Nonrenewal spike train statistics: causes and functional consequences on neural coding

Many neurons display significant patterning in their spike trains (e.g. oscillations, bursting), and there is accumulating evidence that information is contained in these patterns. In many cases, this patterning is caused by intrinsic mechanisms rather than external signals. In this review, we focus on spiking activity that displays nonrenewal statistics (i.e. memory that persists from one firing to the next). Such statistics are seen in both peripheral and central neurons and appear to be ubiquitous in the CNS. We review the principal mechanisms that can give rise to nonrenewal spike train statistics. These are separated into intrinsic mechanisms such as relative refractoriness and network mechanisms such as coupling with delayed inhibitory feedback. Next, we focus on the functional roles for nonrenewal spike train statistics. These can either increase or decrease information transmission. We also focus on how such statistics can give rise to an optimal integration timescale at which spike train variability is minimal and how this might be exploited by sensory systems to maximize the detection of weak signals. We finish by pointing out some interesting future directions for research in this area. In particular, we explore the interesting possibility that synaptic dynamics might be matched with the nonrenewal spiking statistics of presynaptic spike trains in order to further improve information transmission.     

Leptospirosis among zebu cattle in farms in Kaduna State,Nigeria

ObjectiveTo assess the occurrence of Leptospira spp serovar Hardjo among Zebu cattle in some livestock producing areas of Kaduna State, Nigeria.MethodsSera samples were obtained from 164 Zebu breed of cattle above one year osf age in seven cattle farms were screened for antibodies to Leptospira spp. serovar Hardjo using Enzyme linked immunosorbent assay (ELISA).ResultsAntibodies to Leptospira spp. serovar Hardjo were detected in eighteen (10.98%) out of the 164 animals sampled. There was no significant difference (P>0.05) in seropositivity between the different age groups or between different Zebu breeds.ConclusionThe presence of Leptospirosis among the Zebu breeds of cattle may poses a threat to livestock production and has public health implication due to its zoonotic potential.     

Two independent pathways of regulated necrosis mediate ischemia–reperfusion injury

Regulated necrosis (RN) may result from cyclophilin (Cyp)D-mediated mitochondrial permeability transition (MPT) and receptor-interacting protein kinase (RIPK)1-mediated necroptosis, but it is currently unclear whether there is one common pathway in which CypD and RIPK1 act in or whether separate RN pathways exist. Here, we demonstrate that necroptosis in ischemia–reperfusion injury (IRI) in mice occurs as primary organ damage, independent of the immune system, and that mice deficient for RIPK3, the essential downstream partner of RIPK1 in necroptosis, are protected from IRI. Protection of RIPK3-knockout mice was significantly stronger than of CypD-deficient mice. Mechanistically, in vivo analysis of cisplatin-induced acute kidney injury and hyperacute TNF-shock models in mice suggested the distinctness of CypD-mediated MPT from RIPK1/RIPK3-mediated necroptosis. We, therefore, generated CypD-RIPK3 double-deficient mice that are viable and fertile without an overt phenotype and that survived prolonged IRI, which was lethal to each single knockout. Combined application of the RIPK1 inhibitor necrostatin-1 and the MPT inhibitor sanglifehrin A confirmed the results with mutant mice. The data demonstrate the pathophysiological coexistence and corelevance of two separate pathways of RN in IRI and suggest that combination therapy targeting distinct RN pathways can be beneficial in the treatment of ischemic injury.     

APOE ϵ4, rated life experiences,and affect among centenarians

Objectives: The purpose of this study was to assess the relationship between apolipoprotein E (APOE), life events and engagement, and subjective well-being (as measured by positive and negative affect) among centenarians. Based on the life stress paradigm, we predicted that higher levels of stress would allow APOE to influence positive and negative affect.

Method: 196 centenarians and near-centenarians (98 years and older) of the Georgia Centenarian Study participated in this research. The APOE, positive and negative affect, the number of recent (last 2 years) and lifelong (more than 20 years prior to testing) events, as well as a number of life engagement tasks were assessed.

Results: Results suggested that centenarians carrying the APOE ?4 allele rated lower in positive affect, the number of lifelong events, and in engaged lifestyle, when compared to centenarians without the APOE ?4 allele (t = 3.43, p < .01; t = 3.19, p < .01; and t = 2.33, p < .05, respectively). Blockwise multiple regressions indicated that the APOE ?4 predicted positive but not negative affect after controlling for demographics. Gene–environment interactions were obtained for the APOE ?4 and lifelong events, suggesting that carriers of the APOE ?4 allele had higher scores of negative affect after having experienced more events, whereas noncarriers had reduced negative affect levels after having experienced more events.

Conclusion: APOE ?4 is directly related to positive affect and is related to negative affect in interaction with life events.