fMRI of Healthy Older Adults During Stroop Interference

The Stroop interference effect, caused by difficulty inhibiting overlearned word reading, is often more pronounced in older adults. This has been proposed to be due to declines in inhibitory control and frontal lobe functions with aging. Initial neuroimaging studies of inhibitory control show that older adults have enhanced activation in multiple frontal areas, particularly in inferior frontal gyrus, indicative of recruitment to aid with performance of the task. The current study compared 13 younger and 13 older adults, all healthy and well educated, who completed a Stroop test during functional magnetic resonance imaging. Younger adults were more accurate across conditions, and both groups were slower and less accurate during the interference condition. The groups exhibited comparable activation regions, but older adults exhibited greater activation in numerous frontal areas, including the left inferior frontal gyrus. The results support the recruitment construct and suggest, along with previous research, that the inferior frontal gyrus is important for successful inhibition

Frontal Recruitment During Response Inhibition in Older Adults Replicated With fMRI

Recent research has explored age-related differences in multiple areas of cognitive functioning using fMRI, PET, and SPECT. However, because these studies used different tasks, subjects, and methods, little is known about whether the results of these studies are generalizable or repeatable. The present study replicated a previous study [Psychol. Aging 17 (2002) 56] using the same Go/No-go task with a subset of 11 of the original older adult subjects, and using the same fMRI scanner and imaging methods. A direct comparison was made between these participants at Time 1 and Time 2 for both behavioral and functional data. These participants were also compared to a new young adult group of 11 participants. Although the current young adult group did not perform as well as the original young adult group, the original finding of enhanced left prefrontal activation in older adults relative to younger adults was replicated. Furthermore, when comparing Time 1 to Time 2, older adults exhibited comparable areas of activation, but significantly greater magnitude of activation at Time 1 in a few clusters. The findings indicate that older adults exhibit more bilateral brain activity during this task than young adults, which appears compensatory and is repeatable over time. The magnitude of regional activation, however, may vary with extraneuronal factors such as signal-to-noise ratio or task experience. This study adds to existing research suggesting that bilateral frontal activation is a predominant finding in the aging literature, and not specific to certain tasks in age group comparisons

An Evaluation of Distinct Volumetric and Functional MRI Contributions Toward Understanding Age and Task Performance: A Study in the Basal Ganglia

Prior work by our group and others has implicated the basal ganglia as important in age-related differences in tasks involving motor response control. The present study used structural and functional MRI approaches to analyze this region of interest (ROI) toward better understanding the contributions of structural and functional MRI measures to understanding age-related and task performance-related cognitive differences. Eleven healthy elders were compared with 11 healthy younger adults while they completed the “go” portion of a complex Go/No-go task. Separate ROI\u27s in the bilateral caudate (C) and putamen/globus pallidus (PGp) were studied based upon previous findings of age-related functional MRI differences in basal ganglia for this portion of the task. Structural volumes and functional activation (in percent area under the curve during correct responses) were independently extracted for these ROI\u27s. Results showed that age correlated with ROI volume in bilateral PGp and C, while multiple task performance measures correlated with functional activation in the left PGp. The Go/No-go task measures were also significantly correlated with traditional attention and executive functioning measures. Importantly, fMRI activation and volumes from each ROI were not significantly inter-correlated. These findings suggest that structural and functional MRI make unique contributions to the study of performance changes in aging

Comparability of Functional MRI Response in Young and Old During Inhibition

When using fMRI to study age-related cognitive changes, it is important to establish the integrity of the hemodynamic response because, potentially, it can be affected by age and disease. However, there have been few attempts to document such integrity and no attempts using higher cognitive rather than perceptual or motor tasks. We used fMRI with 28 healthy young and older adults on an inhibitory control task. Although older and young adults differed in task performance and activation patterns, they had comparable hemodynamic responses. We conclude that activation during cognitive inhibition, which was predominantly increased in elders, was not due to vascular confounds or specific changes in hemodynamic coupling

Gender Specific Disruptions in Emotion Processing in Younger Adults with Depression

