Divergent Routing of Positive and Negative Information from the Amygdala during Memory Retrieval

Although the basolateral amygdala (BLA) is known to play a critical role in the formation of memories of both positive and negative valence, the coding and routing of valence-related information is poorly understood. Here, we recorded BLA neurons during the retrieval of associative memories and used optogenetic-mediated phototagging to identify populations of neurons that synapse in the nucleus accumbens (NAc), the central amygdala (CeA), or ventral hippocampus (vHPC). We found that despite heterogeneous neural responses within each population, the proportions of BLA-NAc neurons excited by reward predictive cues and of BLA-CeA neurons excited by aversion predictive cues were higher than within the entire BLA. Although the BLA-vHPC projection is known to drive behaviors of innate negative valence, these neurons did not preferentially code for learned negative valence. Together, these findings suggest that valence encoding in the BLA is at least partially mediated via divergent activity of anatomically defined neural populations.

Human post-mortem synapse proteome integrity screening for proteomic studies of postsynaptic complexes

BACKGROUND

Synapses are fundamental components of brain circuits and are disrupted in over 100 neurological and psychiatric diseases. The synapse proteome is physically organized into multiprotein complexes and polygenic mutations converge on postsynaptic complexes in schizophrenia, autism and intellectual disability. Directly characterising human synapses and their multiprotein complexes from post-mortem tissue is essential to understanding disease mechanisms. However, multiprotein complexes have not been directly isolated from human synapses and the feasibility of their isolation from post-mortem tissue is unknown.

RESULTS

Here we establish a screening assay and criteria to identify post-mortem brain samples containing well-preserved synapse proteomes, revealing that neocortex samples are best preserved. We also develop a rapid method for the isolation of synapse proteomes from human brain, allowing large numbers of post-mortem samples to be processed in a short time frame. We perform the first purification and proteomic mass spectrometry analysis of MAGUK Associated Signalling Complexes (MASC) from neurosurgical and post-mortem tissue and find genetic evidence for their involvement in over seventy human brain diseases.

CONCLUSIONS

We have demonstrated that synaptic proteome integrity can be rapidly assessed from human post-mortem brain samples prior to its analysis with sophisticated proteomic methods. We have also shown that proteomics of synapse multiprotein complexes from well preserved post-mortem tissue is possible, obtaining structures highly similar to those isolated from biopsy tissue. Finally we have shown that MASC from human synapses are involved with over seventy brain disorders. These findings should have wide application in understanding the synaptic basis of psychiatric and other mental disorders.

Review of factors susceptible of influencing post-mortem carbohydrate-deficient transferrin

Seric carbohydrate-deficient transferrin (CDT) is a biochemical marker of chronic alcohol abuse. Assessment of the influence of factors likely to modify CDT concentration is necessary to justify its use in the analysis of post-mortem blood samples. Hemolysis, site of collection and storage were tested. Hemolysed samples showed decreased CDT concentration. Statistical analysis of CDT concentration in cardiac blood versus femoral blood revealed no significant differences. Storage for fifteen days at +4 degrees C or +20 degrees C did not affect CDT concentration but repeated freezing and thawing resulted in decreased levels of CDT.

Effect of phosphate supplementation to breast fed very low birthweight infants on urinary calcium excretion, serum immunoreactive parathyroid hormone and plasma 1,25-dihydroxy-vitamin D concentration

The effect of two doses of Phosphorus (P) supplementation to pooled breast milk (BM): 0.48 and 0.800 mmol/kg/24 h given during the second month of life was evaluated in 22 very low birthweight infants. The concentration of calcium and phosphorus in serum and urine, the serum concentration of immunoreactive parathyroid hormone (iPTH) and the plasma 1,25-dihydroxy-vitamin D concentration (1,25-OH-D) were compared to the values in 19 control infants. The mean +/- SD concentrations in control infants and adults are 63 +/- 18 microliters Eq/ml for serum iPTH and 85 +/- pmol/l for plasma 1,25-OH-D. With 0.48 P supplementation, urinary Ca (UCa) excretion (median and range) 0.238 mmol/kg/24 h (0.105-0.520) was lower than in the control group 0.288 (0.205-0.679) (p less than 0.05); the reduction of UCa was larger with 0.8 P supplementation: 0.047 (0.023-0.163) (p less than 0.01). P supplementation induced no change in serum Ca concentration but a slight and significant increase in serum iPTH was observed only with the 0.8 P supplementation: 55 microliters Eq/ml (less than 25-80) (p less than 0.05). With 0.8 P supplementation there was no significant change of plasma 1,25-OH-D concentration: 173 pmol/l (106-271) vs. 255 (132-293) in the control group. These data show that with 0.8 P supplementation, the hypercalciuria in BM-fed infant disappears without secondary hyperparathyroidism, but without any change in plasma 1,25-OH-D concentration.

[Recent data on cerebral circulation and metabolism of the brain in newborn infants]

Recent advances in technology have made it possible to determine cerebral blood flow and metabolism in newborn infants. The mean cerebral blood flow rate falls from 60 to 30 ml/min/100 g during the first 3 hours of life and returns to the initial value after the first week. It increases by about 30% during rapid sleep and feeding. Cerebral blood flow is independent of gestational age and represents 20-25% of cardiac output as against 16% in adults. It is influenced by blood gases and its autoregulation is impaired by asphyxia. Infants with a cerebral blood flow rate below 20 ml/min/100 g are at high risk of leucomalacia. The high metabolic activity of the neonatal brain is reflected in its considerable consumption of oxygen (54% vs 30% in adults) and ketonic bodies which participate for 10% in cerebral energy metabolism. More than 80% of the endogenous glucose is utilized by the brain of neonates despite a transport capacity lower than in adults. In neonatal pathology, it is now possible to investigate cerebral metabolism using positron emission tomography or phosphorous magnetic resonance spectroscopy which provide for better diagnostic and prognostic evaluation of cerebral functions.

[Role of a hypertonic theophylline solution and blood transfusion in necrotizing colitis]

The aim of this study was to evaluate the influence of an hyperosmolar solution of theophylline and of blood transfusion in the occurrence of necrotizing enterocolitis (NEC). By the end of 1982, theophylline previously given in alcoholic solution (osmolality greater than 4000 mosm/kg) was given in a preparation of sodium benzoate isoosmotic to the plasma; in addition, blood was irradiated for 20 minutes by X-Rays (5000 rads) before every transfusion. In the same unit of premature infants, the incidence of NEC was 6.7% in 1981-82; it decreased to 2.7% in 1983-84 (p less than 0.02). In the same periods of time, the incidence of NEC in very low birth weight infants (less than 1500 g) decreased from 18% to 4.7% (p less than 0.001) while the number of these very low birth weight infants had increased significantly. The incidence of blood transfusion prior to NEC was found in 67% of the patients. These data suggest a beneficial role of reducing the osmolality of theophylline and of X-Rays irradiation of blood before transfusion as a prophylaxis of NEC in premature infants.