Reprint of: The effects of distractors and spatial precues on covert visual search in macaque. Vision Research, 76, pp. 43-9.

Covert visual search has been studied extensively in humans, and has been used as a tool for understanding visual attention and cueing effects. In contrast, much less is known about covert search performance in monkeys, despite the fact that much of our understanding of the neural mechanisms of attention is based on these animals. In this study, we characterize the covert visual search performance of monkeys by training them to discriminate the orientation of a briefly-presented, peripheral Landolt-C target embedded within an array of distractor stimuli while maintaining fixation.

The effects of distractors and spatial precues on covert visual search in macaque.

Covert visual search has been studied extensively in humans, and has been used as a tool for understanding visual attention and cueing effects. In contrast, much less is known about covert search performance in monkeys, despite the fact that much of our understanding of the neural mechanisms of attention is based on these animals. In this study, we characterize the covert visual search performance of monkeys by training them to discriminate the orientation of a briefly-presented, peripheral Landolt-C target embedded within an array of distractor stimuli while maintaining fixation.

Demonstration of decreased gray matter concentration in the midbrain encompassing the dorsal raphe nucleus and the limbic subcortical regions in major depressive disorder: an optimized voxel-based morphometry study.

Background: Previous neuroimaging studies in patients with major depressive disorder (MDD) have reported changes in several brain areas, such as the medial and dorsolateral orbital cortex, amygdala, hippocampus, and basal ganglia. However, the results of these studies are inconsistent, and relatively few studies have been conducted using voxel-based morphometry (VBM) to detect gray matter concentration (GMC) abnormalities in patients with MDD.

Methods: We examined 47 MDD patients and 51 healthy controls to investigate structural abnormalities using a 1.

DRD2/ANKK1 TaqI A polymorphism affects corticostriatal activity in response to negative affective facial stimuli.

DRD2/ANKK1 TaqI A polymorphism has been suggested to be involved in a reward-related psychiatric disorders. However, the effect of Dopamine receptor D2 (DRD2) on emotional processing has not been investigated yet. We investigated the possible relationship between DRD2/ANKK1 TaqI A polymorphism and corticostriatal response to negative facial stimuli using functional magnetic resonance imaging.

Neural substrates of affective face recognition in alexithymia: a functional magnetic resonance imaging study.

Background: Alexithymia is a condition characterized by deficits in cognitive processing and the regulation of emotions. Several theories have been proposed for the underlying neurobiology, but the etiology of alexithymia remains unclear.

Methods: Using functional magnetic resonance imaging, we investigated brain activation measured on the scale of alexithymia in 38 individuals who were presented with neutral, sad, or angry affective facial stimuli.

Frontal eye field signals that may trigger the brainstem saccade generator.

Saccades are rapid shifts of gaze that normally place the line of sight on a desired target with a single smooth movement. A number of disease states have been shown to result in saccadic movements that are fragmented, but still end near target position after a multi-step sequence of saccades. Among these disorders are Parkinson's disease and late-onset Tay-Sachs disease (LOTS).

Altered verbal working memory process in patients with Alzheimer's disease: an fMRI investigation.

Impaired working memory processing is one of the broad range of cognitive deficits in patients with Alzheimer's disease (AD). We aimed to elucidate the differences in brain activities involved in the process of working memory between AD patients and healthy comparison subjects. Twelve patients with AD were recruited along with 12 healthy volunteers as a comparison group.

The neural substrates of affective face recognition in patients with Hwa-Byung and healthy individuals in Korea.

Hwa-Byung (HB) is a Korean culture-bound psychiatric syndrome caused by the suppression of anger. HB patients have various psychological and somatic symptoms, such as chest discomfort, a sensation of heat, and the sensation of having an epigastric mass. In this study, we measured brain activity in HB patients and healthy individuals in response to affective facial stimuli.

Monoamine oxidase A-uVNTR genotype affects limbic brain activity in response to affective facial stimuli.

Monoamine oxidase A (MAOA) enzymatically degrades biogenic amines such as norepinephrine, dopamine, and serotonin, and plays a key role in the regulation of their neurotransmission. Allelic variations at the MAOA locus have been implicated in the neurobiology of aggression and impulsivity. We investigated the possible relationship between the MAOA-upstream variable number of tandem repeats (uVNTR) polymorphism and brain responses to negative facial stimuli, using functional magnetic resonance imaging (fMRI).

The neural substrates of affective processing toward positive and negative affective pictures in patients with major depressive disorder.

Previous studies examining neural responses to emotional stimuli in individuals with major depressive disorder (MDD) have indicated increased responses within the left amygdala to sad faces, and increased activity within the visual cortex and striatum to expressions of happiness. Using functional magnetic resonance imaging (fMRI), the current study measured neural responses to neutral, positive and negative pictures of the International Affective Picture System in 15 healthy individuals and 15 patients with MDD. Depressed individuals demonstrated lower activity in the right hippocampus and the right insula to negative affective pictures, whereas they showed lower activity in the right anterior cingulate cortex and the left insula to positive pictures.

An oculomotor decision process revealed by functional magnetic resonance imaging.

It is not known how the brain decides to act on moving objects. We demonstrated previously that neurons in the macaque supplementary eye field (SEF) reflect the rule of ocular baseball, a go/nogo task in which eye movements signal the rule-guided interpretation of the trajectory of a target. In ocular baseball, subjects must decide whether to pursue a moving spot target with an eye movement after discriminating whether the target will cross a distal, visible line segment.

Differential correlation of frontal and parietal activity with the number of alternatives for cued choice saccades.

The time taken to choose a response appropriate for a cue increases with the number of potential response options (Hick's law). We used this temporal constraint of choice behavior in event-related fMRI experiments to identify brain areas carrying out the translation from a cue stimulus to response: Since the process takes longer with more alternatives, the activity of the areas would increase in correlation with the number of alternatives (NA) available at the time of choice decision. During a choice saccade task in which one target is selected among many alternatives based on the color of a cue in the center, the frontal eye fields (FEF) and intraparietal sulcus (IPS) were activated.

Brain activation during music listening in individuals with or without prior music training.

The present study investigated activation during listening to music with and without a task in female musicians and non-musicians. Five subjects with long musical training for a mean period of 19+/-1 years (musician group) and five subjects with no training in musical instruments (non-musician group) were imaged in a 1.5T scanner, while they simply listened to short segments of piano pieces (LIS), and while they performed a distorted tune test, designed using the same pieces (DTT).