Capítulo 2. El discurso de la noticia
2.5. Las superestructuras del discurso de la noticia y el ordenamiento por relevancia
Thefacultyofvoluntarilybringingbackawanderingattention
overandoveragainistheveryrootofjudgment,character,
andwill.
WilliamJames(1842–1910),Principles of Psychology,Vol1,424
Adorsalattentionnetworkenablessensorystimulitobese-lectedbasedoninternalgoalsorexpectations,andlinksthem
toappropriatemotorresponses.Aventralattentionnetwork
detects salient and behaviorally-relevant stimuli in the envi-ronment,especiallywhentheyareunattended.
M.Corbetta,G.Patel,andG.Shulman,20081
Why do these pages keep emphasizing attention?
Becauseattention is our essential, vanguard mental function.
Indeed,attention’ssharppointservesastheforemosttipofcon-sciousness.Attentionisthepointthatimpalesstimuliandanchors
them.Nowheldfixed,theyarereadytobeprocessedaspercep-tions. When we use the phrase “attentive processing,” it simply
makes explicit the fact that attention precedes processing. This
holdstruewhetherwefurtherconceptualizetheformsofatten- tivenessaseitherrequiringeffortorbeingeffortless,asbeingdi-rectedtowardinternalorexternalevents,orasfunctioningeither
consciouslyorunconsciously(seefigure1).
Figure 1 A visual representation of top-down attentive processing on a background of bare awareness
Attentionisthesharppointoutatthetipofourprocessing.Wedirect
mostofourattentivenesstowardeventsinfrontofus,“upcloseand
personal.”Weextenditssharppointtowardexternalorinternaltar-gets.Itspre-attentivetipoperatesintheearlymilliseconds.Attentive
processingfollows.Onlycertainperceptsrisetolevelsabovethethresh-oldofconsciousness.Theremainderregisteronlysubconsciously.
Thefundamentalroleofarousalisillustratednotinfigures1and7,
butinyoutheviewer,whosemorningtideoftonic(sustained)arousal
enabledyoutowakeupthisday.Thereafter,novelorstressfulevents
couldpromptyouintobrief(phasic)arousals,andcauseyoutobecome
Attentionisanassociativefunction.Itsvariousnetworksdraw
theirresourcesfromdiverselevelsinthebrainstem,subcortex,and
cortex. Survival values programmed their sharp preattentive tip.
Itnowexpressesaninnateintelligence.Preattentionhasbecome
so highly evolved that today’s brains now know instantly where
to scan for which kinds of top-priority information and how to
relay the data through our attention channels to be processed
immediately.
Researchduringthepastdecadehasrevealedthatthehigher
levels of attentiveness are directed by lateral cortical networks.
These serve two generic systems of attention [ZBR: 179–183; SI:
29–34].
Background: Attention and Awareness
As you are reading this sentence, you are probably directing your gaze down at a printed page or electronic screen. In this instance, the words are entering from a space down below your usual visual horizon when you are gazing straight ahead. Moreover, these words are entering into your peri-personal space, a relatively small envelope of space close to your own body.
On the other hand, suppose that you are meditating out-side. There, unexpectedly, a bright planet in the predawn sky suddenly captures your attention. Now, as your head is raised, your gaze automatically turns up to see this bright object. It shines far out in the eastern sky, just above the dis-tant horizon. It turns out that two different networks over the outside (lateral) surface of your cortex will have repre-sented each of these two different systems of attention. The first system attends preferentially to external events down in the lower part of the space near you. You feel possessive about this space. It’s your turf, so to speak. This system serves needs distinctly different from those that suddenly shift your gaze up to see the planet Venus.
TheBrain’sDorsalAttentionSystem
The networks of the first, dorsal, system are distributed higher up over the outside of the brain. They direct our more voluntary, “executive” types of focused attention, such as when you’re reading these words on a page. Figure 2 shows that two major modules reside on this dorsal attention net-work as it arches upward to pursue a parieto → frontal course.
The first is the intraparietal sulcus (IPS). The second is the region around the frontal eye field (FEF).
Our dorsal attention system is said to be crossed. This means that each side responds most attentively to stimuli that arrive from the spatial environment over on the opposite side. Moreover, these useful functions converge whenever we need to focus down on nearby things that are in front of us. We use this system’s top-down functions in two ways.
We use them first when we’re already biased by prior cues and then make fine-tuned adjustments to the actual sensory stimuli as they next start coming in. Second, we use them to continually monitor this fresh, incoming data in order to re-spond to each of its new potential short-term conflicts in an appropriate manner. In general, this dorsal network helps us reach out with our hands and respond accurately during tasks that we can already anticipate are going to be reason-ably well defined.
TheVentralAttentionSystem
The ventral system was designed to serve our other attentive needs. It specializes in reflexive, involuntary types of diffuse attention.2 The bottom-up functions of this ventral system respond automatically to each fresh need to disengage atten-tion from whatever target it was fixed on before. The ventral system remains on standby alert. It is poised effortlessly to
Figure 2 A lateral view of the right hemisphere showing the major modules and subdivisions of the dorsal and ventral attention systems Therightfrontallobeispositionedattheviewer’sright.Theventral
(“bottom-up”) subdivision of the attention system is shown as gray
areas composed of diagonal lines. Its chief modules are the TPJ
(temporo-parietaljunction)andtheinferiorfrontalgyrus(iFG).
