Altered binaural hearing in pre-ataxic and ataxic mutation carriers of spinocerebellar ataxia type 3.

Brainstem degeneration is a prominent feature of spinocerebellar ataxia type 3 (SCA3), involving structures that execute binaural synchronization with microsecond precision. As a consequence, auditory processing may deteriorate during the course of disease. We tested whether the binaural "Huggins pitch" effect is suitable to study the temporal precision of brainstem functioning in SCA3 mutation carriers. We expected that they would have difficulties perceiving Huggins pitch at high frequencies, and that they would show attenuated neuromagnetic responses to Huggins pitch. The upper limit of Huggins pitch perception was psychoacoustically determined in 18 pre-ataxic and ataxic SCA3 mutation carriers and in 18 age-matched healthy controls. Moreover, the cortical N100 response following Huggins pitch onset was acquired by means of magnetoencephalography (MEG). MEG recordings were analyzed using dipole source modeling and comprised a monaural pitch condition and a no-pitch condition with simple binaural correlation changes. Compared with age-matched controls, ataxic but not pre-ataxic SCA3 mutation carriers had significantly lower frequency limits up to which Huggins pitch could be heard. Listeners with lower frequency limits also showed diminished MEG responses to Huggins pitch, but not in the two control conditions. Huggins pitch is a promising tool to assess brainstem functioning in ataxic SCA3 patients. Future studies should refine the psychophysiological setup to capture possible performance decrements also in pre-ataxic mutation carriers. Longitudinal observations will be needed to prove the potential of the assessment of Huggins pitch as a biomarker to track brainstem functioning during the disease course in SCA3.

Valuing humans over animals - Gender differences in meat-eating behavior and the role of the Dark Triad.

Empirical findings demonstrate gender differences in attitudes toward meat consumption and actual meat-eating behavior. Furthermore, several studies have found that men score higher on all three Dark Triad personality dimensions (Machiavellianism, narcissism, and psychopathy). In this study, we investigated whether these personality differences mediate the association between gender and meat-eating justification, which in turn was expected to predict meat consumption. Two-hundred-fifty-seven participants took part in the study. We replicated the finding that men score higher on direct justification strategies with respect to meat consumption and report less often that they are vegetarians or vegans. Moreover, and most importantly, gender differences in Machiavellianism (but not in the other Dark Triad traits) significantly mediated these gender differences in meat-eating justification strategies, which in turn predicted meat consumption. These findings support the idea that Machiavellianism is partly able to explain gender differences in meat-eating justification, which is associated with higher meat consumption.