@article{Xu2001, title = {Conjoint and extended neural networks for the computation of speech codes: the neural basis of selective impairment in reading words and pseudowords.}, author = {B. Xu and J. Grafman and W. D. Gaillard and K. Ishii and F. Vega-Bermudez and P. Pietrini and P. Reeves-Tyer and P. DiCamillo and W. Theodore}, journal = {Cerebral Cortex}, pages = {267--277}, volume = 11, year = 2001, pmid = {11230098}, abstract = {The computation of speech codes (i.e. phonology) is an important aspect of word reading. Understanding the neural systems and mech- anisms underlying phonological processes provides a foundation for the investigation of language in the brain. We used high-resolution three-dimensional positron emission tomography (PET) to investigate neural systems essential for phonological processes. The burden of neural activities on the computation of speech codes was maximized by three rhyming tasks (rhyming words, pseudowords and words printed in mixed letter cases). Brain activation patterns associated with these tasks were compared with those of two baseline tasks involving visual feature detection. Results suggest strong left lateralized epicenters of neural activity in rhyming irrespective of gender. Word rhyming activated the same brain regions engaged in pseudoword rhyming, suggesting conjoint neural networks for phonological processing of words and pseudowords. However, pseudoword rhyming induced the largest change in cerebral blood flow and activated more voxels in the left posterior prefrontal regions and the left inferior occipital-temporal junction. In addition, pseudoword rhyming activated the left supramarginal gyrus, which was not apparent in word rhyming. These results suggest that rhyming pseudowords requires active participation of extended neural systems and networks not observed for rhyming words. The implications of the results on theories and models of visual word reading and on selective reading dysfunctions after brain lesions are discussed.}, biburl = {http://www.bibsonomy.org/bibtex/2138a73ed0d25e0e92411b9889cf0cee7/perceptron}, keywords = {Time; Lobe; Net; U.S. Mapping; Adult; Photic Reaction Gov't, Emission-Computed Reading; Stimulation; Phonetics; Male; Cortex; Analysis Research Tomography, Cerebellum; Humans; of Brain Occipital P.H.S.; Temporal Female; Support, Prefrontal Variance; Nerve} } @article{Umilta2001, title = {I know what you are doing. a neurophysiological study.}, author = {M. A. Umilt\`{a} and E. Kohler and V. Gallese and L. Fogassi and L. Fadiga and C. Keysers and G. Rizzolatti}, journal = {Neuron}, number = 1, pages = {155--165}, volume = 31, year = 2001, timestamp = {2007.04.11}, pii = {S0896-6273(01)00337-3}, pmid = {11498058}, owner = {sara}, abstract = {In the ventral premotor cortex of the macaque monkey, there are neurons that discharge both during the execution of hand actions and during the observation of the same actions made by others (mirror neurons). In the present study, we show that a subset of mirror neurons becomes active during action presentation and also when the final part of the action, crucial in triggering the response in full vision, is hidden and can therefore only be inferred. This implies that the motor representation of an action performed by others can be internally generated in the observer's premotor cortex, even when a visual description of the action is lacking. The present findings support the hypothesis that mirror neuron activation could be at the basis of action recognition.}, biburl = {http://www.bibsonomy.org/bibtex/27907b03a0bddb6d675b0ab3dd4e8d668/perceptron}, keywords = {Male; Humans; Hand Animals; Somatosensory Models, Hand; Recognition Visual Habituation, Stimulation; Movement; Psychological; Macaca Electric Psychomotor nemestrina; Cortex; Psychophysiologic; Performance; Activity; Neurons; Neurological; Motor Strength; Perception Female; (Psychology);} } @article{Spiridon2002, title = {How distributed is visual category information in human occipito-temporal cortex? An fMRI study.