Sunday, May 15, 2011
Crete by the end of the mycenae period - Antique Greece
Crete by the end of the mycenae period - Antique Greece
Crete is a Mediterranean island located southeast of the Peloponnese, and which sides act as the cut-off. They are dominated by three mountain ranges: Dhikti mountains to the east, which is not suitable for farming and its inhabitants live mainly from fishing, Idhi massif in the center of Levk on the west of the island. The only wider plain is Mesara in the south, the others likethat in Knos are very small. Moderately fertile soil of these plains were ideal for growing wheat, grapes and olives, while the mountainous land, partly covered with pine forest and cypress, were more suitable as a pasture for livestock or to obtain wood. Although the soil of Crete quality was not better than the other Aegean islands, is geographically accommodation helped to Crete soon occupy a privileged position. The island, situated halfway between Greece and Africa so that seafarers could easily came from their ports to the Nile delta, and also to Asia and the West, soon will be dedicated to commercial sailing. Cretans could easly sail along the Libyan coast or Cyprus which had rich metallic ores and even sail to the Syrian coast. Between the 1600th and 1400th BC Cretan fleet built of wood from their forests, was known all over the Aegean Sea and the island was an important force in the east and an ideal center for technical and economic ties that have emerged from the discovery of processing metal.
Minoan period
Crete and the so-called "Minoan period" are the starting point for the area from which they were derived (although quite different in content) polis, or city of citizens. This form,which first created urban settlement of big format, should be put in touch with the other also a new phenomenon, namely a form of political power that was in the hands of just one man, Minoja despot, at once historical and mythical character who ruled Crete.Both of these phenomena took the island from one civilization to another, from a civilization villages and marketplaces in the civilization of the palaces, symbol of the political, religious and economic power.This period, whose development phase flow with almost no transition can be interpreted only by influence of Egypt and Babylon dynastys.Teritorial expansion of Egypt on Asia and Babylon breakthrough in the Mediterranean area of Crete have enabled the sailors, merchants and travelers, not just to learn new techniques, but primarily to expand their use to the Cretan civilization as a whole.
In Egypt, 2000. years before Christ already existed real palaces, the art of jewelry making, painting and the letter system.We can't precisly speak of a direct connection between Egypt and Crete, but the Phoenicians who have passed here have provided ample opportunity for contacts that were closer to the civilization of Crete need of improvement . It is most likely civilization was born in the east of Crete in middle minoan period. The palace in Malia was probably the first who ruled over the hitherto independent towns in the east and Malia made a kind of provincial capital. It appears that the Festus and Knossos, located in the center and south of the island, developed only later. At the beginning of the second millennium BC in these cities was a strong central government. Minoj ruler who relied on a strong bureaucratic apparatus has held important administrative function and had control over the metalworking and transport. The expression of that power was the construction of large palace, around which were formed urban settlements.
The cities and palaces
The City Palace, the palace that developed the town. We can fully admire the Knosu, unique city, the monument construction in Knosu Palace, residence of the ruler Minoja, the largest and also most famous buildings in Crete. Thanks to the research many individual components were found that have enabled the reconstruction of the upper floors. The current layout of the palace makes visible and understandable only the last period of its use, ie the peak of the Minoan culture from 1600th to 1400th BC.
Palces in Knossos,Festus and Malia
From the first Cretan palaces in Knossos and Festus there are ony few ruins left of the palace built under the later, while palace in Malia, that was built later, preserved the simple lines of the earlier period. Moreover in the Knossos and Festus there were princely palaces and great cities: Hagia Triada in plain Mesara and Kanji. We can say with certainty that this settlement is the first major example of the actual architectural art, and not just an ordinary building techniques.
If we look at first the ruins in Malia which are characteristic of the first palaces of Crete, ie which is generally called "middle-minoan period". Fortification wall was built of finely carved stone blocks and showing your progress sags and bulges,which can still be seen primarily in the western part of the wall. From medieval courtyard, surrounded by colonnades on two sides, of which one enters the different chambers that are spread in a square. In Malia from the early period we can see the occurrence of structures with floors, especially over the western part of the palace, which were available via the large staircase in the middle courtyard, this is part of the palace that has certainly been changed in the future. The eastern part consists only of a simple single-storey warehouse, located between the courtyard and fence walls, that was made for bowls with the food supply. Hall which borders in the north with yard testifies the way of construction of the Egyptian influence on Crete. This hipostil (ie ceiling support columns) is here, though, made very clumsy, but this technique is later found in many shapes in Knossos.
Royal necropolis Krisolak has also discovered in Malia. Fence surrounding the palace, quite similar to the ones that surround huge tombs that show the same way of building as houses. Walls everywhere are made of lower quality building materials, but are always decorated with stucco. These architectural Gazette excavated in Malia showed that there were knowledge of metalworking already in middleminoan period. In workshop of bronze in the palace in Malia were found mold in which they poured various tools such as a two-edged axes, chisels and the similiar tools. In jewelry-making after that period is also noticeable improvement in the processing of metals. Some other pieces of jewelry have been spared from the devastation of the necropolis Krisolak. The stylized forms found indicates that people were more worried about the jewelry, but for the faithful representation. This proves that the Cretans knew very refined and very expressive and even the Syrian and Egyptian art of jewelry making. This love is characterized by the formation of the ceramics of the period. In Malia,there are generally a relatively simple geometric motifs and stylized plants and flowers in only three colors: red, white and black. It is a ceramic art of early minoan period that gave more primitive character.
If we cross to the study of so-called younger palace on Crete. ie, middle, or late minoan period that will take advances in ceramic technology. Villages in the vicinity of large palaces, especially in Knossos, show widespread use of fine ceramics. During the development of the highest authorities in the palaces it reaches a very high technical level: vases are becoming thinner and finally achieve the thickness of eggshell. The fact that the colors are preserved for millennia testifies to its full splendor of the high quality of materials used. Thus, an advanced technique leads to a large market and a high degree of specialization of artistic craftsmanship, in short to civilization at its peak. The transition from the old culture to newer corresponding to the development of the palace and the most important changes that were implemented continuously.
