In neuropsychological assessment, and many areas of research, it is common for the same test to be administered on more than one occasion to measure change. Measured changes are presumed to reflect true changes in the construct being measured by the test; for example, cognitive changes due to processes such as aging, advancing neurological disease, or treatment interventions. However, practice effects, defined as score increases due to factors such as memory for specific test items, learned strategies, or test sophistication, complicate the interpretation of change. This review presents meta-analyses of nearly 1600 individual effect sizes representing changes in mean-level performance on tests commonly used to assess core domains of neuropsychological function, with the goal of quantitatively summarizing the magnitude of practice effects on such tests. The use of alternate forms, the ages of participants, clinical diagnoses of study participants, and length of the test-retest interval were associated with the magnitude of change in many cases. These findings have important implications for the practice of clinical neuropsychology, as well as for research applications, and highlight the need for practice effects to be taken into account in interpreting change across time with multiple measurements.

A considerable body of previous research on the prefrontal cortex (PFC) has helped characterize the regional specificity of various cognitive functions, such as cognitive control and decision making. Here we provide definitive findings on this topic, using a neuropsychological approach that takes advantage of a unique dataset accrued over several decades. We applied voxel-based lesionsymptom mapping in 344 individuals with focal lesions (165 involving the PFC) who had been tested on a comprehensive battery of neuropsychological tasks. Two distinct functional-anatomical networks were revealed within the PFC: one associated with cognitive control (response inhibition, conflict monitoring, and switching), which included the dorsolateral prefrontal cortex and anterior cingulate cortex and a second associated with valuebased decision-making, which included the orbitofrontal, ventromedial, and frontopolar cortex. Furthermore, cognitive control tasks shared a common performance factor related to set shifting that was linked to the rostral anterior cingulate cortex. By contrast, regions in the ventral PFC were required for decision-making. These findings provide detailed causal evidence for a remarkable functional-anatomical specificity in the human PFC.T he prefrontal cortex (PFC) is widely regarded as the pinnacle of brain evolution in humans (1). Its functional organization has long been under scientific scrutiny and has often been subsumed under the rubric "executive functions" (1, 2). Although some early theories attributed a unitary "central executive" to the PFC (3), scientific findings of the past decades have suggested that executive processes fractionate into distinct cognitive functions concerned with motivating behavior (valuation) and controlling behavior (cognitive control), which have been proposed to draw on two partially distinct PFC networks (1,(4)(5)(6). Comparative neuroanatomy suggests a functional and anatomical distinction between ventral PFC with strong connections to the limbic system and dorsolateral PFC (dlPFC) with connections to posterior cortical areas in the parietal lobe (7). Cognitive control, which is thought to draw on multiple processes, including task switching, response inhibition, error detection and response conflict, and working memory (2,4,8), has been associated with the dlPFC and the anterior cingulate cortex (ACC), as well as other sectors of the PFC that together may constitute a rostro-caudally organized hierarchy for behavioral control and planning (9-11). In contrast, valuation, reward learning, and decision-making functions have been mainly associated with ventral and medial sectors of the PFC (vmPFC) (10,(12)(13)(14)(15)(16)(17)(18). Overall, then, the broad functions of "cognitive control" and "valuation" appear to draw on partly distinct, but interacting, networks within the PFC to generate adaptive behavior (6,19,20), although this distinction is sometimes framed between various levels of control and motivation (20) or between executive functions (monitoring and task...

The neuroanatomical correlates of depression remain unclear. Functional imaging data have associated depression with abnormal patterns of activity in prefrontal cortex (PFC), including the ventromedial (vmPFC) and dorsolateral (dlPFC) sectors. If vmPFC and dlPFC are critical neural substrates for the pathogenesis of depression, then damage to either area should affect the expression of depressive symptoms. Using patients with brain lesions we show that, relative to nonfrontal lesions, bilateral vmPFC lesions are associated with markedly low levels of depression, whereas bilateral dorsal PFC lesions (involving dorsomedial and dorsolateral areas in both hemispheres) are associated with substantially higher levels of depression. These findings demonstrate that vmPFC and dorsal PFC are critically and causally involved in depression, although with very different roles: vmPFC damage confers resistance to depression, whereas dorsal PFC damage confers vulnerability.

Test-retest reliability is an important psychometric property relevant to assessment instruments typically used in neuropsychological assessment. This review presents a quantitative summary of test-retest reliability coefficients for a variety of widely used neuropsychological measures. In general, the meta-analytic test-retest reliabilities of the test scores ranged from adequate to high (i.e., r=.7 and higher). Furthermore, the reliability values were largely robust across factors such as age, clinical diagnosis, and the use of alternate forms. The values for some of the memory and executive functioning scores were lower (i.e., less than r=.7). Some of the possible reasons for these lower values include ceiling effects, practice effects, and across time variability in cognitive abilities measured by those tests. In general, neuropsychologists who use these measures in their assessments can be encouraged by the magnitude of the majority of the meta-analytic test-retest correlations obtained.

The working memory (WM) construct is conceptualized similarly across domains of psychology, yet the methods used to measure WM function vary widely. The present study examined the relationship between WM measures used in the laboratory and those used in applied settings. A large sample of undergraduates completed three laboratory-based WM measures (operation span, listening span, and n-back), as well as the WM subtests from the Wechsler Adult Intelligence Scale-III and the Wechsler Memory Scale-III. Performance on all of the WM subtests of the clinical batteries shared positive correlations with the lab measures; however, the Arithmetic and Spatial Span subtests shared lower correlations than the other WM tests. Factor analyses revealed that a factor comprising scores from the three lab WM measures and the clinical subtest, Letter-Number Sequencing (LNS), provided the best measurement of WM. Additionally, a latent variable approach was taken using fluid intelligence as a criterion construct to further discriminate between the WM tests. The results revealed that the lab measures, along with the LNS task, were the best predictors of fluid abilities.