Fiber bundle length and cognition: a length-based tractography MRI study.

Executive function (EF) and cognitive processing speed (CPS) are two cognitive performance domains that decline with advanced age. Reduced EF and CPS are known to correlate with age-related frontal-lobe volume loss. However, it remains unclear whether white matter microstructure in these regions is associated with age-related decline in EF and/or CPS.

Verbal memory declines more rapidly with age in HIV infected versus uninfected adults.

Objectives: In the current era of effective antiretroviral treatment, the number of older adults living with HIV is rapidly increasing. This study investigated the combined influence of age and HIV infection on longitudinal changes in verbal and visuospatial learning and memory.

Method: In this longitudinal, case-control design, 54 HIV seropositive and 30 seronegative individuals aged 40-74 years received neurocognitive assessments at baseline visits and again one year later.

Gender Differences in Cognitive Control: an Extended Investigation of the Stop Signal Task.

Men and women show important differences in clinical conditions in which deficits in cognitive control are implicated. We used functional magnetic resonance imaging to examine gender differences in the neural processes of cognitive control during a stop-signal task. We observed greater activation in men, compared to women, in a wide array of cortical and sub-cortical areas, during stop success (SS) as compared to stop error (SE).

Decreased amygdala activation during risk taking in non-dependent habitual alcohol users: A preliminary fMRI study of the stop signal task.

Background And Objectives: Habitual alcohol use is prodromal to alcohol dependence. It has been suggested that impairment in impulse control contributes to habitual drinking. Little is known whether neural processes associated with impulse control is altered in non-dependent social drinkers.

Altered impulse control in alcohol dependence: neural measures of stop signal performance.

Background: Altered impulse control has been implicated in the shaping of habitual alcohol use and eventual alcohol dependence. We sought to identify the neural correlates of altered impulse control in 24 abstinent patients with alcohol dependence (PAD), as compared to 24 demographics matched healthy control subjects (HC). In particular, we examined the processes of risk taking and cognitive control as the neural endophenotypes of alcohol dependence.

Subcortical processes of motor response inhibition during a stop signal task.

Previous studies have delineated the neural processes of motor response inhibition during a stop signal task, with most reports focusing on the cortical mechanisms. A recent study highlighted the importance of subcortical processes during stop signal inhibition in 13 individuals and suggested that the subthalamic nucleus (STN) may play a role in blocking response execution (Aron and Poldrack, 2006. Cortical and subcortical contributions to Stop signal response inhibition: role of the subthalamic nucleus.

Neural correlates of post-error slowing during a stop signal task: a functional magnetic resonance imaging study.

The ability to detect errors and adjust behavior accordingly is essential for maneuvering in an uncertain environment. Errors are particularly prone to occur when multiple, conflicting responses are registered in a situation that requires flexible behavioral outputs; for instance, when a go signal requires a response and a stop signal requires inhibition of the response during a stop signal task (SST). Previous studies employing the SST have provided ample evidence indicating the importance of the medial cortical brain regions in conflict/error processing.

Neural correlates of impulse control during stop signal inhibition in cocaine-dependent men.

Altered impulse control is associated with substance use disorders, including cocaine dependence. We sought to identify the neural correlates of impulse control in abstinent male patients with cocaine dependence (PCD). Functional magnetic resonance imaging (fMRI) was conducted during a stop signal task that allowed trial-by-trial evaluation of response inhibition.

Greater activation of the "default" brain regions predicts stop signal errors.

Previous studies have provided evidence for a role of the medial cortical brain regions in error processing and post-error behavioral adjustment. However, little is known about the neural processes that precede errors. Here in an fMRI study we employ a stop signal task to elicit errors approximately half of the time despite constant behavioral adjustment of the observers (n=40).