Effects of Auditory Attention Training with the Dichotic Listening Task: Behavioural and Neurophysiological Evidence

<div><p>Facilitation of general cognitive capacities such as executive functions through training has stirred considerable research interest during the last decade. Recently we demonstrated that training of auditory attention with forced attention dichotic listening not only facilitated that performance but also generalized to an untrained attentional task. In the present study, 13 participants underwent a 4-week dichotic listening training programme with instructions to report syllables presented to the left ear (FL training group). Another group (n = 13) was trained using the non-forced instruction, asked to report whichever syllable they heard the best (NF training group). The study aimed to replicate our previous behavioural results, and to explore the neurophysiological correlates of training through event-related brain potentials (ERPs). We partially replicated our previous behavioural training effects, as the FL training group tended to show more allocation of auditory spatial attention to the left ear in a standard dichotic listening task. ERP measures showed diminished N1 and enhanced P2 responses to dichotic stimuli after training in both groups, interpreted as improvement in early perceptual processing of the stimuli. Additionally, enhanced anterior N2 amplitudes were found after training, with relatively larger changes in the FL training group in the forced-left condition, suggesting improved top-down control on the trained task. These results show that top-down cognitive training can modulate the left-right allocation of auditory spatial attention, accompanied by a change in an evoked brain potential related to cognitive control.</p></div

NF condition.

<p>Red bars = left-ear responses, blue bars = right-ear responses. The left-sided bar of each two bars of the same colour represents pre-training results and the right-sided bar post-training results. Error bars display 95% confidence interval for mean.</p

FL condition EEG responses.

<p>Pre-training waveform in red and post-training waveform in black. Negative plotted up.</p

FR condition.

<p>Red bars = left-ear responses, blue bars = right-ear responses. The left-sided bar of each two bars of the same colour represents pre-training results and the right-sided bar post-training results. Error bars display 95% confidence interval for mean.</p

Mean amplitudes (SD) before and after training.

<p>Mean (SD) separately for each DL condition and both groups. Amplitudes are averaged across all ROIs.</p

Risk-Taking Behavior in a Computerized Driving Task: Brain Activation Correlates of Decision-Making, Outcome, and Peer Influence in Male Adolescents

<div><p>Increased propensity for risky behavior in adolescents, particularly in peer groups, is thought to reflect maturational imbalance between reward processing and cognitive control systems that affect decision-making. We used functional magnetic resonance imaging (fMRI) to investigate brain functional correlates of risk-taking behavior and effects of peer influence in 18–19-year-old male adolescents. The subjects were divided into low and high risk-taking groups using either personality tests or risk-taking rates in a simulated driving task. The fMRI data were analyzed for decision-making (whether to take a risk at intersections) and outcome (pass or crash) phases, and for the influence of peer competition. Personality test-based groups showed no difference in the amount of risk-taking (similarly increased during peer competition) and brain activation. When groups were defined by actual task performance, risk-taking activated two areas in the left medial prefrontal cortex (PFC) significantly more in low than in high risk-takers. In the entire sample, risky decision-specific activation was found in the anterior and dorsal cingulate, superior parietal cortex, basal ganglia (including the nucleus accumbens), midbrain, thalamus, and hypothalamus. Peer competition increased outcome-related activation in the right caudate head and cerebellar vermis in the entire sample. Our results suggest that the activation of the medial (rather than lateral) PFC and striatum is most specific to risk-taking behavior of male adolescents in a simulated driving situation, and reflect a stronger conflict and thus increased cognitive effort to take risks in low risk-takers, and reward anticipation for risky decisions, respectively. The activation of the caudate nucleus, particularly for the positive outcome (pass) during peer competition, further suggests enhanced reward processing of risk-taking under peer influence.</p></div

NF condition EEG responses.

<p>Pre-training waveform in red and post-training waveform in black. Negative plotted up.</p

Areas of outcome-related activation manipulated by the social factor (peer competition) in the ventral part of the caudate head (A) and cerebellar vermis (B) obtained from the analysis of the entire sample (both high and low risk-takers together).

<p>Corresponding plots show estimates of average effect size (ordinate, in an arbitrary unit) and SE within 6 mm spherical volumes centered at voxels with the highest values (indicated by crosshairs). The areas are shown overlaid onto three orthogonal slices of the MNI (ICBM152) template at the p < 0.0001 uncorrected threshold for better illustration.</p

FR condition EEG responses.

<p>Pre-training waveform in red and post-training waveform in black. Negative plotted up.</p

Timeline (from left to right) of events in a single round (trial) of the Stoplight game.

<p>Timeline (from left to right) of events in a single round (trial) of the Stoplight game.</p