cognitive neuroscience: development and prospects … · cognitive neuroscience: development and...

Cognitive neuroscience: Development and prospects

MICHAEL I POSNER1,∗ and SHOBINI RAO2

1Department of Psychology, University of Oregon, Eugene, Oregon 97403, USA2Neuropsychology, NIMHANS, Hosur Road, Bangalore 560 029, India

∗e-mail: [email protected]

The field of cognitive neuroscience has enjoyed an explosive growth following the finding thatspecific brain areas could be activated during processing of visual and auditory words. The subse-quent 20 years have provided a variety of techniques that allow the exploration of brain networksrelated to a large number of cognitive, emotional and social tasks and environments and that haveexamined the formation and loss of these networks over the human life span. This chapter reviewsthe various methods developed for noninvasive exploration of human brain function. Substantivecontributions are then examined in several areas of particular importance to the Indian researchcommunity. These include language, consciousness, brain development and training. We considerthe problems remaining to be explored, and possible practical consequences of the research.

Cognitive neuroscience is at the intersection of two prior fields: Cognitive psychology and neuro-science. Both these fields have had a relatively short history under these names, although bothhave roots in ancient philosophy [1]. In this chapter, we will examine the modern history of cogni-tive neuroscience, discuss new tools for the noninvasive exploration of the human brain and applythem to several active fields of research. We will attempt to examine both the changes, whichcognitive neuroscience has produced in our understanding of the mind, and in the understand-ing of the brain. In each area, we consider the relevance of the topic to the Indian scientificcommunity.

1. Cognitive neuroscience

Cognitive psychology was developed in the 1960s.The work of Herbert Simon and Allen Newell,based upon the general problem solver [2] arguedthat computer programs simulating human perfor-mance could serve as a theory of the mind. Thecomputer metaphor left little scope for studies ofthe brain. At about the same time psychologists,adapting the mathematical theory of communi-cation [3] were able to develop important empiri-cal demonstrations describing human performancein terms of laws governing the rate of informationtransfer [4,5]. These studies served as the basis foran approach to the mind based on empirical studieswhich was synthesized by Ulrich Neisser in his1967 book Cognitive Psychology [6]. Over the years,cognitive psychology branched out to incorporate

aspects of linguistics, computer science and philo-sophy under the title ‘Cognitive Science’ [7].

Neuroscience began in the 1950s as the incorpo-ration of many fields that were interested in thebasic study of the brain. While cognitive psycho-logy mainly studied human beings, the study of thebrain, incorporated work from simpler organismswhose brains were more amenable to anatomicaland physiological methods which were by necessityoften very invasive.

1.1 Birth of cognitive neuroscience

The name ‘cognitive neuroscience’ was coined byGeorge Miller and Michael Gazzaniga during theearly 1980s, when Gazzaniga developed an Insti-tute with that name as part of the grant program ofthe Sloan Foundation related to cognitive science.

Keywords. Attention; consciousness; cognitive science; language neuroscience; self regulation.

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420 MICHAEL I POSNER AND SHOBINI RAO

The term ‘neuropsychology’, although it had abroader meaning [8] had come to be associatedwith studies of the brain and performance of peoplewith various forms of brain damage. Althoughexcellent work was done in neuropsychology, parti-cularly in distinguishing the different functionsof the two cerebral hemispheres, its use in braininjury cases made it less influential in understand-ing normal human cognition.

It was not until the late 1980s that neuroimag-ing allowed the normal human brain to be studiedwhile people carried out the kind of tasks whichwere typical in cognitive psychology. The firststudies involved the language system [9]. Thesestudies used a subtractive method adopted fromcognitive psychology to determine activations insensory, motor, phonological, semantic, and atten-tional operations. Probably the most importantoverall result was that even for higher mentalprocesses like word semantics and attention therewere sufficiently common activations to averageacross people. From the work of Karl Lashely [10]and Gestalt Psychologists [11], many believed thathigher mental processes involved the whole brainand did not show any substantial localization.The brain areas involved specifically in semanticprocessing included left ventral frontal lobe, leftposterior tempero-parietal cortex, lateral areas ofthe cerebellum and the dorsal anterior cingulate.Subsequent studies suggested that each area had adifferent function.

