Cognitive neuroscience: Development and prospects
MICHAEL I POSNER1,∗ and SHOBINI RAO2
1
Department of Psychology, University of Oregon, Eugene, Oregon 97403, USA
2
Neuropsychology, NIMHANS, Hosur Road, Bangalore 560 029, India
∗
e-mail: [email protected]
The field of cognitive neuroscience has enjoyed an explosive growth following the finding that
specific brain areas could be activated during processing of visual and auditory words. The subsequent 20 years have provided a variety of techniques that allow the exploration of brain networks
related to a large number of cognitive, emotional and social tasks and environments and that have
examined the formation and loss of these networks over the human life span. This chapter reviews
the various methods developed for noninvasive exploration of human brain function. Substantive
contributions are then examined in several areas of particular importance to the Indian research
community. These include language, consciousness, brain development and training. We consider
the 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 neuroscience. Both these fields have had a relatively short history under these names, although both
have roots in ancient philosophy [1]. In this chapter, we will examine the modern history of cognitive neuroscience, discuss new tools for the noninvasive exploration of the human brain and apply
them to several active fields of research. We will attempt to examine both the changes, which
cognitive neuroscience has produced in our understanding of the mind, and in the understanding of the brain. In each area, we consider the relevance of the topic to the Indian scientific
community.
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] argued
that computer programs simulating human performance could serve as a theory of the mind. The
computer metaphor left little scope for studies of
the brain. At about the same time psychologists,
adapting the mathematical theory of communication [3] were able to develop important empirical demonstrations describing human performance
in terms of laws governing the rate of information
transfer [4,5]. These studies served as the basis for
an approach to the mind based on empirical studies
which was synthesized by Ulrich Neisser in his
1967 book Cognitive Psychology [6]. Over the years,
cognitive psychology branched out to incorporate
aspects of linguistics, computer science and philosophy under the title ‘Cognitive Science’ [7].
Neuroscience began in the 1950s as the incorporation of many fields that were interested in the
basic study of the brain. While cognitive psychology mainly studied human beings, the study of the
brain, incorporated work from simpler organisms
whose brains were more amenable to anatomical
and physiological methods which were by necessity
often very invasive.
1.1 Birth of cognitive neuroscience
The name ‘cognitive neuroscience’ was coined by
George Miller and Michael Gazzaniga during the
early 1980s, when Gazzaniga developed an Institute with that name as part of the grant program of
the Sloan Foundation related to cognitive science.
Keywords. Attention; consciousness; cognitive science; language neuroscience; self regulation.
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MICHAEL I POSNER AND SHOBINI RAO
The term ‘neuropsychology’, although it had a
broader meaning [8] had come to be associated
with studies of the brain and performance of people
with various forms of brain damage. Although
excellent work was done in neuropsychology, particularly in distinguishing the different functions
of the two cerebral hemispheres, its use in brain
injury cases made it less influential in understanding normal human cognition.
It was not until the late 1980s that neuroimaging allowed the normal human brain to be studied
while people carried out the kind of tasks which
were typical in cognitive psychology. The first
studies involved the language system [9]. These
studies used a subtractive method adopted from
cognitive psychology to determine activations in
sensory, motor, phonological, semantic, and attentional operations. Probably the most important
overall result was that even for higher mental
processes like word semantics and attention there
were sufficiently common activations to average
across people. From the work of Karl Lashely [10]
and Gestalt Psychologists [11], many believed that
higher mental processes involved the whole brain
and did not show any substantial localization.
The brain areas involved specifically in semantic
processing included left ventral frontal lobe, left
posterior tempero-parietal cortex, lateral areas of
the cerebellum and the dorsal anterior cingulate.
Subsequent studies suggested that each area had a
different function.
1.2 Implication for brain and mind
In the twenty years of subsequent imaging studies,
some generalizations have emerged about mental
processes and about the human brain that supports
them. These may be summarized under the headings of localization, interaction, control, and plasticity. Table 1 summarizes many studies involving
most of the important areas of cognition, emotion
and social interaction. Indeed sometimes the terms
affective and social neuroscience are used but most
often all fields of research are included in the generalized use of the term cognitive neuroscience.
While there is substantial agreement on the
brain areas activated in studies of attention,
memory and language, there is much less agreement on the exact function of these areas. In addition to separate localization the areas activated
have to be coordinated to carry out the task.
