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Tero Toivanen

Selective aphasia in a brain damaged bilingual patient : Neurophilosophy - 0 views

  • A unique case study published in the open access journal Behavioral and Brain Functions sheds some light on this matter. The study, by Raphiq Ibrahim, a neurologist at the University of Haifa, describes a bilingual Arabic-Hebrew speaker who incurred brain damage following a viral infection. Consequently, the patient experienced severe deficits in Hebrew but not in Arabic. The findings support the view that specific components of a first and second language are represented by different substrates in the brain.
  • A native Arabic speaker, he learned Hebrew at an early age (4th grade) and later used it competently both professionally and academically.
  • A CT scan showed that he had suffered a massive hemorrhage in the left temporal lobe, which was compressing the tissue on both sides of the central sulcus, the prominent gfissure which separates the frontal and parietal lobes.
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  • A craniotomy was performed to relieve the pressure, and afterwards another scan showed moderate hemorrhage and herpes encephalitis in the left temporal lobe, and another hemorrhage beneath the outer membrane (the dura) lying over the right frontal lobe.
  • During his 2 month stay there, he developed epileptic seizures which originated in the left temporal lobe, and amnestic aphasia (an inability to name objects or to recognize their written or spoken names). 
  • After the rehabilitation period, a series of linguistic tests was administered to determine the extent of his speech deficits. M.H. exhibited deficits in both languages, but the most severe deficits were seen only in Hebrew. In this language he had a severe difficulty in recalling words and names, so that his speech was non-fluent and interrupted by frequent pauses. He had difficulty understanding others' spoken Hebrew, and also had great difficulty reading and writing Hebrew. In Arabic, his native language, all of these abilities were affected only mildy.
  • The results support a neurolinguistic model in which the brain of bilinguals contains a semantic system (which represents word meanings) which is common to both languages and which is connected to independent lexical systems (which encode the vocabulary of each language). The findings further suggest that the second language (in this case, Hebrew) is represented by an independent subsystem which does not represent the first language (Arabic) and is more succeptible to brain damage.
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    A unique case study published in the open access journal Behavioral and Brain Functions sheds some light on this matter. The study, by Raphiq Ibrahim, a neurologist at the University of Haifa, describes a bilingual Arabic-Hebrew speaker who incurred brain damage following a viral infection. Consequently, the patient experienced severe deficits in Hebrew but not in Arabic. The findings support the view that specific components of a first and second language are represented by different substrates in the brain.
David McGavock

Scientific Understanding of Consciousness - 0 views

  • During the past 20 years or so, biological sciences have advanced to the point that scientists have begun researching biological mechanisms of brain function and suggesting some reasonably well-founded hypotheses for consciousness. Leading the way in these pioneering efforts, in my judgment, have been:   Gerald Edelman with his hypothesis of the Dynamic Core, Antonio Damasio with his concepts of  Protoself, Core Self, Autobiographical Self, Core Consciousness and Extended Consciousness, Joseph LeDoux and his emphasis on the intricacies of synapses and the emotional brain,
  • Rudolfo Llinás and his researches into ~40 Hz oscillations and synchronization, György Buzsáki with his discussion and exploration of neural mechanisms related to oscillation and synchronization in the neocortex and hippocampus for perception and memory, Joaquín Fuster, the world’s preeminent expert on the frontal lobes, and his concept of the "perception-action cycle," Susan Greenfield's notion of "neuronal gestalts" as a way of conceptualizing a highly variable aggregation of neurons that is temporarily recruited around a triggering epicenter. I use the neuronal gestalts idea in my way of visualizing the functionality of the dynamic core of the thalamocortical system, Eric Kandel who has explored short-term and long-term memory,
  • The late Francis Crick with his collaborator Christof Koch who have pursued the neural correlate of consciousness (NCC), Michael Gazzaniga with the concept of the left hemisphere ‘interpreter’ unifying consciousness experience, Edmund Rolls and Gustavo Deco with their mathematical models of brain function using information theory approaches for biologically plausible neurodynamical modeling of cognitive phenomena corroborated by brain imaging studies, David LaBerge with his discussion of the thalamocortical circuit and attention, Alan Baddeley who continues to refine his model for working memory, Philosopher John Searle who endorses the idea that consciousness is an emergent property of neural networks.
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    "My objective in this website has been to bring together salient features of these assorted interpretations by science experts into a synthesis of my own understanding of consciousness. I consider these statements and interpretations to be a framework on which to build a fuller understanding as further data, concepts and insights develop from ongoing research."
Tero Toivanen

