Publications of year 2009

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Publications of year 2009

Stanislas Dehaene and Christine Petit. Parole et musique. Odile Jacob, 2009. [bibtex-entry]

Stanislas Dehaene. Reading in the brain. Penguin Viking, 2009. [WWW] [bibtex-entry]

Marco Buiatti. Analisi multidimensionale della dinamica neurale di un processo cognitivo. In Bioingegneria per le Scienze Cognitive. Edizioni Patron, Bologna (Italy), 2009. [PDF] [bibtex-entry]

L. Cohen and S. Dehaene. Ventral and dorsal contribution to word reading. In M.S. Gazzaniga, editor,Cognitive Neuroscience, 4th edition. MIT Press, 2009. [PDF] [bibtex-entry]

Edward M. Hubbard, Manuela Piazza, Philippe Pinel, and Stanislas Dehaene. Numerical and Spatial Intuitions: A Role for Posterior Parietal Cortex?. In L. Tommasi, L. Nadel, and M. A. Peterson, editors,Cognitive Biology: Evolutionary and Developmental Perspectives on Mind, Brain and Behavior, pages 221-246. MIT Press, Cambridge, Mass, 2009. [PDF] [bibtex-entry]

Articles in journals

Tristan A Bekinschtein, Stanislas Dehaene, Benjamin Rohaut, François Tadel, Laurent Cohen, and Lionel Naccache. Neural signature of the conscious processing of auditory regularities.. Proc Natl Acad Sci U S A, 106(5):1672--1677, February 2009. [WWW] [PDF]

Abstract:

Can conscious processing be inferred from neurophysiological measurements? Some models stipulate that the active maintenance of perceptual representations across time requires consciousness. Capitalizing on this assumption, we designed an auditory paradigm that evaluates cerebral responses to violations of temporal regularities that are either local in time or global across several seconds. Local violations led to an early response in auditory cortex, independent of attention or the presence of a concurrent visual task, whereas global violations led to a late and spatially distributed response that was only present when subjects were attentive and aware of the violations. We could detect the global effect in individual subjects using functional MRI and both scalp and intracerebral event-related potentials. Recordings from 8 noncommunicating patients with disorders of consciousness confirmed that only conscious individuals presented a global effect. Taken together these observations suggest that the presence of the global effect is a signature of conscious processing, although it can be absent in conscious subjects who are not aware of the global auditory regularities. This simple electrophysiological marker could thus serve as a useful clinical tool.

Manon J N L Benders, Floris Groenendaal, Frank van Bel, Russia Ha Vinh, Jessica Dubois, François Lazeyras, Simon K Warfield, Petra S Hüppi, and Linda S de Vries. Brain development of the preterm neonate after neonatal hydrocortisone treatment for chronic lung disease.. Pediatr Res, 66(5):555--559, November 2009. [WWW] [PDF]

Abstract:

Previous studies reported impaired cerebral cortical gray matter (CGM) development and neurodevelopmental impairment after neonatal dexamethasone treatment for chronic lung disease (CLD) in preterm newborns. No long-term effects on neurocognitive outcome have yet been shown for hydrocortisone treatment. A prospective study was performed to evaluate the brain growth at term in preterm infants who did receive neonatal hydrocortisone for CLD. Thirty-eight preterm infants (n = 19 hydrocortisone, n = 19 controls) were matched for gestational age at birth. Gestational age and birth weight were 27.0+/- 1.4 versus 27.6+/- 1.1 wk (p = ns) and 826+/- 173 versus 1017+/- 202 g, respectively (p < 0.05). Infants were studied at term equivalent age. Hydrocortisone was started with a dose of 5 mg/kg/d for 1 wk, followed by a tapering course over 3 wk. A 3D-MRI technique was used to quantify cerebral tissue volumes: CGM, basal ganglia/thalami, unmyelinated white matter, myelinated white matter, cerebellum, and cerebrospinal fluid. Infants who were treated with hydrocortisone had more severe respiratory distress. There were no differences in cerebral tissue volumes between the two groups at term equivalent age. In conclusion, no effect on brain growth, measured at term equivalent age, was shown after treatment with hydrocortisone for CLD.