Although in agreement with patient studies, many
tasks involved mainly one cerebral hemisphere (e.g.
left for language), most tasks involved activations
in both hemispheres and often in subcortical areas
such as the basal ganglia and cerebellum. The
interaction among these brain areas in terms of networks has been a major concern of recent studies.
Table 1. A list of areas of cognition and emotion for
which neuroimaging studies have indicated neural networks involved. One selected study of the each network is
referenced [12–22].
Function
Arithmetic
Autobiographical Memory
Fear
Faces
Music
Object Perception
Reading and Listening
Reward
Self Reference
Spatial Navigation
Working Memory
Selected reference
[12]
[13]
[14]
[15]
[16]
[17]
[18]
[19]
[20]
[21]
[22,23]
Using high density electrical or magnetic recordings from the scalp in coordination with fMRI,
it has been possible to work out the time course
of these activations and learn something about
the direction of information flow. These studies
have shown the importance of re-entrant signals
so that sensory areas may be activated in the
first 100 millisecs from sensory input, but may be
active again by feedback from attentional networks
beyond the first 100 millisecs. These potentially
overlapping signals make it difficult to determine
the significance of any activity without a full understanding of the network involved.
These new findings have shown that the longstanding serial model of information flow in the
human brain from primary sensory to secondary
and tertiary association areas is incorrect [23].
They also make it more important to understand
the control signals that might provide priority to
particular pathways in any given task. The human
is a learning animal. Ancient networks underlying simpler reflex activity present at birth can be
reworked through experience allowing much more
plasticity than has previously been supposed [24].
The activation of many networks are common to
all people, suggesting their genetic origins. However, the efficiency with which these networks carry
out tasks differ among people and provide ample
opportunity for brain plasticity to influence performance. Recent studies have shown how gene
by environment interaction shapes these individual
differences.
2. Probing human brain networks
In cellular physiology, the idea of a network
involves identified neurons that connect to one
another by synapses or in some cases through other
COGNITIVE NEUROSCIENCE: DEVELOPMENT AND PROSPECTS
Figure 1. Brain networks underlying attention. One
fronto-parietal network is involved in orienting to sensory
events (circles), while a cingulo-opercular network relates to
the resolution of conflict among responses (triangles, executive network), a third network is responsible for achieving
the alert state involving norepinepherine from the midbrain
(squares). [Adapted from 25].
means of communication. Connectionist models,
inspired by neural networks, have considered units
at particular levels that influence each other by
direct or reciprocal connections. Imaging of human
task performance has identified another level of
network function, which is clearly related to both
the models and the underlying cellular structure
by showing that a number of quite separate brain
areas must be orchestrated even in a simple task.
Each of these areas may be performing a different
computation, which taken together allow performance of the task. Typically cognitive neuroscience
regards the set of activations and their connections
as the network that underlies task performance.
In this section, we use attentional networks as
an illustration of the methods currently available
to probe the many networks featured in table 1.
Attentional networks are special in that their primary purpose is to influence the operation of other
brain networks. As illustrated in figure 1, three
attentional functions for which brain networks have
been imaged are: alerting which is involved in
acquiring and maintaining the alert state; orienting
to sensory stimuli and executive control involved
in the resolution of conflict between neural systems and regulating thoughts and feelings [9].
Although the sites at which attention influence can
be demonstrated involve any brain area including
primary sensory, limbic and motor cortex, as shown
in table 1, the sources of these activations are much
more limited.
Orienting to sensory events has been better
studied of these networks both with imaging [26]
and cellular [27] methods. The convergence on the
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set of brain areas serving as the source of the
amplification of sensory signals has been impressive ([28] for a recent review). It is widely agreed
that the frontal eye fields work in conjunction with
superior and inferior parietal areas as the cortical
nodes of the orienting network. In addition, studies
have implicated some subcortical areas including
the pulvinar of the thalamus and the superior colliculus. Most of the studies of this network have
involved visual stimuli, but the sources of the
attention influences in orienting to other modalities
are much the same. Of course the site of amplification of the sensory message is quite different for
each sensory modality.
Evidence to date suggests that both maintained
alertness during task performance (tonic) and
phasic changes induced by a warning signal involving a subcortical structure, the locus coeruleus that
is the source of the brain’s norepinephrine. A great
deal of evidence [29] indicates that the tonic state
depends upon an intact right cerebral hemisphere.
Lesions in this hemisphere can produce profound
difficulty in responding to unexpected targets.
