The discovery of audiovisual mirror neurons in monkeys gave rise to the hypothesis that premotor areas are inherently involved not only when observing actions but also when listening to action-related sound. However, the whole-brain functional formation underlying such "action-listening" is not fully understood. In addition, previous studies in humans have focused mostly on relatively simple and overexperienced everyday actions, such as hand clapping or door knocking. Here we used functional magnetic resonance imaging to ask whether the human action-recognition system responds to sounds found in a more complex sequence of newly acquired actions. To address this, we chose a piece of music as a model set of acoustically presentable actions and trained non-musicians to play it by ear. We then monitored brain activity in subjects while they listened to the newly acquired piece. Although subjects listened to the music without performing any movements, activation was found bilaterally in the frontoparietal motor-related network (including Broca's area, the premotor region, the intraparietal sulcus, and the inferior parietal region), consistent with neural circuits that have been associated with action observations, and may constitute the human mirror neuron system. Presentation of the practiced notes in a different order activated the network to a much lesser degree, whereas listening to an equally familiar but motorically unknown music did not activate this network. These findings support the hypothesis of a "hearing-doing" system that is highly dependent on the individual's motor repertoire, gets established rapidly, and consists of Broca's area as its hub.

In this early pilot study, we sought to determine if the alteration in these physiologic effects in premature infants in response to ambient noise in the NICU could be assessed evaluating cerebral blood saturation. Three premature infants, on high flow nasal cannula oxygen support (HFNC), at less than 34 weeks of gestation were included in the study. Three variables were used to evaluate sound levels due to AAP and EPA guidelines; Leq,1h, L10,1h and Lmax,1min. All of the patients studied were found to be exposed to statistically significant noise levels (above recommendation) throughout all of the time periods measured. Noise levels were found to be similarly elevated during the 1 am and 3 pm time periods as well, though not as much as compared to the 7 am measure. A statistically significant difference was found within every patient's rSO2 levels in both hemispheres, but also in the absolute differences of rSO2. Positive significant statistical correlations were found between the average rSO2 and Leq,1h (ρ=0.14), Lmax,1min (ρ=0.18), L10,1h (ρ=0.15). Significant negative correlations were found between the absolute difference levels and Lmax,1min (ρ=-0.3), and L10,1h (ρ=-0.18) This data highlights the need for further study as to the potential impact of noise on the cerebral physiology of premature infants. Further research is needed to assess the potential long-term side effects of environmental noise on the premature in-fant's brain.

Elevated stress levels and depressive symptoms are already present in mothers of preterm infants upon NICU admission. Being married or living long distance from the hospital is associated with higher stress. Future work is needed to develop effective interventions for alleviating stress in NICU mothers and preventing its potential development into postnatal depression.