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Mark H. Johnson
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Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2011) 23 (9): 2521–2532.
Published: 01 September 2011
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How specialized is the infant brain for perceiving the facial and manual movements displayed by others? Although there is evidence for a network of regions that process biological motion in adults—including individuated responses to the perception of differing facial and manual movements—how this cortical specialization develops remains unknown. We used functional near-infrared spectroscopy [Lloyd-Fox, S., Blasi, A., & Elwell, C. Illuminating the developing brain: The past, present and future of functional near-infrared spectroscopy. Neuroscience and Biobehavioral Reviews, 34, 269–284, 2010] to investigate the ability of 5-month-old infants to process differing biological movements. Infants watched videos of adult actors moving their hands, their mouth, or their eyes, all in contrast to nonbiological mechanical movements, while hemodynamic responses were recorded over the their frontal and temporal cortices. We observed different regions of the frontal and temporal cortex that responded to these biological movements and different patterns of cortical activation according to the type of movement watched. From an early age, our brains selectively respond to biologically relevant movements, and further, selective patterns of regional specification to different cues occur within what may correspond to a developing “social brain” network. These findings illuminate hitherto undocumented maps of selective cortical activation to biological motion processing in the early postnatal development of the human brain.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2010) 22 (5): 903–917.
Published: 01 May 2010
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Face processing in the human brain recruits a widespread cortical network based mainly in the ventral and lateral temporal and occipital lobes. However, the extent to which activity within this network is driven by different face properties versus being determined by the manner in which faces are processed (as determined by task requirements) remains unclear. We combined a functional magnetic resonance adaptation paradigm with three target detection tasks, where participants had to detect a specific identity, emotional expression, or direction of gaze, while the task-irrelevant face properties varied independently. Our analysis focused on differentiating the influence of task demands and the processing of stimulus changes within the neural network underlying face processing. Results indicated that the fusiform and inferior occipital gyrus do not respond as a function of stimulus change (such as identity), but rather their activity depends on the task demands. Specifically, we hypothesize that, whether the task encourages a configural- or a featural-processing strategy determines activation. Our results for the superior temporal sulcus were even more specific in that we only found greater responses to stimulus changes that may engage featural processing. These results contribute to our understanding of the functional anatomy of face processing and provide insights into possible compensatory mechanisms in face processing.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2009) 21 (12): 2276–2286.
Published: 01 December 2009
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We measured looking times and ERPs to examine the cognitive and brain bases of perceptual category learning in 6-month-old infants. In Experiment 1, we showed that categorization and exemplar discrimination rely on different cortical processes. Specifically, the repetition of individual exemplars resulted in differential cortical processing at posterior channels at an early stage during object processing (100–300 msec), whereas discriminating among members of different categories was reflected in ERP differences over anterior cortical regions occurring later in time (300–500 msec) than the repetition effects. In Experiment 2, replicating the findings of Study 1, we found that infants engage the same cortical processes to categorize visual objects into basic-level categories, regardless of whether a basic (bird vs. fish) or global level is crossed (birds vs. cars). This pattern of findings is consistent with perceptual accounts of infant categorization [Quinn, P. C., & Eimas, P. D. Perceptual organization and categorization in young infants. In C. Rovee-Collier & L. P. Lipsitt (Eds.), Advances in infancy research ( pp. 1–36). Norwood, NJ: Ablex, 1996] and accords with recent adult neural-level models of perceptual categorization.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2008) 20 (11): 2070–2087.
Published: 01 November 2008
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This set of three experiments assessed the influence of different psychophysical factors on the lateralization of the N170 event-related potential (ERP) component to words and faces. In all experiments, words elicited a left-lateralized N170, whereas faces elicited a right-lateralized or nonlateralized N170 depending on presentation conditions. Experiment 1 showed that lateralization for words (but not for faces) was influenced by spatial frequency. Experiment 2 showed that stimulus presentation time influenced N170 lateralization independently of spatial frequency composition. Finally, Experiment 3 showed that stimulus size and resolution did not influence N170 lateralization, but did influence N170 amplitude, albeit differentially for words and faces. These findings suggest that differential lateralization for words and faces, at least as measured by the N170, is influenced by spatial frequency (words), stimulus presentation time, and category.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2008) 20 (4): 741–749.