Warning signals, however, may have their influence
more strongly on the left cerebral hemisphere [30].
This distinction may reflect a more general division between the hemispheres where rapidly acting
events are left lateralized while more slowly changing states involve right hemisphere activity.
Tasks that involve conflict between stimulus
dimensions competing for control of the output
often provide activation in the anterior cingulate
gyrus and lateral prefrontal areas. It is thought
that the conflict, induced by a stimulus, is representative of situations where different neural networks
compete for control of consciousness or output.
Because of this we have termed this the executive attention network because it regulates the activity in other brain networks involved in thought
and emotion [31,32]. This network shows a strong
development in childhood and its maturation is
related to what in developmental psychology has
been called self-regulation.
Individual differences are invariably found in
cognitive tasks involving attention. The Attention Network Test (ANT) was developed to examine individual differences in the efficiency of the
brain networks in alerting and orienting the executive attention discussed above [33]. The ANT
uses differences in reaction time (RT) between
conditions to measure the efficiency of each network. Each trial begins with a cue (or a blank
interval, in the no-cue condition) that informs the
participant either that a target will be occurring
soon, or where it will occur or both. The target always occurs either above or below fixation
and consists of a central arrow, surrounded by
flanking arrows that can either point in the same
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MICHAEL I POSNER AND SHOBINI RAO
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 [adapted
from 35]. Abbreviations: aI/fO, anterior insula/frontal operculum; aPFC, anterior prefrontal cortex; dACC/msFC, dorsal
anterior 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 from
incongruent target trials provides a measure of
conflict resolution and assesses the efficiency of
the executive attention network. Subtracting RTs
obtained in the double-cue condition from RT in
the no-cue condition gives a measure of alerting
due to the presence of a warning signal. Subtracting RTs to targets at the cued location (spatial
cue condition) from trials using a central cue gives
a measure of orienting, since the spatial cue, but
not the central cue, provides valid information on
where a target will occur.
2.1 Network connectivity
Neural areas found active in studies of functional
anatomy must be orchestrated in carrying out any
real task. One approach to studying this connectivity uses fMRI to study the correlations between
active areas [34].
An important finding was that even at rest,
common brain areas appear to be active together
(default state). Studies suggest that the connectivity between these areas change over the course
of development. Figure 2 illustrates two sets of
connections active at rest: these are a frontoparietal (related to orienting) and a cinguloopercular (related to executive attention) network.
Connections change over the life span. Children
show many shorter connections and integration
of the dorsal anterior cingulate in both networks.
Adults show more segregation of the two networks
and longer connections.
Some of the same brain areas found active during
rest change when the person is given a task.
For example, while the organization of anatomical
areas in alerting and orienting are not fully known,
some promising beginnings have taken place. In
alerting, the source of the attention appears in the
locus coeruleus (lc). Cells in the lc have two modes
of processing. One mode is sustained and is perhaps related to the tonic level of alertness over
long time intervals. This function is known to
involve the right cerebral hemisphere more strongly
than the left [36]. Alertness is influenced by sensory events and by the diurnal rhythm. However,
its voluntary maintenance during task performance
may be orchestrated from the anterior cingulate
[37]. More phasic shifts of alerting can result from
COGNITIVE NEUROSCIENCE: DEVELOPMENT AND PROSPECTS
423
presenting any environmental signal. However, if
the signal is likely to warn about an impending
target, this shift results in a characteristic suppression of the intrinsic brain rhythms (e.g. alpha)
within a few tens of milliseconds and a strong
negative wave is (contingent negative variation)
recorded from surface electrodes and that moves
from a frontal generator towards the sensory areas
of the hemisphere opposite the expected target.
An analysis of a number of conflict tasks shows
that the more dorsal part of the anterior cingulate is involved in the regulation of cognitive
tasks, while the more ventral part of the cingulate is involved in regulation of emotion [38].
The microstructure of the organization of the cingulate has been studied in detail using correlations between brain areas while the subject rested
(functional connectivity). Dynamic casual modeling (DCM) can then be used to help define
the direction of information within the network.
[39]. These data are related to an analysis of
white matter connections in humans using diffusion
tensor imaging to trace physical connections and
relate them to similar studies in animals [40]. These
converging methods are being applied to trace the
connectivity of brain networks both at rest and
during task performance [33].
can provide a more detailed account of the orchestration of neural networks related to attention or
to other networks illustrated in table 1.