New tool to test stroke victims
New tool to test stroke victims
Flinders University 
The simulator can be used to test a stroke patient's ability to undertake the everyday task of supermarket shopping.
Image: lisegagne/iStockphoto
A virtual reality system that will enable occupational therapists at the Repatriation General Hospital to better assess stroke victims will be launched today by Minister for Ageing Jennifer Rankine.
The Shopping Simulator has been developed by the Medical Device Partnering Program (MDPP) at Flinders University in collaboration with the Department of Rehabilitation and Aged Care.
It allows patients to move through a virtual supermarket, selecting groceries and adding them to a trolley, to demonstrate whether they are capable of making logical decisions.
MDPP Director, Professor Karen Reynolds, said the focus on cognitive assessment through the simulator enables an OT to determine a patient’s ability to undertake the everyday task of supermarket shopping.
“Our simulation software recreates the grocery shopping experience with the aid of a simple touch-screen computer and a ‘trolley handle’,” Professor Reynolds said.
“The level of complexity can be adjusted by OTs, who can specify certain groceries or set a shopping budget to ascertain the cognitive ability of each patient,” she said.
Associate Professor Craig Whitehead, Regional Clinical Director for Rehabilitation and Aged Care in the Southern Adelaide Health Service, said the Shopping Simulator was created in response to requests from hospital clinicians.
“Clinicians need to know what people are capable of, rather than just have an opinion of what they are capable of,” Associate Professor Whitehead said.
“The Shopping Simulator is an effective and efficient way of testing a stroke patient’s alertness, ability to scan both sides of the environment and logical processing,” he said.
“Particularly for older people and people with disability, technological interfaces such as the Shopping Simulator represent the brave new frontier for clinical medicine.”
Minister for Ageing Jennifer Rankine said the State Government was proud to support research projects that have a real impact on people’s quality of life.
“The South Australian Government has provided more than $1 million in funding to the Medical Device Partnering Program at Flinders University to help develop important research that assists South Australians in their everyday lives. I am pleased to see one of the significant projects funded through this program in action,” Minister Rankine said.
“Suffering from a stroke affects not only the patient but their family as well. The success seen in early trials of the simulator is encouraging and hopefully soon this project can be used to help better assess more people in this situation,” she said.
The Medical Device Partnering Program supports the development of cutting-edge medical devices and assistive technologies, through unique collaborations between researchers, industry, clinical end-users and government.
Funded by the South Australian Government through the Premier’s Science and Research Fund and the Disability, Ageing and Carers Branch, it brings together researchers from Flinders University, the University of Adelaide, the University of South Australia and NovitaTech.
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I .T. துறையில் ஜொலிக்க நினைப்பவர்கள் செய்ய வேண்டிய வழிபாடு
I .T. துறையில் ஜொலிக்க நினைப்பவர்கள் செய்ய வேண்டிய வழிபாடு
இன்று பெரும்பாலும் ராகுதிசா நடப்பவர்களே ஐ.டி.பணிகளில் உள்ளனர்.ராகு என்பது யோகக்காரன் என்று கொள்ளப்படுகிறான்.ஒரே நாளில் கோடீஸ்வரர்கள் உருவாகுவதும்,சொத்துக்கள் இழப்பதும் ராகுவின் விளையாட்டு.
நீங்கள் வேலை பார்க்கும் நிறுவனம், கம்பியூட்டர், I . T . துறை, LIC , மக்கள் தொடர்பு அதிகமாக இருக்கும் வேலை என்றால், நீங்கள் அம்மன் வழிபாடு செய்து வந்தால் , உங்கள் துறையில் நீங்கள் வெற்றி பெறுவதோடு, மக்களின் நன் மதிப்பு பெற முடியும்.
சில பெண்களைப் பார்த்தாலே , அவர்கள் ராகுவின் அம்சங்கள் நிறைந்த பெண்கள் என்று தெரிய வரும். நமக்குத் தெரிந்த முகம் என்றால், பருத்தி வீரன் படத்தில் வரும் , முத்தழகு காரேக்டரைப் போல என்று எடுத்துக் கொள்ளுங்கள். இவர்கள் கணினி வேலைகளில் படு வேகமாக செயல்படுவார்கள்.
இதற்கு ஒரு சுலப வழி உண்டு. அது என்னவென்றால், தினமும் ,உங்கள் வீட்டுக்கு அருகில் உள்ள ஒரு அம்மன் கோவில் (உதாரணமாக பத்திரகாளி அம்மன் அல்லது உக்கிர பெண் தெய்வம்) தினமும் ஒரு வேளை சென்று வழிபட்டு வர வேண்டும். அதே சமயம் வீட்டிலும்-வெளியிலும் அசைவம் கண்டிப்பாக தவிர்க்கவேண்டும். (இல்லாவிட்டால் ரத்தகாயம் வழிபடுவோருக்கு ஏற்படும்)
யாருக்கு ராகு திசை நடக்கிறதோ அவர்கள் அல்லது அவர்களது ரத்த உறவுகள் வழிபட்டு வருவதோடு, வெள்ளிக்கிழமை ராகு காலம் காலை 10.30 முதல் 12.00 வரை-அதுவும் 11.30-12.00 கடைசி அரை மணி நேரம் மிக முக்கியம்.அந்த நேரத்தில் எலுமிச்சம்பழத்தில் தாமரை தண்டு திரியில் நெய் தீபம் ஏற்றி வழிபட்டு வரவேண்டும்.
தவிர, ராகு வின் கிழமை ஞாயிறு ஆகும். அன்று மாலை 5.30-6.00 மணிக்கு மேலே எழுதியது போல தீபம் ஏற்றி வழிபட்டு வரவேண்டும். இப்படி ராகு திசா காலம் முழுவதும் 18-ஆண்டுகள் வரை வழிபட்டு வந்தால் குடும்ப வாழ்க்கை நிம்மதியாக இருக்கும்.
