Neural correlates of learning and working memory in the primate posterior parietal cortex

The posterior parietal cortex has been traditionally associated with coordinate transformations necessary for interaction with the environment and with visual-spatial attention. More recently, involvement of posterior parietal cortex in other cognitive functions such as working memory and task learning has become evident. Neurophysiological experiments in non-human primates and human imaging studies have revealed neural correlates of memory and learning at the single neuron and at the brain network level. During working memory, posterior parietal neurons continue to discharge and to represent stimuli that are no longer present. This activation resembles the responses of prefrontal neurons, although important differences have been identified in terms of the ability to resist stimulation by distracting stimuli, which is more evident in the prefrontal than the posterior parietal cortex. Posterior parietal neurons also become active during tasks that require the organization of information into larger structured elements and their activity is modulated according to learned context-dependent rules. Neural correlates of learning can be observed in the mean discharge rate and spectral power of neuronal spike trains after training to perform new task sets or rules. These findings demonstrate the importance of posterior parietal cortex in brain networks mediating working memory and learning.     

Do equilibrium constraints modulate postural reaction when viewing imbalance?

Action observation and action execution are tightly coupled on a neurophysiological and a behavioral level, such that visually perceiving an action can contaminate simultaneous and subsequent action execution. More specifically, observing a model in postural disequilibrium was shown to induce an increase in observers' body sway. Here we reciprocally questioned the role of observers' motor system in the contagion process by comparing participants' body sway when watching displays of antero-posterior vs. lateral imbalance. Indeed, during upright standing, biomechanical constraints differ along the antero-posterior (A-P) and medio-lateral (M-L) axes; hence an impact of observers' postural constraints on the contagion response would result in different reactions to both types of stimuli. In response to the displays, we recorded greater area of center of pressure (CoP) displacement when watching forward/backward compared to left/right imbalance. In addition, after normalizing A-P and M-L CoP displacements by a control condition (fixation cross), A-P CoP path length when viewing forward imbalance tended to be higher than M-L CoP path length when viewing imbalance to the left or right. These results indicate that postural contagion is promoted when the display is compatible with observers' motor stabilization strategy which is mainly oriented along the A-P axis. In terms of clinical application, this study brings new indications for adaptation of observational training devices in rehabilitation programs.     

Selecting for Creativity and Innovation: The relationship between the innovation potential indicator and the team selection inventory

This article describes a study carried out to investigate the relationship between individual scores on the Innovation Potential Indicator (IPI), a measure of individual innovation behaviors for use in personnel selection, and the Team Selection Inventory (TSI), an individual‐level measure of a person's preferred team‐working climate for innovation. Results from a sample of 142 Greek employees found that the Motivation to Change scale of the IPI positively correlated with all of the TSI scales, and that the Adaptation scale positively correlated with the TSI's Vision and Task Orientation scales. Findings are discussed.     

Reading ability is negatively related to Stroop interference

Stroop interference is often taken as evidence for reading automaticity even though young and poor readers, who presumably lack reading automaticity, present strong interference. Here the relationship between reading skills and Stroop interference was studied in a 7th-grade sample. Greater interference was observed in children diagnosed with reading disability (dyslexia) than in unimpaired children. Moreover, poorer reading skills were found to correlate with greater Stroop interference in the general school population. In correlation and regression analyses, interference was primarily associated with reading speed, with an additional unique contribution of reading accuracy. Color naming errors were few and not comparably related to reading skills. The relation of reading skill to Stroop interference was examined in computational modeling simulations. The production model of Roelofs [Roelofs, A. (2003). Goal-referenced selection of verbal action: modeling attentional control in the Stroop task. Psychological Review, 110, 88-125], in which interference is primarily due to word stimuli having direct access to word form encoding whereas color naming must pass through concept activation and lemma selection, was found to account well for the human data after imposing covariation constraints on parameters controlling word processing and blocking latency, in modifications not affecting the model's previous fit to other data. The connectionist model of Cohen, Dunbar, and McClelland [Cohen, J. D., Dunbar, K., & McClelland, J. L. (1990). On the control of automatic processes: a parallel distributed processing account of the Stroop effect. Psychological Review, 97, 332-361], in which interference is caused by differential route strength, implementing an automaticity account, approximated the observed patterns with network-wide parameter manipulations not specific to reading, such as processing speed and response threshold, likely to affect previously optimized performance. On the basis of the empirical and modeling data we argue for a direct link between reading skill and interference, beyond the effects of executive functioning.     

