Low salivary cortisol levels and externalizing behavior problems in youth

Research linking basal cortisol levels with internalizing and externalizing behavior problems in youths has yielded inconsistent results. We hypothesize that the high moment to moment variation in adrenocortical activity requires an analytical strategy that separates variance in cortisol levels attributable to "stable traitlike" versus "state or situationally specific" sources. Early morning saliva samples were obtained from 724 youths (M age = 13.5 years; range = 6-16 years in Year 1) on 2 successive days 1 year apart. Latent state-trait modeling revealed that 70% of the variance in cortisol levels could be attributed to statelike sources, and 28% to traitlike sources. For boys only, higher levels of externalizing problem behaviors were consistently associated with lower cortisol attributable to traitlike sources across 3 years of behavioral assessment. The inverse association between individual differences in cortisol and externalizing problem behavior has previously only been reported in studies of at-risk or clinical groups. The present findings suggest the relationship is a stable phenomenon that spans both normative and atypical child development. Studies are needed to reveal the biosocial mechanisms involved in the establishment and maintenance of this phenomenon, and to decipher whether individual differences in this hormone-behavior link confers risk or resilience.     

Neural mechanisms for generating rate and temporal codes in model CA3 pyramidal cells

The effect of synaptic inhibition on burst firing of a two-compartment model of a CA3 pyramidal cell is considered. We show that, depending on its timing, a short dose of fast decaying synaptic inhibition can either delay or advance the timing of firing of subsequent bursts. Moreover, increasing the strength of the inhibitory input is shown to modulate the burst profile from a full complex burst, to a burst with multiple spikes, to single spikes. We additionally show how slowly decaying inhibitory input can be used to synchronize a network of pyramidal cells. Implications for the phase precession phenomenon of hippocampal place cells and for the generation of temporal and rate codes are discussed.     

Differential effects of the adenosine A1 receptor agonist adenosine amine congener on renal, femoral and carotid vascular conductance in preterm fetal sheep

1. Adenosine A(1) receptor activation is critical for endogenous neuroprotection from hypoxia-ischaemia, raising the possibility that treatment with A(1) receptor agonists may be an effective physiological protection strategy for vulnerable preterm infants. However, the A(1) receptor can mediate unwanted systemic effects, including vasoconstriction of the afferent glomerular arteriole. There is limited information on whether this occurs at doses that improve cerebral perfusion in the immature brain. 2. Therefore, in the present study, we examined whether infusion of the selective A(1) receptor agonist adenosine amine congener (ADAC) is associated with reduced renal perfusion in chronically instrumented preterm (0.7 gestation) fetal sheep. In the present study, ADAC was given in successive doses of 2.5, 5.0 and 15.0 microg, 45 min apart. 3. Treatment with ADAC was associated with a marked reduction in renal vascular conductance (and blood flow), whereas carotid conductance was increased and there was no significant effect on femoral conductance. In contrast with the stable effects of increasing ADAC dose on vascular conductance, there was a significant dose-related fall in fetal heart rate and blood pressure. 4. In conclusion, these short-term data support the concern that A(1) receptor agonist infusion can selectively impair renal perfusion, even at low doses.     

Spectrum of Clinical and Associated MR Imaging Findings in Children with Olfactory Anomalies

