The role of tryptophan and tyrosine in executive function and reward processing

The serotonergic precursor tryptophan and the dopaminergic precursor tyrosine have been shown to be important modulators of mood, behaviour and cognition. Specifically, research on the function of tryptophan has characterised this molecule as particularly relevant in the context of pathological disorders such as depression. Moreover, a large body of evidence has now been accumulated to suggest that tryptophan may also be involved in executive function and reward processing. Despite some clear differentiation with tryptophan, the data reviewed in this paper illustrates that tyrosine shares similar functions with tryptophan in the regulation of executive function and reward, and that these processes in turn, rather than acting in isolation, causally influence each other

Eyeblink rate, a putative dopamine marker, predicts negative reinforcement learning by tDCS of the dlPFC

Studies have shown that anodal transcranial direct current stimulation (tDCS) applied to the dorsolateral prefrontal cortex (dlPFC) increases extracellular dopamine (DA) levels in the striatum [1]..

Occasion setters determine responses of putative dopamine neurons to discriminative stimuli

Midbrain dopamine (DA) neurons are involved in the processing of rewards and reward-predicting stimuli, possibly analogous to reinforcement learning reward prediction errors. Here we studied the activity of putative DA neurons (n=41) recorded in the ventral tegmental area of rats (n=6) performing a behavioural task involving occasion setting. In this task an occasion setter (OS) indicated that the relationship between a discriminative stimulus (DS) and reinforcement is in effect, so that reinforcement of bar pressing occurred only after the OS (tone or houselight) was followed by the DS (houselight or tone). We found that responses of putative DA cells to the DS were enhanced when preceded by the OS, as were behavioural responses to obtain rewards. Surprisingly though, we did not find a population response of putative DA neurons to the OS, contrary to predictions of standard temporal-difference models of DA neurons. However, despite the absence of a population response, putative DA neurons exhibited a heterogeneous response on a single unit level, so that some units increased and others decreased their activity as a response to the OS. Similarly, putative non-DA cells did not respond to the DS on a population level, but with heterogeneous responses on a single unit level. The heterogeneity in the responses of putative DA cells may reflect how DA neurons encode context and point to local differences in DA signalling

Staying out of range: increasing attacking distance in fencing

To avoid being hit, fencers typically adopt an out of range position, which was hypothesized to be governed by body- and action-scaled affordances. This theory was measured in elite and national level junior (u20) fencers. Associations between “reachability” of lunging and step-lunging attacks, was assessed against height, arm-span, leg-span, body mass and lower-body power, and then compared across level. Reachability was determined as the distance covered by fencers during these attacks and was reported as actual and estimated distances. Elite fencers are better at estimating their lunging and step-lunge distance compared to national ranked junior fencers (-0.9 vs. 7.3 % and 5.4 vs. 10.9 % respectively). Surprisingly, elite fencers’ actual and estimated distances for these was less than the junior fencers’ (222.6 vs. 251.5 cm and 299.3 vs. 360.2 cm respectively), and significantly so in the former. Finally only arm (r = .81) and leg span (r = .71) were significantly correlated to estimated lunging distance and this was only in elite fencers. Findings suggest that better fencers can accurately predict their attack range and that reachability appears to be positively influenced by arm and leg-span; these may feed in to talent identification. Given that distances were less in elite fencers, findings suggests that timing and distance estimation are key skills to master, and that the mastery of these in offensive actions can mitigate to a large extent, the physical benefits of an opponent’s greater height

Comunità energetiche: l’evoluzione del quadro regolatorio europeo e italiano

Abstract ENG: Energy communities: the evolution of the European and Italian regulatory frameworks). Climate change is an issue of extreme urgency extreme urgency in global public policies in the energy field, and to combat it, the use of renewable sources in energy planning must be promoted. This paper aims to reconstructs the international and European regulatory framework on the sustainable energy sector to pursue the energy transition, focusing on the evolution of the regulatory landscape, in Europe and Italy, of the energy communities: the ERC and the CEC. Two legal models that encapsulate relevant environmental, social, energy, technological and economic profiles, rethink the energy governance system from the perspective of horizontal subsidiarity, demonstrating how climate neutrality can be achieved starting from the city and its inhabitants

LA SMART CITY E LE INFRASTRUTTURE DIGITALI

The article aims to deepen the concept of smart city, focusing mainly on the importance of the role of digital infrastructures and the need to eliminate the digital divide for the development of smartness in people. In fact, they are both fundamental aspects of a smart city. The essay examines the European and Italian regulations that promote the connection between the smart city and digital infrastructures, showing the relationship between the city and technological innovation. It suggests the legal instrument of public-private-community partnership for the implementation of projects concerning digital infrastructure in order to improve the smartness of the city and reduce disparities in access to telematic and information services. In support of this proposal, the paper proposes the case study of community Wi-Fi in the Municipality of Reggio Emilia, which exemplifies how technological innovation, scientific research and co-governance are key elements to sustainable urban development and resilience for future changes in the city

Dopamine depletion effects on cognitive flexibility as modulated by tDCS of the dlPFC