}, author = {Mona Spiridon and Nancy Kanwisher}, journal = {Neuron}, pages = {1157--1165}, volume = 35, year = 2002, pii = {S0896627302008772}, pmid = {12354404}, abstract = {We used fMRI to study the distribution of object category information in the ventral visual pathway. Extending the findings of, we find that categories of stimuli can be distinguished by the pattern of activation they elicit across this entire pathway, even when the stimuli within a category differ in viewpoint, exemplar, or image format. However, regions within the ventral visual pathway are neither interchangeable nor equipotential. Although the FFA and PPA permit excellent discrimination between preferred versus nonpreferred stimuli (e.g., faces-bottles and houses-bottles, respectively), we find that neither region alone permits accurate discrimination between pairs of nonpreferred stimuli (e.g., bottles-shoes). These findings indicate that the ventral visual pathway is not homogeneous, but contains some regions (including FFA and PPA) that are primarily involved in the analysis of a single class of stimulus.}, biburl = {http://www.bibsonomy.org/bibtex/28dfaed046b5d1ff971a8f02e048294ff/perceptron}, keywords = {Nerve Imaging; Pathways Net; Visual Potentials, Neuropsychological Non-U.S. Gov't; Tests; Visual; Evoked Stimulation; Pattern Research Performance; U.S. Support, Humans; Photic Male; Lobe; Gov't, Recognition, Resonance Cortex; Psychomotor Temporal Female; P.H.S.; Magnetic} } @article{Paulesu2000, title = {A cultural effect on brain function.}, author = {E. Paulesu and E. McCrory and F. Fazio and L. Menoncello and N. Brunswick and S. F. Cappa and M. Cotelli and G. Cossu and F. Corte and M. Lorusso and S. Pesenti and A. Gallagher and D. Perani and C. Price and C. D. Frith and U. Frith}, journal = {Nature Neuroscience}, pages = {91--96}, volume = 3, year = 2000, url = {http://dx.doi.org/10.1038/71163}, pmid = {10607401}, doi = {10.1038/71163}, abstract = {We present behavioral and anatomical evidence for a multi-component reading system in which different components are differentially weighted depending on culture-specific demands of orthography. Italian orthography is consistent, enabling reliable conversion of graphemes to phonemes to yield correct pronunciation of the word. English orthography is inconsistent, complicating mapping of letters to word sounds. In behavioral studies, Italian students showed faster word and non-word reading than English students. In two PET studies, Italians showed greater activation in left superior temporal regions associated with phoneme processing. In contrast, English readers showed greater activations, particularly for non-words, in left posterior inferior temporal gyrus and anterior inferior frontal gyrus, areas associated with word retrieval during both reading and naming tasks.}, biburl = {http://www.bibsonomy.org/bibtex/2da374209ea85dff5191e9c776c22cd37/perceptron}, keywords = {Reading; Time; Tomography, Speech; Gov't; Non-U.S. Culture; Mapping; Stimulation; Humans; England; Support, Brain Temporal Linguistics; Photic Emission-Computed Reaction Italy; Research Adult; Frontal Lobe;} } @article{Op2001, title = {Inferotemporal neurons represent low-dimensional configurations of parameterized shapes}, author = {H. Op de Beeck and J. Wagemans and R. Vogels}, journal = {Nature Neuroscience}, number = 12, pages = {1244--1252}, volume = 4, year = 2001, url = {http://dx.doi.org/10.1038/nn767}, pii = {nn767}, pmid = {11713468}, doi = {10.1038/nn767}, abstract = {Behavioral studies with parameterized shapes have shown that the similarities among these complex stimuli can be represented using a low number of dimensions. Using psychophysical measurements and single-cell recordings in macaque inferotemporal (IT) cortex, we found an agreement between low-dimensional parametric configurations of shapes and the representation of shape similarity at the behavioral and neuronal level. The shape configurations, computed from both the perceived and neuron-based similarities, revealed a low number of dimensions and contained the same stimulus order as the parametric configurations. However, at a metric level, the behavioral and neural representations deviated consistently from the parametric configurations. These findings suggest an ordinally faithful but metrically biased representation of shape similarity in IT.}, biburl = {http://www.bibsonomy.org/bibtex/27c3c05fded3bef96e4039ef6fef6cd70/perceptron}, keywords = {Potentials; Visual Observer Stimulation; Learning; Pattern Macaca Visual; Perception; Performance; Variation; Space Neurons; Discrimination Photic Research Cortex; Non-U.S. Lobe; Psychomotor mulatta; Gov't; Action Pathways Humans; Temporal Support, Recognition, Animals;} } @article{Levy2001, title = {Center-periphery organization of human object areas.}, author = {I. Levy and U. Hasson and G. Avidan and T. Hendler and R. Malach}, journal = {Nature Neuroscience}, pages = {533--539}, volume = 4, year = 2001, url = {http://dx.doi.org/10.1038/87490}, pii = {87490}, pmid = {11319563}, doi = {10.1038/87490}, abstract = {The organizing principles that govern the layout of human object-related areas are largely unknown. Here we propose a new organizing principle in which object representations are arranged according to a central versus peripheral visual field bias. The proposal is based on the finding that building-related regions overlap periphery-biased visual field representations, whereas face-related regions are associated with center-biased representations. Furthermore, the eccentricity maps encompass essentially the entire extent of object-related occipito-temporal cortex, indicating that most object representations are organized with respect to retinal eccentricity. A control experiment ruled out the possibility that the results are due exclusively to unequal feature distribution in these images. We hypothesize that brain regions representing object categories that rely on detailed central scrutiny (such as faces) are more strongly associated with processing of central information, compared to representations of objects that may be recognized by more peripheral information (such as buildings or scenes).}, biburl = {http://www.bibsonomy.org/bibtex/2a7e22d7b575f51b5554e073144a670a2/perceptron}, keywords = {Gov't; Resonance Photic Retina; Research Algorithms; Perception Magnetic Stimulation; Brain Humans; Non-U.S. Middle Visual Cortex; Aged; Adult; Imaging; Male; Mapping; Fields; Female; Support,} } @article{Kronbichler2004, title = {The visual word form area and the frequency with which words are encountered: evidence from a parametric fMRI study.}, author = {Martin Kronbichler and Florian Hutzler and Heinz Wimmer and Alois Mair and Wolfgang Staffen and Gunther Ladurner}, journal = {Neuroimage}, pages = {946--953}, volume = 21, year = 2004, url = {http://dx.doi.org/10.1016/j.neuroimage.2003.10.021}, pii = {S1053811903006748}, pmid = {15006661}, doi = {10.1016/j.neuroimage.2003.10.021}, abstract = {Cohen and Dehaene et al. proposed that the Visual Word Form Area (VWFA) in the left midfusiform gyrus, contrary to its name, is limited to the extraction of an abstract letter string and not involved in proper visual word recognition. We examined this prelexical function of the VWFA by a parametric block design with five levels of written word frequency. The lowest level was represented by pseudowords and the highest level by words of very high frequency. Contrary to the assumed prelexical function of the VWFA, increasing frequency was associated with decreasing brain activation in a large posterior cluster of the left hemisphere including middle and posterior fusiform regions. The same negative relation between frequency and activation was found in several left frontal clusters. The relation of increasing frequency and decreasing activation in occipitotemporal regions corresponds to a similar relation in the same brain regions found by studies which experimentally manipulated object or face familiarity. This convergence suggests that fusiform regions are specialized for extracting and storing abstract patterns when processing visual objects and these patterns serve as recognition units in subsequent encounters with the same objects.}, biburl = {http://www.bibsonomy.org/bibtex/21bb7cdc61dab8e74bc3648d81083d41d/perceptron}, keywords = {Imaging; Female; Stimulation; Adult; Ocular; Processing, Photic Non-U.S. Interpretation, Image Computer-Assisted; Adolescent; Reading; Performance; Factual; Support, Male; Gov't Research Psychomotor Fixation, Humans; Resonance Magnetic Databases,} } @article{Kourtzi2000a, title = {Cortical regions involved in perceiving object shape.