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Archive for the ‘education’ Category

I just love the way that YouTube is developing these days. If you just spend some time searching this wonderful site, you can get access to so many different teaching resources for psychology, neuroscience and philosophy that you could ever dream of. Seeing an interview with the younger Michael Gazzaniga speaking about the callosotomy procedure, BF Skinner speaking, even an item on Pavlov, just just blows my mind.

Below is just a few examples:

Gazzaniga on the split-brain procedure (good thing it’s not in colour)

And here is a thing on split-brain mind-blowing behaviour:

BF Skinner on operant conditioning

Or how about giving a demo of how patients with unilateral neglect actually behave (I’ve seen this many time when I was working clinically, but it’s like “what are you doing?”)

-Thomas

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During the spring of 2009 I organized a course course entitled “Neuroeconomics”, together with Prof.s Elke Weber and Eric Johnson. In this course, we made a compendium of articles on neuroeconomics. Fortunately, almost all of those papers were to be found on the web.

On a new page on the BrainEthics site, we bring you the list of articles we used for the course. Consider this as a suggestion for required readings for those interested in neuroeconomics. We hope to update the list along the way, but still with the aim of retaining a recommended reading rather than comprehensive listing of articles.

– Thomas

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mtl.jpgTake any textbook on cognitive neuroscience. If you go through the book you wil see that there are chapters on perception (e.g. vision), memory, and language. Each chapter has its own vocabulary, theories and experimental evidence. Each chapter may even have been written by different authors (i.e. authorities).

Once reading such a book you will have knowledge about how visual input is processed from the initial steps in the retina, through the thalamic nuclei, and in the visual cortex, just as well as you will learn that as you perceive something as an object you will make use of areas in the temporal lobe, including the fusiform gyrus. You will have learned that memory — especially episodic and semanic memory — is a result of activity occurring in the medial temporal lobe, and especially hippocampus. You will know that theories of language and semantics point to the temporal lobe as important for its functioning.

All in all, you have a nice impression of how the brain is responsible for different perceptual and cognitive functions. But think now of the three examples: they all seem to imply the temporal lobe as important for their functioning. So does this mean that visual perception, memory and language resides in different, non-overlapping parts of the temporal lobe? If so, how do these areas or modules communicate with each other?. What is the lingua franca of neurons comunicating information fro the visual senses to memory and semantics? Add on top of this that parts of the temporal lobe has been implemented in many other functions, including hearing (e.g. the planum temporale and Heschl’s gyrus) and odour processing (e.g. the entorhinal cortex). How does this combine with the other functions? Should we see the temporal lobe as a patchwork of distinct and neatly segregated functions?

For a long time the predominating view of the temporal lobe has been a strictly modular one: one part of the lobe processes visual input, there are language and memory modules. Non-overlapping parts of a lobe that are tuned to process one kind – but not other kinds – of information.

But this view is changing dramatically. Today, following researchers such as Elisabeth Murray, David Gaffan and others (especially from the universities of Cambridge and Oxford, UK) the standard view of temporal lobe function is changing. Instead of a functionally segregated model of the temporal lobe, these researchers now suggest that the lobe has an entirely different way of functioning. In this area, often referred to as the medial temporal lobe one has now documented not only multiple cognitive functions in a brain area once thought to be dedicated to memory, but also redundancy between the structures. Some examples:

  1. There is a functional specialization within the rhinal cortices beyond the involvement in memory: the entorhinal cortex is involved in odour perception as well as multi-modal conjunct perception, i.e. the perception of the entirety of a scene, including sights, sounds and more. The perirhinal cortex is involved in novelty processing, higher-order visual conjunct perception and discrimination, as well as high-specificity semantic processing.
  2. Specific and small anatomical regions are involved in different cognitive functions. For example, the perirhinal cortex has been shown to be involved in memory processes (particularly visual object encoding, but also other forms), novelty processing, semantic processing and high-order visual perception and discrimination

While point 1 does not conflict with a modular view of the brain-mind, point 2 poses a serious problem to any modularist view of the human mind and brain. In many respects, findings now converge on a view of the brain that stresses functional redundancy and degeneracy. In other words: A) one structure can participate in many different functions; and B) many structures are necessary parts of any given cognitive function. A mapping of a 1:1 relationship between a cognitive function and its wetware is thus unsupported by today’s knowledge.

So take that cog-neurosci textbook again, scroll through its pages and ask yourself: how are these cognitive functions connected? Better still, take the chapter to your supervisor, lecturer or whoever you want and ask: “how does the temporal lobe deal with memory, language, visual perception and other multi-modal operations, and how are these processes tied together?” It would be interesting to hear the replies you get.

-Thomas

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alcohol.gifAdolescence is a period of dramatic transformation in the healthy human brain, leading to both regional and general brain volume changes. Recent high-resolution Magnetic Resonance Imaging (MRI) studies emphasize the effects of ongoing myelination, indicating a substantial maturation process (see Figure 1). The period of adolescence is often defined as spanning the second decade of life, although some researchers expand their definition of adolescence to include the early 20s as well. Research into brain maturation in adolescence is particularly important, given that it is normally considered the peak period of neural reorganization that contributes to normal variation in cognitive skills and personality Additionally, it is seen as the period of major mental illness onset, such as schizophrenia. Despite growing evidence for pronounced changes in both the structure and function of the brain during adolescence and early adulthood, few studies have explored this relationship directly using in vivo imaging methods. Thus, little is still known about the relationship between adolescent behaviour and outcomes, and maturational effects on morphological and functional aspects of the brain.

