Neurons Fire Backward in Sleep

Unusual brain cell activity may underlie memory strengthening.

Researchers have long known that sleep is important for forming and retaining memories, but how this process works remains a mystery. A study published in March suggests that strange electrical activity, involving neurons that fire backward, plays a role.

Neuronal activity typically requires sensory input—for example, a taste or smell—that gets received by neurons' dendrites and then transmitted as an electrochemical message to other cells via long axons. Yet the brain is mostly closed off to sensory input during sleep. Instead evidence suggests that during sleep, neurons are controlled by electrical impulses that ripple through the brain like waves. In 2011 researchers found that these waves of electricity cause neurons in the hippocampus, the main brain area involved with memory, to fire backward during sleep, sending an electrical signal from their axons to their own dendrites rather than to other cells. The new work, published in the Proceedings of the National Academy of Sciences USA, confirmed this unusual behavior and suggested that firing in reverse weakens the dendrites' ability to receive input from other neurons.

Weakening neural connections may serve a dual purpose, says R. Douglas Fields, a laboratory chief at the National Institutes of Health and co-author of the study with neuroscientist Olena Bukalo and other colleagues. The authors suggest that firing backward helps to strengthen the electrical signals of neighboring cells, necessary to solidify memories, as well as freeing up space in the brain to store new memories on waking.

This study was conducted in samples taken from rat brains, but sleep is thought to induce backward firing in human neurons, too. In fact, Fields says, this bizarre electrical behavior may underlie the positive effects of deep-brain stimulation, which, though not well understood, has been shown to improve the symptoms of Parkinson's disease and other neurological disorders.

Tomado de: http://www.scientificamerican.com/article.cfm?id=neurons-fire-backward-in-sleep&WT.mc_id=SA_CAT_MB_20131016

Why Your Brain Needs More Downtime

Research on naps, meditation, nature walks and the habits of exceptional artists and athletes reveals how mental breaks increase productivity, replenish attention, solidify memories and encourage creativity.

Every now and then during the workweek—usually around three in the afternoon—a familiar ache begins to saturate my forehead and pool in my temples. The glare of my computer screen appears to suddenly intensify. My eyes trace the contour of the same sentence two or three times, yet I fail to extract its meaning. Even if I began the day undaunted, getting through my ever growing list of stories to write and edit, e-mails to send and respond to, and documents to read now seems as futile as scaling a mountain that continuously thrusts new stone skyward. There is so much more to do—so much work I genuinely enjoy—but my brain is telling me to stop. It's full. It needs some downtime. SEGUIR LEYENDO....

A New Frontier in Animal Intelligence

Evidence that some animals are capable of “mental time travel,” suggests they have a deeper understanding of the world around them.

Santino was a misanthrope with a habit of pelting tourists with rocks. As his reputation for mischief grew, he had to devise increasingly clever ways to ambush his wary victims. Santino learned to stash his rocks just out of sight and casually stand just a few feet from them in order to throw off suspicion. At the very moment that passersby were fooled into thinking that he meant them no harm, he grabbed his hidden projectiles and launched his attack.

Santino was displaying an ability to learn from his past experiences and plan for future scenarios. This has long been a hallmark of human intelligence. But a recently published review paper by the psychologist Thomas Zentall from the University of Kentucky argues that this complex ability should no longer be considered unique to humans.

Santino, you see, is not human. He’s a chimpanzee at Furuvik Zoo in Sweden. His crafty stone-throwing escapades have made him a global celebrity, and also caught the attention of researchers studying how animals, much like humans, might be able to plan their behavior.

Santino is one of a handful of animals that scientists believe are showing a complex cognitive ability called episodic memory. Episodic memory is the ability to recall past events that one has the sense of having personally experienced. Unlike semantic memory, which involves recalling simple facts like “bee stings hurt,” episodic memory involves putting yourself at the heart of the memory; like remembering the time you swatted at a bee with a rolled up newspaper and it got angry and stung your hand.

