Numerical cognition Dehaene is best known for his work on
numerical cognition, a discipline which he popularized and synthesized with the publication of his 1997 book,
The Number Sense (
La Bosse des maths) which won the for best French language general-audience scientific book. He began his studies of numerical cognition with Jacques Mehler, examining the cross-linguistic frequency of number words, whether numbers were understood in an analog or compositional manner, and the connection between numbers and space (the "SNARC effect"). With Changeux, he then developed a computational model of numerical abilities, which predicted log-gaussian tuning functions for number neurons, a finding which has now been elegantly confirmed with single-unit physiology With long-time collaborator Laurent Cohen, a neurologist at the
Pitié-Salpêtrière Hospital in Paris, Dehaene also identified patients with lesions in different regions of the
parietal lobe with impaired multiplication, but preserved subtraction (associated with lesions of the
inferior parietal lobule) and others with impaired subtraction, but preserved multiplication (associated with lesions to the intraparietal sulcus). This
double dissociation suggested that different neural substrates for overlearned, linguistically mediated calculations, like multiplication, are mediated by inferior parietal regions, while on-line computations, like subtraction are mediated by the intraparietal sulcus. Shortly thereafter, Dehaene began
EEG and
functional neuroimaging studies of these capacities, showing that parietal and frontal regions were specifically involved in mathematical cognition, including the dissociation between subtraction and multiplication observed in his previous patient studies. Together with
Pierre Pica, and
Elizabeth Spelke, Stanislas Dehaene has studied the numeracy and numeral expressions of the
Mundurucu (an indigenous tribe living in Para,
Brazil).
Consciousness Dehaene subsequently turned his attention to work on the
neural correlates of consciousness, leading to numerous scientific articles, an edited book, "The Cognitive Neuroscience of
Consciousness" and is the Past President of the
Association for the Scientific Study of Consciousness. Dehaene, together with Jean-Pierre Changeux, has developed computational models of consciousness, based on
Bernard Baars's
Global Workspace Theory, which suggest that only one piece of information can gain access to a "global neuronal workspace". To explore the neural basis of this global neuronal workspace, he has conducted
functional neuroimaging experiments of masking and the
attentional blink, which show that information that reaches conscious awareness leads to increased activation in a network of
parietal and
frontal regions. However, some of his work on this subject has been called into question due to a methodological flaw in the "standard reasoning of unconscious priming".
Neural basis of reading In addition, Dehaene has used brain imaging to study language processing in monolingual and bilingual subjects, and in collaboration with Laurent Cohen, the neural basis of reading. Dehaene and Cohen initially focused on the role of
ventral stream regions in visual word recognition, and in particular the role of the
left inferior temporal cortex for reading written words. They identified a region they called the "visual word form area" (VWFA) that was consistently activated during reading, and also found that when this region was
surgically removed to treat patients with intractable
epilepsy, reading abilities were severely impaired. Dehaene, Cohen and colleagues have subsequently demonstrated that, rather than being a single area, the VWFA is the highest stage in a hierarchy of visual feature extraction for letter and word recognition. More recently, they have turned their attention to how learning to read may depend on a process of "
neuronal recycling" that causes brain circuits originally evolved for object recognition to become tuned to recognize frequent letters, pairs of letters and words, and have tested these ideas examining brain responses in a group of adults who did not learn to read due to social and cultural constraints. == Bibliography ==