Davina Bristow, Ghislaine Dehaene-Lambertz, Jeremie Mattout, Catherine Soares, Teodora Gliga, Sylvain Baillet, and Jean-François Mangin. Hearing Faces: How the Infant Brain Matches the Face It Sees with the Speech It Hears. J Cogn Neurosci, 21:905-21, 2009. [WWW] [PDF]

Abstract:

Abstract Speech is not a purely auditory signal. From around 2 months of age, infants are able to correctly match the vowel they hear with the appropriate articulating face. However, there is no behavioral evidence of integrated audiovisual perception until 4 months of age, at the earliest, when an illusory percept can be created by the fusion of the auditory stimulus and of the facial cues (McGurk effect). To understand how infants initially match the articulatory movements they see with the sounds they hear, we recorded high-density ERPs in response to auditory vowels that followed a congruent or incongruent silently articulating face in 10-week-old infants. In a first experiment, we determined that auditory-visual integration occurs during the early stages of perception as in adults. The mismatch response was similar in timing and in topography whether the preceding vowels were presented visually or aurally. In the second experiment, we studied audiovisual integration in the linguistic (vowel perception) and nonlinguistic (gender perception) domain. We observed a mismatch response for the both types of change at similar latencies. Their topographies were significantly different demonstrating that cross-modal integration of these features is computed in parallel by two different networks. Indeed, brain source modeling revealed that phoneme and gender computations were lateralized toward the left and toward the right hemisphere, respectively, suggesting that each hemisphere possesses an early processing bias. We also observed repetition suppression in temporal regions and repetition enhancement in frontal regions. These results underscore how complex and structured is the human cortical organization which sustains communication from the first weeks of life on

Marco Buiatti, Marcela Peña, and Ghislaine Dehaene-Lambertz. Investigating the neural correlates of continuous speech computation with frequency-tagged neuroelectric responses. Neuroimage, 44(2):509--519, January 2009. [WWW] [PDF]

Abstract:

In order to learn an oral language, humans have to discover words from a continuous signal. Streams of artificial monotonous speech can be readily segmented based on the statistical analysis of the syllables' distribution. This parsing is considerably improved when acoustic cues, such as subliminal pauses, are added suggesting that a different mechanism is involved. Here we used a frequency-tagging approach to explore the neural mechanisms underlying word learning while listening to continuous speech. High-density EEG was recorded in adults listening to a concatenation of either random syllables or tri-syllabic artificial words, with or without subliminal pauses added every three syllables. Peaks in the EEG power spectrum at the frequencies of one and three syllables occurrence were used to tag the perception of a monosyllabic or tri-syllabic structure, respectively. Word streams elicited the suppression of a one-syllable frequency peak, steadily present during random streams, suggesting that syllables are no more perceived as isolated segments but bounded to adjacent syllables. Crucially, three-syllable frequency peaks were only observed during word streams with pauses, and were positively correlated to the explicit recall of the detected words. This result shows that pauses facilitate a fast, explicit and successful extraction of words from continuous speech, and that the frequency-tagging approach is a powerful tool to track brain responses to different hierarchical units of the speech structure

Jessica F Cantlon, Melissa E Libertus, Philippe Pinel, Stanislas Dehaene, Elizabeth M Brannon, and Kevin A Pelphrey. The Neural Development of an Abstract Concept of Number.. J Cogn Neurosci, 21(11):2217-29, November 2009. [WWW] [PDF]

Abstract:

Abstract As literate adults, we appreciate numerical values as abstract entities that can be represented by a numeral, a word, a number of lines on a scorecard, or a sequence of chimes from a clock. This abstract, notation-independent appreciation of numbers develops gradually over the first several years of life. Here, using functional magnetic resonance imaging, we examine the brain mechanisms that 6- and 7-year-old children and adults recruit to solve numerical comparisons across different notation systems. The data reveal that when young children compare numerical values in symbolic and nonsymbolic notations, they invoke the same network of brain regions as adults including occipito-temporal and parietal cortex. However, children also recruit inferior frontal cortex during these numerical tasks to a much greater degree than adults. Our data lend additional support to an emerging consensus from adult neuroimaging, nonhuman primate neurophysiology, and computational modeling studies that a core neural system integrates notation-independent numerical representations throughout development but, early in development, higher-order brain mechanisms mediate this process.

Stanislas Dehaene. Origins of mathematical intuitions: the case of arithmetic.. Ann N Y Acad Sci, 1156:232--259, March 2009. [WWW] [PDF]

Abstract:

Mathematicians frequently evoke their "intuition" when they are able to quickly and automatically solve a problem, with little introspection into their insight. Cognitive neuroscience research shows that mathematical intuition is a valid concept that can be studied in the laboratory in reduced paradigms, and that relates to the availability of "core knowledge" associated with evolutionarily ancient and specialized cerebral subsystems. As an illustration, I discuss the case of elementary arithmetic. Intuitions of numbers and their elementary transformations by addition and subtraction are present in all human cultures. They relate to a brain system, located in the intraparietal sulcus of both hemispheres, which extracts numerosity of sets and, in educated adults, maps back and forth between numerical symbols and the corresponding quantities. This system is available to animal species and to preverbal human infants. Its neuronal organization is increasingly being uncovered, leading to a precise mathematical theory of how we perform tasks of number comparison or number naming. The next challenge will be to understand how education changes our core intuitions of number.

Stanislas Dehaene and Ghislaine Dehaene-Lambertz. Neuro-imagerie cognitive:phylogenèse et ontogenèse. Bull.Acad.Natle Méd, 193:883-89, 2009. [bibtex-entry]

Stanislas Dehaene, Veronique Izard, Pierre Pica, and Elizabeth Spelke. Response to Comment on Log or Linear? Distinct intuitions of the Number Scale in Western and Amazonian Indigene Cultures. Science, 323:38c, 2009. [PDF] [bibtex-entry]

Stanislas Dehaene. The case for a notation-independent representation of number.. Behav Brain Sci, 32(3-4):333--5; discussion 356-73, August 2009. [WWW] [PDF]

Abstract:

Cohen Kadosh & Walsh (CK&W) neglect the solid empirical evidence for a convergence of notation-specific representations onto a shared representation of numerical magnitude. Subliminal priming reveals cross-notation and cross-modality effects, contrary to CK&W's prediction that automatic activation is modality and notation-specific. Notation effects may, however, emerge in the precision, speed, automaticity, and means by which the central magnitude representation is accessed.

A Del Cul, S Dehaene, P Reyes, E Bravo, and A Slachevsky. Causal role of prefrontal cortex in the threshold for access to consciousness. Brain, 132:2531-2540, 2009. [PDF] [bibtex-entry]

Anne-Dominique Devauchelle, Catherine Oppenheim, Luigi Rizzi, Stanislas Dehaene, and Christophe Pallier. Sentence syntax and content in the human temporal lobe: an fMRI adaptation study in auditory and visual modalities.. J Cogn Neurosci, 21(5):1000--1012, May 2009. [WWW] [PDF]

Abstract:

Priming effects have been well documented in behavioral psycholinguistics experiments: The processing of a word or a sentence is typically facilitated when it shares lexico-semantic or syntactic features with a previously encountered stimulus. Here, we used fMRI priming to investigate which brain areas show adaptation to the repetition of a sentence's content or syntax. Participants read or listened to sentences organized in series which could or not share similar syntactic constructions and/or lexico-semantic content. The repetition of lexico-semantic content yielded adaptation in most of the temporal and frontal sentence processing network, both in the visual and the auditory modalities, even when the same lexico-semantic content was expressed using variable syntactic constructions. No fMRI adaptation effect was observed when the same syntactic construction was repeated. Yet behavioral priming was observed at both syntactic and semantic levels in a separate experiment where participants detected sentence endings. We discuss a number of possible explanations for the absence of syntactic priming in the fMRI experiments, including the possibility that the conglomerate of syntactic properties defining "a construction" is not an actual object assembled during parsing.

J. Dubois, L. Hertz-Pannier, A. Cachia, J. F. Mangin, D. Le Bihan, and G. Dehaene-Lambertz. Structural asymmetries in the infant language and sensori-motor networks.. Cereb Cortex, 19(2):414--423, February 2009. [WWW] [PDF]

Abstract:

Both language capacity and strongly lateralized hand preference are among the most intriguing particularities of the human species. They are associated in the adult brain with functional and anatomical hemispheric asymmetries in the speech perception-production network and in the sensori-motor system. Only studies in early life can help us to understand how such asymmetries arise during brain development, and to which point structural left-right differences are the source or the consequence of functional lateralization. In this study, we aimed to provide new in vivo structural markers of hemispheric asymmetries in infants from 1 to 4 months of age, with diffusion tensor imaging. We used 3 complementary analysis methods based on local diffusion indices and spatial localizations of tracts. After a prospective approach over the whole brain, we demonstrated early leftward asymmetries in the arcuate fasciculus and in the cortico-spinal tract. These results suggest that the early macroscopic geometry, microscopic organization, and maturation of these white matter bundles are related to the development of later functional lateralization.

Evelyn Eger, Vincent Michel, Bertrand Thirion, Alexis Amadon, Stanislas Dehaene, and Andreas Kleinschmidt. Deciphering Cortical Number Coding from Human Brain Activity Patterns.. Curr Biol, September 2009. [WWW] [PDF]

Abstract:

BACKGROUND: Neuropsychology and human functional neuroimaging have implicated human parietal cortex in numerical processing, and macaque electrophysiology has shown that intraparietal areas house neurons tuned to numerosity. Yet although the areas responding overall during numerical tasks have been well defined by neuroimaging, a direct demonstration of individual number coding by spatial patterns has thus far been elusive. RESULTS: We used multivariate pattern recognition on high-resolution functional imaging data to decode the information content of fine-scale signals evoked by different individual numbers. Parietal activation patterns for individual numerosities could be accurately discriminated and generalized across changes in low-level stimulus parameters. Distinct patterns were evoked by symbolic and nonsymbolic number formats, and individual digits were less accurately decoded (albeit still with significant accuracy) than numbers of dots. Interestingly, the numerosity of dot sets could be predicted above chance from the brain activation patterns evoked by digits, but not vice versa. Finally, number-evoked patterns changed in a gradual fashion as a function of numerical distance for the nonsymbolic notation, compatible with some degree of orderly layout of individual number representations. CONCLUSIONS: Our findings demonstrate partial format invariance of individual number codes that is compatible with more numerous but more broadly tuned populations for nonsymbolic than for symbolic numbers, as postulated by recent computational models. In more general terms, our results illustrate the potential of functional magnetic resonance imaging pattern recognition to understand the detailed format of representations within a single semantic category, and beyond sensory cortical areas for which columnar architectures are well established.