1.2 Implication for brain and mind

In the twenty years of subsequent imaging studies,some generalizations have emerged about mentalprocesses and about the human brain that supportsthem. These may be summarized under the head-ings of localization, interaction, control, and plas-ticity. Table 1 summarizes many studies involvingmost of the important areas of cognition, emotionand social interaction. Indeed sometimes the termsaffective and social neuroscience are used but mostoften all fields of research are included in the gene-ralized use of the term cognitive neuroscience.

While there is substantial agreement on thebrain areas activated in studies of attention,memory and language, there is much less agree-ment on the exact function of these areas. In addi-tion to separate localization the areas activatedhave to be coordinated to carry out the task.Although in agreement with patient studies, manytasks involved mainly one cerebral hemisphere (e.g.left for language), most tasks involved activationsin both hemispheres and often in subcortical areassuch as the basal ganglia and cerebellum. Theinteraction among these brain areas in terms of net-works has been a major concern of recent studies.

Table 1. A list of areas of cognition and emotion forwhich neuroimaging studies have indicated neural net-works involved. One selected study of the each network isreferenced [12–22].

Function Selected reference

Arithmetic [12]

Autobiographical Memory [13]

Fear [14]

Faces [15]

Music [16]

Object Perception [17]

Reading and Listening [18]

Reward [19]

Self Reference [20]

Spatial Navigation [21]

Working Memory [22,23]

Using high density electrical or magnetic record-ings from the scalp in coordination with fMRI,it has been possible to work out the time courseof these activations and learn something aboutthe direction of information flow. These studieshave shown the importance of re-entrant signalsso that sensory areas may be activated in thefirst 100 millisecs from sensory input, but may beactive again by feedback from attentional networksbeyond the first 100 millisecs. These potentiallyoverlapping signals make it difficult to determinethe significance of any activity without a full under-standing of the network involved.

These new findings have shown that the long-standing serial model of information flow in thehuman brain from primary sensory to secondaryand tertiary association areas is incorrect [23].They also make it more important to understandthe control signals that might provide priority toparticular pathways in any given task. The humanis a learning animal. Ancient networks underly-ing simpler reflex activity present at birth can bereworked through experience allowing much moreplasticity than has previously been supposed [24].

The activation of many networks are common toall people, suggesting their genetic origins. How-ever, the efficiency with which these networks carryout tasks differ among people and provide ampleopportunity for brain plasticity to influence per-formance. Recent studies have shown how geneby environment interaction shapes these individualdifferences.

2. Probing human brain networks

In cellular physiology, the idea of a networkinvolves identified neurons that connect to oneanother by synapses or in some cases through other

COGNITIVE NEUROSCIENCE: DEVELOPMENT AND PROSPECTS 421

Figure 1. Brain networks underlying attention. Onefronto-parietal network is involved in orienting to sensoryevents (circles), while a cingulo-opercular network relates tothe resolution of conflict among responses (triangles, exec-utive network), a third network is responsible for achievingthe alert state involving norepinepherine from the midbrain(squares). [Adapted from 25].

means of communication. Connectionist models,inspired by neural networks, have considered unitsat particular levels that influence each other bydirect or reciprocal connections. Imaging of humantask performance has identified another level ofnetwork function, which is clearly related to boththe models and the underlying cellular structureby showing that a number of quite separate brainareas must be orchestrated even in a simple task.Each of these areas may be performing a differentcomputation, which taken together allow perfor-mance of the task. Typically cognitive neuroscienceregards the set of activations and their connectionsas the network that underlies task performance.

In this section, we use attentional networks asan illustration of the methods currently availableto probe the many networks featured in table 1.Attentional networks are special in that their pri-mary purpose is to influence the operation of otherbrain networks. As illustrated in figure 1, threeattentional functions for which brain networks havebeen imaged are: alerting which is involved inacquiring and maintaining the alert state; orientingto sensory stimuli and executive control involvedin the resolution of conflict between neural sys-tems and regulating thoughts and feelings [9].Although the sites at which attention influence canbe demonstrated involve any brain area includingprimary sensory, limbic and motor cortex, as shownin table 1, the sources of these activations are muchmore limited.