திருவாதிரை, சுவாதி, சதயம் - இந்த நட்சத்திரத்தில் பிறந்த எல்லேஈரும் மேற்சொன்ன வழிபாடு செய்து வந்தால் 2-3 ஆண்டுகள் கடந்த பிறகு உங்கள் வாழ்க்கையில் நிம்மதி உண்டாகும். இதுவும் அனுபவ உண்மை
Read more: http://www.livingextra.com/2011/02/i-t.html#ixzz1MQnu40fS
Learning to understand others' actions
Learning to understand others' actions
+ Author Affiliations
- *↵ Author for correspondence (c.m.press@reading.ac.uk).
Abstract
Despite nearly two decades of research on mirror neurons, there is still much debate about what they do. The most enduring hypothesis is that they enable ‘action understanding’. However, recent critical reviews have failed to find compelling evidence in favour of this view. Instead, these authors argue that mirror neurons are produced by associative learning and therefore that they cannot contribute to action understanding. The present opinion piece suggests that this argument is flawed. We argue that mirror neurons may both develop through associative learning and contribute to inferences about the actions of others.
1. Introduction
Mirror neurons, which have been discovered in the premotor area F5 [1] and inferior parietal lobule, area PF [2] of macaque monkeys, discharge not only when the monkey executes an action of a certain type (e.g. precision grip), but also when it observes the experimenter performing the same action. A number of neuroimaging studies have provided evidence that a similar system also exists in humans (e.g. [3]). A matter of much debate is whether activity in the so-called ‘mirror neuron system’ (MNS) reflects neural processes engaged in ‘action understanding’, that is, inferences about the goals and intentions driving an observed action. It has been suggested that mirror neurons are simply the result of learned sensorimotor associations, as proposed in the associative sequence learning (ASL) model [4,5], and that this ontogeny is inconsistent with a role in understanding the actions of others [6,7]. In contrast, we argue that mirror neurons may develop through associative learning and subsequently contribute to action understanding.
2. ASL model
The ASL model [4,5] proposes that the mirror properties of the MNS emerge through sensorimotor associative learning. Under this hypothesis, we are not born with an MNS. Rather, experience in which observation of an action is correlated with its execution establishes excitatory links between sensory and motor representations of the same action. We have abundant experience of matching relationships between observed and executed actions during our lives [8]. Following such experience, observation of an action is sufficient to activate its motor representation. Therefore, representations that were originally motor become ‘mirror’ (activated when observing and executing the same action, figure 1).
Figure 1.
Associative sequence learning. Before learning, sensory neurons (S1, S2 and Sn) which are responsive to different high-level visual properties of an observed action are weakly and unsystematically connected (dashed arrows) to some motor neurons (M1, M2 and Mn), which discharge during the execution of actions. The kind of learning that produces mirror neurons occurs when there is correlated (i.e. contiguous and contingent) activation of sensory and motor neurons that are each responsive to similar actions.
If the ASL model is correct, mirror neurons do not have an ‘adaptive function’, they did not evolve ‘for’ action understanding or to meet the demands of any other cognitive task [5]. However, as a by-product of associative learning, mirror neurons could still be recruited in the course of development to play some part in a variety of cognitive tasks. Therefore, according to the ASL model, they could be useful without being essential, and without their utility explaining their origins. Specifically, mirror neurons could play a part in action understanding even if this functional role was not favoured by natural selection in the course of phylogenetic evolution.
So why has the ASL hypothesis been interpreted as evidence against a functional role of mirror neurons in action understanding? Hickok [6] argued that some of the evidence that has been published in support of ASL is inconsistent with the hypothesis that the MNS is involved in action understanding. The studies in question require participants to observe actions while systematically executing non-matching actions, and subsequently record indices of MNS functioning. The rationale for these experiments assumes that, if the MNS develops through associative learning, then experiences that differ from those typically encountered during life should reconfigure the MNS and change the way it operates. Consistent with this prediction, it has been found that training in which participants are required to perform index finger actions when they see little finger actions, and vice versa, results in activation of primary motor cortical representations of the index finger when passively observing little finger actions, and activation of representations of the little finger when observing index finger actions [9,10]. Catmur et al. [11] demonstrated that such training effects are likely to be mediated by cortical circuits that overlap with areas of the MNS. They required one group of participants to lift their hand when they saw a hand lift, and to lift their foot when they saw a foot lift (matching group). Another group was required to lift their hand when they saw a foot lift, and to lift their foot when they saw a hand lift (non-matching group). Following such training, voxels in premotor and inferior parietal cortices that responded more when observing hand than foot actions in the matching group responded more to foot than hand actions in the non-matching group. This finding suggests that, following non-matching training, observation of hand actions activates motor representations of foot actions. Similar ‘counter-mirror’ training effects have also been observed in behavioural paradigms (e.g. [12,13], see also [14,15] for ‘logically related’ activations that may have been generated through naturally occurring non-matching experience).
Hickok [6] argued that these studies provide evidence that mirror neurons cannot underlie action understanding. Embracing the idea that counter-mirror training reconfigures the MNS—making it responsive to the sight of one action and the execution of a different action—he reasoned that, if the MNS contributes to action understanding, this reconfiguration should have an impact on action understanding. However, he considered that participants who showed counter-mirror activation (e.g. stronger activation of the index finger muscle during observation of little than of index finger movement) ‘presumably did not mistake the perception of index finger movement for little finger movement and vice versa’ ([6], p.1236). The key word here is ‘presumably’. Neither the focal study by Catmur et al. [9], nor any other study, has examined the effects of counter-mirror training on indices of action understanding.