Raphael Gaillard, Stanislas Dehaene, Claude Adam, Stephane Clemenceau, Dominique Hasboun, Michel Baulac, Laurent Cohen, and and Lionel Naccache. Converging Intracranial Markers of Conscious Access. PLoS Biol, 7(3), 2009. [PDF]

Abstract:

We compared conscious and nonconscious processing of briefly flashed words using a visual masking procedure while recording intracranial electroencephalogram (iEEG) in ten patients. Nonconscious processing of masked words was observed in multiple cortical areas, mostly within an early time window (,300 ms), accompanied by induced gamma- band activity, but without coherent long-distance neural activity, suggesting a quickly dissipating feedforward wave. In contrast, conscious processing of unmasked words was characterized by the convergence of four distinct neurophysiological markers: sustained voltage changes, particularly in prefrontal cortex, large increases in spectral power in the gamma band, increases in long-distance phase synchrony in the beta range, and increases in long-range Granger causality. We argue that all of those measures provide distinct windows into the same distributed state of conscious processing. These results have a direct impact on current theoretical discussions concerning the neural correlates of conscious access.

Linda Heinemann, Andreas Kleinschmidt, and Notger G Müller. Exploring BOLD changes during spatial attention in non-stimulated visual cortex.. PLoS One, 4(5):e5560, 2009. [WWW] [PDF]

Abstract:

Blood oxygen level-dependent (BOLD) responses were measured in parts of primary visual cortex that represented unstimulated visual field regions at different distances from a stimulated central target location. The composition of the visual scene varied by the presence or absence of additional peripheral distracter stimuli. Bottom-up effects were assessed by comparing peripheral activity during central stimulation vs. no stimulation. Top-down effects were assessed by comparing active vs. passive conditions. In passive conditions subjects simply watched the central letter stimuli and in active conditions they had to report occurrence of pre-defined targets in a rapid serial letter stream. Onset of the central letter stream enhanced activity in V1 representations of the stimulated region. Within representations of the periphery activation decreased and finally turned into deactivation with increasing distance from the stimulated location. This pattern was most pronounced in the active conditions and during the presence of peripheral stimuli. Active search for a target did not lead to additional enhancement at areas representing the attentional focus but to a stronger deactivation in the vicinity. Suppressed neuronal activity was also found in the non distracter condition suggesting a top-down attention driven effect. Our observations suggest that BOLD signal decreases in primary visual cortex are modulated by bottom-up sensory-driven factors such as the presence of distracters in the visual field as well as by top-down attentional processes.

Edward M. Hubbard, Mariagrazia Ranzini, Manuela Piazza, and Stanislas Dehaene. What Information is Critical to Elicit Interference in Number-Form Synaesthesia?. Cortex, 45:1200-16, 2009. [PDF] [bibtex-entry]

Véronique Izard, Coralie Sann, Elizabeth S Spelke, and Arlette Streri. Newborn infants perceive abstract numbers.. Proc Natl Acad Sci U S A, 106(25):10382--10385, June 2009. [WWW] [PDF]

Abstract:

Although infants and animals respond to the approximate number of elements in visual, auditory, and tactile arrays, only human children and adults have been shown to possess abstract numerical representations that apply to entities of all kinds (e.g., 7 samurai, seas, or sins). Do abstract numerical concepts depend on language or culture, or do they form a part of humans' innate, core knowledge? Here we show that newborn infants spontaneously associate stationary, visual-spatial arrays of 4-18 objects with auditory sequences of events on the basis of number. Their performance provides evidence for abstract numerical representations at the start of postnatal experience.

Armen Kalashyan, Marco Buiatti, and Paolo Grigolini. Ergodicity breakdown and scaling in single sequences. Chaos, Solitons & Fractals, 39:895-909, 2009. [PDF] [bibtex-entry]

Andre Knops, Bertrand Thirion, Edward M Hubbard, Vincent Michel, and Stanislas Dehaene. Recruitment of an Area Involved in Eye Movements During Mental Arithmetic.. Science, 324, May 2009. [WWW] [PDF]

Abstract:

Throughout the history of mathematics, concepts of number and space have been tightly intertwined. We tested the hypothesis that cortical circuits for spatial attention contribute to mental arithmetic. We trained a multivariate classifier to infer the direction of an eye movement, left or right, from the brain activation measured in posterior parietal cortex. Without further training, the classifier then generalized to an arithmetic task. Its left versus right classification could be used to sort out subtraction versus addition trials, whether performed with symbols or with sets of dots. These findings are consistent with the suggestion that mental arithmetic co-opts parietal circuitry associated with spatial coding.