Orienting to sensory events has been betterstudied of these networks both with imaging [26]and cellular [27] methods. The convergence on the

set of brain areas serving as the source of theamplification of sensory signals has been impres-sive ([28] for a recent review). It is widely agreedthat the frontal eye fields work in conjunction withsuperior and inferior parietal areas as the corticalnodes of the orienting network. In addition, studieshave implicated some subcortical areas includingthe pulvinar of the thalamus and the superior colli-culus. Most of the studies of this network haveinvolved visual stimuli, but the sources of theattention influences in orienting to other modalitiesare much the same. Of course the site of amplifi-cation of the sensory message is quite different foreach sensory modality.

Evidence to date suggests that both maintainedalertness during task performance (tonic) andphasic changes induced by a warning signal involv-ing a subcortical structure, the locus coeruleus thatis the source of the brain’s norepinephrine. A greatdeal of evidence [29] indicates that the tonic statedepends upon an intact right cerebral hemisphere.Lesions in this hemisphere can produce profounddifficulty in responding to unexpected targets.Warning signals, however, may have their influencemore strongly on the left cerebral hemisphere [30].This distinction may reflect a more general divi-sion between the hemispheres where rapidly actingevents are left lateralized while more slowly chang-ing states involve right hemisphere activity.

Tasks that involve conflict between stimulusdimensions competing for control of the outputoften provide activation in the anterior cingulategyrus and lateral prefrontal areas. It is thoughtthat the conflict, induced by a stimulus, is represen-tative of situations where different neural networkscompete for control of consciousness or output.Because of this we have termed this the execu-tive attention network because it regulates the acti-vity in other brain networks involved in thoughtand emotion [31,32]. This network shows a strongdevelopment in childhood and its maturation isrelated to what in developmental psychology hasbeen called self-regulation.

Individual differences are invariably found incognitive tasks involving attention. The Atten-tion Network Test (ANT) was developed to exam-ine individual differences in the efficiency of thebrain networks in alerting and orienting the exec-utive attention discussed above [33]. The ANTuses differences in reaction time (RT) betweenconditions to measure the efficiency of each net-work. Each trial begins with a cue (or a blankinterval, in the no-cue condition) that informs theparticipant either that a target will be occurringsoon, or where it will occur or both. The tar-get always occurs either above or below fixationand consists of a central arrow, surrounded byflanking arrows that can either point in the same


Figure 2. The fronto-parietal network (orienting, online control) and the cingulo-opercular network (executive, set control)are active at rest and undergo a long developmental process shown as graphs for children C (age 9) and adults A [adaptedfrom 35]. Abbreviations: aI/fO, anterior insula/frontal operculum; aPFC, anterior prefrontal cortex; dACC/msFC, dorsalanterior cingulate cortex/medial superior frontal cortex; dlPFC, dorsolateral prefrontal cortex; dF, dorsal frontal; IPL,inferior parietal lobule; IPS, intraparietal sulcus.

direction (congruent) or in the opposite direction(incongruent). Subtracting RTs for congruent fromincongruent target trials provides a measure ofconflict resolution and assesses the efficiency ofthe executive attention network. Subtracting RTsobtained in the double-cue condition from RT inthe no-cue condition gives a measure of alertingdue to the presence of a warning signal. Subtract-ing RTs to targets at the cued location (spatialcue condition) from trials using a central cue givesa measure of orienting, since the spatial cue, butnot the central cue, provides valid information onwhere a target will occur.

2.1 Network connectivity

Neural areas found active in studies of functionalanatomy must be orchestrated in carrying out anyreal task. One approach to studying this connec-tivity uses fMRI to study the correlations betweenactive areas [34].

