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Human speech can be divided into short, rhythmically timed elements, similar to syllables within words. Even our cries and laughs, as well as the vocalizations of other species, are periodic. However, the cellular and molecular mechanisms underlying the tempo of mammalian vocalizations remain unknown. Furthermore, even the core cells that produce vocalizations remain ill-defined. Here, we describe rhythmically timed neonatal mouse vocalizations that occur within single breaths and identify a brainstem node that is necessary for and sufficient to structure these cries, which we name the intermediate reticular oscillator (iRO). We show that the iRO acts autonomously and sends direct inputs to key muscles and the respiratory rhythm generator in order to coordinate neonatal vocalizations with breathing, as well as paces and patterns these cries. These results reveal that a novel mammalian brainstem oscillator embedded within the conserved breathing circuitry plays a central role in the production of neonatal vocalizations.

Objective: We sought to determine the incidence, clinical features, and demographic profile of head injury secondary to suspected child maltreatment (abuse or neglect) in Canada to help inform the development and evaluation of prevention programs for abusive head injuries. Methods: From March 1, 2005 to February 28, 2008, an average of 2,545 paediatricians and paediatric subspecialists were surveyed monthly through the established network of the Canadian Paediatric Surveillance Program. We calculated incidence rates using the number of confirmed cases over the product of the duration of the study (3 years) and population estimates by age group. Results: There were 220 confirmed cases of head injury from suspected child maltreatment. The annual incidence rate was 14.1 per 100,000 for children less than 1 year of age and 1.4 per 100,000 for those less than 15 years. Seventy three percent (141) of cases involved infants less than 12 months of age and 52% (100) of cases involved infants less than 6 months of age. Seventy-five percent (165) of cases presented to the emergency room. With regard to outcome, 12% (27) of cases resulted in death and 45% (75) of survivors had neurological sequelae at discharge. Thirty percent (67) of all cases, as well as 30% (8) of deaths were previously known to child welfare authorities. Conclusion: This study provides an estimate of the rate of head injury secondary to suspected child maltreatment in Canada. The young age and poor medical outcomes of those involved highlights the need for prevention efforts that are implemented early in life. Given that a significant percentage of injured infants and children were already known to child welfare authorities, the study also highlights the need to establish and evaluate additional preventive efforts for parents and caregivers already in the child welfare system. (Contains 5 tables.)

Objective: Shaken Baby Syndrome (SBS) is now recognized as being the main cause of severe traumatic brain injury in infancy. However, our understanding of the impact of this type of abuse on child development remains sketchy. The main objective of the current study was therefore to shed light on the cognitive dysfunctions that are particular to SBS victims once they are school-aged. Method: A clinical group was formed of 11 children diagnosed with SBS who had been admitted between 1988 and 1999 to a tertiary pediatric hospital in Quebec, Canada. The children were matched for age, gender, socio-economic status, and family composition to 11 healthy Quebec children, who made up the control group. A battery of composite tests was developed to assess the children's main cognitive functions and was administered individually to the 22 children. A univariate t-test was used to compare the performances of the two groups. Results: The mean age of the children in the clinical and control groups at the time of the assessment was 87.64 months and 90.18 months, respectively. Pairing and birth data were equivalent for both groups. Significant weaknesses were noted in the clinical group for intelligence quotient (IQ), working memory, mental organization, alternation, and inhibition. These deficits seemed to have a greater impact on the verbal sphere of the children's mental functioning. Conclusion: Primary results point to the anterior cerebral regions of the brain as the principal site of dysfunctions that persist years post-trauma. It is important to consider these results longitudinally, even in children apparently less extensively affected, since the frontal regions only reach maturity at the end of adolescence.