If an animal can imagine itself interacting with the world in the past via episodic memory – like Santino recalling a failed attack when a human spotted him holding a rock, or you remembering swatting at a bee – it stands to reason that the animal might also be able to imagine itself in the future in a similar scenario, and thus plan its behavior. Santino might opt to hide his rocks, and you might decide to stop antagonizing bees. The ability to represent oneself and one’s actions in the mind’s eye – both in the past in in the future – is what scientists refer to as mental time travel.

Mental time travel is a vital skill in the arsenal of human intelligence.  When it goes right, we can devise and execute complex hunting strategies that allow us to herd woolly mammoths into a canyon for easy slaughter– something our ancestors excelled at in the late Pleistocene. When it goes really right, we can spend years devising and executing a plan to rocket astronauts through the coldness of space and land them safely on the moon. If it turns out that other species might have even the smallest hint of this ability, it raises the question of just how much we might be underestimating their ability to interact with, and understand, the world around them.

Zentall argues that mental time travel based on episodic memory has been observed in a number of species, including non-human primates like Santino, as well as dolphins, scrub-jays, rats, and pigeons. Scrub-jays in particular seem skilled at planning their food hiding (caching) behavior. In experimental conditions, they learned to cache food in areas where they knew they’d be hungry the following day, and made sure that their favorite food was cached in such a way that they’d always have access to it in the future.

But there is longstanding opposition to the idea of suggesting that animals are capable of mental time travel. The University of Queensland psychologist Thomas Suddendorf argues that despite “ingenious attempts to demonstrate episodic memory or future simulation in non-human animals,” it still seems that “there are few signs that animals act with the flexible foresight that is so characteristic of humans.” While animals like scrub-jays might be able to adapt their behavior to make the most of their food-caching, they do not display similar flexibility outside of this narrow domain. Unlike scrub-jays, “humans,” states Suddendorf, “can simulate virtually any event and evaluate it in terms of likelihood and desirability”

Zentall, however, has recently acquired a high-profile ally in Michael Corballis, a psychologist at the University of Auckland who once famously argued alongside Suddendorf that episodic memory was unique to humans. It was Suddendorf and Corballis who together coined the phrase mental time travel in 1997, and established a set of criteria that, if satisfied, could prove its existence in animals. By the age of 4, human children satisfy these criteria via their ability to choose the correct key to open a box that they’d never seen before based only on experience with similar boxes and keys in different locations in the past. Animals are typically only able to devise a similar solution after repeated exposure to the same test materials in the same setting, which means they might be solving problems via associative learning as opposed to mental time travel.

Corballis revealed earlier this year that new evidence has come to light that obliged him to change his mind as to whether these criteria had been met in animals. The evidence that tipped the scale for Corballis, however, was not found by observing animals’ behavior, but by measuring their brains. “Mental time travel has neurophysiological underpinnings that go far back in evolution, and may not be, as some (including myself) have claimed, unique to humans,” writes Corballis.

Recently published research shows how brain activity in rats suggest that they might be envisioning solutions to problems in their mind’s eye – in this case, an eye located in their hippocampus. After the rats ran a series of mazes during the day, researchers measured neuronal activity as they slept, concentrating on the hippocampus – the part of the brain where the mental map of the maze was stored. The rats appeared to not only be replaying their past experiences running through the maze in their sleep, but also replaying the parts of the maze that they had only considered running, but not actually run. For Corballis, this is neurological evidence of mental time travel at work.

And yet, some behavioral evidence seems like convincing evidence of mental time travel in animals, regardless of underlying brain activity. In one experiment, Bonobos and orangutans practiced using tools to retrieve food rewards – like a juice bottle hanging on a string that was only reachable with a hook. Knowing that they’d likely face a similar test situation the next day, the apes took the appropriate tool with them to their sleeping quarters and used it to retrieve their reward the next morning.

These skills do not seem a far cry from those employed by early humans to plan out the next day’s mammoth hunting excursion. Why then do we not see more examples of animals engaging in behaviors that unequivocally show the ability for mental time travel?

