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Archive for the ‘neurology’ Category

face recognition in the brain

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One of my heroes in the field of neuroscience is Wilder Penfield. He pioneered the use of electrical stimulation of the brain, prior to surgery for treating epilepsy. The goal was to identify brain functions in the areas surrounding the locus of epilepsy and spare as much tissue as possible, if critical functions had been identified. The most remarkable part of this exercise was that the patient was fully conscious (although under a local anesthetic) and could verbally report sensations and perceptions experienced by the electrical stimulation of the probes. This technique contributed enormously to deriving functional maps of the human brain.

Penfield’s legacy is alive and well.  A couple of days ago, ScienceNow website reported on a study published in the Journal of Neuroscience.  By using techniques similar to Penfield’s, scientists at Stanford Univ, were able to determine the precise locus of face recognition in humans. Huffington Post has also included a really remarkable video of the patient’s experience as he is being stimulated by electrical current.  You must watch it!

That our three pound universe is a constructed reality, is on ample display in the video. Soul theorists, go figure!

What lay people may not appreciate, in this story and the video, is that our ability to recognize faces is confined to a small piece of our cerebral cortex. Destroying this piece of brain tissue only knocks out face recognition. One can still recognize objects (in the video, the perception of the scientist’s suit and tie is not distorted.) In fact, back in graduate school, I had the privilege of meeting a person, who due to an accident in early childhood, lost the ability to recognize faces, even his own! His non-face object perception was intact. He used salient features like a mustache, glasses, or other unique feature to remember and identify people he met.

This study and the video gave me the cognitive high for the day.

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Written by asterix98

October 25, 2012 at 6:24 am

Traumatic brain injury

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Here is an interesting NYTimes opinion piece – Starting again after a Brain Injury . The author shares here experiences after an accident that left her quite debilitated cognitively and physically. She talks about a complete change in personality, loss of memory, disrupted cognitive social map,  and coping with the world anew after 45 yrs in existence! She is somewhat more fortunate (or is she ?) than the famous neurological case of Phineas Gage.

Because of the injury, her cognitive apparatus, responsible for weaving her past, present and future  into a coherent canvas, is now in disarray, mostly cutting her loose from her past, resulting in the loss of all of her anchors, her bearings. Much of the narrative is about her journey piecing together her life again. Less poignant and more resolute.

 

 

 

Written by asterix98

October 16, 2011 at 5:10 pm

The tell-tale human brain

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I just finished reading a book entitled “The tell-tale human brain” by V.S.Ramachandran. [For those of you who do not know the name, Ramachandran, is a world renowned neuroscientist. He is a remarkably gifted scientist and has conducted many path breaking studies that have significantly advanced the status quo in our understanding of the human brain. Some people even think he may be a Nobel prize candidate for his pioneering work in neuroscience]. His research is one of the contributing causes to the many neuroX subdisciplines (neurotheology, neuroeconomics, neuromarketing to name a few) that have mushroomed in academia and industry.

This book is a good synthesis of much of his research. If you ignore his not so great sense of humor and sometimes chest beating, there is a lot of great material in the book to ponder on. What I love about his books is his rich catalog of neurological patients and their attendant deficits. Through their abnormalities, we are lead to an understanding of the inner workings of a normal human brain.  My favorite is the “god center” located in the temporal lobes. Patients with temporal lobe epilepsies see visions of god!! [My advisor used to say, irreverently, that the claims of received wisdom from God are actually manifestations of a hallucinating brain. I must say I agree with him.]

Some of the topics include mirror neurons and their role in social cognition, neural plasticity, synesthesia (blending of the senses), impostors moms and dads. It is utterly fascinating when we consider the remarkable insight that our unified percept of the external reality is really the orchestration of many interacting functionally specific brain modules [the timing and sychronization of these processes are also extensively studied topics in neuroscience]. Blindsight, a phenomenon, described in some detail, will make you wonder about what we really mean when we talk about consciousness.

Ultimately, the book is about what sets humans apart in the animal kingdom. The book format allows the author to speculate a great deal. If you pick this book up, I urge you to do so with a fairly wide open mind.

Written by asterix98

August 3, 2011 at 2:38 pm

what abnormal vision tells us

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I recently finished reading Mind’s Eye by Oliver Sacks. He is a neurologist and an excellent author.

In this book, he catalogues the lives of several people (including himself) who have lost some function of the visual sense, in some cases dramatically, and in others gradually. For those of us who take vision for granted, this book is an eye opener (no pun intended!). Although a bit drier than his other books, I highly recommend it, both to understand an important sense organ as well as to fully realize that our mental universe is a constructed reality.

I also recommend his other books (Man who mistook his wife for a hat, Anthropologist on Mars, and Awakenings{was made into a movie} which are also mind bending.

Written by asterix98

February 20, 2011 at 7:54 am

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