}, author = {Z. Kourtzi and N. Kanwisher}, journal = {Journal of Neuroscience}, number = 9, pages = {3310--3318}, volume = 20, year = 2000, url = {http://www.jneurosci.org/cgi/content/full/20/9/3310}, pmid = {10777794}, abstract = {The studies described here use functional magnetic resonance imaging to test whether common or distinct cognitive and/or neural mechanisms are involved in extracting object structure from the different image cues defining an object's shape, such as contours, shading, and monocular depth cues. We found overlapping activations in the lateral and ventral occipital cortex [known as the lateral occipital complex (LOC)] for objects defined by different visual cues (e.g., grayscale photographs and line drawings) when each was compared with its own scrambled-object control. In a second experiment we found a reduced response when objects were repeated, independent of whether they appeared in the same or a different format (i.e., grayscale images vs line drawings). A third experiment showed that activation in the LOC was no stronger for three-dimensional shapes defined by contours or monocular depth cues, such as occlusion, than for two-dimensional shapes, suggesting that these regions are not selectively involved in processing three-dimensional shape information. These results suggest that common regions in the LOC are involved in extracting and/or representing information about object structure from different image cues.}, biburl = {http://www.bibsonomy.org/bibtex/21e9a06fac2fd1b279f50d8605482bb50/perceptron}, keywords = {Photic Magnetic Mapping; Cues; Form Perception; Visual Cortex Stimulation; Humans; Brain Resonance Imaging;} } @article{Kiehl1999, title = {Neural pathways involved in the processing of concrete and abstract words.}, author = {K. A. Kiehl and P. F. Liddle and A. M. Smith and A. Mendrek and B. B. Forster and R. D. Hare}, journal = {Human Brain Mapping}, pages = {225--233}, volume = 7, year = 1999, pii = {3.0.CO;2-P}, pmid = {10408766}, abstract = {The purpose of this study was to delineate the neural pathways involved in processing concrete and abstract words using functional magnetic resonance imaging (fMRI). Word and pseudoword stimuli were presented visually, one at a time, and the participant was required to make a lexical decision. Lexical decision epochs alternated with a resting baseline. In each lexical decision epoch, the stimuli were either concrete words and pseudowords, or abstract words and pseudowords. Behavioral data indicated that, as with previous research, concrete word stimuli were processed more efficiently than abstract word stimuli. Analysis of the fMRI data indicated that processing of word stimuli, compared to the baseline condition, was associated with neural activation in the bilateral fusiform gyrus, anterior cingulate, left middle temporal gyrus, right posterior superior temporal gyrus, and left and right inferior frontal gyrus. A direct comparison between the abstract and concrete stimuli epochs yielded a significant area of activation in the right anterior temporal cortex. The results are consistent with recent positron emission tomography work showing right hemisphere activation during processing of abstract representations of language. The results are interpreted as support for a right hemisphere neural pathway in the processing of abstract word representations.}, biburl = {http://www.bibsonomy.org/bibtex/24cff6cb8aedf2b36daa97c871ab7c0e4/perceptron}, keywords = {Stimulation; Resonance Verbal Processes; Pathways; Neural Cerebral Support, Brain Magnetic Behavior; Humans; Gov't; Research Imaging; Learning Mental Cortex; Male; Mapping; Non-U.S. Adult; Photic} } @article{Gauthier2000, title = {The fusiform "face area" is part of a network that processes faces at the individual level.