Convergent evidence suggests that the dorsal medial prefrontal cortex (dmPFC) makes an important contribution to goal-directed action selection. The dmPFC is also part of a network of brain regions that becomes compromised in old age. It was hypothesized that during decision-making, some process of comparison takes place in the dmPFC between the representation of available actions and associated values, and that this process is changed with aging. These hypotheses were tested in aged and young adult rats performing a novel 3-choice, 2-cue decision task. Neuron and local field potential activity revealed that the dmPFC experienced different states during decision and outcome phases of the task, with increased local inhibition and oscillatory (gamma and theta) activity during cue presentation, and increased excitatory neuron activity (among regular firing neurons) at goal zones. Although excitatory and inhibitory activity appeared anti-correlated over phases of the decision task, cross-correlations and the prominent gamma oscillation revealed that excitation and inhibition were highly correlated on the millisecond scale. This "micro-scale" coupling between excitation and inhibition was altered in aged rats and the observed changes were correlated with changes in decision and movement speeds of the aged animals, suggesting a putative mechanism for age-related behavioral slowing. With respect to decision-making, both aged and young adult rats learned over multiple days to follow the rewarded cue in the 3-choice, 2-cue task. Support for the hypothesis that the dmPFC simultaneously represents alternative actions was not found; however, neuron activity selective for particular goal zones was observed. Interestingly, goal-selective neural activity during the decision period was more likely to take place on error trials, particularly on high-performing sessions and when rats exhibited a preference for a particular feeder. A possible interpretation of these patterns is that goal representations in the dmPFC might have sometimes overruled learned habits, which are likely to be involved in following the correct cue and which are known to be supported by other brain regions. These results describe fundamental properties of network dynamics and neural coding in the dmPFC, and have important implications for the neural basis of processing speed and goal-directed action.

A significant subset of mild traumatic brain injury (mild TBI) and chronic pain (CP) patients report, and sometimes show objective evidence of, persisting cognitive problems. Despite differences in injury mechanisms, there is considerable overlap in the types of persisting cognitive symptoms that are reported by the two populations. Psychogenic, rather than physiogenic, factors are thought to play an important role in the maintenance of these persisting symptoms. The current investigation examined the contributions somatization, depression, and anxiety had on an objective measure of “working attention.” In order to best elucidate the influences these psychological factors had on attentional performance, only individuals who passed well-validated and popular indicators of cognitive and self-report validity were included in the study. Two hundred and forty-nine individuals (n = 116 TBI; n = 133 CP) met the inclusionary criteria for the study. Psychological factors were assessed using Scales 1 (Hypochondriasis), 2 (Depression), 3 (Hysteria), and 7 (Psychasthenia) of the Minnesota Multiphasic Personality Inventory-II. “Working attention” was measured using the demographically-adjusted T-scores for the Working Memory and Processing Speed Indexes of the Wechsler Adult Intelligence Scale- 3. Results indicated that a high rate of psychological complications was observed in the mild TBI and CP groups but not the moderate-severe traumatic brain injury (M/S TBI) comparison group. Analysis indicated that psychological elevations were not significantly related to spontaneously-reported symptoms or working attention deficits for the mild TBI group but were for the CP and M/S TBI groups. The current results are important for understanding the psychological complications that may occur in individuals exhibiting persisting cognitive problems in these clinical populations.

The current study investigates the effects of vascular disease on white matter health by comparing participants with atherosclerotic vascular disease (AVD) to healthy control participants (HC). The comparison between groups will help elucidate the differences between early-stage mild vascular disease and normal aging processes in terms of their effects on white matter health as measured by diffusion tensor imaging (DTI). Relationships between white matter health and depression, attention, and processing speed are studied by the application of a variety of DTI neuroimaging techniques, which will allow investigation of these relationships at the levels of global, lobe-wise, and subregional analysis. The specific subregion of interest in the depression study is Brodmann Area 25, which has shown significant relationships with depressive symptomatology in patients with treatment refractory depression, but has not been studied in the context of aging, vascular disease, or subthreshold depressive symptoms. Results indicate that there are significant differences between AVD and HC participants in global and regional FA measures. Within the AVD group, significant relationships of FA with depressive symptoms and attentional function have been observed in the current study. Several unexpected findings emerged, most important of which was the observation that there is a significant relationship between FA in Brodmann Area 25 and depressive symptoms in AVD participants which is specific to the right hemisphere. These findings have implications for the treatment of depressive symptoms in older adults and participants with vascular disease.

The purpose of this study was to investigate the relationship between word reading and white matter (WM) integrity in the reading system and test a theory-based moderated mediation model such that relationship of WM integrity with word reading is mediated by processing speed and indirect effect is moderated by group. Thirty-seven adult survivors of childhood brain tumor and typically developing adults participated (mean age=24.19(4.51) years, 62% female). Tractography identified the WM tract for three reading system connections. Fractional anisotropy of the IFOF and PT-OT tracts were significantly correlated with word reading in survivors (r=.55, .46, respectively; p

Mitochondrial Diseases (MD) are disorders of function in cellular oxidative phosphorylation caused by diverse nuclear DNA and mtDNA mutations and seen in 1/5,000 births. The purpose of this study was to examine relationships across medical indices, biochemical measures, and neurobehavioral functioning in children with MD. Findings from Western Blot, Native Gels, High Resolution Respirometry, and the Nijmegen diagnostic criteria were assessed in relation to children’s processing speed and attention, based on the prediction that impaired functioning of proteins, complexes, and cellular respiration, that are critical in ATP production, will impact neurodevelopment and related neuropsychological processes in children with MD. Twenty-five children (ages 4-13) were administered subtests from the DAS-II and NEPSY-II. Results from multiple regression analyses suggest that processing speed and attention deficits may be markers of abnormal protein expression that interferes with the production of ATP in the oxidative phosphorylation process; implications for future research are presented.

Research has focused on the potential cognitive determinants of individual and developmental differences in intelligence. Two competing views influenced by information-processing theory propose important roles for the constructs of working memory capacity and perceptual speed, respectively. This study aimed to clarify the relationship between these constructs by examining the performance of younger adults who were high and low in working memory capacity on an experimental version of traditional perceptual speed tasks. The results suggested that working memory capacity is important for performance on perceptual speed tasks because of the attention and memory demands of these tasks. Eye-tracking measures corroborated the behavioral data, which suggest that individual differences on perceptual speed tasks are the result of individual differences in working memory capacity in healthy, younger adults.

People use facial appearance to infer the social attributes of others. A primary indicator of facial attractiveness is prototypicality (the proximity of an object to its categorical central tendency); faces and objects closer to the central tendency are judged as more attractive. Perceptual fluency theory suggests that cognitive processing speed directly generates positive affect. This dissertation examined the relationships among attractiveness, prototypicality, and affective response in faces and non-face objects across adult and 8-year-old participants using a reaction time (RT) paradigm. RT predicted positive affect and disgust responses to facial stimuli. Of particular note are the series of complementary findings suggesting that reaction to unattractive faces may be both quantitatively (i.e., longer RT latencies) and qualitatively (i.e., judged to be less typical) different from high and medium attractive faces. These findings may help explain how appearance-based stereotypes are formed and maintained. / text

