Rare and remarkable animals of Scotland, represented from living subjects: with practical observations on their nature. By Sir John Graham Dalyell, baronet ...

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Countermanding in rats as a practical model for investigation of adaptive control of behaviour, lifespan changes in behavioural control and neurotransmitter function

The countermanding paradigm was designed to investigate the ability to cancel a prepotent response when a stop signal is presented and allows estimation of the stop signal response time (SSRT), an otherwise unobservable behaviour. Humans exhibit adaptive control of behaviour in the countermanding task, proactively lengthening response time (RT) in expectation of stopping and reactively lengthening RT following stop trials or errors. Human performance changes throughout the lifespan, with longer RT, SSRT and greater emphasis on post-error slowing reported for older compared to younger adults. Inhibition in the task has generally been improved by drugs that increase extracellular norepinephrine. The current thesis examined a novel choice response countermanding task in rats to explore whether rodent countermanding performance is a suitable model for the study of adaptive control of behaviour, lifespan changes in behavioural control and the role of neurotransmitters in these behaviours. Rats reactively adjusted RT in the countermanding task, shortening RT after consecutive correct go trials and lengthening RT following non-cancelled, but not cancelled stop trials, in sessions with a 10 s, but not a 1 s post-error timeout interval. Rats proactively lengthened RT in countermanding task sessions compared to go trial-only sessions. Together, these findings suggest that rats strategically lengthened RT in the countermanding task to improve accuracy and avoid longer, unrewarded timeout intervals. Next, rats exhibited longer RT and relatively conserved post-error slowing, but no significant change in SSRT when tested at 12, compared to 7 months of age, suggesting that rats exhibit changes in countermanding task performance with aging similar to those observed in humans. Finally, acute administration of yohimbine (1.25, 2.5 mg/kg) and d-amphetamine (0.25, 0.5 mg/kg), which putatively increase extracellular norepinephrine and dopamine respectively, resulted in RT shortening, baseline-dependent effects on SSRT, and attenuated adaptive RT adjustments in rats in the case of d-amphetamine. These findings suggest that dopamine and norepinephrine encouraged motivated, reward-seeking behaviour and supported inhibitory control in an inverted-U-like fashion. Taken together, these observations validate the rat countermanding task for further study of the neural correlates and neurotransmitters mediating adaptive control of behaviour and lifespan changes in behavioural control.

Do arquivo ao novo : impactos da tecnologia digital no armazenamento e disseminação da informação na cultura contemporânea

While taking paths from the archive to the new, this dissertation reflects on the resulting impacts of the introduction, massification and dissemination of digital technology, in the way we store and deal with information, inside the complex that we understand as culture. To this end, a theoretical investigation is performed in order to build a conceptual body from which concepts are drawn in order to effectuate a practical research. The theoretical research starts with an exordium in which the concept of the archive is deconstructed in order to identify it as a device of power and to analyse its transition from a technical analog object into a digital technology. Following this, a historical context is established, drawing on the evolution of power exercises and apparatuses, and a reading of the impacts of the present technological mediation on experience, knowledge cons¬truction and forms of control is developed. Finally, some hypotheses on the evolution of technology are formulated. The practical research materializes in the form of a digital platform which takes place in two moments: one of archive, the other of program. The first moment, of archive, con¬sists of a repository of projects dealing with the dissertation’s subject. The second moment, of program, is configured as a cultural program implemented through computer programs. These, in their execution, result in performances which, taking from the information col¬lected on the archive generate a new experience of that same information. To this effect, a framework was structured in order to have computational processes systematized in a way that the performances result in experiences with a potential for novelty, expression and reflection. Both theoretical and practical components of the research seek to address digital technology not as an end in itself, but as a factor that affects human experience and behaviour