The dorsal (“top-down”) subdivision is shown in black checks. Its
chief modules are the pIPSUL (posterior intraparietal sulcus) and the
FEF(frontaleyefield).Thetwopaledottedzonesintherightinferior
frontalgyrus(iFG)andmiddlefrontalgyrus(mFG)representregionsof
“executiveoverlap.”Theyhelpintegratethefunctionsofthesubdivi-sionsinpracticalwaysthatserveourglobalneedstoattendtoevents
onbothsidesoftheenvironment.
Thefigureisfreelyadaptedbothfromthetextandfromfigure5in
M. Fox, M. Corbetta, A. Snyder et al. Spontaneous neuronal activity
distinguisheshumandorsalandventralattentionsystems.Proceedings of the National Academy of Sciences U.S.A.2006;103:10046–10051.See
alsothecolorplatefacingpage168of[SI]foracolorversionofthis
figure.
help the brain receive stimuli, detect them, and shift atten-tion. Toward what? Toward any kind of relevant stimulus that might enter unexpectedly. Where might such a stimulus come from? From either side of the environment, crossed or un-crossed. This ventral system also has two major cortical modules. Each is represented much lower down, yet again over the outside of the brain. One is the temporo-parietal junction (TPJ). The other is the inferior frontal gyrus (IFG).
A key point: The functions of this ventral attention sys-tem are represented asymmetrically. Indeed, figure 2 shows the right side of the brain because this right side dominates the ventral system. How is this possible? The circuits on this right side cross over the midline to co-opt those other ventral at-tentive mechanisms that we represent over on the left lower side of our brain. So what? The result is that the right lower side of our brain assumes a bilateral responsibility. Its job is to respond attentively the instant any unexpected, behaviorally relevant stimulus—a bird call, for example—suddenly arises from anywhere.
These physiological properties of the ventral system serve involuntary reorienting functions. They are more b ottom-up and reflexive in nature. We don’t choose to direct them. They redirect attention instantly—as choicelessly as our leg reacts with a jerk when its knee tendon is tapped by a reflex hammer. Redirect it, to what? To whatever new stimulus happens to arrive from the vast global sen-sory world outside our skin. This key distinction—between voluntary and involuntary—will soon become fundamen-tal to our discussion of the different techniques we use to meditate.
Later we expand on James’s original emphasis on vol-untary attention. Chapters 7, 11, 12, and 16 suggest that we engage the involuntary faculty of re-mindful attentiveness in the character development that evolves during later medita-tive training.
What’s so special about the right-sided cerebral dominance of this bilateral, wide-open attentiveness?
Itimpliesthattherightventralattentionsystemisrelatively
free from the same heavy commitment to language with which
evolutionburdenedsimilarregionsofthecortexoverintheoppo-sitefrontalandtemporallobes.Thisraisesanintriguingpossibility.
Afterrepeatedtraining,couldprofoundlyselflessinsightsbeable
toevolvewordlessly,especiallyiftheymostlyhappenedtobeflow-ingthroughthebottom-upprocessingpathwaysonthelowerright
side?
How does attention differ from ordinary bare awareness?
Wedirecttop-downattentiontowardatarget.Bottom-upat-tentioniscapturedbyafreshstimulus.Bareawarenessimpliesa
morebasic,baselinelevelofreceptivityfordiversesensatestimuli
ingeneral[SI:14–21;ZBR:184–187].Event-relatedpotential(ERP)
studies help specify the ways bare awareness differs from atten-tiveness.Forexample,ERPresearchindicatesthatwefirstneedto
bedeployingsomekindofmentalconstructofspaceinorderfor
our awareness to be able to detect, subjectively—at around 200
milliseconds—the mere presence of a faint visual stimulus that
arriveswithinsuchaspace.3
Suppose,ontheotherhand,thatresearchersdefineattention
as tapping into our later processing stages—the particular func-tionsthatnowenableustogoontoidentifythecognitive features
of a stimulus using our higher levels of reflective consciousness.
This is a much more sophisticated event. It correlates with ERP
peaksthatarise400millisecondsafterthestimulus.
Awareness of a visual stimulus causes a stronger nega-tive afterimage than does attention per se.4 It also tends to correlate with earlier processing sequences. These begin in the lateral geniculate nucleus and relay up to the primary visual cortex. Such an association with afterimages is of in-terest in relation to a negative afterimage that can occur late during kensho [ZBR: 426 – 428].
Are these two lateral systems the only avenues we have for attending to stimuli?
No,wealsohaveinteroceptivepathwaysthatrelatemoresub-tly to our Self than do the pain pathways, which are inherenNo,wealsohaveinteroceptivepathwaysthatrelatemoresub-tly
Self-centered.Othermessagesfromourvisceralorgansfollowan
“insidepassageway”thatleadsupthroughthemedialthalamusto
theinsula.Throughthisroutewecanalsoattendtostimuliarising
fromthevestibularsystemofourinnerear.Thesemessagesauto-maticallyhelpourbodyremainbalanced[ZBR:95–99;SI:253–256].
Animportantfunctionalmagneticresonanceimaging(fMRI)study
byFarbandcolleagues5demonstratesinterestingresultsafteronly
eightweeksofmindfulness-basedmeditativetraining:adecrease
in the (unconscious) connections that would habitually link the
rightinsulawiththeventromedialprefrontalcortex;anincreasein
theconnectionsthatalsolinkthisrightinsulawiththedorsolateral
prefrontal cortex (suggesting an acquired capacity for different
messages that are now more accessible to consciousness); plus a
decreaseintheactivityoftheleftdorsalamygdala(whichiscon-sistent with a reduction in the meditators’ emotional tone and
reactivity).
4