3. Predictive coding and action understanding
The aim of the predictive coding (PC) account [16,17] was to answer the question ‘if mirror neurons enable the observer to infer the intention of an observed action, how might they do this’? In many accounts of the MNS, it is assumed that mirror neurons are driven by the sensory data and that when the mirror neurons discharge, the action is ‘understood’. However, within this scheme mirror neurons could only enable action understanding if there was a one-to-one mapping between the sensory stimulus and the intention of the action. This is not the case. If you see someone in the street raise their hand, they could be hailing a taxi or swatting a wasp. The context must establish which intention is more likely to drive an action. Consistent with the PC account, the empirical evidence does not support the view that mirror neurons are driven solely by sensory data from focal action stimuli. For example, Umilta et al. [18] found that neurons in F5, which fire both when the monkey executes and observes grasping actions, also fired when the monkey observed the experimenter's grasping action disappear behind a screen. That is, the premotor neurons represented a grasping action in its entirety, but where the grasping phase was not actually seen. Therefore, mirror neurons could not be driven entirely by the focal stimulus input. The PC account provides a framework that resolves these issues.
The essence of the PC account is that, when we observe someone else executing an action, we use our own motor system to generate a model of how we would perform that action to understand it [19,20]. PC enables inference of the intentions of an observed action by assuming that the actions are represented at several different levels [21] and that these levels are organized hierarchically such that the description of one level will act as a prior constraint on sub-ordinate levels. These levels include: (i) the intention level that defines the long-term desired outcome of an action, (ii) the goal level that describes intermediate outcomes that are necessary to achieve the long-term intention, (iii) the kinematic level that describes, for example, the shape of the hand and the movement of the arm in space and time. Therefore, to understand the intentions or goals of an observed action, the observer must be able to represent the observed movement at either the goal level or the intention level, having access only to a visual representation of the kinematic level.
PC proposes that contextual cues generate a prior expectation about the intention of the person we are observing. In the above example of the hand-raising action, these cues could be the presence of a taxi or wasp, or a facial expression. On the basis of these intentions, we can generate a prior expectation of the person's intermediate goals. Given their intermediate goals, we can predict the perceptual kinematics. Backward connections convey the prediction to the lower level where it is compared with the representation at this sub-ordinate level to produce a prediction error. This prediction error is then sent back to the higher level, via forward connections, to update the representation at this level (figure 2). By minimizing the prediction error at all the levels of action representation, the most likely cause of the action, at both the intention and the intermediate goal level, will be inferred. Thus, the PC process uses information, supplied by the MNS, about which goals are most likely, given a certain intention, and which kinematics are most likely, given a certain goal, to test hypotheses about the observed actors' intentions.
Figure 2.
Predictive coding. Each level of the hierarchy predicts representations in the level below, via backward connections. These predictions are compared with the representations at the sub-ordinate level to produce a prediction error. This prediction error is then sent back to the higher level, via forward connections, to update the representation. By minimizing the prediction error at all the levels of the MNS, the most likely cause of the action will be inferred. Dotted line, prediction error; thick line, prediction.
The assumptions of the PC model are consistent with those of ASL. If both models are correct, the MNS develops through associative learning and subsequently supports inferences about the goals and intentions driving others' actions. Therefore, it remains an open and important empirical question whether any intervention that systematically changes the MNS has correlated effects on action understanding.
4. Conclusion
PC and ASL accounts of the MNS address different questions and offer compatible answers. The PC account considers the requirements that are necessary to enable goal or intention inference during action observation. It assumes that the sensorimotor connection strengths have been learned, but does not propose a mechanism by which these are learned. ASL provides an associative mechanism for such learning. Although ASL does not provide a mechanistic account of how such learning could enable action understanding, it allows for the possibility that the MNS, once acquired, could support such functions. In other words, the MNS could enable inferences about the intentions of others, even if this function is not an evolutionary adaptation. Therefore, if both the PC and ASL hypotheses are correct, we learn, via the principles specified in associative learning theory, to predict others' intentions using our own motor systems.
Acknowledgements
C.P. was funded by an Interdisciplinary Postdoctoral Fellowship awarded by the MRC and ESRC. J.M.K. was funded by the Wellcome Trust. C.H. is a Senior Research Fellow of All Souls College, University of Oxford.
This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
A Moon on Fire
A Moon on Fire
Credit: Xianzhe Jia/ U. of Michigan and Krishan Khurana/UCLA
The jovian moon Io harbors a globe-girdling pool of molten rock beneath its volcano-riddled surface. That’s the conclusion of a reanalysis of decade-old data from the Galileo spacecraft that once orbited Jupiter, reported online today in Science. Theoreticians had long predicted that Jupiter’s massive gravity must raise tides in Io that knead its solid but still malleable rock to produce heat until at least part of the interior melts. And planetary geologists had seen signs in the moon’s surface lavas that indicate that its 100 known volcanic hot spots are fed by a deep magma “ocean.” But high-flying volcanic debris frustrated space physicists’ attempts to use Jupiter’s powerful magnetic field as a probe of Io’s interior. Now researchers report that they have finally sorted through the interference to reveal a magnetic signature that Io could only produce if it contains an electrically conductive layer of magma—or crystal-laden magma mush—50 kilometers or more thick (thin orange layer) beneath its rocky crust. The find is reminiscent of the solar system’s earliest days, when most large, rocky bodies sported a magma ocean until they cooled down.
The beginnings of the brain
All of the tissues and organs of the body arise from one of three embryonic precursors: the ectoderm, mesoderm and endoderm. The ectoderm contributes to several tissues, including the nervous system and the skin, but some studies have suggested that development into neurons requires nothing more than the absence of specific inhibitory signals.
This phenomenon has led biologists to formulate what is called the ‘neural default model’. “The simplest interpretation of the neural default model is that the neural fate is a ‘left-over’ choice, passively determined by the elimination of other pathways of differentiation,” explains Yoshiki Sasai of the RIKEN Center for Developmental Biology in Kobe. This model fails to address the identities of the factors that actively drive neuronal development, but new findings from Sasai and colleagues have spotlighted a single protein that appears to set this process into motion.
