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At least 1,171 records · Page 65Linked to original sources
PubMed2000

A hierarchical neural system with attentional top-down enhancement of the spatial resolution for object recognition.

We present a hierarchical neurodynamical system for object recognition based on attentional control of the spatial resolution with which an object is analyzed during an iterative hypothesis testing cycle. Psychophysical evidence strongly suggests that attentional processing results in the enhancement of the spatial resolution in the input region corresponding to the focus of attention. We adopt a computational neuroscience approach in order to analyze this attentional enhancement of the spatial resolution for object recognition. The system consists of a where- and a what-module which include networks with feedforward and feedback interconnections describing the mutual links between different areas of the visual cortex.

Attention↗
PubMed1999

Brain activity differentiates face and object processing in 6-month-old infants.

Event-related potentials were used to determine whether infants, like adults, show differences in spatial and temporal characteristics of brain activation during face and object recognition. Three aspects of visual processing were identified: (a) differentiation of face vs. object (P400 at occipital electrode was shorter latency for faces), (b) recognition of familiar identity (Nc, or negative component, at fronto-temporal electrodes [FTEs] was of larger amplitude for familiar stimuli), and (c) encoding novelty (slow wave at FTEs was larger for unfamiliar stimuli). The topography of the Nc was influenced by category type: Effects of familiarity were limited to the midline and right anterior temporal electrodes for faces but extended to all temporal electrodes for objects. Results show that infants' experience with specific examples within categories and their general category knowledge influence the neural correlates of visual processing.

Adult↗
PubMed1999

Visual expertise.

Explore the source record for details and available documents.

Clinical Competence↗
PubMed2005

Impaired face discrimination in acquired prosopagnosia is associated with abnormal response to individual faces in the right middle fusiform gyrus.

The middle fusiform gyrus (MFG) and the inferior occipital gyrus (IOG) are activated by both detection and identification of faces. Paradoxically, patients with acquired prosopagnosia following lesions to either of these regions in the right hemisphere cannot identify faces, but can still detect faces. Here we acquired functional magnetic resonance imaging (fMRI) data during face processing in a patient presenting a specific deficit in individual face recognition, following lesions encompassing the right IOG. Using an adaptation paradigm we show that the fMRI signal in the rMFG of the patient, while being larger in response to faces as compared to objects, does not differ between conditions presenting identical and distinct faces, in contrast to the larger response to distinct faces observed in controls. These results suggest that individual discrimination of faces critically depends on the integrity of both the rMFG and the rIOG, which may interact through re-entrant cortical connections in the normal brain.

Discrimination Learning↗
PubMed2003

Age-related differences in neural correlates of face recognition during the toddler and preschool years.

Research on the development of face recognition in infancy has shown that infants respond to faces as if they are special and recognize familiar faces early in development. Infants also show recognition and differential attachment to familiar people very early in development. We tested the hypothesis that infants' responses to familiar and unfamiliar faces differ at different ages. Specifically, we present data showing age-related changes in infants' brain responses to mother's face versus a stranger's face in children between 18 and 54 months of age. We propose that these changes are based on age-related differences in the perceived salience of the face of the primary caregiver versus strangers.

Arousal↗
PubMed1988

Neuronal correlate of visual associative long-term memory in the primate temporal cortex.

In human long-term memory, ideas and concepts become associated in the learning process. No neuronal correlate for this cognitive function has so far been described, except that memory traces are thought to be localized in the cerebral cortex; the temporal lobe has been assigned as the site for visual experience because electric stimulation of this area results in imagery recall and lesions produce deficits in visual recognition of objects. We previously reported that in the anterior ventral temporal cortex of monkeys, individual neurons have a sustained activity that is highly selective for a few of the 100 coloured fractal patterns used in a visual working-memory task. Here I report the development of this selectivity through repeated trials involving the working memory. The few patterns for which a neuron was conjointly selective were frequently related to each other through stimulus-stimulus association imposed during training. The results indicate that the selectivity acquired by these cells represents a neuronal correlate of the associative long-term memory of pictures.

Animals↗