The activation of brain networks does not mean
that all parts of the network are needed to carry out
the task. In the past, effects of brain lesions have
been a primary way to indicate brain areas which
when lost will prevent the persons from carrying
out certain tasks. For example, damage to areas of
the right parietal lobe have led to neglect of the left
side of space in multiple sensory systems. It is now
possible to use brief magnetic pulses applied to the
scalp overlying the brain area of interest (transcortical magnetic stimulation TMS) to disrupt parts
of the network at particular times to observe its
influences on task performance [42]. In this way,
one can determine what parts of the network are
necessary for task performance.
Taken together, the methods reviewed above
have provided tools for probing human brain networks. In the case of attention, there has been
increasing coordination of these studies with animals studies that allow probing of single units and
examination of the micro-circuitry and molecular
events related to these activations.
2.2 Mental chronometry
In the 1970s, behavioral studies using habituation to a repeated stimulus provided evidence that
from birth, infants are able to discriminate basic
phonemic units not only in their own language but
also in other languages to which they have never
been exposed [43]. Studies using these behavioral methods together with electrical recording
from the scalp have probed some of the early
development of the phonemic structure underlying
language.
Recently infants have been exposed to language while resting in fMRI scanners to examine
the brain mechanisms activated by language [44].
The infant language system appears to involve the
same left hemisphere language structures found in
adults [44]. In one study, infants listened to sentences presented aurally in their language. Brain
areas in the superior temporal lobe (Wernicke’s
area) and in Broca’s area were active. When
the same sentence was presented after a delay
of 14 seconds, Broca’s area activity increased, as
though this area was involved in the memory
trace. It has long been supposed that the early
acquisition of language might involve very different mechanisms than are active in adults [45]. Left
hemisphere lesions in infancy do not produce a
permanent loss of language function as they might
do in adults. Nonetheless, the new fMRI data suggests the left hemisphere speech areas are involved
in receptive language in infancy.
Although the fMRI method has become increasingly useful in understanding the sequence of
mental operations, their speed may be too fast for
analysis by the relatively slow changes involved
in imaging based on vascular changes. Another
way to examine network activity is to use scalp
EEG electrodes to record neural activity synchronized in different frequency bands. This method
can be used to separate rapid temporal events,
for example, it can separate the cue effects from
the target effects in the ANT. There is increasing interest in the various frequencies of electrical activity involved in correlations between neural
areas. For example, in one study using the ANT
[41], a spatial cue indicating the location of the
target produced increased high frequency gamma
activity (above 30 Hz) about 200 milliseconds after
the cue presentation. When the cue brought attention to the target location, gamma activity was
found following the cue, but not following the
target. When the cue indicated the center location
so that a shift of attention was needed following
the target, the gamma activity was present following the target. These data suggest that gamma
activity is associated with orienting attention. It
may occur 200 millisecs after the cue or only after
the target depending upon when attention shifts.
Taken together, the fMRI, EEG and DTI methods
3. Language
MICHAEL I POSNER AND SHOBINI RAO
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3.1 Phonemes
3.2 Reading
It has been possible to study changes in phonemic
discrimination due to exposure to the native language at least by ten months of age [46,47]. Infants
appear to acquire a sharpened representation of
the native phonemic distinctions [48]. During the
same period they also lose the ability to distinguish
representations not made in their own language
[49]. At least a part of the loss occurs when the nonnative language requires a distinction that is within
a single phonemic category in the native language.
An example is the ‘ra-la’ distinction important in
English is lost because it is within a single category
in Japanese [50]. It is as though Japanese no longer
hear this distinction and even when exposed to
English they may not improve in distinguishing ‘ra’
from ‘la’. Training by several methods [50,51] seems
to improve this ability even in adults, although it
is not known how well this knowledge can be incorporated into normal daily life communication.
It might be useful to find a way that will preserve the distinctions originally made for the nonnative language during infancy. One study showed
that 12 sessions of exposure to a mandarin speaker
during the first year was effective [52]. A similar
amount of exposure to a computerized version of
the speaker was not effective, suggesting the importance of social interaction in this early form of
learning. More needs to be learned about how
and whether media presentation can be effective in
learning.