The five ages of the brain: Adolescence - life - 04 April 2009 - New Scientist - 0 views

  • Jay Giedd at the National Institute of Mental Health in Bethesda, Maryland, and his colleagues have followed the progress of nearly 400 children, scanning many of them every two years as they grew up. They found that adolescence brings waves of grey-matter pruning, with teens losing about 1 per cent of their grey matter every year until their early 20s (Nature Neuroscience, vol 2, p 861).
  • This cerebral pruning trims unused neural connections that were overproduced in the childhood growth spurt, starting with the more basic sensory and motor areas.
  • Among the last to mature is the dorsolateral prefrontal cortex at the very front of the frontal lobe. This area is involved in control of impulses, judgement and decision-making, which might explain some of the less-than-stellar decisions made by your average teen. This area also acts to control and process emotional information sent from the amygdala - the fight or flight centre of gut reactions - which may account for the mercurial tempers of adolescents.
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  • As grey matter is lost, though, the brain gains white matter
  • These changes have both benefits and pitfalls. At this stage of life the brain is still childishly flexible, so we are still sponges for learning. On the other hand, the lack of impulse control may lead to risky behaviours such as drug and alcohol abuse, smoking and unprotected sex.
  • Substance abuse is particularly concerning, as brain imaging studies suggest that the motivation and reward circuitry in teen brains makes them almost hard-wired for addiction.
  • since drug abuse and stressful events - even a broken heart - have been linked to mood disorders later in life, this is the time when both are best avoided.
  • Making the most of this time is a matter of throwing all that teen energy into learning and new experiences - whether that means hitting the books, learning to express themselves through music or art, or exploring life by travelling the world.
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    Jay Giedd at the National Institute of Mental Health in Bethesda, Maryland, and his colleagues have followed the progress of nearly 400 children, scanning many of them every two years as they grew up. They found that adolescence brings waves of grey-matter pruning, with teens losing about 1 per cent of their grey matter every year until their early 20s (Nature Neuroscience, vol 2, p 861).
Tero Toivanen

Sign language study shows multiple brain regions wired for language - 1 views

  • A new study from the University of Rochester finds that there is no single advanced area of the human brain that gives it language capabilities above and beyond those of any other animal species.
  • Instead, humans rely on several regions of the brain, each designed to accomplish different primitive tasks, in order to make sense of a sentence.
  • "We're using and adapting the machinery we already have in our brains," said study coauthor Aaron Newman. "Obviously we're doing something different [from other animals], because we're able to learn language unlike any other species. But it's not because some little black box evolved specially in our brain that does only language, and nothing else."
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  • The team of brain and cognitive scientists
  • published their findings in the latest edition of the journal Proceedings of the National Academies of Sciences.
  • The study found that there are, in fact, distinct regions of the brain that are used to process the two types of sentences: those in which word order determined the relationships between the sentence elements, and those in which inflection was providing the information.
  • In fact, Newman said, in trying to understand different types of grammar, humans draw on regions of the brain that are designed to accomplish primitive tasks that relate to the type of sentence they are trying to interpret. For instance, a word order sentence draws on parts of the frontal cortex that give humans the ability to put information into sequences, while an inflectional sentence draws on parts of the temporal lobe that specialize in dividing information into its constituent parts, the study demonstrated.
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    A new study from the University of Rochester finds that there is no single advanced area of the human brain that gives it language capabilities above and beyond those of any other animal species.
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