Strengthening Connections: Functional Connectivity and Brain Plasticity

The ascendancy of functional neuroimaging has facilitated the addition of network-based approaches to the neuropsychologist’s toolbox for evaluating the sequelae of brain insult. In particular, intrinsic functional connectivity (iFC) mapping of resting state fMRI (R-fMRI) data constitutes an ideal approach to measuring macro-scale networks in the human brain. Beyond the value of iFC mapping for charting how the functional topography of the brain is altered by insult and injury, iFC analyses can provide insights into experience-dependent plasticity at the macro level of large-scale functional networks. Such insights are foundational to the design of training and remediation interventions that will best facilitate recovery of function. In this review, we consider what is currently known about the origin and function of iFC in the brain, and how this knowledge is informative in neuropsychological settings. We then summarize studies that have examined experience-driven plasticity of iFC in healthy control participants, and frame these findings in terms of a schema that may aid in the interpretation of results and the generation of hypotheses for rehabilitative studies. Finally, we outline some caveats to the R-fMRI approach, as well as some current developments that are likely to bolster the utility of the iFC paradigm for neuropsychology.     

When attention is intact in adults with ADHD

Is covert visuospatial attention—selective processing of information in the absence of eye movements—preserved in adults with attention-deficit/hyperactivity disorder (ADHD)? Previous findings are inconclusive due to inconsistent terminology and suboptimal methodology. To settle this question, we used well-established spatial cueing protocols to investigate the perceptual effects of voluntary and involuntary attention on an orientation discrimination task for a group of adults with ADHD and their neurotypical age-matched and gender-matched controls. In both groups, voluntary attention significantly improved accuracy and decreased reaction times at the relevant location, but impaired accuracy and slowed reaction times at irrelevant locations, relative to a distributed attention condition. Likewise, involuntary attention improved accuracy and speeded responses. Critically, the magnitudes of all these orienting and reorienting attention effects were indistinguishable between groups. Thus, these counterintuitive findings indicate that spatial covert attention remains functionally intact in adults with ADHD.     

Development and validation of a questionnaire about the main variables affecting the individual investor's behavior in the Stock Exchange

Development and validation of a questionnaire about the main variables affecting the individual investor's behavior in the Stock Exchange. There is a considerable lack of information about the methodology usually used in most of the studies about individual investor's behavior. The studies reviewed do not show the method used in the selection of the items or the psychometric properties of the questionnaires. Because of the importance of investment in the Stock Exchange nowadays, it seems relevant to obtain a reliable instrument to understand individual investor's behavior in the Stock Exchange. Therefore, the goal of the present work is to validate a questionnaire about the main variables involved in individual investors' behavior in the Stock Exchange. Based on previous studies, we elaborated a questionnaire using the Delphi methodology with a group of experts. The internal consistency (Cronbach alpha=.934) and validity evidence of the questionnaire show that it may be an effective instrument and can be applied with some assurance.     

Adaptation of anterior pituitary hormones to chronic noise stress in male rats

We have studied the effects of acute and chronic noise on serum levels of pituitary hormones in male Wistar rats. Acute noise increased serum levels of corticosterone, prolactin, and luteinizing hormone and decreased serum GH. FSH was unaffected by this stressor. Chronic noise did not modify basal levels of any hormone studied, however responsiveness of some hormones to the same stimuli was altered. Reduced corticosterone, prolactin, and GH responses to noise was observed after previous chronic exposure to this stimuli. LH response followed the same pattern although it did not reach statistical significance. It might be concluded that adaptation to a repeated stress stimulus is not confined to the pituitary-adrenal axis, however, the degree of adaptation could vary between different hormones.     

Assessing bilingual and monolingual Latino students with translations of the MMPI-2: initial data

This article presents the results of 2 studies conducted with Spanish versions of the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) with Latino students. Study 1 compared the results of 2 administrations of the MMPI-2, one in English and the other in Spanish. Study 2 compared the results of administrations of 2 Spanish versions of the MMPI-2, the official Mexican adaptation and the Version Hispana. In both cases, scale score differences were not found. Comparability, as operationally defined by test-retest reliability, was found to be higher for the group that was administered the English and Spanish versions than the group administered the 2 Spanish versions. Overall, the results were found to suggest correspondence. Yet, the authors warn against concluding "perfect" correspondence because other key groups need to be studied, including psychiatric patients and persons from the Latino community. Also, the determination of linguistic equivalence needs further refinement.     

Characterizing variation in the functional connectome: promise and pitfalls

The functional MRI (fMRI) community has zealously embraced resting state or intrinsic functional connectivity approaches to mapping brain organization. Having demonstrated their utility for charting the large-scale functional architecture of the brain, the field is now leveraging task-independent methods for the investigation of phenotypic variation and the identification of biomarkers for clinical conditions. Enthusiasm aside, questions regarding the significance and validity of intrinsic brain phenomena remain. Here, we discuss these challenges and outline current developments that, in moving the field toward discovery science, permit a shift from cartography toward a mechanistic understanding of the neural bases of variation in cognition, emotion and behavior.     

Does exposure to ambient odors influence the emotional content of memories?

This study examined the effects of implicitly presented odors on the emotional content of memory narratives. Participants were exposed to low levels of perfumes or no odors while they reconstructed a memory from childhood and a recurrent dream. Narratives were analyzed for emotional content using the Linguistic and Inquiry Word Count program. Exposure to perfumes increased the percentage of positive emotion words used by participants in recalling both dreams and childhood memories. In addition, exposure to odors decreased the percentage of negative emotion words that men used in their narratives, whereas the opposite effect was found for women. Discussion focuses on gender differences in written emotional expression, possible ways by which perfumes may exert their effects, and the usefulness of using ambient odors and objective content analysis when studying emotions in memories.     

Increasing task difficulty enhances effects of intersensory redundancy: testing a new prediction of the Intersensory Redundancy Hypothesis

Prior research has demonstrated intersensory facilitation for perception of amodal properties of events such as tempo and rhythm in early development, supporting predictions of the Intersensory Redundancy Hypothesis (IRH). Specifically, infants discriminate amodal properties in bimodal, redundant stimulation but not in unimodal, nonredundant stimulation in early development, whereas later in development infants can detect amodal properties in both redundant and nonredundant stimulation. The present study tested a new prediction of the IRH: that effects of intersensory redundancy on attention and perceptual processing are most apparent in tasks of high difficulty relative to the skills of the perceiver. We assessed whether by increasing task difficulty, older infants would revert to patterns of intersensory facilitation shown by younger infants. Results confirmed our prediction and demonstrated that in difficult tempo discrimination tasks, 5‐month‐olds perform like 3‐month‐olds, showing intersensory facilitation for tempo discrimination. In contrast, in tasks of low and moderate difficulty, 5‐month‐olds discriminate tempo changes in both redundant audiovisual and nonredundant unimodal visual stimulation. These findings indicate that intersensory facilitation is most apparent for tasks of relatively high difficulty and may therefore persist across the lifespan.