Exogenous orienting of visual-spatial attention in ADHD children.

Visual spatial orienting of attention towards exogenous cues has been one of the attentional functions considered to be spared in ADHD. Here we present a design in which 60 (30 ADHD) children, age: 10.9±1.

Viewing loved faces inhibits defense reactions: a health-promotion mechanism?

We have known for decades that social support is associated with positive health outcomes. And yet, the neurophysiological mechanisms underlying this association remain poorly understood. The link between social support and positive health outcomes is likely to depend on the neurophysiological regulatory mechanisms underlying reward and defensive reactions.

Modulation of the outcome-related negativity associated with nicotine abstinence.

Cue-reactivity studies have shown that when consumers are exposed to a substance-related stimulus, potential tobacco use contributes significantly to craving and motivational drive. Although the motivational response to cues signaling tobacco availability has been widely studied, less is known about physiological reactivity to perceived cigarette availability. The aim of the present study was to examine the outcome-related negativity (ORN) evoked by stimuli that signal potential tobacco use in abstinent and sated smokers.

Filial versus romantic love: contributions from peripheral and central electrophysiology.

A major problem in recent neuroscience research on the processing of loved familiar faces is the absence of evidence concerning the elicitation of a genuine positive emotional response (love). These studies have two confounds: familiarity and arousal. The present investigation controlled for both factors in female university students.

Affective processing of loved familiar faces: integrating central and peripheral electrophysiological measures.

A major problem in the electrophysiological studies of emotional processing linked to recognition of familiar faces is the unambiguous differentiation of effects due to emotional valence, arousal, and familiarity. The present paper summarizes a set of three studies aimed at investigating the affective processing of loved familiar faces using Lang's picture-viewing paradigm, with a special emphasis on teasing apart the individual contributions of affective valence, undifferentiated emotional arousal, and familiarity The results of the three studies support the conclusion that viewing the faces of familiar loved ones elicits an intense positive emotional reaction that cannot be explained either by familiarity or arousal alone.

Affective processing of loved faces: contributions from peripheral and central electrophysiology.

Research on the neural mechanisms of face identity constitutes a fruitful method to explore the affective contributions to face processing. Here, we investigated central and peripheral electrophysiological indices associated with the perception of loved faces. Subjects viewed black-and-white photographs of faces that belonged to one of five categories: loved ones, famous people, unknown people, babies, and neutral faces from the Eckman and Friesen system.

The dynamics of cardiac defense: from attention to action.

The attentional and motivational significance of cardiac defense is examined in two studies. In Study 1, cardiac defense was evoked by an intense acoustic stimulus in the context of either a visual search or a memory search task using letters as stimuli. Results showed a potentiation of the long latency acceleration of cardiac defense in the visual search task.

Processing of semantic relations in normal aging and Alzheimer's disease.

The decline in semantic memory observed in Alzheimer's disease is presumed to result from progressive loss of the attributes underlying category representation. Here, we explored the possibility that semantic deterioration would affect attributes differently, depending on the type of semantic relationship connecting the subject and the object of the attribution. We compared the performance of 50 patients with probable Alzheimer's disease (APs) to that of 30 elderly controls in two semantic tasks: a verbal sentence verification task and a visual test of analogical relations, both including several types of semantic relations.

Inhibitory deficits in ocular motor behavior in adults with attention-deficit/hyperactivity disorder.

Background: Many of the symptoms of attention-deficit/hyperactivity disorder (ADHD) have been attributed to deficits in behavioral inhibition mediated by the frontostriatal system. The ability to suppress unwanted saccadic eye movements is mediated by prefrontal cortex-basal ganglia circuitry and thus constitutes a useful measure of inhibitory ability.

Methods: To evaluate the functional integrity of this circuitry in ADHD, adult ADHD subjects unmedicated for at least 48 hours and normal comparison adults were studied by means of a comprehensive battery of ocular motor paradigms.

Electrophysiological analysis of cortical mechanisms of selective attention to high and low spatial frequencies.

Objectives: This study investigated whether short-latency (<100ms) event-related potential (ERP) components were modulated during attention to spatial frequency (SF) cues.

Methods: Sinusoidally modulated checkerboard stimuli having high (5 cycles per degree (cpd)) or low (0.8cpd) SF content were presented in random order at intervals of 400-650ms.

