cognition – Page 4 – Replicated Typo

The arcuate fasciculus within the dual stream model pt.2

3.1 What is the dual stream model?

Given these separate anatomical accounts, attributing a function(s) to the arcuate is not clear cut, and any current account is far from the authoritative statement on the matter. Nonetheless, a vast majority of literature does place the arcuate as part of the dual stream model[1] of speech processing, although its exact role within these neural networks is still being disputed – and largely depends on which anatomical account you prescribe to.

The basic assumption of dual stream accounts is that phonological networks interact with both conceptual-semantic and motor-articulatory systems, leading to a distinction between the neural networks that process this speech information. These separate interactions are summarised under two processing streams: the dorsal stream and the ventral stream (Hickok and Poeppel, 2007). Connecting phonological networks with conceptual-semantic systems, using structures in the superior and middle portions of the temporal lobe, is the ventral stream. Meanwhile, the dorsal stream is linked via structures in the posterior frontal lobe to the posterior temporal lobe and parietal operculum, which connects phonological networks with motor-articulatory systems (ibid).

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Inconsistent, yes… But here are some links.

Okay, I promised a post a day and failed miserably. But it does say in my profile that I’m inconsistent. So it’s probably best to not believe everything I write, even if there is one valuable lesson in my broken promises: avoid targets. Anyway, I just thought I’d do a quick post on some articles that have caught my attention over the past few days:

Pop over to read the hairy nipple of the angry walrus — quite possibly the only other blog written by a “humanistic evolutionary linguist from Wales”. In fact, the blogger in question is a PhD student in my former department at Edinburgh. In keeping with this Welsh theme, you should check out his post concerning common misconceptions about the Welsh language: http://garics.blogspot.com/2009/10/silly-things-people-say-about-welsh-ii.html
Next on the agenda is a massive deviation from my comfort zone of cognition, evolution and linguistics into the entangled world of quantum physics, and how through “linking the electrical currents of two superconductors large enough to be seen with the naked eye, researchers have extended the domain of observable quantum effects.“
Babel’s Dawn discusses Prof. Jim Hurford‘s (my former lecturer) presentation at the Torun Proto-language conference about the word-sentence continuum.
And lastly, thanks to her mentioning my article on Broca’s area, I’ve discovered a new cognitive science blog: Nou Stuff. A wealth of information on this website; plus, she’s got some really cool links, one of which I’m about to start watching — Life Without Memory: The Case of Clive Wearing.

Discerning the role of the arcuate fasciculus in speech processing pt.1

Originally identified by Reil (1809) and subsequently named by Burdach (1819), the arcuate fasciculus is a white-matter, neural pathway that intersects with both the lateral temporal cortex and frontal cortex via a “dorsal projection that arches around the Sylvain fissure.” (Rilling et al., 2008, pg. 426). Classical hypotheses saw this pathway as a critical component in connecting two centres of language: Broca’s area (speech production) and Wernicke’s area (speech comprehension) (Catani and Mesulam, 2008).

Much of these assumptions were based on a tentative relationship between language-impairment and damaged portions of the brain. Notably, damage to the arcuate fasciculus is implicated in a syndrome known as conduction aphasia, where an individual has difficulty in speech repetition. Often characterised by errors in spontaneous speech, an individual with conduction aphasia will be fully aware of their mistake, retaining well-preserved auditory comprehension and speech production while also being syntactically and grammatically correct (ibid).

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Language as a complex adaptive system

A prominent idea in linguistics is that humans have an array of specialised organs geared towards the production, reception and comprehension of language. For some features, particularly the physical capacity to produce and receive multiple vocalizations, there is ample evidence for specialisation: a descended larynx (Lieberman, 2003), thoracic breathing (MacLarnon & Hewitt, 1999), and several distinct hearing organs (Hawks, in press). Given that these features are firmly in the domain of biology, it makes intuitive sense to apply the theory of natural selection to solve the problem: humans are specially adapted to the production and reception of multiple vocalizations.