His team had previously designed a culture system that promotes neural differentiation of mouse embryonic stem (mES) cells2, and they used this technique to identify genes that are specifically switched on in these cells. They identified one intriguing candidate, Zfp521, which activated several other genes involved in neural development, even when the mES cells were cultured in the presence of factors that would normally curb this process (Fig. 1).
When Sasai and colleagues examined expression in developing mouse embryos, they noted that the spatial and temporal distribution of Zfp521 activity closely mirrored known sites of neural differentiation. Likewise, early stage mouse embryos injected with mES cells in which Zfp521 expression was abrogated largely failed to incorporate these cells into the developing nervous system. By systematically identifying the genes whose expression is disrupted in the absence of Zfp521, the researchers were able to determine that this gene acts as a driver for the maturation of ectodermal cells into neuroectoderm, the developmental stage that immediately precedes formation of actual neural progenitors.
“The most important message of this study is that the neural fate is acquired by an active determination process,” says Sasai. Understanding how this developmental switch works could ultimately provide scientists with a powerful tool for efficiently transforming human stem cells into mature nervous tissue suitable for experimental use or even transplantation, although it remains to be determined whether human ES cells obey the exact same principles. “We have preliminary data showing a conserved essential role for Zfp521 in both species,” says Sasai, “but we need to analyze the similarities and differences in greater depth.”
More information: Kamiya, D., et al. Intrinsic transition of embryonic stem-cell differentiation into neural progenitors. Nature 470, 503–509 (2011).
Watanabe, K., et al. Directed differentiation of telencephalic precursors from embryonic stem cells. Nature Neuroscience 8, 288–296 (2005).
Provided by RIKEN
"The beginnings of the brain." May 13th, 2011. http://medicalxpress.com/news/2011-05-brain.html
Posted by
Robert Karl Stonjek
New test may help distinguish between vegetative and minimally conscious state
(PhysOrg.com) -- In a new study published in Science, researchers from the University of Liege in Belgium, led by Dr. Melanie Boly, share the discovery of a new test that could aid physicians in differentiating between vegetative and minimally conscious states in patients with brain damage. It is currently difficult to differentiate between a vegetative state where patients lack cognitive function yet display wakefulness and those in a minimally conscious state. Recent awareness to this issue arose in the Terri Schiavo case in Florida. Shiavo had been in a vegetative state for 15 years and on life support before a judge issued a court order to take her off life support. The question of brain function and the possibility of recovery was an issue in the court battle and this test could aid physicians in making that determination.
Using an electroencephalogram to record brain activity, Boly and her team looked at brain activity in 43 patients with 22 healthy individuals and 21 brain-damaged patients. The patients ranged in age from 16-83. Of the brain-damaged patients, 13 were in a minimally conscious state and 8 were in a vegetative state.
The subjects were played a series of tones, varying in pitch. With the change in pitch being a surprising event, the temporal cortex of the brain would send the frontal cortex a message for it to consider a reaction. This occurred in all of the subjects, regardless of the level of brain-damage. After the frontal cortex receives the message, it should send back a message to the temporal cortex. However, while this did occur in the healthy and minimally conscious patients, those in a vegetative state did not show that backwards communication.
Combined with the current Coma Recovery Scale, an assessment test currently administered to determine the level of consciousness, Boly hopes to be able to better distinguish between the actual level of consciousness.
More information: "Preserved feedforward but impaired top-down processes in the vegetative state" Boly M, Garrido MI, Gosseries O, Bruno MA, Boveroux P Schnakers C, Massimini M, Litvak V, Laureys S, Friston K, Science 13 May 2011. DOI: 10.1126/science.1202043
ABSTRACT
Frontoparietal cortex is involved in the explicit processing (awareness) of stimuli. Frontoparietal activation has also been found in studies of subliminal stimulus processing. We hypothesized that an impairment of top-down processes, involved in recurrent neuronal message-passing and the generation of long-latency electrophysiological responses, might provide a more reliable correlate of consciousness in severely brain-damaged patients, than frontoparietal responses. We measured effective connectivity during a mismatch negativity paradigm and found that the only significant difference between patients in a vegetative state and controls was an impairment of backward connectivity from frontal to temporal cortices. This result emphasizes the importance of top-down projections in recurrent processing that involve high-order associative cortices for conscious perception.
© 2010 PhysOrg.com
"New test may help distinguish between vegetative and minimally conscious state." May 13th, 2011. http://medicalxpress.com/news/2011-05-distinguish-vegetative-minimally-conscious-state.html
Posted by
Robert Karl Stonjek
The protein that makes us remember pain
(PhysOrg.com) -- New research by scientists in Arizona in the US has demonstrated that an enzyme makes the body remember and remain sensitive to pain after an injury has healed.
Research in 2006 by Professor Todd C. Sacktor of the State University of New York Downstate Medical Center found that the protein kinase M zeta (PKMzeta) appears at the synapses (gaps between neurons) and must be continually recreated at the synapses. If it disappears, so do memories of the pain. Sacktor’s team were able to irreversibly erase memories of pain in rats by using a chemical called zeta-inhibiting peptide (ZIP) which inhibits PKMzeta. In later research the showed that extra PKMzeta affected the brains of rats by boosting old memories.
Now new research by Marina Asiedu and Dipti Tillu and colleagues from the University of Arizona Medical School has shown that PKMzeta is also responsible for the lingering pain and sensitivity felt after an injury. The researchers knew that when pain is experienced the neurons carrying the pain signals develop stronger connections, especially in the dorsal horn section of the spinal cord. The same thing happens in the brain when we learn something new, and so they decided to test the hypothesis that PKMzeta is involved in both processes.
The team injected mice in the paw with Interleukin-6 (IL-6), a protein that produces mild swelling and makes the paw more sensitive for up to three days. They later injected prostaglandin E2 (PGE2) into the paw, and the mice reacted to the chemical, but only if they had previously been injected with IL-6. If the mice were injected with ZIP at the same time as IL-6 or up to three days afterwards, their paws never became more sensitive to PGE2, indicating they had not developed a memory for the pain. When they injected a protein that mimics PKMzeta, the sensitivity returned.
Researchers in Korea made similar discoveries for chronic pain in research published in 2010. Dr Xiang-Yao Li and colleagues found that PKMzeta creates memories in chronic pain caused by nerve damage, and in this research they found the protein affects the anterior cingulated cortex (ACC) part of the brain. An injection of ZIP was found to ease the pain, but only for a few hours and not permanently.
If the protein kinase M zeta produces the same effects in humans, new treatments could be developed that target PKMzeta to treat severe or chronic pain, and conditions such as central neuropathic pain syndrome, in which people retain the memory of a pain long after the injury has healed. PKMzeta may also play a role in other conditions such as addictions and post traumatic stress disorder.
More information: Spinal Protein Kinase M ζ Underlies the Maintenance Mechanism of Persistent Nociceptive Sensitization, The Journal of Neuroscience, 4 May 2011, 31(18): 6646-6653; doi:10.1523/JNEUROSCI.6286-10.2011
Abstract
Sensitization of the pain pathway is believed to promote clinical pain disorders. We hypothesized that the persistence of a sensitized state in the spinal dorsal horn might depend on the activity of protein kinase M ζ (PKMζ), an essential mechanism of late long-term potentiation (LTP). To test this hypothesis, we used intraplantar injections of interleukin-6 (IL-6) in mice to elicit a transient allodynic state that endured ∼3 d. After the resolution of IL-6-induced allodynia, a subsequent intraplantar injection of prostaglandin E2 (PGE2) or intrathecal injection of the metabotropic glutamate receptor 1/5 (mGluR1/5) agonist DHPG (dihydroxyphenylglycol) precipitated allodynia and/or nocifensive responses. Intraplantar injection of IL-6 followed immediately by intrathecal injection of a PKMζ inhibitor prevented the expression of subsequent PGE2-induced allodynia. Inhibitors of protein translation were effective in preventing PGE2-induced allodynia when given immediately after IL-6, but not after the initial allodynia had resolved. In contrast, spinal PKMζ inhibition completely abolished both prolonged allodynia to hindpaw PGE2 and enhanced nocifensive behaviors evoked by intrathecal mGluR1/5 agonist injection after the resolution of IL-6-induced allodynia. Moreover, spinal PKMζ inhibition prevented the enhanced response to subsequent stimuli following resolution of hypersensitivity induced by plantar incision. The present findings demonstrate that the spinal cord encodes an engram for persistent nociceptive sensitization that is analogous to molecular mechanisms of late LTP and suggest that spinally directed PKMζ inhibitors may offer therapeutic benefit for injury-induced pain states.
via Discover
© 2010 PhysOrg.com
"The protein that makes us remember pain." May 13th, 2011. http://medicalxpress.com/news/2011-05-protein-pain.html
Posted by
Robert Karl Stonjek
A giant interneuron for sparse coding
A single "giant", non-spiking, GABAergic interneuron (right, labelled by intracellular injection of fluorescent dye) forms an all-to-all negative feedback loop with a population of about 50,000 Kenyon cells, principal neurons of the mushroom bodies, a structure involved in olfactory memory in the insect brain. This normalizing feedback loop serves to ensure relatively constant sparseness of mushroom body output across varying input strengths. Sparseness is an important feature of sensory representations in areas involved in memory formation. Credit: MPI for Brain Research A single interneuron controls activity adaptively in 50,000 neurons, enabling consistently sparse codes for odors.
The brain is a coding machine: it translates physical inputs from the world into visual, olfactory, auditory, tactile perceptions via the mysterious language of its nerve cells and the networks which they form. Neural codes could in principle take many forms, but in regions forming bottlenecks for information flow (e.g., the optic nerve) or in areas important for memory, sparse codes are highly desirable. Scientists at the Max Planck Institute for Brain Research in Frankfurt have now discovered a single neuron in the brain of locusts that enables the adaptive regulation of sparseness in olfactory codes. This single giant interneuron tracks in real time the activity of several tens of thousands of neurons in an olfactory centre and feeds inhibition back onto all of them, so as to maintain their collective output within an appropriately sparse regime. In this way, representation sparseness remains steady as input intensity or complexity varies.
Signals from the world (electromagnetic waves. pressure, chemicals etc) are converted to electrical activity in sensory neurons and processed by neuronal networks in the brain. Insects sense smells via their antennae. Odours are detected by sensory neurons there, and olfactory data are then sent to and processed by the antennal lobes and a region of the brain known as the mushroom bodies. Neurons in the antennal lobes tend to be "promiscuous": odours are thus represented by specific combinations of neuronal activity. Neurons in the mushroom bodies—they are called Kenyon cells—, however, respond with great specificity and thus extremely rarely. In addition, they generally respond with fewer than three electrical impulses when stimulated with the right odour. This "sparse coding" strategy has the advantage that it simplifies the task of storing odour representations in memory.
Surprisingly, each Kenyon cell is connected on average to half of all possible presynaptic neurons in the antennal lobes. So how do the Kenyon cells manage to respond only extremely rarely, and with a sparseness that varies little over large ranges of stimulation conditions? Gilles Laurent of the Max Planck Institute for Brain Research and his group found that a single giant interneuron plays a key role. Along with colleagues in his lab (formerly at Caltech) and Great Britain, he has discovered that this neuron, with its extensive arbour, is activated by the entire Kenyon cell population and in turn inhibits them all back. "The giant interneuron and the Kenyon cells form a simple negative feed-back loop: the more strongly it is activated by the Kenyon cell population, the more strongly it curtails their activity in return", explains Laurent. The interneuron itself does not generate any action potentials, but inhibits Kenyon cells via nonspiking and graded release of the neurotransmitter GABA (gamma aminobutyric acid). This smooth, graded property enables this giant interneuron to do a kind of real-time, population averaging, thus carrying out an operation that might otherwise require the involvement of hundreds or thousands of individual spiking neurons.