Andre Knops, Arnaud Viarouge, and Stanislas Dehaene. Dynamic representations underlying symbolic and nonsymbolic calculation: Evidence from the operational momentum effect.. Atten Percept Psychophys, 71(4):803--821, May 2009. [WWW] [PDF]

Abstract:

When we add or subtract, do the corresponding quantities "move" along a mental number line? Does this internal movement lead to spatial biases? A new method was designed to investigate the psychophysics of approximate arithmetic. Addition and subtraction problems were presented either with sets of dots or with Arabic numerals, and subjects selected, from among seven choices, the most plausible result. In two experiments, the subjects selected larger numbers for addition than for subtraction problems, as if moving too far along the number line. This operational momentum effect was present in both notations and increased with the size of the outcome. Furthermore, we observed a new effect of spatial-numerical congruence, related to but distinct from the spatial numerical association of response codes effect: During nonsymbolic addition, the subjects preferentially selected numbers at the upper right location, whereas during subtraction, they were biased toward the upper left location. These findings suggest that approximate mental arithmetic involves dynamic shifts on a spatially organized mental representation of numbers. Supplemental materials for this study may be downloaded from app.psychonomic-journals.org/content/supplemental.

Sid Kouider and Stanislas Dehaene. Subliminal number priming within and across the visual and auditory modalities.. Exp Psychol, 56(6):418--433, 2009. [WWW] [PDF]

Abstract:

Whether masked number priming involves a low-level sensorimotor route or an amodal semantic level of processing remains highly debated. Several alternative interpretations have been put forward, proposing either that masked number priming is solely a byproduct of practice with numbers, or that stimulus awareness was underestimated. In a series of four experiments, we studied whether repetition and congruity priming for numbers reliably extend to novel (i.e., unpracticed) stimuli and whether priming transfers from a visual prime to an auditory target, even when carefully controlling for stimulus awareness. While we consistently observed cross-modal priming, the generalization to novel stimuli was weaker and reached significance only when considering the whole set of experiments. We conclude that number priming does involve an amodal, semantic level of processing, but is also modulated by task settings.

Sid Kouider, Evelyn Eger, R Dolan, and R.N. Henson. Activity in face-responsive brain regions in modulated by invisible attended faces: evidence from masked priming. Cereb Cortex, 19:13-23, 2009. [bibtex-entry]

Julien Lefevre, François Leroy, Sheraz Khan, Jessica Dubois, Petra S Huppi, Sylvain Baillet, and Jean-François Mangin. Identification of growth seeds in the neonate brain through surfacic Helmholtz decomposition.. Inf Process Med Imaging, 21:252--263, 2009. [PDF]

Abstract:

We report on a new framework to investigate the rapid brain development of newborns. It is based on the analysis of depth maps of the cortical surface through the study of a displacement field estimated by surfacic optical flow methods. This displacement field shows local evolution of sulci directly on the cortical surface. Detection of its critical points is performed with the Helmholtz decomposition which allows us to identify sources of the developmental process. They can be viewed as growth seeds or in other terms points around which the sulcal growth organizes itself. We show the reproducibility of such growth seeds across 4 neonates and make a link of this new concept to the "sulcal roots" one proposed to explain the variability of human brain anatomy.

Vincent Navarro, Christine Delmaire, Valérie Chauviré, Marie-Odile Habert, Rosalie Footnick, Stéphane Lehéricy, Michel Baulac, Christophe Pallier, and Laurent Cohen. What is it? A functional MRI and SPECT study of ictal speech in a second language.. Epilepsy Behav, 14(2):396--399, February 2009. [WWW] [PDF]

Abstract:

Neuronal networks involved in second language (L2) processing vary between normal subjects. Patients with epilepsy may have ictal speech automatisms in their second language. To delineate the brain systems involved in L2 ictal speech, we combined functional MRI during bilingual tasks and ictal--interictal single-photon emission computed tomography in a patient who presented L2 ictal speech productions. These analyses showed that the networks activated by the seizure and those activated by L2 processing intersected in the right hippocampus. These results may provide some insights both into the pathophysiology of ictal speech and into the brain organization for L2.

