Heritability of Stroop and flanker performance in 12-year old children

Background  

There is great interest in appropriate phenotypes that serve as indicator of genetically transmitted frontal (dys)function, such as ADHD. Here we investigate the ability to deal with response conflict, and we ask to what extent performance variation on response interference tasks is caused by genetic variation. We tested a large sample of 12-year old monozygotic and dizygotic twins on two well-known and closely related response interference tasks; the color Stroop task and the Eriksen flanker task. Using structural equation modelling we assessed the heritability of several performance indices derived from those tasks.     

The contribution of high frequencies to human brain activity underlying horizontal localization of natural spatial sounds

Background  

In the field of auditory neuroscience, much research has focused on the neural processes underlying human sound localization. A recent magnetoencephalography (MEG) study investigated localization-related brain activity by measuring the N1m event-related response originating in the auditory cortex. It was found that the dynamic range of the right-hemispheric N1m response, defined as the mean difference in response magnitude between contralateral and ipsilateral stimulation, reflects cortical activity related to the discrimination of horizontal sound direction. Interestingly, the results also suggested that the presence of realistic spectral information within horizontally located spatial sounds resulted in a larger right-hemispheric N1m dynamic range. Spectral cues being predominant at high frequencies, the present study further investigated the issue by removing frequencies from the spatial stimuli with low-pass filtering. This resulted in a stepwise elimination of direction-specific spectral information. Interaural time and level differences were kept constant. The original, unfiltered stimuli were broadband noise signals presented from five frontal horizontal directions and binaurally recorded for eight human subjects with miniature microphones placed in each subject's ear canals. Stimuli were presented to the subjects during MEG registration and in a behavioral listening experiment.     

Observation of band structures in the odd-odd nucleus126La

The odd-odd nucleus¹²⁶La has been studied in the reactions¹¹¹Cd(¹⁹F,4n) and⁹³Nb(³⁷Cl,p3n). Three band structures have been identified, two of them having both signature members and ΔI=1 character. These are proposed, respectively, to have πh_11/2 ? νh_11/2 and πh_11/2 ? νg_7/2 configurations and tentative 4⁺ and 3^? band heads.     

High-spin structure in154Er

High spin states in the nucleus¹⁵⁴Er have been reinvestigated using the¹²³Sb(³⁵Cl, 4n) reaction and a variety of spectroscopic techniques including excitation functions,γ-γ coincidences,γ angular distribution and linear polarization measurements. From the measured energies, relative intensities and transition multipolarities a new level scheme has been deduced up to an excitation energy of ～12 MeV and spin 36. An interpretation of the experimental results is given in terms of the deformed Woods-Saxon orbitals. Gigantic backbending (superdeformation) effect is studied theoretically within the cranking model.     

Multipolarity of the continuum γ-rays in 152Dy and 160Er via linear polarisation measurements

The multipolarity of the continuum transitions in ¹⁵²Dy and ¹⁶⁰Er has been deduced from γ-ray linear polarisation and angular distribution measurements. The yrast part for ¹⁶⁰Er agrees with the predicted stretched E2 cascade. The statistical parts for both ¹⁵²Dy and ¹⁶⁰Er consist of a mixture of dipolar stretched and non-stretched transitions, predominantly of electrical character. Below 1.5 MeV, the data of ¹⁵²Dy exhibit a different structure, and reveal a stretched M1 component in the low-energy region.     

Configuration assignments and decay of 126La high-spin bands

High spin states of ¹²⁶La have been populated using the reaction ¹¹⁶Sn+¹⁴N at 68 MeV. γ-rays and conversion electrons were detected with the GAREL array. Multipolarities of the lowest-lying in-band dipole transitions have been determined from the deduced internal conversion coefficients. Experimental B(M1)/B(E2) ratios have been derived for the bands and compared with calculated values using the D?nau-Frauendorf geometrical model. Configurations are proposed for the bands comparing them with cranked shell model calculations and on the basis of the measured B(M1)/B(E2) ratios. The β-decay of ¹²⁶La has also been revisited. The population of the ¹²⁶Ba levels gives a probable spin value of five for the decaying high-spin ¹²⁶La state with T _1/2≈ 64 s which may indicate a signature inversion in the πh_11/2νh_11/2 band. Received: 12 October 1999