Nov. 28/2013 – Last lecture – ATTENTION
Part 1 – Spatial Neglect
Part 2 – Simultagnosia – difficult making sense of more than one thing in the visual field.
Part 3 – Attentional dyslexia - can occur due to left hemisphere damage.
There’s a lot of answers we don’t have yet.
The explanation for why it occurs:
ANOPIA what does it mean. A (means someone has a problem with something) OP
(optical) .. sounds like a visual deficit. HEMIANOPIA: a problem processing information
in one of the two visual fields. Left functioning is great you can see fine on the right side
Often confuse neglect with blind sight. Blindsight occurs due to damage to the visual cortex.
They cant see things in one of the fields, blindsight sounds weird.. what happens with BS is
that patients with this disorder are actually visually processing things in their blind field, at
a low almost unconscious level. One of the things that can happen with a BS patient, you
can put an object in their blind field, and ask them what it is.. they cant see it. I don’t know, I
cant see anything in my blind field. If you force them to choose between two different
objects, ex: an apple or a hairbrush.. they often are very accurate (if the shape of the objects
is difficult enough)
Contralateriality processing something in the opposite visual field gets processed in the
Blindsight hemianopia is a sensory deficit. its something that was only studied after
the first world war. (almost 100 yrs ago). Head injuries in their cortexes and they showed
blindsight and were studied. REMEMBER the structure of the eye.
The photoreceptors surrounding the fovea are the RODS very motion sensitive, but if
you use RODS to look at something, its going to look fuzzy. We want to use foveal cone
vision to see things clearly. RODS are more like the eyes motion detectors.
We have two different pathways from our eyes to our brain. One is older and it first goes to
the brain stem then the thalamus then to the visual cortex. The newer one goes straight to
the thalamus and then the visual cortex.
OLDER = secondary pathway
NEWER = primary pathway
We are not that aware of the ____________________________________
The secondary visual pathway may still be providing input but we are not consciously
aware of it.
People with spatial neglect are NOT aware
Spatial-neglect hemianopia is an attentional deficit ANOSOGNOSIA. Its good that family
come along wit
Neglect patients do NOT make compensatory head movements
People with NEGLECT almost always from STROKE
artery is narrowed by atherosclerosis (plaque build up on the inside walls of
arteries caused by fatty diets, smoking, etc.). Young healthy arteries are flexible, but
old arteries OR young arteries with high blood pressure.. they start to stiffen up, they are not going to flex that much. this increases the probability of a stroke. A
bit of this plaque breaks off and the bodies response to this is to send clots to this
area. And then it will stop the blood flow narrowed artery blocked by blood clot
(ischemic stroke) The brain is deprived from freshly oxygenated blood, and it
starts to burn glucose and its not very efficient, that goes HAYWIRE. Synapses and
neurotransmitters get messed up too. The reuptake might not be proper. Glutamine
Weak section of an artery wall balloons out and kind of breaks (hemorrhage). Its
important to know about the signs of stroke.
SIGNS OF A STROKE
- Weakness: sudden loss of strength or sudden numbness in their face arm or leg
- trouble speaking: sudden difficulty speaking or understanding or sudden confusion
- vision problems: trouble with vision
- headache: sever unusual headache
go to the hospital and they have to have a CT scan in the case of stroke.. TIME IS
BRAIN. Get to the right place, ER you can go right through.
Spatial Neglect almost always happens for the left visual field, cause it’s the right parietal