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Figure 1Brain development during adolescence

The psychological and social changes of that occur during adolescence include a higher level or orientation towards and identification with peers, group socialism and personality consolidation. A main social behavioural change is the tendency to use alcohol and other stimulants. In European countries and especially Denmark, 60% of all adolescents report having had their first alcoholic whole drink before age 15, the majority reporting a debut at around age 12 (see Figure 2). Today, alcohol is considered a normal part of adolescent culture.

 

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Figure 2Age of alcohol use debut, as measured by the first consumption of a full alcoholic unit. Note that the majority of debuts are around 12 years. Furthermore, note the relatively high number (8%) reporting a <9 year old debut. (x-axis numbers indicate age of reported first full drink of alcoholic beverage; “yngre end 9” = “younger than 9”; “jeg har ikke drukket” = “I have not yet tried alcohol”)

The effects of prolonged regular alcohol consumption in adults are today considered well documented. Studies of extreme cases such as Wernicke’s encephalopathy and foetal alcohol syndrome have shown that alcohol at critical periods or over time can have severe effects on significant modification and damage of brain structure, physiology and function. In adults, heavy alcohol consumption results in atrophy of grey and white matter, particularly in the frontal lobes, cerebellum, and limbic structures. Heavy drinking also raises the risk of ischemic and hemorrhagic stroke.

Adolescents tend to drink larger quantities on each drinking occasion that adults, possibly a combination of lower sensitivity to some of the unpleasant effects of intoxication and altered patterns of social interaction, including a willingness to indulge in more risky activities. However, it has been suggested that adolescents may be more sensitive to some of alcohol’s harmful effects on brain function. Research now suggests that, even over the shorter time frame of adolescence, drinking alcohol can harm the liver, bones, endocrine system, and brain, and interfere with normal growth. Studies in humans have found that alcohol can lower the levels of growth- and sex hormones in both adolescent genders.

Recent studies using animal models have demonstrated that the adolescent brain is even more sensitive to alcohol consumption. Alcohol inhibits normal neurogenesis, the process in which neurons are created. The magnitude of this effect has been related to the level of consumption; higher levels of consumption (e.g. binge consumption) had the most severe effects on the brain. Furthermore, alcohol impairs spatial memory function in adolescent animals more than adults, a result that is thought to be mediated by a larger inhibitory effect of alcohol on neural transmission in adolescence.

The long-term effects of alcohol consumption on brain maturation are yet poorly understood in human adolescence. Studies report that a history of high alcohol consumption in adolescence has been associated with reduced hippocampal volumes (see Figure 3), and with subtle white-matter microstructure abnormalities in the corpus callosum. In order to understand the effects of alcohol on the brain these findings must be compared to several factors pertaining to alcohol consumption in young adults, including 1) onset of alcohol use; 2) amount of alcohol consumed regularly; 3) type of alcohol consumption (regular use or binge drinking). In addition, a number of confounding factors need to be addressed and controlled between different study groups, including 1) general cognitive function; 2) the effects of gender and pubic stage; 3) gender-related preferences for alcoholic beverages; and 4) the effects of gene-related differences in neurotransmitter function.

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Figure 3Hippocampus volume differences in adolescents with alcohol use disorder (AAU, right) compared to healthy adolescents (left). Volume estimation is corrected for general brain size.

So who says alcohol is not damaging? We know it is in adults. We know it is in prenatal development. Why not during adolescence? Even more so; during this period of brain development so much is happening; the continuation of brain development; pruning and consolidation of brain, cognition and personality; all combined with the coctail of changes resulting from hormonal changes. Add alcohol, and in heavy doses in binge drinking, and you’ve got a recipe for brain dysfunction and detrimental brain development.

In most cultures, alcohol is seen as acceptable, even for adolescents. Alcohol is possibly even more problematic in countries such as Denmark, since it is not illegal for children and adolescents to drink alcoholic beverages (although it is strangely enough illegal for them to buy it; i.e. they have to get it from their parents or another >15 year old). Statistically, Denmark ranges among the countries that has the earliest alcohol debut and the highest mean weekly/monthly alcohol consumption in adolescence. In general, alcohol is more socially and culturally accepted in the Western world (or all cultures?). But given that alcohol has such damaging effects should we allow it if it turns out to have detrimental effects on brain development and cognitive functions?

You can put it another way: given that you know this, would you allow your teenage son or daughter to drink alcohol? If you knew that her or his brain would respond negatively (both long and short term) to the alcohol, would you let it happen? Thick twice

-Thomas

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Ever heard about evidence-based medicine? Now we should all start talking about evidence-based teaching (or paedagogics), too. Usha Goswami has a nice article in Nature Reviews Neuroscience about the way that (neuro-)science should be communicated to teachers, who again should implement these ideas in schools. I'm all in for it, although I think we should be careful about saying too much and feel too confident that our word may come through the way we want it to. there are a lot of flaky uses of science terms in software, teaching applications and so forth, to feel confident that we may do well enough to bring the correct information to the fore. As Goswami also writes in his paper, much of the current science-based talks are "reality testers" that ultimately point out how that other approaches are plain wrong. This may very well backfire. As he writes:

(…) At the Cambridge conference, prominent neuroscientists working in areas such as literacy, numeracy, IQ, learning, social cognition and ADHD spoke directly to teachers about the scientific evidence being gathered in scientists' laboratories. The teachers were amazed by how little was known. Although there was enthusiasm for and appreciation of getting first-hand information, this was coupled with frustration at hearing that many of the brain-based programmes currently in schools had no scientific basis. The frustration arose because the neuroscientists were not telling the teachers 'what works instead'. One delegate said that the conference "Left teachers feeling [that] they had lots stripped away from them and nothing put in [its] place". Another commented that "Class teachers will take on new initiatives if they are sold on the benefits for the children. Ultimately this is where brains live!".

-Thomas

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