}, author = {I. Gauthier and M. J. Tarr and J. Moylan and P. Skudlarski and J. C. Gore and A. W. Anderson}, journal = {Journal Cognitive Neuroscience}, pages = {495--504}, volume = 12, year = 2000, pmid = {10931774}, abstract = {According to modular models of cortical organization, many areas of the extrastriate cortex are dedicated to object categories. These models often assume an early processing stage for the detection of category membership. Can functional imaging isolate areas responsible for detection of members of a category, such as faces or letters? We consider whether responses in three different areas (two selective for faces and one selective for letters) support category detection. Activity in these areas habituates to the repeated presentation of one exemplar more than to the presentation of different exemplars of the same category, but only for the category for which the area is selective. Thus, these areas appear to play computational roles more complex than detection, processing stimuli at the individual level. Drawing from prior work, we suggest that face-selective areas may be involved in the perception of faces at the individual level, whereas letter-selective regions may be tuning themselves to font information in order to recognize letters more efficiently.}, biburl = {http://www.bibsonomy.org/bibtex/2cd7f8681b80d31c7f40de4c5a515a2d3/perceptron}, keywords = {Recognition, Stimulation; Support, Gov't; Imaging; Face; Humans; Non-P.H.S.; Non-U.S. Photic Adult; Habituation Magnetic P.H.S.; U.S. Pattern Cortex Visual Visual; Resonance Gov't, Research (Psychophysiology);} } @article{Gauthier2000a, title = {Expertise for cars and birds recruits brain areas involved in face recognition.}, author = {I. Gauthier and P. Skudlarski and J. C. Gore and A. W. Anderson}, journal = {Nature Neuroscience}, number = 2, pages = {191--197}, volume = 3, year = 2000, url = {http://dx.doi.org/10.1038/72140}, pmid = {10649576}, doi = {10.1038/72140}, abstract = {Expertise with unfamiliar objects ('greebles') recruits face-selective areas in the fusiform gyrus (FFA) and occipital lobe (OFA). Here we extend this finding to other homogeneous categories. Bird and car experts were tested with functional magnetic resonance imaging during tasks with faces, familiar objects, cars and birds. Homogeneous categories activated the FFA more than familiar objects. Moreover, the right FFA and OFA showed significant expertise effects. An independent behavioral test of expertise predicted relative activation in the right FFA for birds versus cars within each group. The results suggest that level of categorization and expertise, rather than superficial properties of objects, determine the specialization of the FFA.}, biburl = {http://www.bibsonomy.org/bibtex/296451d59d696e85cae59c01ba702b37f/perceptron}, keywords = {U.S. Occipital Recognition, and Birds; Automobiles; Adult; Support, Humans; Visual; Male; Face; Competence; Temporal Research Gov't, Gov't; P.H.S.; Lobe; Non-U.S. Imaging; Brain Magnetic Task g Animals; Mappin; Data Resonance Professional Stimulation; Performance Display; Analysis; Pattern Photic} } @article{Gangitano2001, title = {Phase-specific modulation of cortical motor output during movement observation.}, author = {M. Gangitano and F. M. Mottaghy and A. Pascual-Leone}, journal = {Neuroreport}, number = 7, pages = {1489--1492}, volume = 12, year = 2001, timestamp = {2007.04.11}, pmid = {11388435}, owner = {sara}, abstract = {The effects of different phases of an observed movement on the modulation of cortical motor output were studied by means of transcranial magnetic stimulation (TMS). A video-clip of a reaching-grasping action was shown and single TMS pulses were delivered during its passive observation. Times of cortical stimulation were related to the phases of the shown movement, locking them to the appearance of specific kinematic landmarks. The amplitude of the motor evoked potentials (MEPs) induced by TMS in the first dorsal interosseus (FDI) muscle was modulated by the amount of the observed finger aperture. The presence of such an effect is consistent with the notion of a mirror neuron system in premotor areas that couples action execution and action observation also in terms of temporal coding.}, biburl = {http://www.bibsonomy.org/bibtex/22b75e0a007d82f2479babdf2a16172cd/perceptron}, keywords = {Photic Neurons; Performance Neuropsychological Humans; Adult; Arm; Hand Motor Cortex; Electric Psychomotor Tests; Stimulation; Acoustic Strength; Evoked Magnetics; Motor; Potentials, Movement;} } @article{Cohen2002, title = {Language-specific tuning of visual cortex? Functional properties of the Visual Word Form Area.