An important finding was that even at rest,common brain areas appear to be active together(default state). Studies suggest that the connecti-vity between these areas change over the course

of development. Figure 2 illustrates two sets ofconnections active at rest: these are a fronto-parietal (related to orienting) and a cingulo-opercular (related to executive attention) network.Connections change over the life span. Childrenshow many shorter connections and integrationof the dorsal anterior cingulate in both networks.Adults show more segregation of the two networksand longer connections.

Some of the same brain areas found active duringrest change when the person is given a task.For example, while the organization of anatomicalareas in alerting and orienting are not fully known,some promising beginnings have taken place. Inalerting, the source of the attention appears in thelocus coeruleus (lc). Cells in the lc have two modesof processing. One mode is sustained and is per-haps related to the tonic level of alertness overlong time intervals. This function is known toinvolve the right cerebral hemisphere more stronglythan the left [36]. Alertness is influenced by sen-sory events and by the diurnal rhythm. However,its voluntary maintenance during task performancemay be orchestrated from the anterior cingulate[37]. More phasic shifts of alerting can result from


presenting any environmental signal. However, ifthe signal is likely to warn about an impendingtarget, this shift results in a characteristic sup-pression of the intrinsic brain rhythms (e.g. alpha)within a few tens of milliseconds and a strongnegative wave is (contingent negative variation)recorded from surface electrodes and that movesfrom a frontal generator towards the sensory areasof the hemisphere opposite the expected target.

An analysis of a number of conflict tasks showsthat the more dorsal part of the anterior cin-gulate is involved in the regulation of cognitivetasks, while the more ventral part of the cin-gulate is involved in regulation of emotion [38].The microstructure of the organization of the cin-gulate has been studied in detail using correla-tions between brain areas while the subject rested(functional connectivity). Dynamic casual mode-ling (DCM) can then be used to help definethe direction of information within the network.[39]. These data are related to an analysis ofwhite matter connections in humans using diffusiontensor imaging to trace physical connections andrelate them to similar studies in animals [40]. Theseconverging methods are being applied to trace theconnectivity of brain networks both at rest andduring task performance [33].

2.2 Mental chronometry

Although the fMRI method has become increas-ingly useful in understanding the sequence ofmental operations, their speed may be too fast foranalysis by the relatively slow changes involvedin imaging based on vascular changes. Anotherway to examine network activity is to use scalpEEG electrodes to record neural activity synchro-nized in different frequency bands. This methodcan be used to separate rapid temporal events,for example, it can separate the cue effects fromthe target effects in the ANT. There is increas-ing interest in the various frequencies of electri-cal activity involved in correlations between neuralareas. For example, in one study using the ANT[41], a spatial cue indicating the location of thetarget produced increased high frequency gammaactivity (above 30 Hz) about 200 milliseconds afterthe cue presentation. When the cue brought atten-tion to the target location, gamma activity wasfound following the cue, but not following thetarget. When the cue indicated the center locationso that a shift of attention was needed followingthe target, the gamma activity was present follow-ing the target. These data suggest that gammaactivity is associated with orienting attention. Itmay occur 200 millisecs after the cue or only afterthe target depending upon when attention shifts.Taken together, the fMRI, EEG and DTI methods

can provide a more detailed account of the orches-tration of neural networks related to attention orto other networks illustrated in table 1.

The activation of brain networks does not meanthat all parts of the network are needed to carry outthe task. In the past, effects of brain lesions havebeen a primary way to indicate brain areas whichwhen lost will prevent the persons from carryingout certain tasks. For example, damage to areas ofthe right parietal lobe have led to neglect of the leftside of space in multiple sensory systems. It is nowpossible to use brief magnetic pulses applied to thescalp overlying the brain area of interest (transcor-tical magnetic stimulation TMS) to disrupt partsof the network at particular times to observe itsinfluences on task performance [42]. In this way,one can determine what parts of the network arenecessary for task performance.

Taken together, the methods reviewed abovehave provided tools for probing human brain net-works. In the case of attention, there has beenincreasing coordination of these studies with ani-mals studies that allow probing of single units andexamination of the micro-circuitry and molecularevents related to these activations.