Andreas Nieder and Stanislas Dehaene. Representation of number in the brain.. Annu Rev Neurosci, 32:185--208, 2009. [WWW] [PDF]

Abstract:

Number symbols have allowed humans to develop superior mathematical skills that are a hallmark of technologically advanced cultures. Findings in animal cognition, developmental psychology, and anthropology indicate that these numerical skills are rooted in nonlinguistic biological primitives. Recent studies in human and nonhuman primates using a broad range of methodologies provide evidence that numerical information is represented and processed by regions of the prefrontal and posterior parietal lobes, with the intraparietal sulcus as a key node for the representation of the semantic aspect of numerical quantity.

Manuela Piazza and Veronique Izard. What is an (abstract) neural representation of quantity?. Behavioral and Brain Sciences, 32:348-349, 2009. [bibtex-entry]

Manuela Piazza and Veronique Izard. How humans count: numerosity and the parietal cortex.. Neuroscientist, 15(3):261--273, June 2009. [WWW] [PDF]

Abstract:

Numerosity (the number of objects in a set), like color or movement, is a basic property of the environment. Animal and human brains have been endowed by evolution by mechanisms based on parietal circuitry for representing numerosity in an highly abstract, although approximate fashion. These mechanisms are functional at a very early age in humans and spontaneously deployed in the wild by animals of different species. The recent years have witnessed terrific advances in unveiling the neural code(s) underlying numerosity representations and showing similarities as well as differences across species. In humans, during development, with the introduction of symbols for numbers and the implementation of the counting routines, the parietal system undergoes profound (yet still largely mysterious) modifications, such that the neural machinery previously evolved to represent approximate numerosity gets partially "recycled" to support the representation of exact number.

Mariagrazia Ranzini, Stanislas Dehaene, Manuela Piazza, and Edward M Hubbard. Neural mechanisms of attentional shifts due to irrelevant spatial and numerical cues.. Neuropsychologia, 47:2615-2624, May 2009. [WWW] [PDF]

Abstract:

Studies of endogenous (cue-directed) attention have traditionally assumed that such shifts must be volitional. However, recent behavioural experiments have shown that participants make automatic endogenous shifts of attention when presented with symbolic cues that are systematically associated with particular spatial directions, such as arrows and numerals, even when such cues were not behaviourally relevant. Here we used event-related potentials (ERPs) to test whether these automatic shifts of attention use the same mechanisms as volitional shifts of attention. We presented participants with non-predictive (50\% valid) task-irrelevant arrow and numeral cues while measuring cue- and target-locked ERPs. Although the cues were task-irrelevant, they elicited attention-related ERP components previously found in studies that used informative and/or task-relevant cues. These findings further substantiate the dissociation between endogenous and volitional attentional control, and suggest that the same fronto-parietal networks involved in volitional shifts of attention are also involved in reflexive endogenous shifts of attention.

Pekka Rasanen, Jonna Salminen, Anna Wilson, Pirjo Aunio, and Stanislas Dehaene. Computer-assisted intervention for children with low numeracy skills. Cognitive Development, 24:450-72, 2009. [PDF] [bibtex-entry]

F. Reuter, B. Audoin, C. Liegois-Chauvel, I. Malikov, L. Naccache, L. Cohen, A. Del Cul, P. Cozzone, A.A. Cherif, S. Dehaene, J.P. Ranjeva, and J. Pelletier. Approach in IRMF of the visual conscious and non conscious perception in the precocious stadium of sclerosis in patches. Rev Neurol, 165:s49-s50, 2009. [bibtex-entry]

Françoise Reuter, Antoine Del Cul, Irina Malikova, Lionel Naccache, Sylviane Confort-Gouny, Laurent Cohen, André Ali Chérif, Patrick J. Cozzone, Jean Pelletier, Jean Philippe Ranjeva, Stanislas Dehaene, and Bertrand Audoin. White matter damage impairs access to consciousness in multiple sclerosis. Neuroimage, 44(2):590--599, January 2009. [WWW] [PDF]

Abstract:

Global neuronal workspace theory predicts that damage to long-distance white matter (WM) tracts should impair access to consciousness during the perception of brief stimuli. To address this issue, we studied visual backward masking in 18 patients at the very first clinical stage of multiple sclerosis (MS), a neurological disease characterized by extensive WM damage, and in 18 matched healthy subjects. In our masking paradigm, the visibility of a digit stimulus increases non-linearly as a function of the interval duration between this target and a subsequent mask. In order to characterize quantitatively, for each subject, the transition between non-conscious and conscious perception of the stimulus, we used non-linear regression to fit a sigmoid curve to objective performance and subjective visibility reports as a function of target-mask delay. The delay corresponding to the inflexion point of the sigmoid, where visibility suddenly increases, was termed the "non-linear transition threshold" and used as a summary measure of masking efficiency. Objective and subjective non-linear transition thresholds were highly correlated across subjects in both groups, and were higher in patients compared to controls. In patients, variations in the non-linear transition threshold were inversely correlated to the Magnetization transfer ratio (MTR) values inside the right dorsolateral prefrontal WM, the right occipito-frontal fasciculus and the left cerebellum. This study provides clinical evidence of a relationship between impairments of conscious access and integrity of large WM bundles, particularly involving prefrontal cortex, as predicted by global neuronal workspace theory

