Genetic influences on prefrontal activation during a verbal fluency task in children: A twin study using near-infrared spectroscopy

Objective: The genetic and environmental influences on prefrontal function in childhood are underinvestigated due to the difficulty of measuring prefrontal function in young subjects, for which near‐infrared spectroscopy (NIRS) is a suitable functional neuroimaging technique that facilitates the easy and noninvasive measurement of blood oxygenation in the superficial cerebral cortices.Method: Using a two‐channel NIRS arrangement, we measured changes in bilateral prefrontal blood oxygenation during a category version of the verbal fluency task (VFT) in 27 monozygotic twin pairs and 12 same‐sex dizygotic twin pairs ages 5–17 years. We also assessed the participant's full‐scale intelligence quotient (FIQ) and retrieved parental socioeconomic status (SES). Classical structured equation modeling was used to estimate the heritability.Results: The heritability of VFT‐related brain activation was estimated to be 44% and 37% in the right and left prefrontal regions, respectively. We also identified a significant genetic contribution (74%) to FIQ, but did not to VFT task performance. Parental SES was not correlated with FIQ, task performance, or task‐related prefrontal activation.Conclusions: This finding provides further evidence that variance in prefrontal function has a genetic component since childhood and highlights brain function, as measured by NIRS, as a promising candidate for endophenotyping neurodevelopmental disorders

Spontaneous Ejaculation in a Wild Indo-Pacific Bottlenose Dolphin (<i>Tursiops aduncus</i>)

<div><p>Spontaneous ejaculation, which is defined as the release of seminal fluids without apparent sexual stimulation, has been documented in boreoeutherian mammals. Here we report spontaneous ejaculation in a wild Indo-Pacific bottlenose dolphin (<i>Tursiops aduncus</i>), and present a video of this rare behavior. This is the first report of spontaneous ejaculation by an aquatic mammal, and the first video of this behavior in animals to be published in a scientific journal.</p></div

Spontaneous ejaculation by a wild Indo-Pacific bottlenose dolphin off Mikura Island, Japan.

<p>(A) Dense seminal fluid was ejaculated from the tip of the penis with initial contraction of the peduncle muscle downward. (B) A few seconds after the first ejaculation of seminal fluid, the remaining seminal fluid was ejaculated for 0.86 s (26 frames at (1/30 s)/frame).</p