Analysis of Fracture Distribution in the Surgical Neck Region of the Proximal Humerus: a 3D Bone Cortical Thickness Mapping Study

Objection: Among the many studies on the proximal humerus, few have focused on cortical bone distribution around the surgical neck region and its relationship with the epiphysis. Materials and methods: Ninety-five surgical neck fracture patients with available plain X-rays and CT scans were enrolled. In addition, 38 normal subjects were also included to illustrate the cortical thickness of the diaphysis, cortical change region and greater tuberosity.Results: The fracture lines were mainly distributed in the cortical change region. Significant differences were found in cortical thickness between the diaphysis, surgical region and greater tuberosity in men and women. The thickest cortex was noted in the diaphysis, and the thinnest cortex was noted in the greater tuberosity. No significant differences were observed in the width of the cortical change region in man and women.Conclusion: The surgical neck region had decreased cortical thickness. It was concluded that the epiphysis connection region had an effect and acted on the proximal humeral fracture pattern in adults; therefore, the surgical neck fracture was identified as an epiphyseal relative fracture.

Act Now, Play Later: Temporal Expectations Regarding the Onset of Self-initiated Sensations Can Be Modified with Behavioral Training

Mechanisms of motor-sensory prediction are dependent on expectations regarding when self-generated feedback will occur. Existing behavioral and electrophysiological research suggests that we have a default expectation for immediate sensory feedback after executing an action. However, studies investigating the adaptability of this temporal expectation have been limited in their ability to differentiate modified expectations per se from effects of stimulus repetition. Here, we use a novel, within-participant procedure that allowed us to disentangle the effect of repetition from expectation and allowed us to determine whether the default assumption for immediate feedback is fixed and resistant to modification or is amenable to change with experience. While EEG was recorded, 45 participants completed a task in which they repeatedly pressed a button to produce a tone that occurred immediately after the button press (immediate training) or after a 100-msec delay (delayed training). The results revealed significant differences in the patterns of cortical change across the two training conditions. Specifically, there was a significant reduction in the cortical response to tones across delayed training blocks but no significant change across immediate training blocks. Furthermore, experience with delayed training did not result in increased cortical activity in response to immediate feedback. These findings suggest that experience with action–sensation delays broadens the window of temporal expectations, allowing for the simultaneous anticipation of both delayed and immediate motor-sensory feedback. This research provides insights into the mechanisms underlying motor-sensory prediction and may represent a novel therapeutic avenue for psychotic symptoms, which are ostensibly associated with sensory prediction abnormalities.

Changes in ventromedial prefrontal and insular cortex support the development of metamemory from childhood into adolescence

Metamemory monitoring, or the ability to introspect on the accuracy of one’s memories, improves considerably during childhood, but the underlying neural changes and implications for intellectual development are largely unknown. The present study examined whether cortical changes in key brain areas hypothesized to support metacognition contribute to the development of metamemory monitoring from late childhood into early adolescence. Metamemory monitoring was assessed among 7- to 12-y-old children (n = 145) and adults (n = 31). Children returned for up to two additional assessments at 8 to 14 y of age (n = 120) and at 9 to 15 y of age (n = 107) (n = 347 longitudinal scans). Results showed that metamemory monitoring continues to improve from childhood into adolescence. More pronounced cortical thinning in the anterior insula and a greater increase in the thickness of the ventromedial prefrontal cortex over the three assessment points predicted these improvements. Thus, performance benefits are linked to the unique patterns of regional cortical change during development. Metamemory monitoring at the first time point predicted intelligence at the third time point and vice versa, suggesting parallel development of these abilities and their reciprocal influence. Together, these results provide insights into the neuroanatomical correlates supporting the development of the capacity to self-reflect, and highlight the role of this capacity for general intellectual development.

Differences in Pre-Attentive Processes of Sound Intensity Change Between High- and Low-Sensation Seekers

High-sensation seekers are prone to search for changing stimuli. Pre-attentive processes reveal the earliest cortical change detection in response to external stimulus changes. This study recorded the mismatch negativity (MMN) to intensity increments and decrements in a repetitive tone in high- and low-sensation seekers. It was found that the MMN amplitude for intensity-decrement deviants was larger in high- than low-sensation seekers. However, with regard to deviant-increment stimulation, the difference between the two groups was not significant. Consequently, the sensitivity of high-sensitivity seekers to pre-attentively detect a decrease in sound intensity is higher than that of low-sensation seekers.

Neurodevelopmental origins of lifespan changes in brain and cognition

Neurodevelopmental origins of functional variation in older age are increasingly being acknowledged, but identification of how early factors impact human brain and cognition throughout life has remained challenging. Much focus has been on age-specific mechanisms affecting neural foundations of cognition and their change. In contrast to this approach, we tested whether cerebral correlates of general cognitive ability (GCA) in development could be extended to the rest of the lifespan, and whether early factors traceable to prenatal stages, such as birth weight and parental education, may exert continuous influences. We measured the area of the cerebral cortex in a longitudinal sample of 974 individuals aged 4–88 y (1,633 observations). An extensive cortical region was identified wherein area related positively to GCA in development. By tracking area of the cortical region identified in the child sample throughout the lifespan, we showed that the cortical change trajectories of higher and lower GCA groups were parallel through life, suggesting continued influences of early life factors. Birth weight and parental education obtained from the Norwegian Mother–Child Cohort study were identified as such early factors of possible life-long influence. Support for a genetic component was obtained in a separate twin sample (Vietnam Era Twin Study of Aging), but birth weight in the child sample had an effect on cortical area also when controlling for possible genetic differences in terms of parental height. Our results provide novel evidence for stability in brain–cognition relationships throughout life, and indicate that early life factors impact brain and cognition for the entire life course.