There is also some reason to believe that the
process of phonemic discrimination being developed in infancy is important for later efficient use
of spoken and written language [53,54]. Electrical
recording taken in infancy during the course of
phonemic distinctions [53,54] have been useful in
predicting later difficulties in language and reading. There is a history of using event related potentials to assess infant deafness early in life and
being able to do so reliably has been very useful in
the development of sign language and other interventions to hasten the infants’ ability at communication. Perhaps a similar role will prove to be
possible for ERPs in the development of methods
to insure a successful phonemic structure in the
native language.
There have been efforts to develop appropriate intervention in later childhood for difficulties in the use of language and reading such
as the widely used FASTFORWARD programs
[http://www.scilearn.com, 55]. Although there are
disputes about exactly why and for what populations this method works, it remains important
to develop remedies for language difficulties based
upon research.
Reading is a high level skill and in alphabetic languages such as English, it has properties related to
the phonemic structure of language. There have
been many studies of adult reading and much more
is known than can be reviewed here [see 25,56 for
reviews]. The child’s ability in phonemic awareness
(e.g. rhyming of auditory words), is a good predictor of their being able to learn to read alphabetic languages such as English. Adult studies of
reading have revealed a complex neural network
involved in the translation of words into meaning.
Two important nodes of this network are the visual
word form area, of the left fusiform gyrus and an
area of the left temporal-parietal junction for translating visual letters into sounds.
The visual word form area is involved in integrating or chunking visual letters into units of
words [57]. The visual word form has been localized to the fusiform gyrus of the left hemisphere’s
visual system. Although there has been some dispute about the operation it appears to be a part
of the visual system that becomes expert in dealing with letters as reading skill develops in later
childhood. It is thought that without the functioning of this area, reading cannot become fluent. For
example, a patient with a lesion that interrupted
the flow of information from the right hemisphere
to the visual word form area used letter by letter
reading when words were presented left of fixation
(going to the right hemisphere), while they read
words normally when the word was projected to
the left hemisphere and thus reached the visual
word form area [58]. Children from 7 to 18 who
were deficient in reading skills failed to activate
this area, but were able to do so after extensive
training [59].
Languages like English that are highly irregular at the visual level are heavily dependent upon
brain areas that translate visual words to sound.
These areas are at the temporal parietal boundary
of the left hemisphere. Children who have difficulty in learning to read show little activation in
these phonological areas. However, phonics training even after 20 sessions can produce relatively
normal activity in these areas and also improve
reading by several grade levels.
The time course of development of the visual
word form area in English is important for the
development of fluent reading. Phonics training
often leaves the child with improved decoding skill,
but with a lack of fluency. Evidence that the visual
word form develops rather late and first only for
words with which the child is familiar [60], suggests
the importance of continuous practice in reading to
develop fluency [59]. More research is needed on the
COGNITIVE NEUROSCIENCE: DEVELOPMENT AND PROSPECTS
best methods for developing fluency, particularly
in non-alphabetic languages.
The multiple languages in India makes of particular importance findings suggesting superior performance of multi-linguals on executive attention
scores, such as the Attention Network Test (ANT)
[61,62]. The ties to attention have been supported by the use of ANT to assess differences in
executive attention between mono and bilinguals.
A study of Spanish English bilinguals found strong
advantages over monolingual controls in a wide
variety of executive tasks [63]. One study [64] compared Korean and Chinese native speakers who
were bilingual in English with French and Spanish
speakers bilingual in English and with English
monolinguals. Both bilingual groups showed better
executive attention than monolinguals and, the
Asian group, whose languages differed the most
from English, were superior to the Romance bilinguals. This study shows the close ties between language and attention. It also suggests that the need
to select among languages when speaking, as occurs
in multilinguals may form one important basis for
training improved executive attention.
4. Consciousness
There is a long tradition of the study of consciousness within Eastern and Western philosophy,
however, cognitive neuroscience provides a somewhat new perspective on awareness and will, both
of which have been central to the discussions of
consciousness.
An important distinction in studies of awareness [65] is between general knowledge of our environment (ambient awareness) and detailed focal
knowledge of a scene (focal awareness). As lay
people we generally believe that we have full conscious awareness of our environment, even when
our focal attention is upon our own internal
thoughts. Experimental studies [66] show us how
much this opinion is in error. In the study of
‘change blindness’ when cues such as motion, that
normally lead to a shift of attention, are suppressed, we have only a small focus for which
we have full knowledge and even major semantic
changes in the remainder of the environment are
not reported.
