Sunday, January 20, 2013

Seeing and responding to the big picture

The Master and His Emissary

Previously in this series:

The malleableness of things   Dec18/12  
Two brain halves, disappearing bridge Dec 21/12  
Mind: the brain's experience of itself Dec 22/12  
Asymmetry of brain sides: size, structure, neurochemistry Dec 31/12
Those great big lobes Jan 4/13


From page 40-41:
If we try to rely only on left-hemisphere attention on its own, i.e., if the right hemisphere is knocked out somehow, we end up with:
1. inability to adjust the "spotlight"of attention
2. permanent narrowing of the attentional window
3. the need to start with pieces to build up a picture, rather than being able to see the entire picture in one go.

Like looking out at life through a crack in the wall instead of being able to stick one's head clear out the window.

".. in almost every case what is new must first be present in the right hemisphere, before it can come into focus for the left. For one thing, the right hemisphere alone attends to the peripheral field of vision from which new experience tends to come; only the right hemisphere can direct attention to what comes to us from the edges of our awareness, regardless of side."
"Anything newly entering our experiential world instantly triggers a release of noradrenaline - mainly in the right hemisphere." 
(my bold)
"Novel experience induces changes in the right hippocampus, but not the left."
In other words, "phenomenologically it is the right hemisphere that is attuned to the apprehension of anything new." Novel stimuli. Contact with a patient's body. Threat detection. Salience conferring. Critter brain.

He goes on:
" Not just new experience, but the learning of new information or new skills also engages right-hemispheric attention more than left, even if the information is verbal in nature." 
Once learned through practice, the left hemisphere takes them over, "even for skills such as playing a musical instrument."

The right hemisphere is the novelty seeker. Scans for discrepancy. Looks for, brings in new information.
"The left hemisphere deals with what it knows, and therefore prioritizes the expected - its process is predictive. It positively prefers what it knows." 
(My bold)

The left hemisphere is a good manager when everything is going along as usual, but it's useless in a crisis. Because it relies on its own expectations.
"The right hemisphere outperforms the left whenever prediction is difficult." 
Even horses prefer to size up a new element in their immediate environment (potential threat, "possibly emotionally arousing stimuli") with their left eye/right hemisphere. 
"The right hemisphere is... more capable of a frame shift".. especially important for flexibility of thought." 
Damage to it leads to perseveration, pathological inability to respond flexibly to changing situations, incapacity to figure out a new way to deal with a novel situation.
"It is the right frontal cortex that is responsible for inhibiting one's immediate response, and hence for flexibility and set-shifting, as well as the power of inhibiting immediate response to environmental stimuli." 
"..the right hemisphere presents an array of possible solutions, which remain live while alternatives are being explored. The left.. takes the single solution that seems best to fit what it already knows and latches on to it." 
The left jumps to conclusions. Inappropriately. The right hemisphere sounds more thoughtful, more exploratory, more comfortable with uncertainty and possibility, more "scientific".

The left has the "tendency to deny discrepancies that do not fit its already generated schema of things. The right.. by contrast, is actively watching for discrepancies, more like a devil's advocate. These approaches are both needed but pull in opposite directions."

Both hemispheres participate:
"..the left hemisphere actively narrows its attentional focus to highly related words while the right activates a broader range of words."  
" The left hemisphere operates focally, suppressing meanings that are not currently relevant. By contrast, the right hemisphere 'processes information in a non-focal manner with widespread activation of related meanings'"  
" ..close lexical semantic relationships rely more on the left hemisphere, looser semantic relationships rely on the right."
The right hemisphere "makes infrequent or distantly related word meanings available", is involved in "generating unusual or distantly related words or novel uses for objects."
The right anterior temporal region is involved in "making connections across distantly related information during comprehension." The right posterior superior temporal sulcus might have something to do with verbal creativity. 
"In the 'close' situation..the left hemisphere actively suppresses the right, to exclude associations which are semantically only distantly related."
The right hemisphere can use the left hemisphere's preferred style, but the left cannot use the right's. Huh. Who'da thunk it. 
"..although the left hemisphere gains more benefit from a single strong association than several weaker associations, only the right hemisphere can use either equally." 
I must admit, I am enjoying these revelations. 

1. Larose CRichard-Yris MAHausberger MRogers LJLaterality of horses associated with emotionality in novel situationsLaterality. 2006 Jul;11(4):355-67.

No comments: