Cortical Activity Related to Accuracy of Letter Recognition

University of California at Davis, Davis, California 95616, USA.
NeuroImage (Impact Factor: 6.36). 03/2000; 11(2):111-23. DOI: 10.1006/nimg.1999.0528
Source: PubMed


Previous imaging and neurophysiological studies have suggested that the posterior inferior temporal region participates in tasks requiring the recognition of objects, including faces, words, and letters; however, the relationship between accuracy of recognition and activity in that region has not been systematically investigated. In this study, positron emission tomography was used to estimate glucose metabolism in 60 normal adults performing a computer-generated letter-recognition task. Both a region of interest and a voxel-based method of analysis, with subject state and trait variables statistically controlled, found task accuracy to be: (1) negatively related to metabolism in the left ventrolateral inferior temporal occipital cortex (Brodmann's area 37, or ventrolateral BA 37) and (2) positively related to metabolism in a region of the right ventrolateral frontal cortex (Brodmann's areas 47 and 11, or right BA 47/11). Left ventrolateral BA 37 was significantly related both to hits and to false alarms, whereas the right BA 47/11 finding was related only to false alarms. The results were taken as supporting an automaticity mechanism for left ventrolateral BA 37, whereby task accuracy was associated with automatic letter recognition and in turn to reduced metabolism in this extrastriate area. The right BA 47/11 finding was interpreted as reflecting a separate component of task accuracy, associated with selectivity of attention broadly and with inhibition of erroneous responding in particular. The findings are interpreted as supporting the need for control of variance due to subject and task variables, not only in correlational but also in subtraction designs.

Download full-text


Available from: Amy S Garrett,
82 Reads
  • Source
    • "The first, a regionof-interest analysis, provided an in-depth look at processing in the fusiform gyrus. This neural region is known to be engaged in letter processing in the literate individual [20] [24] [34] and it was affected by children's letter printing experience in James [31]. The second analysis probed whole brain functioning to see how the different training conditions engaged other regions of the brain. "
    [Show abstract] [Hide abstract]
    ABSTRACT: In an age of increasing technology, the possibility that typing on a keyboard will replace handwriting raises questions about the future usefulness of handwriting skills. Here we present evidence that brain activation during letter perception is influenced in different, important ways by previous handwriting of letters versus previous typing or tracing of those same letters. Preliterate, five-year old children printed, typed, or traced letters and shapes, then were shown images of these stimuli while undergoing functional MRI scanning. A previously documented ‘‘reading circuit’’ was recruited during letter perception only after handwriting—not after typing or tracing experience. These findings demonstrate that handwriting is important for the early recruitment in letter processing of brain regions known to underlie successful reading. Handwriting therefore may facilitate reading acquisition in young children.
    Trends in Neuroscience and Education 08/2012; 1(1):32-42. DOI:10.1016/j.tine.2012.08.001
  • Source
    • "According to Freyd [1987], such findings implicate that the underlying dynamic representations are formed during viewing of static handwritten traces. Most of the studies dealing with letter perception have focused on the potential selectivity of the posterior cortical regions [the equivalent of the visual word form area for single letters: Flowers et al., 2004; Garrett et al., 2000; Gauthier et al., 2000; Gros et al., 2001; James et al., 2005; Pernet et al., 2005; Polk and Farah, 1998; Polk et al., 2002; Wong et al., 2009]. However, the investigation of wholebrain activations has established that visual perception of static single letters relies, not only on extrastriate brain areas, but also on cortical motor areas [James and Gauthier , 2006; Longcamp et al., 2003, 2006]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: In models of letter recognition, handwritten letters are considered as a particular font exemplar, not qualitatively different in their processing from printed letters. Yet, some data suggest that recognizing handwritten letters might rely on distinct processes, possibly related to motor knowledge. We applied functional magnetic resonance imaging to compare the neural correlates of perceiving handwritten letters vs. standard printed letters. Statistical analysis circumscribed to frontal brain regions involved in hand-movement triggering and execution showed that processing of handwritten letters is supported by a stronger activation of the left primary motor cortex and the supplementary motor area. At the whole-brain level, additional differences between handwritten and printed letters were observed in the right superior frontal, middle occipital, and parahippocampal gyri, and in the left inferior precentral and the fusiform gyri. The results are suggested to indicate embodiment of the visual perception of handwritten letters.
    Human Brain Mapping 08/2011; 32(8):1250-9. DOI:10.1002/hbm.21105 · 5.97 Impact Factor
  • Source
    • "The effects for false font symbols corresponded to previous findings for written words [48] and letter and symbols [49], [51] that are contrasted against baseline activity. However, our obtained activation pattern did not include the anterior left fusiform gyrus which is proposed to mediate sublexical properties of letters and words [52], [53] and is influenced by word frequency [54] and related to task accuracy [55]. Our results suggest that the increased activity for the false font symbols was largely caused by familiarity effects: although matched in visual complexity, the control graphemes were more frequent in written language. "
    [Show abstract] [Hide abstract]
    ABSTRACT: In synaesthesia, sensations in a particular modality cause additional experiences in a second, unstimulated modality (e.g., letters elicit colour). Understanding how synaesthesia is mediated in the brain can help to understand normal processes of perceptual awareness and multisensory integration. In several neuroimaging studies, enhanced brain activity for grapheme-colour synaesthesia has been found in ventral-occipital areas that are also involved in real colour processing. Our question was whether the neural correlates of synaesthetically induced colour and real colour experience are truly shared. First, in a free viewing functional magnetic resonance imaging (fMRI) experiment, we located main effects of synaesthesia in left superior parietal lobule and in colour related areas. In the left superior parietal lobe, individual differences between synaesthetes (projector-associator distinction) also influenced brain activity, confirming the importance of the left superior parietal lobe for synaesthesia. Next, we applied a repetition suppression paradigm in fMRI, in which a decrease in the BOLD (blood-oxygenated-level-dependent) response is generally observed for repeated stimuli. We hypothesized that synaesthetically induced colours would lead to a reduction in BOLD response for subsequently presented real colours, if the neural correlates were overlapping. We did find BOLD suppression effects induced by synaesthesia, but not within the colour areas. Because synaesthetically induced colours were not able to suppress BOLD effects for real colour, we conclude that the neural correlates of synaesthetic colour experience and real colour experience are not fully shared. We propose that synaesthetic colour experiences are mediated by higher-order visual pathways that lie beyond the scope of classical, ventral-occipital visual areas. Feedback from these areas, in which the left parietal cortex is likely to play an important role, may induce V4 activation and the percept of synaesthetic colour.
    PLoS ONE 08/2010; 5(8):e12074. DOI:10.1371/journal.pone.0012074 · 3.23 Impact Factor
Show more