BACKGROUND AND PURPOSE:The olfactory apparatus, consisting of the bulb and tract, is readily identifiable on MR imaging. Anomalous development of the olfactory apparatus may be the harbinger of anomalies of the secondary olfactory cortex and associated structures. We report a large single-site series of associated MR imaging findings in patients with olfactory anomalies.MATERIALS AND METHODS:A retrospective search of radiologic reports (2010 through 2014) was performed by using the keyword “olfactory”; MR imaging studies were reviewed for olfactory anomalies and intracranial and skull base malformations. Medical records were reviewed for clinical symptoms, neuroendocrine dysfunction, syndromic associations, and genetics.RESULTS:We identified 41 patients with olfactory anomalies (range, 0.03–18 years of age; M/F ratio, 19:22); olfactory anomalies were bilateral in 31 of 41 patients (76%) and absent olfactory bulbs and olfactory tracts were found in 56 of 82 (68%). Developmental delay was found in 24 (59%), and seizures, in 14 (34%). Pituitary dysfunction was present in 14 (34%), 8 had panhypopituitarism, and 2 had isolated hypogonadotropic hypogonadism. CNS anomalies, seen in 95% of patients, included hippocampal dysplasia in 26, cortical malformations in 15, malformed corpus callosum in 10, and optic pathway hypoplasia in 12. Infratentorial anomalies were seen in 15 (37%) patients and included an abnormal brain stem in 9 and an abnormal cerebellum in 3. Four patients had an abnormal membranous labyrinth. Genetic testing was performed in 23 (56%) and findings were abnormal in 11 (48%).CONCLUSIONS:Olfactory anomalies should prompt careful screening of the brain, skull base, and the pituitary gland for additional anomalies. Genetic testing should be considered.

Olfaction involves recognition of myriad chemicals in various concentrations enabling discrimination among scents. In humans, the olfactory system provides less survival advantage than the other senses and the olfactory apparatus is proportionately much smaller than that in other mammals but is readily identifiable on routine MR imaging.¹The olfactory system begins to form early in gestation and has multiple origins, including the olfactory placode, cranial neural crest, and the olfactory bulb (OB), which is an extension of the telencephalon. The olfactory placode develops into the olfactory epithelium and nerves, which migrate toward the developing OB. Olfactory ensheathing cells are likely neural crest derivatives, which serve as a scaffolding for initial migration.² Adjacent to the olfactory placode is the developing adenohypophyseal placode. The OB projection neurons or olfactory tracts (OTs) innervate multiple cortical regions and are collectively referred to as the olfactory cortex. The olfactory cortex comprises the anterior olfactory nucleus, olfactory tubercle, piriform cortex, entorhinal cortex, and septal, habenular, and brain stem nuclei as well as the amygdale, hippocampus, and parahippocampal gyrus.^2,3Thus, anomalies of the primary olfactory system might be associated with diverse and widespread anomalies of the remainder of the brain. Syndromes associated with malformed primary olfactory pathways include Kallmann syndrome; CHARGE syndrome (Coloboma of the eye, Heart defects, Atresia of the choanae, Retardation of growth and/or development, Genital and/or urinary abnormalities [hypogonadism], Ear anomalies and/or deafness); septo-optic dysplasia; and craniotelencephalic dysplasia, malformations for which the molecular genetics are variably defined.^3,4 We reviewed a sizable population of patients with abnormalities of the primary olfactory pathways to further categorize the clinical presentation, syndromic associations, and genetic results and expand the range of associated brain malformations and provide correlative diffusion tensor imaging and results of genetic testing.     

The Criminal Justice Experience of African American Cocaine Users in Arkansas

Background: African Americans are incarcerated at rates much higher than other racial and ethnic groups in the United States. Objectives: We sought to qualitatively explore the relationships between ongoing involvement in the criminal justice system and continued drug use in a population of urban and rural African American cocaine users in a southern state. Methods: Semi-structured qualitative interviews were conducted among African American cocaine users in Arkansas between 2010 and 2012. Participants resided in both rural (two counties located in the eastern Arkansas Mississippi delta region) and urban (the county including the capital city of Little Rock) areas. Results: Numerous important themes emerged from participants’ narratives, including chronic involvement with the criminal justice system (being a “career criminal”), continued access to drugs while incarcerated, relapse, and reincarceration and lack of access to effective drug treatment. Conclusion/Importance: The themes which emerged from our data speak to the collective experience that many substance using populations in the United States face in dealing with the criminal justice system. Our findings highlight the need to better, more holistic ways of engaging African American substance users in community based substance use treatment and supportive services.