3. Language

In the 1970s, behavioral studies using habitua-tion to a repeated stimulus provided evidence thatfrom birth, infants are able to discriminate basicphonemic units not only in their own language butalso in other languages to which they have neverbeen exposed [43]. Studies using these behavio-ral methods together with electrical recordingfrom the scalp have probed some of the earlydevelopment of the phonemic structure underlyinglanguage.

Recently infants have been exposed to lang-uage while resting in fMRI scanners to examinethe brain mechanisms activated by language [44].The infant language system appears to involve thesame left hemisphere language structures found inadults [44]. In one study, infants listened to sen-tences presented aurally in their language. Brainareas in the superior temporal lobe (Wernicke’sarea) and in Broca’s area were active. Whenthe same sentence was presented after a delayof 14 seconds, Broca’s area activity increased, asthough this area was involved in the memorytrace. It has long been supposed that the earlyacquisition of language might involve very differ-ent mechanisms than are active in adults [45]. Lefthemisphere lesions in infancy do not produce apermanent loss of language function as they mightdo in adults. Nonetheless, the new fMRI data sug-gests the left hemisphere speech areas are involvedin receptive language in infancy.


3.1 Phonemes

It has been possible to study changes in phonemicdiscrimination due to exposure to the native lang-uage at least by ten months of age [46,47]. Infantsappear to acquire a sharpened representation ofthe native phonemic distinctions [48]. During thesame period they also lose the ability to distinguishrepresentations not made in their own language[49]. At least a part of the loss occurs when the non-native language requires a distinction that is withina single phonemic category in the native language.An example is the ‘ra-la’ distinction important inEnglish is lost because it is within a single categoryin Japanese [50]. It is as though Japanese no longerhear this distinction and even when exposed toEnglish they may not improve in distinguishing ‘ra’from ‘la’. Training by several methods [50,51] seemsto improve this ability even in adults, although itis not known how well this knowledge can be incor-porated into normal daily life communication.

It might be useful to find a way that will pre-serve the distinctions originally made for the non-native language during infancy. One study showedthat 12 sessions of exposure to a mandarin speakerduring the first year was effective [52]. A similaramount of exposure to a computerized version ofthe speaker was not effective, suggesting the impor-tance of social interaction in this early form oflearning. More needs to be learned about howand whether media presentation can be effective inlearning.

There is also some reason to believe that theprocess of phonemic discrimination being deve-loped in infancy is important for later efficient useof spoken and written language [53,54]. Electricalrecording taken in infancy during the course ofphonemic distinctions [53,54] have been useful inpredicting later difficulties in language and read-ing. There is a history of using event related poten-tials to assess infant deafness early in life andbeing able to do so reliably has been very useful inthe development of sign language and other inter-ventions to hasten the infants’ ability at commu-nication. Perhaps a similar role will prove to bepossible for ERPs in the development of methodsto insure a successful phonemic structure in thenative language.

There have been efforts to develop appropri-ate intervention in later childhood for difficul-ties in the use of language and reading suchas the widely used FASTFORWARD programs[http://www.scilearn.com, 55]. Although there aredisputes about exactly why and for what popu-lations this method works, it remains importantto develop remedies for language difficulties basedupon research.

3.2 Reading

Reading is a high level skill and in alphabetic lang-uages such as English, it has properties related tothe phonemic structure of language. There havebeen many studies of adult reading and much moreis known than can be reviewed here [see 25,56 forreviews]. The child’s ability in phonemic awareness(e.g. rhyming of auditory words), is a good pre-dictor of their being able to learn to read alpha-betic languages such as English. Adult studies ofreading have revealed a complex neural networkinvolved in the translation of words into meaning.Two important nodes of this network are the visualword form area, of the left fusiform gyrus and anarea of the left temporal-parietal junction for trans-lating visual letters into sounds.

The visual word form area is involved in inte-grating or chunking visual letters into units ofwords [57]. The visual word form has been locali-zed to the fusiform gyrus of the left hemisphere’svisual system. Although there has been some dis-pute about the operation it appears to be a partof the visual system that becomes expert in deal-ing with letters as reading skill develops in laterchildhood. It is thought that without the function-ing of this area, reading cannot become fluent. Forexample, a patient with a lesion that interruptedthe flow of information from the right hemisphereto the visual word form area used letter by letterreading when words were presented left of fixation(going to the right hemisphere), while they readwords normally when the word was projected tothe left hemisphere and thus reached the visualword form area [58]. Children from 7 to 18 whowere deficient in reading skills failed to activatethis area, but were able to do so after extensivetraining [59].

Languages like English that are highly irregu-lar at the visual level are heavily dependent uponbrain areas that translate visual words to sound.These areas are at the temporal parietal boundaryof the left hemisphere. Children who have diffi-culty in learning to read show little activation inthese phonological areas. However, phonics train-ing even after 20 sessions can produce relativelynormal activity in these areas and also improvereading by several grade levels.

The time course of development of the visualword form area in English is important for thedevelopment of fluent reading. Phonics trainingoften leaves the child with improved decoding skill,but with a lack of fluency. Evidence that the visualword form develops rather late and first only forwords with which the child is familiar [60], suggeststhe importance of continuous practice in reading todevelop fluency [59]. More research is needed on the


best methods for developing fluency, particularlyin non-alphabetic languages.

The multiple languages in India makes of parti-cular importance findings suggesting superior per-formance of multi-linguals on executive attentionscores, such as the Attention Network Test (ANT)[61,62]. The ties to attention have been sup-ported by the use of ANT to assess differences inexecutive attention between mono and bilinguals.A study of Spanish English bilinguals found strongadvantages over monolingual controls in a widevariety of executive tasks [63]. One study [64] com-pared Korean and Chinese native speakers whowere bilingual in English with French and Spanishspeakers bilingual in English and with Englishmonolinguals. Both bilingual groups showed betterexecutive attention than monolinguals and, theAsian group, whose languages differed the mostfrom English, were superior to the Romance biling-uals. This study shows the close ties between lang-uage and attention. It also suggests that the needto select among languages when speaking, as occursin multilinguals may form one important basis fortraining improved executive attention.

4. Consciousness

There is a long tradition of the study of consci-ousness within Eastern and Western philosophy,however, cognitive neuroscience provides a some-what new perspective on awareness and will, bothof which have been central to the discussions ofconsciousness.

An important distinction in studies of aware-ness [65] is between general knowledge of our envi-ronment (ambient awareness) and detailed focalknowledge of a scene (focal awareness). As laypeople we generally believe that we have full con-scious awareness of our environment, even whenour focal attention is upon our own internalthoughts. Experimental studies [66] show us howmuch this opinion is in error. In the study of‘change blindness’ when cues such as motion, thatnormally lead to a shift of attention, are sup-pressed, we have only a small focus for whichwe have full knowledge and even major semanticchanges in the remainder of the environment arenot reported.

Change blindness is closely related to studiesof visual search which have been prominent inthe field of attention and involve an interactionbetween information in the ventral visual pathwayabout the object identity and information in thedorsal visual pathway that controls orienting tosensory information (for a review, see [67]). Visualsearch tasks have been important for examiningwhat constraints attention provides to the nature

of our awareness of a target event. There is clearevidence that attention to a visual event increasesthe brain activity associated with it. Most evi-dence arises from studies using event related elec-trical potentials with visual stimuli and these haveclearly shown that early sensory components of thevisual evoked potential P1 and N2 (80–150 millisec)are enlarged by the presence of attention [28].

As shown in figure 1 focal attention to thetarget of a visual search appears to involve a brainnetwork that includes the anterior cingulate andlateral prefrontal areas [33]. Humans have a convic-tion of conscious control that allows us to regulateour thoughts, feelings and behaviors in accord withour goals and people believe that voluntary con-scious choice guides at least a part of the action wetake. These beliefs have been studied under variousnames in different fields of psychology. In cognition,cognitive control is the usual name for the volun-tary exercise of intentions, while in developmentalpsychology many of the same issues are studiedunder the name self-regulation [68].

