Archivio per 2 luglio 2015

02
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15

Network Hubs in the Brain Have the Biggest Impact on Behavior

See on Scoop.itSocial Foraging

The most highly evolved brain region in mammals is the prefrontal cortex, which regulates our thoughts, actions, and emotions through extensive connections with other brain regions. Studies in humans have shown that multiple parts of the prefrontal cortex are activated during memory tasks, but patients with damage to some of these areas do not always have memory problems. As a result, researchers have disputed whether memory deficits are caused by damage to individual brain areas subserving specific cognitive functions or by an interruption in the flow of information among widely distributed areas in the prefrontal cortex.

A recently proposed hypothesis reconciles these views by suggesting that cortical areas form a highly ordered network containing hubs that play a critical role in information processing, such that damage to a hub results in severe cognitive impairment. However, most investigations of network structure have relied on either anatomical studies or functional neuroimaging of spontaneous activity at rest, ignoring brain activity related to specific cognitive tasks.

In a study published this week in PLOS Biology, Yasushi Miyashita of the University of Tokyo School of Medicine and his colleagues used functional magnetic resonance imaging (fMRI) and a novel simulated-lesion method in monkeys to show that virtual damage to a prefrontal cortex hub, which was the most highly interconnected with other brain areas activated during a memory task, was predicted to produce the most severe memory impairment. By contrast, virtual damage to a highly interconnected prefrontal cortex hub that was previously identified in anatomical tracer studies was not predicted to produce severe memory problems. According to the authors, these findings lay the foundation for precisely predicting the behavioral and cognitive impact of injuries or surgical interventions in the human brain.

See on journals.plos.org

02
Lug
15

Diffusion of innovations in Axelrod’s model

See on Scoop.itSocial Foraging

Axelrod’s model for the dissemination of culture contains two key factors required to model the process of diffusion of innovations, namely, social influence (i.e., individuals become more similar when they interact) and homophily (i.e., individuals interact preferentially with similar others). The strength of these social influences are controlled by two parameters: F, the number of features that characterizes the cultures and q, the common number of states each feature can assume. Here we assume that the innovation is a new state of a cultural feature of a single individual – the innovator – and study how the innovation spreads through the networks among the individuals. For infinite regular lattices in one and two dimensions, we find that initially the innovation spreads linearly with the time t and diffusively in the long time limit, provided its introduction in the community is successful. For finite lattices, the growth curves for the number of adopters are typically concave functions of t. For random graphs with a finite number of nodes N, we argue that the classical S-shaped growth curves result from a trade-off between the average connectivity K of the graph and the per feature diversity q. A large q is needed to reduce the pace of the initial spreading of the innovation and thus delimit the early-adopters stage, whereas a large K is necessary to ensure the onset of the take-off stage at which the number of adopters grows superlinearly with t. In an infinite random graph we find that the number of adopters of a successful innovation scales with tγ with γ=1 for K>2 and ½<γ<1 for K=2. We suggest that the exponent γ may be a useful index to characterize the process of diffusion of successful innovations in diverse scenarios.

See on arxiv.org

02
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15

Here is How The Next Crisis Will Play Out | Zero Hedge

See on Scoop.itGold and What Moves it.

As I noted yesterday, the Fuse on the Global Debt Bomb has been lit. We are now officially in the Crisis to which the 2008 Meltdown was just the warm up.

The process will take time to unfold. The Tech Bubble, arguably the single biggest stock market bubble of all time, was both obvious to investors AND isolated to a single asset class: stocks. In spite of this, it took two years for stocks to finally bottom.

Hal’s insight:

Click through for the rest.

See on zerohedge.com

02
Lug
15

Posture promotes success

See on Scoop.itBounded Rationality and Beyond

Amazingly, Cuddy, Dana R. Carney and Andy J. Yap of Columbia University found that high-power poses elevate the hormone testosterone (which is linked to power and dominance in the animal and human world) by 19 percent in both men and women and decreased the stress hormone cortisol (which can cause impaired immune functioning, hypertension and memory loss) by about 19 percent for both men and women. Amy Cuddy’s work as a social psychologist at Harvard Business School focuses on body language and how the poses people hold impact their sense of power, confidence and spirit — and how they will affect how well they do in challenging situations and ultimately in life. Cuddy’s research proves that when a person holds an expansive power pose — standing straight with hands on hips and stance widened, or sitting upright in a chair with legs uncrossed and a bright smile — the pose creates those same feelings of inner strength, authority and dynamic spirit that allow for positive, empowered behaviors.

See on helpinus.net

02
Lug
15

Mentalism versus behaviourism in economics: a philosophy-of-science perspective

See on Scoop.itBounded Rationality and Beyond

Abstract

Behaviourism is the view that preferences, beliefs, and other mental states in socialscientific theories are nothing but constructs re-describing people’s behaviour. Mentalism is the view that they capture real phenomena, on a par with the unobservables in science, such as electrons and electromagnetic fields. While behaviourism has gone out of fashion in psychology, it remains influential in economics, especially in ‘revealed preference’ theory. We defend mentalism in economics, construed as a positive science, and show that it fits best scientific practice. We distinguish mentalism from, and reject, the radical neuroeconomic view that behaviour should be explained in terms of brain processes, as distinct from mental states.

See on personal.lse.ac.uk




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