The effectiveness of the giant interneuron is such that it can actually turn off the Kenyon cell population completely. But the research team also discovered that the giant interneuron is, in turn, controlled by another inhibitory neuron. "This allows the network activity to be potentiated or attenuated, and the sensitivity of this feedback loop to be adjusted", says Gilles Laurent. This is an important feature for brain regions such as the mushroom bodies, which are responsible not only for olfactory processing, but also for learning and memory. Mushroom bodies are where smells can be associated with other sensory modalities, enabling the formation of complex representations.
The scientists' findings show how massive negative feed-back loops can be formed in neuronal networks and what roles they can play. In vertebrates, the piriform cortex, part of the olfactory cortical complex, sits in a position equivalent to the mushroom bodies. "It is very likely that mammals have similar all-to-all control mechanisms in cortical and other circuits. They might not consist of single interneurons, however, but rather of populations of inhibitory neurons with means to couple their responses and actions", surmises Laurent. "Insect brains never cease to give us insights about neural computation, and to put elegant solutions right on our laps, if we know where to look and are a bit lucky."
More information: Normalization for sparse encoding of odours by a wide-field interneuron, Maria Papadopoulou, Stijn Cassenaer, Thomas Nowotny, Gilles Laurent, Science, 6 May 2011. DOI: 10.1126/science.1201835
ABSTRACT
Sparse coding presents practical advantages for sensory representations and memory storage. In the insect olfactory system, the representation of general odors is dense in the antennal lobes but sparse in the mushroom bodies, only one synapse downstream. In locusts, this transformation relies on the oscillatory structure of antennal lobe output, feed-forward inhibitory circuits, intrinsic properties of mushroom body neurons, and connectivity between antennal lobe and mushroom bodies. Here we show the existence of a normalizing negative-feedback loop within the mushroom body to maintain sparse output over a wide range of input conditions. This loop consists of an identifiable “giant” nonspiking inhibitory interneuron with ubiquitous connectivity and graded release properties.
Provided by Max-Planck-Gesellschaft
"A giant interneuron for sparse coding." May 13th, 2011. http://medicalxpress.com/news/2011-05-giant-interneuron-sparse-coding.html
Comment:
There is two ways that the amount of information processed can be controlled: constant resolution and constant density. A visual analogue can demonstrate this for us.
A constant resolution requires ever greater density of information as the amount of information increases eg consider a nice clear photograph of a face. Let's say you are using a 10 megapixel camera. Now we take a picture of a scene in which the face of the person is seen, say in a grandstand containing 5,000 people. For the resolution of the face to be retained at 10 mega pixels, what resolution camera do you now require? The answer is that it would have to be in the order of 100 times higher as, when you blow up the picture so that just the face is seen, as in the first shot, we are looking at only a tiny area of the CCD.
Now consider a constant density. The first photograph is the same as before but when we now photograph that grand stand the density of information remains the same, but the detail of the face falls precipitously ~ you'd be hard pressed to even recognise the face in that huge crowd.
Thus constant density (photograph size) will retain the same size pictures regardless of what is photographed but the constant resolution (constant for every object in the scene) changes the amount of information when there is more detail.
Note that for the ten megapixel camera mentioned earlier, the resolution of a face will fall as the person you are photographing is ever further away from your camera (or as you zoom out).
A further dimension that occurs in practice is the change in set density in the constant density model eg when you are very tired the set point falls and when you are distracted the density of information from any given modality eg senses also falls. Concentrating on something allows the density to rise and so the resolution of the thing concentrated on also rises.
Posted by
Robert Karl Stonjek
MIND
In current English usage the word "mind" means something entirely
subjective. This usage is comparatively recent, probably not more than
about 400 years. The ancient Greek word "nous" is often translated as
"mind" but this is inaccurate. "Nous" meant something better conveyed
as "intellect" (that which thinks) but that automatically implied the
objective part of the psyche. There simply is no equivalent in Ancient
Greek for our use of the word "mind".
According to Joe Sachs in his enlightening translation of "On the
Soul", Green Lion Press, 2001; whereas Aristotle uses over two dozen
words for 'thinking' - one primary, the "energeia nous" (often
translated as "actual mind" or "active mind" but far better as
"being-at-work thinking") and many degradations and broadenings from
this. Degradations is an accurate word because the energeia nous alone
is permanent and true, in Aristotle's book. I say these things because
Sachs description of Aristotle is very similar to my learning from
Steiner. Sachs writes on page 201-2
<< thinking (noein, noesis) This is Aristotle's broadest word for
thinking of any kind, from the contemplative act that merges with the
thing it thinks (429b 3-7, 430a 19-20 431b 17), through all the ways
of dividing up and putting back together those intelligible wholes
(430b 1-4), to mere imagining (427a 27-28); but it is also used in its
most governing sense for the primary kind of thinking that underlies
them all (430a 25), as a synonym for contemplation (theoria, an
intellectual _seeing - MMcC) ... Modern philosphers such as Descartes
and Locke homogenize the objects of all these into the contents of
consciousness or "ideas in the mind". >>
It is this sense of the mind as a dogmatic abstraction from its
concrete reality that I struggle to overcome in myself. Essentially my
whole world view turns upon a single observation, one which it takes a
certain effort to make: namely that thinking (in the primary sense
given above) is an entirely self-sustaining essence. It does not
require me nor anyone else but, rather I and all others exist and know
we exist through it. I insist that is an observation, an experience
and not therefore a matter of faith or belief. Unlike sense perception
which gives us observations for which we ourselves make no special
effort, this one requires that we do. Yet without it each of us is
trapped in our single world views and cannot appreciate philosophy as
a whole, comprising all world views, each with its own time and place.
That thinking is a self-sustaining essence ought to be the fundamental
proposition of all philosophy and it is so entirely irrespective of
the world view.
To move back to what you wrote, I had describe mind a potential (from
Sachs I would use the better word potency, a sort of inner force or
energy) and you thought it might be like a reservoir.