Elena Rusconi, Philippe Pinel, Evelyn Eger, Denis LeBihan, Bertrand Thirion, Stanislas Dehaene, and Andreas Kleinschmidt. A disconnection account of Gerstmann syndrome: functional neuroanatomy evidence.. Ann Neurol, 66(5):654--662, November 2009. [WWW] [PDF]

Abstract:

OBJECTIVE: To examine the functional neuroanatomy that could account for pure Gerstmann syndrome, which is the selective association of acalculia, finger agnosia, left-right disorientation, and agraphia. METHODS: We used structural and functional neuroimaging at high spatial resolution in healthy subjects to seek a shared cortical substrate of the Grundstrung posited by Gerstmann, ie, a common functional denominator accounting for this clinical tetrad. We construed a functional activation paradigm that mirrors each of the four clinical deficits in Gerstmann syndrome and determined cortical activation patterns. We then applied fiber tracking to diffusion tensor images and used cortical activation foci in the four functional domains as seed regions. RESULTS: None of the subjects showed parietal overlap of cortical activation patterns from the four cognitive domains. In every subject, however, the parietal activation patterns across all four domains consistently connected to a small region of subcortical parietal white matter at a location that is congruent with the lesion in a well-documented case of pure Gerstmann syndrome. INTERPRETATION: Our functional neuroimaging findings are not in agreement with Gerstmann's postulate of damage to a common cognitive function underpinning clinical semiology. Our evidence from intact functional neuroanatomy suggests that pure forms of Gerstmann's tetrad do not arise from lesion to a shared cortical substrate but from intraparietal disconnection after damage to a focal region of subcortical white matter.

Jérôme Sackur and Stanislas Dehaene. The cognitive architecture for chaining of two mental operations.. Cognition, 111(2):187--211, May 2009. [WWW] [PDF]

Abstract:

A simple view, which dates back to Turing, proposes that complex cognitive operations are composed of serially arranged elementary operations, each passing intermediate results to the next. However, whether and how such serial processing is achieved with a brain composed of massively parallel processors, remains an open question. Here, we study the cognitive architecture for chained operations with an elementary arithmetic algorithm: we required participants to add (or subtract) two to a digit, and then compare the result with five. In four experiments, we probed the internal implementation of this task with chronometric analysis, the cued-response method, the priming method, and a subliminal forced-choice procedure. We found evidence for an approximately sequential processing, with an important qualification: the second operation in the algorithm appears to start before completion of the first operation. Furthermore, initially the second operation takes as input the stimulus number rather than the output of the first operation. Thus, operations that should be processed serially are in fact executed partially in parallel. Furthermore, although each elementary operation can proceed subliminally, their chaining does not occur in the absence of conscious perception. Overall, the results suggest that chaining is slow, effortful, imperfect (resulting partly in parallel rather than serial execution) and dependent on conscious control.

Sepideh Sadaghiani, Guido Hesselmann, and Andreas Kleinschmidt. Distributed and antagonistic contributions of ongoing activity fluctuations to auditory stimulus detection.. Journal of Neuroscience, 29(42):13410--13417, October 2009. [WWW] [PDF]

Abstract:

Recent studies have shown that ongoing activity fluctuations influence trial-by-trial perception of identical stimuli. Some brain systems seem to bias toward better perceptual performance and others toward worse. We tested whether these observations generalize to another as of yet unassessed sensory modality, audition, and a nonspatial but memory-dependent paradigm. In a sparse event-related functional magnetic resonance imaging design, we investigated detection of auditory near-threshold stimuli as a function of prestimulus baseline activity in early auditory cortex as well as several distributed networks that were defined on the basis of resting state functional connectivity. In accord with previous studies, hits were associated with higher prestimulus activity in related early sensory cortex as well as in a system comprising anterior insula, anterior cingulate, and thalamus, which other studies have related to processing salience and maintaining task set. In contrast to previous studies, however, higher prestimulus activity in the so-called dorsal attention system of frontal and parietal cortex biased toward misses, whereas higher activity in the so-called default mode network that includes posterior cingulate and precuneus biased toward hits. These results contradict a simple dichotomic view on the function of these two latter brain systems where higher ongoing activity in the dorsal attention network would facilitate perceptual performance, and higher activity in the default mode network would deteriorate perceptual performance. Instead, we show that the way in which ongoing activity fluctuations impact on perception depends on the specific sensory (i.e., nonspatial) and cognitive (i.e., mnemonic) context that is relevant.