Background Recent evidence suggests that transcranial direct current stimulation (tDCS) may interact with the dopaminergic system to affect cognitive flexibility. Objective/hypotheses: We examined whether putative reduction of dopamine levels through the acute phenylalanine/tyrosine depletion (APTD) procedure and excitatory anodal tDCS of the dorsolateral prefrontal cortex (dlPFC) are causally related to cognitive flexibility as measured by task switching and reversal learning. Method A double-blind, sham-controlled, randomised trial was conducted to test the effects of combining anodal tDCS and depletion of catecholaminergic precursor tyrosine on cognitive flexibility. Results Anodal tDCS and tyrosine depletion had a significant effect on task switching, but not reversal learning. Whilst perseverative errors were significantly improved by anodal tDCS, the APTD impaired reaction times. Importantly, the combination of APTD and anodal tDCS resulted in cognitive performance which did not statistically differ to that of the control condition. Conclusions Our results suggest that the effects of tDCS on cognitive flexibility are modulated by dopaminergic tone

Influence of Physicochemical Factors on Adsorption of Ten Shigella flexneri Phages

Bacterial viruses known as bacteriophages have been demonstrated to be effective in killing foodborne pathogens such as Shigella flexneri. Adsorption is the first step in the phage–host interaction. In the present work, 10 Shigella phages were used to characterize the adsorption process on Shigella flexneri ATCC12022 in several physicochemical conditions related to food and in a food matrix. One-step growth curves were drawn for all the Shigella-phages evaluated. Furthermore, the adsorption rate for each of the 10 phages was determined. In addition, the influence of temperature, Na+, Mg2+, pH, sucrose and glycerol on phage adsorption was investigated. Two phages (Shi22 and Shi30) showed higher burst sizes values (67 and 64 PFU cell−1, respectively) and burst times of 25 min to 30 min, while the other eight phages exhibited burst sizes ranging from 14 to 17 PFU cell−1 with slower burst times. Furthermore, most phages achieved a high adsorption rate, and the adsorption constants (k) ranged from ~10−9 to 10−10 mL min−1. Regarding the influence of temperature, cations and pH, a high or moderate percentage of adsorption was observed for most of the phages evaluated. The adsorption decreased at increasing concentrations of Na+, sucrose and glycerol, although at different levels, since adsorption was more affected by sucrose than by glycerol and Na+ for most phages. The adsorption obtained in Triptein soy broth (TSB) for most of the phages/strain systems evaluated was moderate or high, as well as those observed in a food matrix. Thus, our phages could potentially be used to improve food safety under a wide range of environmental conditions against foodborne pathogens.Fil: Tomat, David Damián. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina.Fil: Aquili, Virginia. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina.Fil: Casabonne, Cecilia. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; Argentina.Fil: Quiberoni, Andrea. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentina

Behavioral flexibility is increased by optogenetic inhibition of neurons in the nucleus accumbens shell during specific time segments

Behavioral flexibility is vital for survival in an environment of changing contingencies. The nucleus accumbens may play an important role in behavioral flexibility, representing learned stimulus–reward associations in neural activity during response selection and learning from results. To investigate the role of nucleus accumbens neural activity in behavioral flexibility, we used light-activated halorhodopsin to inhibit nucleus accumbens shell neurons during specific time segments of a bar-pressing task requiring a win–stay/lose–shift strategy. We found that optogenetic inhibition during action selection in the time segment preceding a lever press had no effect on performance. However, inhibition occurring in the time segment during feedback of results—whether rewards or nonrewards—reduced the errors that occurred after a change in contingency. Our results demonstrate critical time segments during which nucleus accumbens shell neurons integrate feedback into subsequent responses. Inhibiting nucleus accumbens shell neurons in these time segments, during reinforced performance or after a change in contingencies, increases lose–shift behavior. We propose that the activity of nucleus shell accumbens shell neurons in these time segments plays a key role in integrating knowledge of results into subsequent behavior, as well as in modulating lose–shift behavior when contingencies change

Catecholaminergic modulation of indices of cognitive flexibility:a pharmaco-tDCS study

Background: Dopaminergic activity within the dorsolateral prefrontal cortex (dlPFC) has been implicated in the control of cognitive flexibility. Much of the evidence for a causative relationship between cognitive flexibility and dopamine has come from animal studies, whilst human data have largely been correlational. Objective/Hypothesis:The current study examines whether changes in dopamine levels through tyrosine administration and suppression of dlPFC activity via cathodal tDCS could be causally related to cognitive flexibility as measured by task switching and reversal learning. Methods: Using a crossover, double-blind, sham controlled, counterbalanced, randomized trial, we tested the effects of combining cathodal tDCS with tyrosine, a catecholaminergic precursor, with appropriate drug and tDCS placebo controls, on two measures of cognitive flexibility: probabilistic reversal learning, and task switching. Results: While none of the manipulations had an effect on task switching, there was a significant main effect of cathodal tDCS and tyrosine on reversal learning. Reversal learning performance was significantly worsened by cathodal tDCS compared with sham tDCS, whilst tyrosine significantly improved performance compared with placebo. However, there was no significant tDCS × drugs interaction. Interestingly, and as predicted by our model, the combined administration of tyrosine with cathodal tDCS resulted in performance that was equivalent to the control condition (i.e. tDCS sham + placebo). Conclusions: Our results suggest a causative role for dopamine signalling and dorsolateral prefrontal cortex activity in regulating indices of cognitive flexibility in humans