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Reading Round Up

Here’s some stuff I’ve been reading over the last month or so:

Babel’s Dawn discusses Michael Arbib’s paper, Invention and Community in the Emergence of Language: Insights from New Sign Languages.
Over at Neurophilosophy there is an overview of a fascinating paper on the Universal Grammar of birdsong (also check out my comment, it’s the first one under JW).
John Hawks talks about some of my favourite topics: learning, population size, and modern human behaviour.
The recent resurgence of the Sapir-Whorf hypothesis and Lera Boroditsky are the topics of discussion over at Mind Hacks.
Deric Bownds’ MindBlog mentions the “origins of altruism toward one’s own social group and the emergence of cultural complexity“.
Evolution can occur in less than 10 years… In guppy fish.
Researchers at Brown find: “A front portion of the brain that handles tasks like decision-making also helps decipher different phonetic sounds“.
And lastly, Dienekes’ anthropology blog discusses a paper that investigates the role of drift and selection in the shaping of human skulls, concluding “that neutral processes have been much more important than climate in shaping the human cranium”.

Okay, so that brings you up to date with my reading from May through to July. Next round up will cover August. How fascinating :-/

Continuity or Discontinuity: are our minds purely shaped by natural selection?

The debate concerning the origin of our minds stems back to the diverging opinions of Darwin (1871) and Wallace (1870). When Charles Darwin first discussed the evolution of our seemingly unique cognitive faculties, he proposed that there is “no fundamental difference between man and the higher mammals in their mental faculties.” (Darwin, 1871, pg. 66). Conversely, Wallace was suspicious of whether natural selection alone could have shaped the human mind, writing: “[…] that the same law which appears to have sufficed for the development of animals, has been alone the cause of man’s superior mental nature, […] will, I have no doubt, be overruled and explained away. But I venture to think they will nevertheless maintain their ground, and that they can only be met by the discovery of new facts or new laws, of a nature very different from any yet known to us.” In the intervening years, the debate surrounding the degree of continuity between animal and human minds still rages on in contemporary discussions (Bolhuis & Wynne, 2009; Penn, Holyoak & Povinelli, 2009).

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Memory master chimp

Having already written an article about the wonders of Orangutans, I felt that Chimps needed to reclaim their rightful place as the second-best primate. What better way to demonstrate their rightful genius than to beat the presumed kings of short term memory, us mere (and slightly less impressive) humans. Don’t believe me, well watch this great National Geographic clip:

N.B. I know this is hardly cutting edge news, but I was writing a best of 2008 post earlier this year, and forgot to finish writing the post. So, expect a whole slew of articles over the next 24 hours.

Current Issues in Language Evolution

As part of my assessment this term I’m to write four mock peer-reviewed items for a module called Current Issues in Language Evolution. It’s a great module run by Simon Kirby, examining some of the best food for thought in the field. Alone this is an interesting endeavour, after all we’re right in the middle of a language evolution renaissance, however, even cooler are the lectures, where students get to do their own presentations on a particular paper. I already did my presentation at the start of this term, on Dediu and Ladd’s paper, which went rather well, even if one of my slip ups did not go unnoticed (hint: always label the graphs). So, over the next few weeks, in amongst additional posts covering some of the presentations in class, I’ll hopefully be writing articles on these four five papers:

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Orangutans – probably more interesting than you

In the past few years there has been a recent spate of articles concerning orangutan intelligence. So, as I’m fairly bored, and in need of a break from university work, I’ve decided to write a bit of an essay on some of these finds.

Orangutans… They’re orange, right?

Correct; but Pongo pygmaeus abelii are so much more than just some arboreal orange ape that eats a lot of fruit. In fact, these great apes, the last surviving members of the genus Pongo, are highly resourceful and intelligent creatures, as evident in their ability to make and use tools, perform calculated reciprocity and even whistle a tune.

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