Imaging studies suggest that whenever we bringto mind information, whether extracted from sen-sory input or from memory, we activate the execu-tive attention network. In some studies a whole setof frontal areas become activated together formingwhat is called a global workspace [69]. This globalworkspace becomes active about 300 millisecs aftera target event is presented. It provides the neuralbasis for the set of information on which a per-son is currently working in the process of problemsolving.

The distinction between awareness and control(will) is traditional in studies of consciousness.However, one form of awareness, focal awareness,appears to involve the same underlying mecha-nism as involved in control. In this sense, eventhough some forms of consciousness (e.g. ambi-ent awareness) may have diverse sources withinsensory specific cortex, there is also a degree ofunity of the underlying mechanisms involving focalawareness and conscious control. The distinctionbetween focal and ambient factors in consciousnessmay help to clarify the sense of awareness that canbe present even when detailed accounts of the sceneare not possible as in change blindness [66].

5. Genes and experience build networks

The common nature of brain networks such asthose in table 1 among people argue stronglyfor the role of genes in their construction. Thishas led cognitive neuroscience to incorporate datafrom the growing field of human genetics. Onemethod for doing this relates individual differencesto different forms of genes (genetic alleles) that


Figure 3. A strategy for relating brain networks to underlying molecular events [adapted from 70]. Bottom of figure arepsychological functions, these are related to neural networks as shown in brain images and then to differences in proteinconfiguration and genetic variation.

may relate to them. Brain activity can serve as anintermediate level for relating genes to behavior asillustrated in figure 3.

As one example, the Attention Network Test(ANT) was used to examine individual differencesin the efficiency of executive attention. Strong heri-tability of the executive network supported thesearch for genes related to individual differences innetwork efficiently.

The association of the executive network withthe neuromodulator dopamine is a way of search-ing for candidate genes that might relate to theefficiency of the network [71]. For example, seve-ral studies employing conflict related tasks, foundthat alleles of the catechol-o-methyl transferase(COMT) gene were related to the ability to resolveconflict. A number of other dopamine genes havealso proven related to this form of attention, inaddition, research has suggested that genes relatedto serotonin transmission also influence executiveattention ([72] for a summary). It was also possi-ble to show that some of these genetic differencesinfluenced the degree to which the anterior cingu-late was activated during task performance in stud-ies using brain imaging. In the future, as suggestedby figure 3, it may be possible to relate genes tospecific nodes within neural networks, allowing amuch more detailed understanding of the origins ofbrain networks.

While genes are important for common neuralnetworks and individual differences in efficiencythere is also an important role for specific

experiences. For example, several genes includingthe DRD4 gene and the COMT gene have bothshown to interact with aspects of quality of parent-ing. This provides evidence that aspects of the cul-ture in which children are raised can influence theway in which genes shape neural networks influenc-ing child behavior.

If brain networks are influenced by parentingand other culture influences, it should be possi-ble to develop specific training methods that canbe used to influence underlying brain networks.For example, one study tested the effect of train-ing during the period of major development ofexecutive attention, which takes place between 4to 7 years of age [73]. An improvement in conflictresolution as measured by the ANT was found intrained children, along with changes in the under-lying network and generalization to other aspectsof cognition. EEG data showed clear evidence ofimprovement in network efficiency in resolving con-flict following training. The N2 component of thescalp recorded ERP has been shown to arise in theanterior cingulate and is related to the resolutionof conflict [74]. The N2 differences between congru-ent and incongruent trials of the ANT were foundin trained six year olds, that resembled differencesfound in adults. No such N2 difference was foundin the untrained controls. These data suggest thattraining altered the network for the resolution ofconflict in the direction of being more like what isfound in adults. There was also a greater improve-ment in intelligence in the trained group compared


to the control children. This finding suggested thattraining effects had generalized to a measure ofcognitive processing that is far removed from thetraining exercises.