Published: 01 April 2008
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Previous work has shown that gamma-band electroencephalogram oscillations recorded over the posterior cortex of infants play a role in maintaining object representations during occlusion. Although it is not yet known what kind of representations are reflected in these oscillations, behavioral data suggest that young infants maintain spatiotemporal (but not featural) information during the occlusion of graspable objects, and surface feature (but not spatiotemporal) information during the occlusion of faces. To further explore this question, we presented infants with an occlusion paradigm in which they would, on half of the trials, see surface feature violations of either a face or an object. Based on previous studies, we predicted higher gamma-band activation when infants were presented with a surface feature violation of a face, but not of an object. These results were confirmed. A further analysis revealed that whereas infants exhibited a significant increase in gamma during the occlusion of an object (as reported in previous studies), no such increase was evident during the occlusion of a face. These data suggest markedly different processing of objects and faces in the infant brain and, furthermore, indicate that the representation underpinned by the posterior gamma increase may contain only spatiotemporal information.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2006) 18 (6): 966–973.
Published: 01 June 2006
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Common-onset visual masking (COVM) occurs when a mask and a target have common onset but delayed offset, with the mask persisting beyond the duration of the target [Di Lollo, V., Enns, J. T., & Rensink, R. A. Competition for consciousness among visual events: The psychophysics of reentrant visual events. Journal of Experimental Psychology: General, 129, 481–507, 2000]. We report the first behavioral and electrophysiological evidence of COVM in infants. An initial behavioral study included a familiarization phase during which a visual pattern (the target) surrounded by four black dots (the mask) was flashed 15 times to the infant. In the “unmasked” condition, the mask disappeared with the target. In the “masked” condition, the mask remained on the screen after deletion of the target for a further 93 msec. During the test phase, the familiar target pattern was paired with a new pattern. Infants in the unmasked condition showed a significant familiarity preference, suggesting that they had encoded the target during familiarization, whereas those in the masked condition showed no preference, suggesting that they had not encoded the target during familiarization. In the second experiment, high-density event-related potentials were used to investigate the electrophysiological pattern of activity that accompanies COVM. Six-month-old infants viewed both masked and unmasked conditions. Electrophysiological data indicated that over posterior channels the masked condition elicited a larger amplitude positive wave around 300 msec after stimulus onset than trials in the unmasked condition.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2004) 16 (8): 1320–1326.
Published: 01 October 2004
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Previous work has shown that infants are sensitive to the direction of gaze of another's face, and that gaze direction can cue attention. The present study replicates and extends results on the ERP correlates of gaze processing in 4-month-olds. In two experiments, we recorded ERPs while 4-month-olds viewed direct and averted gaze within the context of averted and inverted heads. Our results support the previous finding that cortical processing of faces in infants is enhanced when accompanied by direct gaze. However, this effect is only found when eyes are presented within the context of an upright face.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (2002) 14 (2): 199–209.
Published: 15 February 2002
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Newborn infants respond preferentially to simple face-like patterns, raising the possibility that the face-specific regions identified in the adult cortex are functioning from birth. We sought to evaluate this hypothesis by characterizing the specificity of infants' electrocortical responses to faces in two ways: (1) comparing responses to faces of humans with those to faces of nonhuman primates; and 2) comparing responses to upright and inverted faces. Adults' face-responsive N170 event-related potential (ERP) component showed specificity to upright human faces that was not observable at any point in the ERPs of infants. A putative “infant N170” did show sensitivity to the species of the face, but the orientation of the face did not influence processing until a later stage. These findings suggest a process of gradual specialization of cortical face processing systems during postnatal development.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (1991) 3 (4): 335–344.
Published: 01 October 1991
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Three aspects of the development of visual orienting in infants of 2, 3, and 4 months of age are examined in this paper. These are the age of onset and sequence of development of (1) the ability to readily disengage gaze from a stimulus, (2) the ability to consistently show “anticipatory” eye movements, and (3) the ability to use a central cue to predict the spatial location of a target. Results indicated that only the 4--month-old group was easily able to disengage from an attractive central stimulus to orient toward a simultaneously presented target. The 4--month-old group also showed more than double the percentage of “anticipatory” looks than did the other age groups. Finally, only the 4--month-old group showed significant evidence of being able to acquire the contingent relationship between a central cue and the spatial location (to the right or to the left) of a target. Measures of anticipatory looking and contingency learning were not correlated. These findings are, in general terms, consistent with the predictions of matura-tional accounts of the development of visual orienting.
Journal Articles
Publisher: Journals Gateway
Journal of Cognitive Neuroscience (1990) 2 (2): 81–95.
Published: 01 April 1990
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Bronson (1974) reviewed evidence in support of the claim that the development of visually guided behavior in the human infant over the first few months of life represents a shift from subcortical to cortical visual processing. Recently, this view has been brought into question for two reasons; first, evidence revealing apparently sophisticated perceptual abilities in the newborn, and second, increasing evidence for multiple cortica streams of visual processing. The present paper presents a reanalysis of the relation between the maturation of cortical pathways and the development of visually guided behavior, focusing in particular on how the maturational state of the primary visual cortex may constrain the functioning of neural pathways subserving oculomotor control.