Background: One of the principal theories regarding the biological basis of major depressive disorder (MDD) implicates a dysregulation of emotion-processing circuitry. Gender differences in how emotions are processed and relative experience with emotion processing might help to explain some of the disparities in the prevalence of MDD between women and men. This study sought to explore how gender and depression status relate to emotion processing. Methods: This study employed a 2 (MDD status) × 2 (gender) factorial design to explore differences in classifications of posed facial emotional expressions (N=151). Results: For errors, there was an interaction between gender and depression status. Women with MDD made more errors than did nondepressed women and men with MDD, particularly for fearful and sad stimuli (Ps Ps P=.01). Men with MDD, conversely, performed similarly to control men (P=.61). Conclusions: These results provide novel and intriguing evidence that depression in younger adults (years) differentially disrupts emotion processing in women as compared to men. This interaction could be driven by neurobiological and social learning mechanisms, or interactions between them, and may underlie differences in the prevalence of depression in women and men. Depression and Anxiety, 2009. Published 2008 Wiley-Liss, Inc

Arabidopsis BTB/POZ protein-dependent PENETRATION3 trafficking and disease susceptibility

The outermost cell layer of plant roots (epidermis) constantly encounters environmental challenges. The epidermal outer plasma membrane domain harbours the PENETRATION3 (PEN3)/ABCG36/PDR8 ATP-binding cassette transporter that confers non-host resistance to several pathogens. Here, we show that the Arabidopsis ENDOPLASMIC RETICULUM-ARRESTED PEN3 (EAP3) BTB/POZ-domain protein specifically mediates PEN3 exit from the endoplasmic reticulum and confers resistance to a root-penetrating fungus, providing prime evidence for BTB/POZ- domain protein-dependent membrane trafficking underlying disease resistance.The PENETRATION3 (PEN3/ABCG36/PDR8) ATP-binding cassette transporter of Arabidopsis thaliana is a crucial component of preinvasive defence against some fungal and bacterial non-host pathogens entering by direct penetration1,2,3,4. In above-ground organs, PEN3 is recruited to sites of pathogen attack at the cell surface3,4. In seedling roots, PEN3 polarly localizes to the epidermal outer membrane domain in the absence of pathogens5,6. Root epidermal cells display four major polar plasma membrane domains: the outer domain facing the environment, the inner domain oriented towards the cortical cell layer, the shootward-oriented, apical, and the root tip-oriented, basal, domain6. Proteins in the outer domain that function in regulating the transport of inorganic compounds include, for example, the NIP5;1 boric acid uptake channel7. Factors required for PEN3 and NIP5;1 trafficking from the trans-Golgi network to the outer domain have been identified8,9,10, and exocyst complex components promote polar tethering of several outer domain proteins9,11. However, factors that specifically mediate trafficking of polar outer membrane cargos involved in responses to root-penetrating pathogens remain to be discovered.In a genetic screen for mislocalization of PEN3 fused to green-fluorescent protein (PEN3- GFP) in the root epidermis of seedlings9, we recovered one recessive mutant in which PEN3-GFP localized to a cytoplasmic structure resembling the endoplasmic reticulum (ER) (Fig. 1a–d). This er-arrested pen3-1 (eap3-1) mutation indistinguishably affected localization of PEN3-GFP from that of PEN3-mCherry (Supplementary Fig. 1a,b), which colocalized with the ER-intrinsic chaperone BIP in the eap3-1 mutant (Supplementary Fig. 1c,d), corroborating an ER arrest of PEN3

The Sensitivity and Psychometric Properties of a Brief Computer-Based Cognitive Screening Battery in a Depression Clinic

At present, there is poor accuracy in assessing cognitive and vegetative symptoms in depression using clinician or self-rated measures, suggesting the need for development of standardized tasks to assess these functions. The current study assessed the psychometric properties and diagnostic specificity of a brief neuropsychological screening battery designed to assess core signs of depression; psychomotor retardation, attention and executive functioning difficulties, and impaired emotion perception within an outpatient psychiatry setting. Three hundred eighty-four patients with mood disorders and 77 healthy volunteers participated. A large percentage of patients met diagnostic criteria for Major Depressive Disorder alone (49%) or with another comorbid psychiatric disorder (24%). A brief, 25-min battery of computer-based tests was administered to control participants and patients measuring the constructs of inhibitory control, attention, visual perception, and both executive and visual processing speed. The patient groups performed significantly worse than the control group regardless of diagnosis on visual perception and attention accuracy and processing speed factors. Surprisingly, the anxiety disorder group performed better than several other psychiatric disorder groups in inhibitory control accuracy. Developing valid and reliable measures of cognitive signs in mood disorders creates excellent opportunities for tracking cognitive status prior to initiation of treatment, and allows for reliable retest following treatment