Effects of imagery training on cognitive performance and use of physiological measures as an assessment tool of mental effort

The effectiveness of motor imagery training on cognitive performance was examined and the physiological mechanisms involved in the contribution of mental practice to motor learning were considered. The subject's mental effort during motor imagery was assessed by using psychophysiological measures and particularly eye blink activity as an 'indirect' measurement of subjects' attention. An electronic flight simulation program (Multiple Attribute Task Battery--MATB) was used to assess performance. Twenty healthy volunteers participated in the study divided in two groups: the control group and the imagery-training group. The subjects of the imagery group were asked for additional imagery training. The subjects of the actual performing group were asked additionally to passively observe the task in order to have equal time of exposure to the task. Performance scores and physiological parameters such as heart rate, respiratory rate, eye blinking activity and muscular activity were recorded during all sessions. The results revealed significantly higher performance level of the imagery-training group than the control group. Heart rate and respiratory rate significantly increased during imagery sessions compared to rest. A slight electromyographic activity was observed during the imagination of movement. Our findings support the notion that mental practice improves motor performance in a task where spatiotemporal or dynamic control of the action is highly required. The effects of mental practice on motor performance could be explained by the existence of a top-down mechanism based on the activation of a central representation of the movements, since the vegetative activation during motor imagery seems to be centrally controlled.     

A case-control study of hopelessness and suicidal behavior in the city of Athens,Greece. The role of the financial crisis

This study aimed to examine the psychometric properties of Beck Hopelessness Scale (BHS) in Greek patients with a recent suicide attempt, the predictive ability of BHS especially in terms of age and the possible effect of the financial crisis on hopelessness as it has been identified as a significant suicide risk factor. The study included a total of 510 individuals, citizens of Athens, Greece. Three hundred and forty individuals (170 attempted suicide patients, and 170 -age and gender- matched healthy individuals used as controls) completed BHS before the financial crisis onset (from 2009 to 2010). A sample of 170 healthy individuals also completed the BHS after the financial crisis onset (from 2013 to 2014), when the impact of the austerity measures was being felt by the Greek society. The Greek BHS version demonstrated good psychometric properties and a sufficient degree of internal consistency. Attempted suicide patients (M = 9) presented higher hopelessness than the controls (M = 3). The patients’ age positively correlated with hopelessness (r_s = .35, p < .001), and the ROC curve revealed that the BHS ability to discriminate the individuals with pathological rates of hopelessness from those without, strengthened as age increased. No significant differences were found between the individuals evaluated before (M = 3) and after (M = 3, p > .05) the crisis onset. Nevertheless, regarding the latter group, the women, the younger individuals, the less educated, the unemployed and the participants with low or mediocre self-reported financial status presented increased hopelessness. Our findings suggest that BHS could be a useful instrument especially when screening for suicide risk in people of older age, and that the financial crisis in Greece had a greater impact on subgroups of the population regarding hopelessness.     

Laboratory strength measures of talented and less talented Greek children ages 9 to 10 years

The purpose was twofold: (1) to assess whether laboratory tests can distinguish talented groups and less talented groups of children identified by their total scores in a battery of field tests and (2) to evaluate whether scores in field and laboratory tests are correlated. 36 children (ages 9 to 10 years) were divided into groups of higher and lower total scores on standing long jump, medicine ball throw, and sprint. Both groups were tested for maximum isometric force, force produced at the initial 100 msec., reactive force index, drop jump height, squat jump height, and maximum pedaling rate. Analysis showed the talented group had significantly (p < or = .05) higher scores on maximum isometric force, force produced in the initial 100 msec., and drop jump height than less talented children. Moderate to high correlations were found among scores for field performance tests with maximum pedaling rate. In conclusion, the laboratory tests distinguished the talented and less talented children in maximal isometric force, the force produced at the initial 100 msec., the reactive force index, and the drop jump height.     

Beat the Heat: Effects of a Motivational Self-Talk Intervention on Endurance Performance

The study examined the effects of a motivational self-talk intervention on endurance cycling performance in hot conditions. Participants were 16 physically active adult men. After a baseline VO₂ peak assessment and two training sessions, participants completed a 30 min cycling trial in a hot environment (35°C, 45% relative humidity) while maintaining a steady rate of perceived exertion. Participants of the intervention group produced greater power output during the final third of the trial. Findings suggest that the self-talk strategy seems to have compromised the aversive effects of the demanding environmental conditions and provide support for the psychobiological model of endurance performance.