Change blindness is closely related to studies
of visual search which have been prominent in
the field of attention and involve an interaction
between information in the ventral visual pathway
about the object identity and information in the
dorsal visual pathway that controls orienting to
sensory information (for a review, see [67]). Visual
search tasks have been important for examining
what constraints attention provides to the nature
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of our awareness of a target event. There is clear
evidence that attention to a visual event increases
the brain activity associated with it. Most evidence arises from studies using event related electrical potentials with visual stimuli and these have
clearly shown that early sensory components of the
visual evoked potential P1 and N2 (80–150 millisec)
are enlarged by the presence of attention [28].
As shown in figure 1 focal attention to the
target of a visual search appears to involve a brain
network that includes the anterior cingulate and
lateral prefrontal areas [33]. Humans have a conviction of conscious control that allows us to regulate
our thoughts, feelings and behaviors in accord with
our goals and people believe that voluntary conscious choice guides at least a part of the action we
take. These beliefs have been studied under various
names in different fields of psychology. In cognition,
cognitive control is the usual name for the voluntary exercise of intentions, while in developmental
psychology many of the same issues are studied
under the name self-regulation [68].
Imaging studies suggest that whenever we bring
to mind information, whether extracted from sensory input or from memory, we activate the executive attention network. In some studies a whole set
of frontal areas become activated together forming
what is called a global workspace [69]. This global
workspace becomes active about 300 millisecs after
a target event is presented. It provides the neural
basis for the set of information on which a person is currently working in the process of problem
solving.
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 mechanism as involved in control. In this sense, even
though some forms of consciousness (e.g. ambient awareness) may have diverse sources within
sensory specific cortex, there is also a degree of
unity of the underlying mechanisms involving focal
awareness and conscious control. The distinction
between focal and ambient factors in consciousness
may help to clarify the sense of awareness that can
be present even when detailed accounts of the scene
are not possible as in change blindness [66].
5. Genes and experience build networks
The common nature of brain networks such as
those in table 1 among people argue strongly
for the role of genes in their construction. This
has led cognitive neuroscience to incorporate data
from the growing field of human genetics. One
method for doing this relates individual differences
to different forms of genes (genetic alleles) that
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MICHAEL I POSNER AND SHOBINI RAO
Figure 3. A strategy for relating brain networks to underlying molecular events [adapted from 70]. Bottom of figure are
psychological functions, these are related to neural networks as shown in brain images and then to differences in protein
configuration and genetic variation.
may relate to them. Brain activity can serve as an
intermediate level for relating genes to behavior as
illustrated in figure 3.
As one example, the Attention Network Test
(ANT) was used to examine individual differences
in the efficiency of executive attention. Strong heritability of the executive network supported the
search for genes related to individual differences in
network efficiently.
The association of the executive network with
the neuromodulator dopamine is a way of searching for candidate genes that might relate to the
efficiency of the network [71]. For example, several studies employing conflict related tasks, found
that alleles of the catechol-o-methyl transferase
(COMT) gene were related to the ability to resolve
conflict. A number of other dopamine genes have
also proven related to this form of attention, in
addition, research has suggested that genes related
to serotonin transmission also influence executive
attention ([72] for a summary). It was also possible to show that some of these genetic differences
influenced the degree to which the anterior cingulate was activated during task performance in studies using brain imaging. In the future, as suggested
by figure 3, it may be possible to relate genes to
specific nodes within neural networks, allowing a
much more detailed understanding of the origins of
brain networks.
While genes are important for common neural
networks and individual differences in efficiency
there is also an important role for specific
experiences. For example, several genes including
the DRD4 gene and the COMT gene have both
shown to interact with aspects of quality of parenting. This provides evidence that aspects of the culture in which children are raised can influence the
way in which genes shape neural networks influencing child behavior.
If brain networks are influenced by parenting
and other culture influences, it should be possible to develop specific training methods that can
be used to influence underlying brain networks.
For example, one study tested the effect of training during the period of major development of
executive attention, which takes place between 4
to 7 years of age [73]. An improvement in conflict
resolution as measured by the ANT was found in
trained children, along with changes in the underlying network and generalization to other aspects
of cognition. EEG data showed clear evidence of
improvement in network efficiency in resolving conflict following training. The N2 component of the
scalp recorded ERP has been shown to arise in the
anterior cingulate and is related to the resolution
of conflict [74]. The N2 differences between congruent and incongruent trials of the ANT were found
in trained six year olds, that resembled differences
found in adults. No such N2 difference was found
in the untrained controls. These data suggest that
training altered the network for the resolution of
conflict in the direction of being more like what is
found in adults. There was also a greater improvement in intelligence in the trained group compared
COGNITIVE NEUROSCIENCE: DEVELOPMENT AND PROSPECTS
to the control children. This finding suggested that
training effects had generalized to a measure of
cognitive processing that is far removed from the
training exercises.