Aaron Schurger, Francisco Pereira, Anne Treisman, and Jonathan D. Cohen. Reproducibility Distinguishes Conscious From Non-conscious Neural Representations. Science, November 12, 2009. [bibtex-entry]

Philipp Sterzer, Andreas Kleinschmidt, and Geraint Rees. The neural bases of multistable perception.. Trends Cogn Sci, June 2009. [WWW] [PDF]

Abstract:

Multistable perception is the spontaneous alternation between two or more perceptual states that occurs when sensory information is ambiguous. Multistable phenomena permit dissociation of neural activity related to conscious perception from that related to sensory stimulation, and therefore have been used extensively to study the neural correlates of consciousness. Here, we review recent work on the neural mechanisms underlying multistable perception and how such work has contributed to understanding the neural correlates of consciousness. Particular emphasis is put on the role of high-level brain mechanisms that are involved in actively selecting and interpreting sensory information, and their interactions with lower-level processes that are more directly concerned with the processing of sensory stimulus properties.

Marcin Szwed, Laurent Cohen, Emilie Qiao, and Stanislas Dehaene. The role of invariant line junctions in object and visual word recognition.. Vision Res, February 2009. [WWW] [PDF]

Abstract:

Object recognition relies heavily on invariant visual features such as the manner in which lines meet at vertices to form viewpoint-invariant junctions (e.g. T, L). We wondered whether these features also underlie readers' competence for fast recognition of printed words. Since reading is far too recent to have exerted any evolutionary pressure on brain evolution, visual word recognition might be based on pre-existing mechanisms common to all visual object recognition. In a naming task, we presented partially deleted pictures of objects and printed words in which either the vertices or the line midsegments were preserved. Subjects showed an identical pattern of behavior with both objects and words: they made fewer errors and were faster to respond when vertices were preserved. Our results suggest that vertex invariants are used for object recognition and that this evolutionarily ancient mechanism is being co-opted for reading.

Virginie van Wassenhove. Minding time in an amodal representational space.. Philos Trans R Soc Lond B Biol Sci, 364(1525):1815--1830, July 2009. [WWW] [PDF]

Abstract:

How long did it take you to read this sentence? Chances are your response is a ball park estimate and its value depends on how fast you have scanned the text, how prepared you have been for this question, perhaps your mood or how much attention you have paid to these words. Time perception is here addressed in three sections. The first section summarizes theoretical difficulties in time perception research, specifically those pertaining to the representation of time and temporal processing. The second section reviews non-exhaustively temporal effects in multisensory perception. Sensory modalities interact in temporal judgement tasks, suggesting that (i) at some level of sensory analysis, the temporal properties across senses can be integrated in building a time percept and (ii) the representational format across senses is compatible for establishing such a percept. In the last section, a two-step analysis of temporal properties is sketched out. In the first step, it is proposed that temporal properties are automatically encoded at early stages of sensory analysis, thus providing the raw material for the building of a time percept; in the second step, time representations become available to perception through attentional gating of the raw temporal representations and via re-encoding into abstract representations.

Anna J. Wilson, Stanislas Dehaene, Ophélie Dubois, and Michel Fayol. Effects of an Adaptive Game Intervention on Accessing Number Sense in Low-Socioeconomic-Status Kindergarten Children. Mind, Brain, and Education, 3(4):224-234, 2009. [PDF] [bibtex-entry]

Marc Wittmann and Virginie van Wassenhove. The experience of time: neural mechanisms and the interplay of emotion, cognition and embodiment.. Philos Trans R Soc Lond B Biol Sci, 364(1525):1809--1813, July 2009. [WWW] [PDF]

Abstract:

Time research has been a neglected topic in the cognitive neurosciences of the last decades: how do humans perceive time? How and where in the brain is time processed? This introductory paper provides an overview of the empirical and theoretical papers on the psychological and neural basis of time perception collected in this theme issue. Contributors from the fields of cognitive psychology, psychiatry, neurology and neuroanatomy tackle this complex question with a variety of techniques ranging from psychophysical and behavioural experiments to pharmacological interventions and functional neuroimaging. Several (and some new) models of how and where in the brain time is processed are presented in this unique collection of recent research that covers experienced time intervals from milliseconds to minutes. We hope this volume to be conducive in developing a better understanding of the sense of time as part of complex set of brain-body factors that include cognitive, emotional and body states.

Ariel Zylberberg, Stanislas Dehaene, Gabriel B. Mindlin, and Mariano Sigman. Neurophysiological bases of exponential sensory decay and top-down memory retrieval: a model. Frontiers in Computational Neuroscience, 3:1-16, 2009. [PDF] [bibtex-entry]

Stanislas Dehaene. La neuroéthique, une nouvelle frontière pour les sciences humaines.. laviedesidees.fr, 2009. [PDF] [bibtex-entry]

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