This study had three main purposes. First, the relationship between Processing Speed (Gs) and poor word recognition skills was examined. Second, various formats of processing speed tests that measure different types of processing speed (i.e. naming facility, perceptual speed, semantic speed, attention and concentration) were administered to determine what aspects of Gs were more strongly correlated with word reading performance. Pearson correlations and coefficients of determination were used to evaluate the strength of the relationships and the shared variance. Third, the study sample was evaluated to determine what percentage of the poor readers participating in the study had slow processing speed.Forty-four students in grades 1-3, ages six- to ten-years old were administered the Woodcock-Johnson III Achievement reading tests of Letter-Word Identification, Reading Fluency, and Word Attack. The subjects were additionally administered the Woodcock-Johnson III Cognitive Abilities tests of Verbal Comprehension, Visual-Auditory Learning, Sound Blending, Visual Matching, Numbers Reversed, Decision Speed, Rapid Picture Naming, Pair Cancellation, and Cross Out.The results of the study indicated processing speed, as measured by the Gs Cluster score, was strongly correlated with word reading, r = .749, r2=.56. The Gs tests of Visual Matching, (r = .663, r2 = .44) and Decision Speed (r = .811, r2 = .66) were most strongly correlated with poor word reading skill. The Basic Reading Skills Cluster and the Test of Letter-Word Identification were both moderately correlated at various strengths with different formats of Gs tests. Tests of Visual Matching, Rapid Picture Naming, Pair Cancellation and Cross Out all had a moderate, significant correlation.Lastly, 47% of the poor readers (SS<85 on any of the measures of>reading) also had low Gs scores (SS<85).The results from the study demonstrate the need for further exploration of the impact of poor Gs on the development of reading skills, as well as determination of the most effective interventions for poor readers with slow processing speed.

The purpose of the current study was to investigate, and expain, the effects of an intervention known as “The Five Task Approach” (TFTA); a cognitive intervention hereby utilized within the realm of the geriatric population, as a means of taxing and strengthening cortical areas associated with memory, and visual processing. This study revealed that even short-term exposure to cognitive activities, and therapeutic cueing known to tax areas connected to visual perception, may have an effect on one’s global cognition, generalized memory, and the accuracy of one’s visual perception. It was demonstrated that even brief cognitive intervention geared at taxing cortical areas associated with memory and visual processing, in conjunction with the therapuetic cueing utilized in this study, has the potential to significantly increase participant performance in terms of global cognitive function, including skills associated with executive functioning, working memory, visual processing, visual processing speed, auditory processing, and global cognitive status.

BACKGROUND: Cognitive deficits are a core component of schizophrenia and among the strongest determinants of functional disability in psychotic illnesses. In particular, impairment in information processing speed has been demonstrated to be among the most significant in patients. Poor processing speed not only frequently occurs prior to psychosis onset during the prodromal or clinical high risk phase of psychotic illness, it has also been found to be a strong predictor of conversion to psychosis. However, the neurobiological basis of impaired processing speed in the clinical high risk population is not well understood. Functional connectivity during resting state fMRI provides useful insights into the organization and communication between brain regions that may elucidate the brain circuit basis underlying processing speed. OBJECTIVE: To identify the strongest link between brain functional connectivity and a measure of information processing speed in individuals at clinical high risk for conversion to psychosis by utilizing a data-driven analysis. METHODS: Cognitive and resting state fMRI data were collected from 198 clinical high risk participants and 123 neurotypical controls in the second phase of the North American Prodromal Longitudinal Study. Processing speed was measured by the Brief Assessment of Cognition in Schizophrenia Symbol Coding task. A multivariate pattern analysis was used to identify, at the individual voxel level, how functional connectivity correlates with information processing speed. RESULTS: Clinical high risk participants demonstrated significantly reduced processing speed, relative to neurotypical controls. Similarly, at risk patients who later converted to psychosis (n=17) also showed poorer performance on the BACS Symbol Coding task compared to non-converters. The strongest whole-brain link between connectivity and processing speed within the clinical high risk population was the bilateral amygdala. Specifically, connectivity between the bilateral amygdala and a functional brain network known as the salience network correlated with processing speed. CONCLUSIONS: Functional connectivity between the bilateral amygdala and the salience network was linked to individual variation in processing speed in the clinical high risk population. This affirmed a growing literature that implicates amygdala involvement in cognitive function and provides a potential biomarker for psychosis risk prior to diagnosis.