Valtermar:
<< From your description, I gather you take the word "mind" as
representing something like a "container" where memories are stored in
an organized way. It starts as an empty reservoir (the central "dot"
alone) and it grows as experiences are registered there in an
associative way. >>
Perhaps if I'd thought of the word "potency" then the spatial metaphor
of a reservoir might not have been so seductive. In one way it has its
clarity but it is important to me that the sense of movement and
action and so I am uncomfortable that the image of reservoir does not
convey what I intend. Yet I agree that in, at least a one-sided way,
it has merit.
Again the idea of the relation between the mind and brain as similar
to software and hardware has many strengths, yet there is something
which disturbs me and I have returned to this time and again without
ever becoming clear just what. For one thing, software and hardware
each require a designer and usually they are separate people.
Evolution gives us the appearance of design without a designer but I
do not get how it divides into two in the manner to create a mind and
brain. It is a matter I need to think on again.
The nature of knowledge is the most central question of all.
Best Wishes
Maurice
subjective. This usage is comparatively recent, probably not more than
about 400 years. The ancient Greek word "nous" is often translated as
"mind" but this is inaccurate. "Nous" meant something better conveyed
as "intellect" (that which thinks) but that automatically implied the
objective part of the psyche. There simply is no equivalent in Ancient
Greek for our use of the word "mind".
According to Joe Sachs in his enlightening translation of "On the
Soul", Green Lion Press, 2001; whereas Aristotle uses over two dozen
words for 'thinking' - one primary, the "energeia nous" (often
translated as "actual mind" or "active mind" but far better as
"being-at-work thinking") and many degradations and broadenings from
this. Degradations is an accurate word because the energeia nous alone
is permanent and true, in Aristotle's book. I say these things because
Sachs description of Aristotle is very similar to my learning from
Steiner. Sachs writes on page 201-2
<< thinking (noein, noesis) This is Aristotle's broadest word for
thinking of any kind, from the contemplative act that merges with the
thing it thinks (429b 3-7, 430a 19-20 431b 17), through all the ways
of dividing up and putting back together those intelligible wholes
(430b 1-4), to mere imagining (427a 27-28); but it is also used in its
most governing sense for the primary kind of thinking that underlies
them all (430a 25), as a synonym for contemplation (theoria, an
intellectual _seeing - MMcC) ... Modern philosphers such as Descartes
and Locke homogenize the objects of all these into the contents of
consciousness or "ideas in the mind". >>
It is this sense of the mind as a dogmatic abstraction from its
concrete reality that I struggle to overcome in myself. Essentially my
whole world view turns upon a single observation, one which it takes a
certain effort to make: namely that thinking (in the primary sense
given above) is an entirely self-sustaining essence. It does not
require me nor anyone else but, rather I and all others exist and know
we exist through it. I insist that is an observation, an experience
and not therefore a matter of faith or belief. Unlike sense perception
which gives us observations for which we ourselves make no special
effort, this one requires that we do. Yet without it each of us is
trapped in our single world views and cannot appreciate philosophy as
a whole, comprising all world views, each with its own time and place.
That thinking is a self-sustaining essence ought to be the fundamental
proposition of all philosophy and it is so entirely irrespective of
the world view.
To move back to what you wrote, I had describe mind a potential (from
Sachs I would use the better word potency, a sort of inner force or
energy) and you thought it might be like a reservoir.
Valtermar:
<< From your description, I gather you take the word "mind" as
representing something like a "container" where memories are stored in
an organized way. It starts as an empty reservoir (the central "dot"
alone) and it grows as experiences are registered there in an
associative way. >>
Perhaps if I'd thought of the word "potency" then the spatial metaphor
of a reservoir might not have been so seductive. In one way it has its
clarity but it is important to me that the sense of movement and
action and so I am uncomfortable that the image of reservoir does not
convey what I intend. Yet I agree that in, at least a one-sided way,
it has merit.
Again the idea of the relation between the mind and brain as similar
to software and hardware has many strengths, yet there is something
which disturbs me and I have returned to this time and again without
ever becoming clear just what. For one thing, software and hardware
each require a designer and usually they are separate people.
Evolution gives us the appearance of design without a designer but I
do not get how it divides into two in the manner to create a mind and
brain. It is a matter I need to think on again.
The nature of knowledge is the most central question of all.
Best Wishes
Maurice
U.S. Government Backs Concentrated Photovoltaics
Big solar: Massive solar panels like the 24-meter-wide ones shown here will be installed at a 30-megawatt solar farm being supported by the U.S. Department of Energy.
Credit: Amonix
Credit: Amonix
Energy
A 30-megawatt plant will be one of the largest to use the technology.
The project is part of a surge in photovoltaic projects in the United States over the last few years. A total of 878 megawatts' worth of solar panels were installed last year, up from just 79 megawatts in 2005. This year total installation is expected to double 2010 levels, according to the Solar Energy Industries Association. The industry is starting to approach the scale of the wind industry, which saw over 5,000 megawatts of capacity installed last year (down from over 10,000 the year before).
Concentrated photovoltaics is different from concentrated solar power, which is also known as solar thermal. In solar thermal plants, mirrors and lenses concentrate sunlight to generate the temperatures needed to produce steam that drives a turbine and generator.
In CPV, arrays of lenses are used to focus sunlight onto small solar cells. The concentrated light improves the efficiency of the cells and reduces the amount of expensive solar cell material needed to produce a given amount of electricity. Amonix, the company that will be supplying the concentrated photovoltaic systems for the project, says its system can generate twice as much power per acre as conventional solar panel technology. It uses 23.5-meter-wide panels with more than 1,000 pairs of lenses and solar cells on each. The panels are mounted on tracking systems that keep the lenses pointed within 0.8 degrees of the angle of the sun throughout the day, to ensure that light falls on the system's 0.7-square-centimeter solar cells.
Some analysts expect the CPV market to more than double every year through 2015 as more companies scale up production. At least one other company, Soitec, is planning a 200-megawatt CPV plant in the next few years.
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