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Biomedical subjects

Mark H Johnson

Publications and source records attributed to Mark H Johnson.

At least 19 recordsLinked to original sources
PubMed2007

Neuroconstructivism.

Neuroconstructivism is a theoretical framework focusing on the construction of representations in the developing brain. Cognitive development is explained as emerging from the experience-dependent development of neural structures supporting mental representations. Neural development occurs in the context of multiple interacting constraints acting on different levels, from the individual cell to the external environment of the developing child. Cognitive development can thus be understood as a trajectory originating from the constraints on the underlying neural structures. This perspective offers an integrated view of normal and abnormal development as well as of development and adult processing, and it stands apart from traditional cognitive approaches in taking seriously the constraints on cognition inherent to the substrate that delivers it.

Adult↗
PubMed2007

Developing a social brain.

UNLABELLED: A new account of human postnatal functional brain development, interactive specialization (IS), is introduced and applied to one important domain of human development: the social brain. Behavioural, ERP and fMRI evidence from newborns, infants and children in face processing tasks is briefly reviewed, and is shown to be consistent with predictions from the IS account. CONCLUSION: It is suggested that this new view of functional brain development can also be applied to other domains of typical and atypical human development.

Adult↗
PubMed2006

Neural correlates of the perception of goal-directed action in infants.

We investigated the neural correlates of the perception of human goal-directed action by 8-month-old infants. Infants viewed video loops of complete and incomplete actions, which they could discriminate according to our pilot study, while we recorded their electrophysiological brain activity. Analysis of bursts of gamma-band oscillations resulting from passive viewing of these stimuli indicated increased gamma-band activity over left frontal regions when viewing incomplete actions as compared with complete actions. These results suggest that by 8 months infants are sensitive to the disruption of perceived goal-directed actions.

Analysis of Variance↗
PubMed2006

Factors influencing newborns' preference for faces with eye contact.

We investigated newborns' sensitivity to the direction of gaze of another's face by using a preferential looking technique. This study extends earlier work on a preference for faces with direct gaze in newborns. In Experiment 1, we replicate the basic finding of Farroni and colleagues that newborns prefer to look at faces with direct gaze. In Experiments 2 and 3, we establish that a preference for faces with direct gaze in newborns is present only within the context of an upright face and a straight head, suggesting that relatively primitive configuration-sensitive mechanisms may be operating. Overall, these results further the view that relatively simple perceptual biases in newborns may be an essential foundation for later social-cognitive development.

Choice Behavior↗
PubMed2006

Biological motion: a perceptual life detector?

Detecting the direction of motion of other animals is critical for a variety of adaptive behaviours, including filial attachment and hunting prey. Two new studies support the view that some vertebrates, including humans, have primitive brain systems for the visual detection of other legged vertebrates.

Animals↗
PubMed2006

Frames of reference for anticipatory action in 4-month-old infants.

The spatial representations of 4-month-old infants were examined in two experiments using a modified version of the visual expectation paradigm (VExP). The experiments were designed in order to determine what spatial frames of reference were available to infants for making anticipatory saccades. In Experiment 1, we found that infants most often used a retinocentric frame of reference that did not take into account their current eye position in making an anticipatory saccade. However, Experiment 2 revealed that under certain conditions infants are more likely to make anticipatory saccades consistent with a body- or object-centred frame of reference. The main difference between the two experiments was the degree to which the featural properties of the stimuli varied. The results shed light on the development of spatial representations for action in infancy.

Female↗
PubMed2006

Direct gaze modulates face recognition in young infants.

From birth, infants prefer to look at faces that engage them in direct eye contact. In adults, direct gaze is known to modulate the processing of faces, including the recognition of individuals. In the present study, we investigate whether direction of gaze has any effect on face recognition in four-month-old infants. Four-month infants were shown faces with both direct and averted gaze, and subsequently given a preference test involving the same face and a novel one. A novelty preference during test was only found following initial exposure to a face with direct gaze. Further, face recognition was also generally enhanced for faces with both direct and with averted gaze when the infants started the task with the direct gaze condition. Together, these results indicate that the direction of the gaze modulates face recognition in early infancy.

Analysis of Variance↗
PubMed2006

Common-onset visual masking in infancy: behavioral and electrophysiological evidence.

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.

Attention↗
PubMed2005

Newborns' preference for face-relevant stimuli: effects of contrast polarity.

There is currently no agreement as to how specific or general are the mechanisms underlying newborns' face preferences. We address this issue by manipulating the contrast polarity of schematic and naturalistic face-related images and assessing the preferences of newborns. We find that for both schematic and naturalistic face images, the contrast polarity is important. Newborns did not show a preference for an upright face-related image unless it was composed of darker areas around the eyes and mouth. This result is consistent with either sensitivity to the shadowed areas of a face with overhead (natural) illumination and/or to the detection of eye contact.

Bias↗
PubMed2005

Oscillatory activity in the infant brain reflects object maintenance.

The apparent failure of infants to understand "object permanence" by reaching for hidden objects is perhaps the most striking and debated phenomenon in cognitive development. Of particular interest is the extent to which infants perceive and remember objects in a similar way to that of adults. Here we report two findings that clarify infant object processing. The first is that 6-mo-old infants are sensitive to visual cues to occlusion, particularly gradual deletion. The second finding is that oscillatory electroencephalogram activity recorded over right temporal channels is involved in object maintenance. This effect occurs only after disappearance in a manner consistent with occlusion and the object's continued existence.

Adult↗
PubMed2005

Processes of change in brain and cognitive development.

We review recent advances in the understanding of the mechanisms of change that underlie cognitive development. We begin by describing error-driven, self-organizing and constructivist learning systems. These powerful mechanisms can be constrained by intrinsic factors, other brain systems and/or the physical and social environment of the developing child. The results of constrained learning are representations that themselves are transformed during development. One type of transformation involves the increasing specialization and localization of representations, resulting in a neurocognitive system with more dissociated streams of processing with complementary computational functions. In human development, integration between such streams of processing might occur through the mediation of language.

Adolescent↗
PubMed2005

Neural correlates of eye-gaze detection in young children with autism.

Various reports have demonstrated difficulties in eye-gaze processing in older children and adults with autism. However, little is known about the neural or developmental origin of such difficulties. In the present study, we used high-density Event-Related Potentials (HD-ERPs) to record the neural correlates of gaze processing in young children with autism, and their age-matched controls. In addition, to determine normal gaze processing development we also tested a non-autism adult group. The data obtained from the children with autism resembled that previously observed in typical 4-month old infants. In contrast, the control group showed the same pattern as typical adults. These findings suggest that the neural correlates of gaze direction processing may be delayed in young children with autism.

Adult↗
PubMed2005

The emergence of the social brain network: evidence from typical and atypical development.

Several research groups have identified a network of regions of the adult cortex that are activated during social perception and cognition tasks. In this paper we focus on the development of components of this social brain network during early childhood and test aspects of a particular viewpoint on human functional brain development: "interactive specialization." Specifically, we apply new data analysis techniques to a previously published data set of event-related potential (ERP) studies involving 3-, 4-, and 12-month-old infants viewing faces of different orientation and direction of eye gaze. Using source separation and localization methods, several likely generators of scalp recorded ERP are identified, and we describe how they are modulated by stimulus characteristics. We then review the results of a series of experiments concerned with perceiving and acting on eye gaze, before reporting on a new experiment involving young children with autism. Finally, we discuss predictions based on the atypical emergence of the social brain network.

Adult↗