Monday 29 July 2013

Prosopagnosia: Seeing without discriminating

Taken literally, in Greek, "prosopo" means face and  "agnosia" means without knowledge.

Clinically speaking, agnosia refers to the inability to recognize and identify sensory inputs from a specific modality, be it visual, tactile, auditory,olfactory, or even cognitive. For example, a interesting but difficult to diagnose agnosia is Anosognosia (difficult because it can be mistaken for denial)

Pet peeve: A prefix of "a" (agnosia) refers to a "total inability to". A prefix of "dy" (dysgnosia) refers to "an impairment in". However, both are used interchangeably, at the expense of the person with the condition. Let's try to be specific and no sloppily label, ne?

Anyway. So you just had a stroke, and now you're having some difficulties adjusting back to regular life. Your memory is fuzzy, trying to remember things is like holding onto a wet noodle, and you have these insistent headaches that refuse to budge. But...this is normal for you. Well, you think so anyway. You are convinced that your forgetting simple dates and these horrible headaches are from being over worked, or tired, or...something.

Anosognosia is characterized by "lack of insight". A profound inability to recognize one's own disorder, or impairment. People may confabulate reasons for which they are symptomatic (e.g., In this case blaming your memory issues on sleep). This agnosia commonly manifests after traumatic brain injury, strokes (and other neurological events), and it's especially common in schizophrenia. Wonder why patient compliance to antipsychotic medication is low? That can be a large reason.

Anyway, another example is visual agonsia. This can be presented in a few ways, but one is with an inability to recognize objects. Like, that thing that's reflective and I see myself on...that thing......I don't know what it is....

Hint: a mirror.

So, in the second episode of Perception, they introduced a man with prosopagnosia, or "face blindness".

This is a super interesting condition, because it can be congenital, though it's usually because of an cerebral accident or trauma. In the cases of developmental prosopagnosia, most individuals don't even know they have it. Fascinating, huh? In cases of neurological accidents, the symptoms tend to be more severe than in developmental, understandably so since the brain has not had years to adapt.

Symptoms can be mild (e.g., difficulty recognizing faces) to severe (e.g., absolute inability to recognize wife, or son's face).

The area that's affected in the brain is the fusiform face area in the fusiform gyrus, which is just posterior to the parahippocampal place area, and anterior to the occipital lobe. As a result, damage to this area may cause difficulties in recognizing faces. While facial recognition in this area is bilateral, damage to the right side of the cortex may cause significantly greater damage than the left due to lateralization.

Very interesting, not everyone has a fusiform face area! The research continues.....

While we're here...the parahippocampal place area encodes information particular to recognizing places,such as your hometown or school.

And the lateral occipital complex specializes in recognizes objects.

Here's some pics from my fMRI poster a year back showing these areas when active:

Fusiform face area 

Lateral Occipital Complex

Parahippocampal Place Area 

Interestingly, IIRC, this student showed the lowest activation  in his FFA, and the highest in his PPA compared to the other six participants. Goes to show how incredibly unique each brain is!

Alright, enough brains. Time for CAKE.

chrisy

Sunday 28 July 2013

Setting up shop

Since Xanga finally exploded, and because  I have no patience for WordPress, seems I'm back here.

I still remember the first blogspot I made. Stigma Octanus. That was probably around the same time I started on xanga back nearly 9 nears ago...

Anyway, this blog will be a bit different, I've been throwing around some ideas, and decided this will probably be much more organized blog.

The purpose:

a) Typical blog shenanigans as per usual

b) Unlike my other blogs, I'll actually be focusing on reviewing and talking about different topics relating mostly to the brain and other shiny and magical things.

I've started watching a show called "Perception". Think House MD meets CSI, except it only revolves around neurology and psychiatry. Anyway, in each episode a different disease/disorder/issue is presented, so I thought that this show would act as a great springboard to discuss these afflictions.

Anyway, for those that are on Blogger, you can follow my posts by going to your Dashboard (clicking your blog from your home page), scroll down to "Reading List", and add me. 

It's definitely more cumbersome than Xanga, but eh. Otherwise, from what I gather....unless I post to Facebook (if I have you there), you can only follow my posts by pressing the "Follow by Email" in the bottom right of my page.

Pretty lamn they got rid of the follower app, but whatever.

Ja ne
-chrisy