There’s more to the human intellect and ability to pull off successful mammoth hunts and moon landings than episodic memory of course, and other intellectual feats – not the least of which is our ability to convey our thoughts and plans via language – appear absent in non-human animals. There is also the question of how humans’ complex understanding of our own and others’ minds might be involved. Mental time travel likely requires some form of consciousness or self-knowledge to allow an animal to place itself at the heart of its memories and future plans, and much of this debate focuses on whether animals’ observed behavior or neurological activity are evidence of consciousness at work.  Consciousness is the unknowable singularity at the heart of the black box.

Zentall is confident that future research will provide evidence that animals have skills like mental time travel that far exceed what we now attribute to them. He is surely correct. But as we slowly pry open the lid on the black box of animal minds, scientists will continue to disagree as to what shapes they see emerging from the darkness.

Tomado de: http://www.scientificamerican.com/article.cfm?id=new-frontier-animal-intelligence&WT.mc_id=SA_CAT_EVO_20131014

Mind Wandering: A New Personal Intelligence Perspective

Once accused of being absent-minded, the founder of American Psychology, William James, quipped that he was really just present-minded to his own thoughts.


Most recent studies depict mind wandering as a costly cognitive failure with relatively few benefits (Mooneyham and Schooler, 2013). This perspective makes sense when mind wandering is observed by a third party and when costs are measured against externally imposed standards such as speed or accuracy of processing, reading fluency or comprehension, sustained attention, and other external metrics.

There is, however, another way of looking at mind wandering, a personal perspective, if you will. For the individual, mind wandering offers the possibility of very real, personal reward, some immediate, some more distant.

We mind wander, by choice or accident, because it produces tangible reward when measured against goals and aspirations that are personally meaningful. Having to reread a line of text three times because our attention has drifted away matters very little if that attention shift has allowed us to access a key insight, a precious memory or make sense of a troubling event.
Pausing to reflect in the middle of telling a story is inconsequential if that pause allows us to retrieve a distant memory that makes the story more evocative and compelling. Losing a couple of minutes because we drove past our off ramp, is a minor inconvenience if the attention lapse allowed us finally to understand why the boss was so upset by something we said in last week’s meeting. Arriving home from the store without the eggs that necessitated the trip is a mere annoyance when weighed against coming to a decision to ask for a raise, leave a job, or go back to school.

Some recent studies (Baird et al., 2011, 2012; Smallwood et al., 2011b; Immordino-Yang etal., 2012) have provided glimpses of how mind wandering or “constructive, internal reflection” (Immordino-Yangetal.,2012) might benefit the individual, but we are just beginning to scratch the surface. To gain a fuller understanding of the benefits of positive constructive daydreaming we need to apply tools and metrics (as in Klinger et al., 1980; Hoelscher et al., 1981; Nikles et al., 1998; Cox and Klinger, 2011; Klinger and Cox, 2011) that enable us identify the personally meaningful goals, aspirations, and dreams of individuals and determine how mind wandering supports or undermines those goals. Given the highly personal nature of mind wandering, we need a new focus and new metrics.

Personal Intelligence

Intelligence theories provide an interesting parallel. Traditional theories of intelligence emphasize cognitive control, deliberate planning, and decontextualized problem solving as the essence of human intelligence (Kaufman, 2011). This is largely due to the purpose of the first intelligence test: to identify students in need of alternative education. Because intelligence tests were designed to predict school grades, the tests were intentionally designed to measure the ability to profit from explicit instruction, concentrate on an external goal, and engage in abstract reasoning. Therefore it should come as no surprise that IQ test performance is strongly associated with activation of the executive attention brain network (e.g., Jung and Haier, 2007; Barbey et al., 2012):

Executive Attention Network

These rewards include self- awareness, creative incubation, improvisation and evaluation, memory consolidation, autobiographical planning, goal driven thought, future planning, retrieval of deeply personal memories, reflective consideration of the meaning of events and experiences, simulating the perspective of another person, evaluating the implications of self and others’ emotional reactions, moral reasoning, and reflective compassion (Singer and Schonbar, 1961; Singer, 1964b; Singer, 1966, 1974, 1975, 1993, 2009; Wang et al., 2009; Baars, 2010; Baird et al., 2011, 2012; Kaufman and Singer, 2011; Stawarczyk et al., 2011; Immordino-Yang et al., 2012; Kaufman, 2013).

