It is recognized that the brain plays a pivotal role in the maintenance of blood pressure and the control of myocardial function. By combining direct sampling of internal jugular venous blood with a noradrenaline isotope dilution method, for examining neuronal transmitter release, and microneurographic nerve recording, we were able to quantify the release of central nervous system noradrenaline and its metabolites and investigate their association with efferent sympathetic nervous outflow in healthy subjects and patients with pure autonomic failure. To further investigate the relationship between brain noradrenaline, sympathetic nervous activity and blood pressure regulation we examined brain catecholamine turnover, based on the internal jugular venous overflow of noradrenaline and its principal central nervous system metabolites, in response to a variety of pharmacological challenges. A substantial increase was seen in brain noradrenaline turnover following trimethaphan, presumably resulting from a compensatory response in sympathoexcitatory forebrain noradrenergic neurones in the face of interruption of sympathetic neural traffic and reduction in arterial blood pressure. In contrast, reduction in central nervous system noradrenaline turnover accompanied the blood pressure fall produced by intravenous clonidine administration, thus representing the blood pressure lowering action of the drug. Following vasodilatation elicited by intravenous adrenaline infusion, brain noradrenaline turnover increased in parallel with elevation in muscle sympathetic nervous activity. While it is difficult to assess the source of the noradrenaline and metabolites determined in our studies, available evidence implicates noradrenergic cell groups of the posterolateral hypothalamus, amygdala, the A5 region and the locus coeruleus as being involved in the regulation of sympathetic outflow and autonomic cardiovascular control.

Stressful and emotionally arousing experiences create strong memories that seem to lose specificity over time. It is uncertain, however, how the stress system contributes to the phenomenon of time-dependent fear generalization. Here, we investigated whether the glucocorticoid hormonal system affects the specificity of contextual fear memories at several timepoints. We trained male Wistar rats on the contextual fear conditioning (CFC) task using two footshock intensities (mild CFC, 3 footshocks of 0.3 mA, or moderate CFC, 3x 0.6 mA) and immediately after the training session we administered corticosterone (CORT-HBC) systemically. We first tested the animals in a novel context and then in the training context at different intervals following training (2, 14, 28 or 42 days). By measuring freezing in the novel context and then contrasting freezing times shown in both contexts, we inferred contextual fear generalization for each rat, classifying them into Generalizers or Discriminators. Following mild CFC training, the glucocorticoid induced an increased discriminative contextual memory that lasted from two up to 28 days. In contrast, after moderate CFC training, CORT-HBC facilitated contextual generalization at 14 days, compared to the control group that maintained contextual discrimination at this timepoint. For this training intensity, however, CORT-HBC did not have any effect on recent memory specificity. These findings indicate that manipulating glucocorticoid levels after mild or moderately arousing experiences may differentially modulate memory consolidation and time-dependent fear generalization.

A long range, low power UHF RFID analog front-end suitable for batteryless wireless sensors has been designed using a low cost 0.35µm CMOS standard process. The proposed front-end architecture allows the implementation of power management techniques that together with the power optimized blocks such as voltage limiter, ASK demodulator… provides a long reading range. The implemented voltage multiplier uses Schottky diodes to provide efficiencies higher than 35%. The measured UHF RFID analog front-end current consumption is 7.4µA. When assembling the analog front-end to a matched dipole antenna, the analog front-end would be able to provide a wireless communication up to 2.4m, from a 2W EIRP output power reader to a digital module + sensor, with an average power consumption up to 37.5µW. These characteristics allow the use of the proposed analog front-end in batteryless wireless sensor networks. WE4A: RFID and Power Harvesting Technologies

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