Putting spatial attention on the map: timing and localization of stimulus selection processes in striate and extrastriate visual areas.

This study investigated the cortical mechanisms of visual-spatial attention in a task where subjects discriminated patterned targets in one visual field at a time. Functional magnetic imaging (fMRI) was used to localize attention-related changes in neural activity within specific retinotopic visual areas, while recordings of event-related brain potentials (ERPs) traced the time course of these changes. The earliest ERP components enhanced by attention occurred in the time range 70-130 ms post-stimulus onset, and their neural generators were estimated to lie in the dorsal and ventral extrastriate visual cortex.

The role of spatial selective attention in working memory for locations: evidence from event-related potentials.

We investigated the hypothesis that the covert focusing of spatial attention mediates the on-line maintenance of location information in spatial working memory. During the delay period of a spatial working-memory task, behaviorally irrelevant probe stimuli were flashed at both memorized and nonmemorized locations. Multichannel recordings of event-related potentials (ERPs) were used to assess visual processing of the probes at the different locations.

Involvement of striate and extrastriate visual cortical areas in spatial attention.

We investigated the cortical mechanisms of visual-spatial attention while subjects discriminated patterned targets within distractor arrays. Functional magnetic resonance imaging (fMRI) was used to map the boundaries of retinotopic visual areas and to localize attention-related changes in neural activity within several of those areas, including primary visual (striate) cortex. Event-related potentials (ERPs) and modeling of their neural sources, however, indicated that the initial sensory input to striate cortex at 50-55 milliseconds after the stimulus was not modulated by attention.

Spatio-temporal dynamics of attention to color: evidence from human electrophysiology.

This study characterized patterns of brain electrical activity associated with selective attention to the color of a stimulus. Multichannel recordings of event-related potentials (ERPs) were obtained while subjects viewed randomized sequences of checkerboards consisting of isoluminant red or blue checks superimposed on a grey background. Stimuli were presented foveally at a rapid rate, and subjects were required to attend to the red or blue checks in separate blocks of trials and to press a button each time they detected a dimmer target stimulus of the attended color.

Event-related brain potentials in the study of visual selective attention.

Event-related brain potentials (ERPs) provide high-resolution measures of the time course of neuronal activity patterns associated with perceptual and cognitive processes. New techniques for ERP source analysis and comparisons with data from blood-flow neuroimaging studies enable improved localization of cortical activity during visual selective attention. ERP modulations during spatial attention point toward a mechanism of gain control over information flow in extrastriate visual cortical pathways, starting about 80 ms after stimulus onset.

Selective attention to the color and direction of moving stimuli: electrophysiological correlates of hierarchical feature selection.

Event-related brain potentials (ERPs) were recorded from subjects who attended to pairs of adjacent colored squares that were flashed sequentially to produce a perception of movement. The task was to attend selectively to stimuli in one visual field and to detect slower moving targets that contained the critical value of the attended feature, be it color or movement direction. Attention to location was reflected by a modulation of the early P1 and N1 components of the ERP, whereas selection of the relevant stimulus feature was associated with later selection negativity components.

Shifting attention in visual space: the effects of peripheral cueing on brain cortical potentials.

The effects of attentional shifts following peripheral cues were studied in humans using event-related potentials (ERPs) and reaction times. Subjects released a key following the presentation of a target preceded by a predictive cue in the same (valid) or the opposite (invalid) visual field, or a bilateral, non-predictive cue. The stimulus onset asynchrony (SOA) separating cue and target was either 200 or 600 ms.

Event-related potentials, spatial orienting, and reading disabilities.

Event-related potentials (ERPs) were used to investigate the effects of visual-spatial orienting on selective neural processing in boys with learning disabilities. Twenty-seven 8-12 year old boys were classified into four groups depending on whether or not they had a reading disability or attention deficit disorder. Event-related potentials were recorded over the left and right occipital, central, and frontal cortical regions.

Separate brain potential characteristics in children with reading disability and attention deficit disorder: color and letter relevance effects.

This experiment was on event-related potential (ERP) indicants of the selective neural processing of black vs. white and letter vs. nonletter stimuli in boys (8-12 years of age) with and without a reading disability (RD) and/or attentional deficit disorder (ADD).