Given the wide range of individual differences inthe efficiency of attention, it is expected that atten-tion training could be especially beneficial for thosechildren with poorer initial efficiency. These couldbe children with pathologies that involve atten-tional networks, children with genetic backgroundsassociated with poorer attentional performance, orchildren raised in different degrees of deprivation.

6. Brain plasticity

Training studies discussed in the last section showevidence that performance of networks can bealtered by experience. This idea has been impor-tant in rehabilitation in cases of brain injury andpsychiatric disorders. It has also led to suggestionsfor improved education for normal people based onideas coming from cognitive neuroscience.

Brain networks are frequently damaged by neu-rological or psychiatric disorders and head trauma.Neuro-imaging has made it easier to determine theextent and location of brain damage, so a majorarea of application of cognitive studies is to thetreatment of such disorders. The National Instituteof Mental Health and Neuroscience (NIMHANS)in Bangalore has been a pioneer in these efforts.

The NIMHANS neuropsychology battery con-sists of 21 neuropsychological tests. This batterywas administered to 540 normal males and females,aged between 16–65 years, including illiterates andliterates whose educational levels differed widely[75]. There have been a series of studies using thisbattery before and after training. Improved basiccognitive functions were found using both hospi-tal based computerized and home based paper andpencil training [76,77].

A number of randomized studies have also shownimprovements in attention and memory in normalchildren and adults [78–81]. All these methodsinvolve practice in some cognitive skills includingrepetitive trials on tasks similar to what mightbe tested in schools or cognitive laboratories. Allinvolve a training group showing significantly moreimprovement than control groups. The controlgroups often involve the same number of laboratorysessions with training or experiences not thought toinvolve the elements of attention working memoryused in the experimental group.

These methods differ considerably from mindful-ness training, exposure to nature settings or inte-grative body-mind training (IBMT), all of whichalso affect the state of attention. Recently, bothIBMT (using body-mind optimization) [82], and

nature exposure [83] (using attention restorationtheory) have conducted similar randomized designusing similar before and after assays as thoseused in attention training. These attention statemethods appear to achieve similar success to atten-tion training in the attention network test and alsohelp control of stress, improve self-regulation, etc.These two training streams represent the differ-ent traditions/cultures and methodologies in theEast (IBMT, mindfulness) and West (practice andbrain plasticity). These techniques provide sup-port for the idea that training can provide generalchanges in brain networks that can lead to wide-spread improvement in cognitive processes. Since itis likely that the various methods activate differentbrain networks, imaging may be used to combinemethods to produce improved effectiveness.

7. Future developments

Cognitive neuroscience has developed a numberof methods than in concert can link importantaspects of human behavior to underlying neuralnetworks and to the cellular and molecular levelsthat underlie them. It is likely that new methods ofimaging will eventually provide more details aboutthe functioning of the human brain when activeand in the resting state. One of the major accom-plishments of cognitive neuroscience is to attractthe attention of physical and mathematical scien-tists who are capable of contributing to imagingapparatus and new algorithms.

Imaging and cognitive theory may also con-tribute to new forms of compensation for braininjuries and pathologies. Already deep brain stimu-lation, guided by imaging theories have been usedin treatments of depression [84] and in an effortto improve the integrative behavior for patientsin vegetative neurological states [85]. We canalso expect additional training and state changemethods, guided by imaging of what specific brainnetwork(s) are influenced by the method, designedto assist people with brain injuries or other formsof pathology.

Interfaces between humans, computers and pros-thetic devices are playing an important role inextending the sensory and motor capacities ofpatients of all kinds [86]. A better understand-ing of the neuronal networks related to humancapacities could lead us toward improvements inthese methods and the development of methodsto extend the cognitive range of normal people indirections of human improvement.

This chapter is a brief overview of the achieve-ments and potential of cognitive neuroscienceduring the twenty years of its existence as ascientific discipline. In addition to the technical


findings discussed in this review, imaging studiesare having a wide influence in the general cultureby giving people who read or watch television, apicture of brain activity during many human tasksand situations. As a result, there is likely to be alarge continuing interest in the application of cog-nitive neuroscience perspective to many societalissues.

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