left fusiform gyrus, in the “visual word form area” (VWFA, e.g., Dehaene, 2009). Consequently, reading must rely on pre-existing neural systems for vision and language, which may be partially “recycled” for the specific problems posed by reading (Dehaene, 2005; Dehaene and Cohen, 2007). This consistent localization is related to prior properties of the corresponding tissue, which make it particularly suitable to the specific problems posed by the invariant visual recognition of written words (Dehaene, 2009): bias for foveal stimuli (Hasson et al., 2002), posterior-toanterior increase in perceptual invariance (Grill-Spector et al., 1998; Lerner et al., 2001), and more direct projection fibers to language areas (Cohen et al., 2000; Epelbaum et al., 2008). The neuronal recycling model predicts that, as cortical territories dedicated to evolutionarily older functions are invaded by novel cultural objects, their prior organization should slightly shift away from the original function (though the original function is never entirely erased). As a result, reading acquisition should displace whichever evolutionary older function is implemented in the site of the VWFA. In a recent fMRI study (Dehaene et al., 2010) comparing illiterate to literate adults, we showed that learning to read competes with the cortical representation of other visual objects, especially faces. With increasing literacy, cortical responses to faces decrease slightly in the left fusiform region, while increasing strongly in the right fusiform area (FFA). Thus, right-hemispheric lateralization for faces is increased in literates compared to illiterates. Consistent evidence was also reported when comparing 9-year-old normal readers and dyslexic children. Not only did responses to written words showed a greater left lateralization in normal readers, but responses to faces were also more strongly right lateralized (Monzalvo et al., 2012; cf. also Monzalvo, 2011). Further developmental studies also reveal a tight link between reading acquisition and changes in face processing. Cantlon et al. (2011) demonstrated that 4-year-old-children show decreasing responses to faces in the left fusiform gyrus with increasing knowledge of letter and number symbols. Li et al. (2013) found for Chinese preschooler’s a facilitative effect of early exposure to reading in neural responses to visual words. Such a facilitative effect had a temporary cost in neural response to faces, which did not show the mature pattern seen in adults. Dundas et al. (2012) studied the development of hemispheric specialization for written words and faces in children, adolescents and adults, and found that the left-hemispheric specialization for words develops prior to the right-hemispheric specialization for faces, with face lateralization related to reading comprehension ability (cf. also Pinel et al., 2014). The competition between different categories seems to rely on enhanced neuronal specificity, namely on decreased responses to non-preferred stimuli as opposed to an increased response to the preferred category. Indeed, Cantlon et al. (2011) found a decrease for non-preferred stimuli in VWFA and FFA during child development. Joseph et al. (2011) reported both progressive changes, i.e., increasing face-specialization in a brain region with age, and regressive changes, i.e., decreasing face-specialization with age. Indeed, many brain regions recruited in children for face processing showed reduced specialization for faces by adulthood. Such regressive changes support the idea that some areas of the face network may lose out, at a cellular and a functional level, to promote specialization. Consistent with this scenario, in Pinel et al. (2014)’s study stronger leftward asymmetry for the VWFA and rightward asymmetry for the FFA were characterized by reduced activation in homolog areas of the contralateral hemisphere. All these observations support the existence of competition for cortical space between the VWFA and the preexisting neural coding of faces (Dehaene, 2005; Dehaene and Cohen, 2007; Plaut and Behrmann, 2011), with some displacement of fusiform face-sensitive areas toward the right hemisphere. A similar theoretical perspective (Nestor et al., 2012; Behrmann and Plaut, 2013) espouses a competitive interaction between distributed circuits for faces and word recognition for foveally-biased cortex, constrained by the need to integrate reading with the language system primarily left-lateralized. Recently, we investigated the behavioral consequences of this brain reorganization (Ventura et al., 2013). Using the face composite task, we found that literates are consistently less holistic than illiterate

Neural Plasticity, Neuronal Recycling and Niche Construction

AbstractInReading in the Brain, Stanislas Dehaene presents a compelling account of how the brain learns to read. Central to this account is his neuronal recycling hypothesis: neural circuitry is capable of being ‘recycled’ or converted to a different function that is cultural in nature. The original function of the circuitry is not entirely lost and constrains what the brain can learn. It is argued that the neural niche co‐evolves with the environmental niche in a way that does not undermine the core ideas of neuronal recycling, but which is quite different from the models of cognitive and cultural evolution provided by evolutionary psychology and epidemiology.Dehaene contrasts neuronal recycling with a naïve model of the brain as a general learning device that is unconstrained in what it can learn. Consequently a tension develops in Dehaene's account of the role of plasticity in the acquisition of language. It is argued that the functional and structural changes in the brain that Dehaene documents in great detail are driven by learning and that this learning‐driven plasticity does not commit us to a naïve model of the brain.

The Neuronal Recycling Hypothesis for Reading and the Question of Reading Universals

AbstractAre there universals of reading? There are three ways of construing this question. Is the region of the brain where reading is implemented identical regardless of what writing system the reader uses? Is the mental information‐processing system used for reading the same regardless of what writing system the reader uses. Do the word's writing systems share certain universal features? Dehaene offers affirmative answers to all three questions in his book. Here I suggest instead that the answers should be negative. And I ask: if reading is not universal in any sense, what does this imply about Dehaene's Neuronal Recycling hypothesis for reading?

Pattern separation by neuronal turnover in a feed-forward network

Numerous studies have revealed a role for the hippocampal dentate gyrus in behavioral discrimination between similar contexts or objects, referred to as pattern separation. Recently many behavioral studies have demonstrated a role for dentate neurogenesis in such pattern separation. While several computational studies have modeled the effect of neuronal turnover on learning in simple [1-3] and more detailed networks [4], the computational advantage of neurogenesis for pattern separation has remained obscure. Here we present a simple, feed-forward network, with a biologically plausible learning rule for implementing neuronal recycling that reveals the pattern separation properties of neurogenesis. Our model consists of a three-layer network including entorhinal cortical inputs (EC), dentate gyrus (DG) as the hidden layer, and a single CA3 readout unit. The weights between EC and DG are fixed random, while those from DG to CA3 are trained with a perceptron learning rule. A context consists of a set of patterns presented to EC with their respective target readouts at CA3. Pereceptron training results in a weight vector with approximately normally distributed weights. Neurogenesis is implemented by replacing units with weak weights to the CA3 readout, thus a new hidden unit with random weights replaces the prior unit. Thereupon another round of perceptron learning is implemented. This simple rule results in a markedly reduced generalization error at the CA3 readout that continues to decline with each subsequent round of neurogenesis. Intuitively, this neurogenesis improves linear separability in the DG space allowing the CA3 readout to draw a decision hyperplane with a greater margin between the classes. This form of neuronal turnover may represent a biologically plausible replacement for error backpropagation.

Stanislas Dehaene’s Les neurones de la lecture

ABSTRACT— Stanislas Dehaene has published a remarkable book on the neurons of reading. It is a comprehensive description of the main issues related to the “paradox of reading”: how humans process linguistic information using the visual brain path while the brain has not evolved in the short period of time since the invention of writing. The article presents a powerful “neuronal recycling” hypothesis to explain the remarkable properties of our cultural neuroplasticity. Scientists and educators will find a trove of information and deep discussions regarding the universal challenge of teaching and learning to read.

Abstracts: 1

Lead (Pb) is a known neurotoxic agent, however, mechanisms of its neurotoxicity are still an open question. The aim of the study was to assess the function of nerve endings and astroglia in regard to the relationships between GABA, glutamate and glutamine using the rodent model of Pb toxicity. Synaptosomal processes of radioactive neurotransmitter transport, both GABA and glutamate, were impaired. Moreover, the uptake of glutamine, involved in the neuronal recycling of the neurotransmitters GABA and glutamate, decreased. However, evidences of astroglial activation (enhanced uptake of glutamate and activation of glutamine synthetase) were observed, together with parallel existing weakness of glutamine transport. The results suggest that the disturbances in GABAergic and glutamateric neurotransmission may be partially the effect of impaired neuronal–astrocytic interaction, mainly in intercellular trafficking of glutamine.