Given the wide range of individual differences in
the efficiency of attention, it is expected that attention training could be especially beneficial for those
children with poorer initial efficiency. These could
be children with pathologies that involve attentional networks, children with genetic backgrounds
associated with poorer attentional performance, or
children raised in different degrees of deprivation.
6. Brain plasticity
Training studies discussed in the last section show
evidence that performance of networks can be
altered by experience. This idea has been important in rehabilitation in cases of brain injury and
psychiatric disorders. It has also led to suggestions
for improved education for normal people based on
ideas coming from cognitive neuroscience.
Brain networks are frequently damaged by neurological or psychiatric disorders and head trauma.
Neuro-imaging has made it easier to determine the
extent and location of brain damage, so a major
area of application of cognitive studies is to the
treatment of such disorders. The National Institute
of Mental Health and Neuroscience (NIMHANS)
in Bangalore has been a pioneer in these efforts.
The NIMHANS neuropsychology battery consists of 21 neuropsychological tests. This battery
was administered to 540 normal males and females,
aged between 16–65 years, including illiterates and
literates whose educational levels differed widely
[75]. There have been a series of studies using this
battery before and after training. Improved basic
cognitive functions were found using both hospital based computerized and home based paper and
pencil training [76,77].
A number of randomized studies have also shown
improvements in attention and memory in normal
children and adults [78–81]. All these methods
involve practice in some cognitive skills including
repetitive trials on tasks similar to what might
be tested in schools or cognitive laboratories. All
involve a training group showing significantly more
improvement than control groups. The control
groups often involve the same number of laboratory
sessions with training or experiences not thought to
involve the elements of attention working memory
used in the experimental group.
These methods differ considerably from mindfulness training, exposure to nature settings or integrative body-mind training (IBMT), all of which
also affect the state of attention. Recently, both
IBMT (using body-mind optimization) [82], and
427
nature exposure [83] (using attention restoration
theory) have conducted similar randomized design
using similar before and after assays as those
used in attention training. These attention state
methods appear to achieve similar success to attention training in the attention network test and also
help control of stress, improve self-regulation, etc.
These two training streams represent the different traditions/cultures and methodologies in the
East (IBMT, mindfulness) and West (practice and
brain plasticity). These techniques provide support for the idea that training can provide general
changes in brain networks that can lead to widespread improvement in cognitive processes. Since it
is likely that the various methods activate different
brain networks, imaging may be used to combine
methods to produce improved effectiveness.
7. Future developments
Cognitive neuroscience has developed a number
of methods than in concert can link important
aspects of human behavior to underlying neural
networks and to the cellular and molecular levels
that underlie them. It is likely that new methods of
imaging will eventually provide more details about
the functioning of the human brain when active
and in the resting state. One of the major accomplishments of cognitive neuroscience is to attract
the attention of physical and mathematical scientists who are capable of contributing to imaging
apparatus and new algorithms.
Imaging and cognitive theory may also contribute to new forms of compensation for brain
injuries and pathologies. Already deep brain stimulation, guided by imaging theories have been used
in treatments of depression [84] and in an effort
to improve the integrative behavior for patients
in vegetative neurological states [85]. We can
also expect additional training and state change
methods, guided by imaging of what specific brain
network(s) are influenced by the method, designed
to assist people with brain injuries or other forms
of pathology.
Interfaces between humans, computers and prosthetic devices are playing an important role in
extending the sensory and motor capacities of
patients of all kinds [86]. A better understanding of the neuronal networks related to human
capacities could lead us toward improvements in
these methods and the development of methods
to extend the cognitive range of normal people in
directions of human improvement.
This chapter is a brief overview of the achievements and potential of cognitive neuroscience
during the twenty years of its existence as a
scientific discipline. In addition to the technical
MICHAEL I POSNER AND SHOBINI RAO
428
findings discussed in this review, imaging studies
are having a wide influence in the general culture
by giving people who read or watch television, a
picture of brain activity during many human tasks
and situations. As a result, there is likely to be a
large continuing interest in the application of cognitive neuroscience perspective to many societal
issues.
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