From this personal perspective, it is much easier to understand why people are drawn to mind wandering and willing to invest nearly 50% of their waking hours engaged in it.

Default Mode Network

While the cognitive functions measured on traditional metrics of intelligence are undoubtedly important contributors to intellectual functioning, they are mostlydecontextualized. Rarely are the test takers allowed to dip into their inner stream of consciousness and produce an original response that incorporates self-relevant information.

To help correct this imbalance in the literature, I recently proposed the Theory of Personal Intelligence. According to the theory, intelligence is the dynamic interplay of engagement and ability over an extended period of time in pursuit of personal goals (Kaufman, 2013). The emphasis is adaptation to task demands that are relevant to attaining one’s personal goals, not just adaptation to the external goals dictated by educators and experimental psychologists.

Therefore, the theory takes into account an individual’s personal goals, and considers both controlled forms of cognition (e.g., working memory, attentional focus, etc.) andspontaneous forms of cognition (e.g., intuition, affect, insight, implicit learning, latent inhibition, and the spontaneous triggering of episodic memories and declarative knowledge) are important potential contributors to that personal adaptation.

This broadened conceptualization of human intelligence is in line with the plethora of research on the adaptive value of positive constructive daydreaming (see Jerome L. Singer’s seminal research– e.g., Singer, 1964b, 1966, 1974, 1975, 2009). When daydreaming, the contents of consciousness tend to be focused on upcoming personally meaningful events, indicating that they may play a role in autobiographical planning (Smallwood et al., 2009b; Morsella et al., 2010). In particular, Klinger (1999) showed that people’s daydreams and night dreams reflect “current concerns” ranging from constant thought of incomplete tasks to unresolved desires, ranging from sexual and social strivings to altruistic or revenge urges and the panoply of human motivations.

This deeply personal conceptualization of intelligence is also in line with the latest research in cognitive neuroscience. D’Argembeau et al. (2010) found that imagining personal future events elicited stronger activation in two key hubs of the default mode network– the ventral medial prefrontal cortex (MPFC) and the posterior cingulate cortex (PCC) – compared to imagining non-personal future events.

The researchers suggest that these brain areas support a collection of mental processes that evaluate, code, and contextualize the relevance of mental representations with regard to personal goals. Since traditional measures of intelligence do not allow individuals to imagine personal future events, or connect the test information to their large store-house of episodic memories, functioning of these key regions of the default mode network are ignored in the assessment of intellectual functioning.

Another key implication is that sometimes behavior that appears “unintelligent” measured by external standards may actually be quite intelligent as judged by its relevance to achieving personally meaningful goals. Importantly, these different ways of being “smart” can conflict with each other.

According to the neural global workspace theory of consciousness, different streams of consciousness compete for access to a global conscious workspace (Baars, 1993). This may explain why the executive attention network and the default mode network tend to be anticorrelated (Fox et al., 2005). Daily life often demands that we choose one information stream or the other. For instance, in a decontextualized educational context, or in a cognitive psychology experiment, the ability to concentrate on a task requires silencing the inner chatter. Vice versa, when we would like to dip into our inner stream of consciousness, we must block out our external percepts (Dehaene and Changeux, 2005; Smallwood et al., 2011b; Kam et al., 2013).

However, as Kam et al. (2013) point out, when the executive attention network works in concert with the default mode network to sustain an inner train of thought, selective attention processes are not absent – they just are turned inward to select the most relevant associations and ideas that emerge from episodic memory. This has important implications, because traditional views of selective attention erroneously assume that the main function of the executive attention network is to select relevant stimuli from the external environment for deliberate, conscious processing.

However, these traditional models miss a key feature of human cognition: when working in cooperation with the default mode network, the executive attention network is equally equipped to select relevant episodic associations that can help keep an inner stream of thought both positive and constructive.

Tomado de: http://blogs.scientificamerican.com/beautiful-minds/2013/09/25/mind-wandering-a-new-personal-intelligence-perspective/?WT_mc_id=SA_WR_20131002