}, author = {Laurent Cohen and St�phane Leh�ricy and Florence Chochon and Cathy Lemer and Sophie Rivaud and Stanislas Dehaene}, journal = {Brain}, pages = {1054--1069}, volume = 125, year = 2002, url = {http://brain.oxfordjournals.org/cgi/reprint/125/5/1054}, pmid = {11960895}, abstract = {The first steps in the process of reading a printed word belong to the domain of visual object perception. They culminate in a representation of letter strings as an ordered set of abstract letter identities, a representation known as the Visual Word Form (VWF). Brain lesions in patients with pure alexia and functional imaging data suggest that the VWF is subtended by a restricted patch of left-hemispheric fusiform cortex, which is reproducibly activated during reading. In order to determine whether the operation of this Visual Word Form Area (VWFA) depends exclusively on the visual features of stimuli, or is influenced by language-dependent parameters, brain activations induced by words, consonant strings and chequerboards were compared in normal subjects using functional MRI (fMRI). Stimuli were presented in the left or right visual hemifield. The VWFA was identified in both a blocked-design experiment and an event-related experiment as a left-hemispheric inferotemporal area showing a stronger activation to alphabetic strings than to chequerboards, and invariant for the spatial location of stimuli. In both experiments, stronger activations of the VWFA to words than to strings of consonants were observed. Considering that the VWFA is equally activated by real words and by readable pseudowords, this result demonstrates that the VWFA is initially plastic and becomes attuned to the orthographic regularities that constrain letter combination during the acquisition of literacy. Additionally, the use of split-field stimulation shed some light on the cerebral bases of the classical right visual field (RVF) advantage in reading. A left occipital extrastriate area was found to be activated by RVF letter strings more than by chequerboards, while no symmetrical region was observed in the right hemisphere. Moreover, activations in the precuneus and the left thalamus were observed when subjects were reading RVF versus left visual field (LVF) words, and are likely to reflect the attentional component of the RVF advantage.}, biburl = {http://www.bibsonomy.org/bibtex/2c4765fe128c4ca7d54e339f0efa02043/perceptron}, keywords = {Recognition, Gov't; Perception Visual Male; Language; Stimulation; Magnetic Pattern Reading; Evoked Imaging; Cortex; Support, Nonparametric; Resonance Photic Female; Comparative Adult; Research Statistics, Potentials; Humans; Study; Non-U.S. Visual;} } @article{Brewer2005, title = {Visual field maps and stimulus selectivity in human ventral occipital cortex.}, author = {Alyssa A Brewer and Junjie Liu and Alex R Wade and Brian A Wandell}, journal = {Nature Neuroscience}, number = 8, pages = {1102--1109}, volume = 8, year = 2005, url = {http://dx.doi.org/10.1038/nn1507}, pii = {nn1507}, pmid = {16025108}, doi = {10.1038/nn1507}, abstract = {Human visual cortex is organized into distinct visual field maps whose locations and properties provide important information about visual computations. There are two conflicting models of the organization and computational role of ventral occipital visual field maps. We report new functional MRI measurements that test these models. We also present the first coordinated measurements of visual field maps and stimulus responsivity to color, objects and faces in ventral occipital cortex. These measurements support a model that includes a hemifield map, hV4, adjacent to the central field representation of ventral V3. In addition, the measurements demonstrate a cluster of visual field maps in ventral occipital cortex (VO cluster) anterior to hV4. We describe the organization and stimulus responsivity of two new hemifield maps, VO-1 and VO-2, within this cluster. The maps and stimulus responsivity support a general organization of visual cortex based on clusters of maps that serve distinct computational functions.}, biburl = {http://www.bibsonomy.org/bibtex/27edfcd550f50d8475a3ad55a7cc72689/perceptron}, keywords = {Occipital Stimulation; Humans; Lobe; Neurological; Fields Models, Photic Perimetry; Visual} }