A study investigated the usefulness of cerebral magnetic resonance imaging (MRI) in detecting possible child abuse in 12 children with unexplained neurologic findings. MRI findings were diagnostic for physical abuse in eight cases. A diagnosis of child abuse was made in two more cases by a combination of MRI and survey findings. (Author/CR)

All forms of locomotion are repetitive motor activities that require coordinated bilateral activation of muscles. The executive elements of locomotor control are networks of spinal neurons that determine gait pattern through the sequential activation of motor-neuron pools on either side of the body axis (1-4). However, little is known about the constraints that link left-right coordination to locomotor speed. Recent advances have indicated that both excitatory and inhibitory commissural neurons maybe involved in left-right coordination (5-7). But the neural underpinnings of this, and a possible causal link between these different groups of commissural neurons and left-right alternation, are lacking. Here we show, using intersectional mouse genetics, that ablation of a group of transcriptionally defined commissural neurons--the V0 population--leads to a quadrupedal hopping at all frequencies of locomotion. The selective ablation of inhibitory V0 neurons leads to a lack of left-right pattern at low frequencies, mixed coordination at medium frequencies, and alternation at high locomotor frequencies. When ablation is targeted to excitatory V0 neurons, left-right alternation is present at low frequencies, and hopping is restricted to medium and high locomotor frequencies. Therefore, the intrinsic logic of the central control of locomotion incorporates a modular organization, with two subgroups of V0 neurons required for the existence of left-right alternating modes at different speeds of locomotion. The two molecularly distinct sets of commissural neurons may constrain species-related naturally occurring frequency-dependent coordination and be involved in the evolution of different gaits., V0 neurons, characterized by the early expression of the transcription factor Dbx1 (refs 8, 9), represent a major class of commissural neurons in the ventral spinal cord, where the locomotor [...]

The well-known diffraction grating equation can be represented by a simple and useful graph that makes the analysis of the diffraction orders produced by a grating easier. This paper explains the construction of the graph and how to use it with an example. [DOI: 10.1119/1.2787016]

We present a novel scheme of tunable semiconductor laser based on the use of a chirped grating in an external cavity. The chirped grating is fabricated using a simple holographic technique: two Gaussian beams having wavefronts with different radii of curvature are brought to interfere on a photoresist layer. The tuning properties of chirped gratings have been investigated with semiconductor lasers operated with an external cavity. With this type of grating positioned in Littrow configuration, the wavelength selection can be done by translating the grating without any need to rotate it. This cavity configuration provides a tunable output beam with an angle of propagation that is independent of the wavelength. The translation of chirped gratings was shown to tune a visible diode laser and an infrared diode laser over the same spectral band as the conventional tuning scheme where an unchirped grating is rotated. OCIS codes: 050.2770, 090.2890, 140.2020, 140.3570, 140.5960, 220.1230, 230.1950.

We have developed a new design of optical spectrometer based on the use of a chirped holographic grating inscribed on a flat substrate. This type of grating has a surface modulation with a spatially varying period. The ability of the chirped grating to focus a beam is exploited to reduce significantly the physical dimensions of the instrument. Wavelength selection is achieved by a pure translation of the chirped grating. The properties of the chirped grating spectrometer have been characterized with different lasers and arc lamps and compared with those of two commercial spectrometers. A performance parameter has been defined, enabling the various instruments to be compared.

The first important monograph describing the battered child syndrome was written in 1860 by Ambroise Tardieu, a French forensic physician. Here is a translation of his article, published in the Annales d'hygiene publique el de mdecine legale, with the title 'Etude medico-legale sur les sevices et mauvais traitements exerces sur des enfants.' The first part of his article is entirely translated. A brief summary of the 32 cases report described by Tardieu in the second part of his article is presented. Keywords: Ambroise Tardieu; History of child abuse

Respiration is a rhythmic motor behavior that appears in the fetus and acquires a vital importance at birth. It is generated centrally, within neuronal networks of the hindbrain. This region of the brain is of particular interest since it is the best understood with respect to the cellular and molecular mechanisms that underlie its development. Examination of hindbrain activities in the chick embryo has revealed that the central rhythm generator is active before fetal maturation and conforms to the rhombomeric organization of the embryonic hindbrain. Inactivation of genes required for the normal formation of rhombomeres in mice leads to perturbations of the reticular formation that affect respiration after birth and compromise the probability of survival. From studies of hindbrain development we might gain an understanding of how genes govern the early embryonic development of neuronal networks and how this might specify patterns of motor activities operating throughout life.