The evolutionary emergence of the mammalian neocortex is
generally accepted as the key neural innovation underlying advanced reason.
Cortical evolution, if the neural constructivists are correct, is not simply a
story about the addition of new, special purpose brain structures. Rather, it
is a story about the addition of a plastic resource geared to allowing the
encountered environment to build dedicated, delicately fitted neural
substructures “on- the-hoof.” The human neocortex and prefrontal cortex, along
with the extended developmental period of human childhood, allows the
contemporary environment an opportunity an opportunity to partially redesign
aspects of our basic neural hardware itself. The designer environments are thus
matched, step-by-step, by dedicated designer brains, with each side of the
co-adaptive equation growing, chaining, and evolving to better fit- and
maximally exploit- the other. It is in this way that the human learner becomes
“dovetailed” to the set of reliable external problem- solving resources that
she encounters during early learning.
The neural constructivist vision thus depicts neural and
especially cortical growth as experience –dependent and involving the actual
construction of new neural circuitry (synapses, axons , dendrites) rather than
just the fine- tuning of circuitry whose basic shape and function is already
determine. The learning device itself changes as a result of organism-
environmental interactions; learning does not just alter the knowledge base for
fixed computational engine, it alters the internal computational architecture
itself.
As a concrete example, consider the development of hearing.
Congenitally deaf children, whose brains are thus never exposed to the complex
and distinctly structured inputs that the auditory world provides, fail to
develop the complex web of inner connectivity that supports normal hearing. If
such stimulation is artificially provided, using cochlear implant, recovery is
rapid. The neural bases of this recovery are increasingly well understood and
involve complex changes in the connectivity and response characteristics of
auditory cortex. Vision cortex, likewise, requires extensive, experience-
dependent rewriting to support seeing. New born human infants have very bad
vision; it is highly restricted in scope and the resolution is forty times worse
than adult vision. Depth appreciation is pretty well nonexistent. It takes
about a year of “cortical training” for the visual system to become normal, a
process that can be blocked by cataracts or other impairments, which deprive
the visual cortex of the experience it needs. Remove the cataracts and replace
the affected lens with a clear artificial one, and improvement is again
dramatically fast. According to one researcher, this kind of result
“demonstrates the amazing plasticity of the young brain and underscores the
importance of complex, balanced, early sensory input for guiding subsequent
brain development.
So, great in fact, is the plasticity of immature cortex (and
especially that of prefrontal cortex, according to Quartz and Sejnowski) that
O’Leary dubs it “Protocortex”. The whole sensory, linguistic, and technological
environment in which the human brain grows and develops is thus poised to
function as one of the anchor points around which such flexible neural
resources adapt and fit. Such neural plasticity is, of course, not restricted
to the human species; in factor, some of the early work on cortical transplants
was performed on rats. But our brains do appear to be far and away the most
plastic of them all. Combined with this plasticity, however, we benefit from a
unique kind of developmental space; the unusually protracted human childhood.
In a recent evolutionary account, Griffiths and stotz argue
that the long human childhood provides a unique of opportunity in which
“cultural scaffolding [can] change the dynamics of the cognitive system in a
way that opens up new cognitive possibilities. “ These authors argue against
what they describe as the “dualist account of human biology and human culture”
according to which biological evolution must first create the “anatomically
modern human” before being followed by the long and ongoing process of Cultural
Revolution. Such a picture, they suggest, invites us to believe in something
like a basic biological human nature, gradually co-opted and obscured by the
trappings and effects of culture and society. This vision (which is perhaps not
so far removed from that found in some of the more excessive versions of
evolutionary psychology) is akin, they argue to looking for true nature of the
ant by “removing the distorting influence of the nest”.
12.
Which of the following is true of the neural
constructivist model?
A.
The environment encountered by the mammalian
organism leads to the creation of new neural circuitry involving changes in
internal architecture.
B.
It involves the addition of a plastic resource
designed to build neural substructures.
C.
It envisages the creation of designer
environments geared to bringing about lasting changes in neural circuitry
design.
D.
None of these
13.
It can be genuinely inferred from this passage
that development of visual and auditory abilities.
A.
Require the development of suitable neural
structures.
B.
Is a function of appropriate environmental stimulation?
C.
Both A and B
D.
Is a function of time
14.
From the passage, what can be understood about the
notion of plasticity?
A.
The ability to mould as per circumstances.
B.
The ability to regain lost faculties quickly in
the presence of suitable conditions.
C.
The training needed to re-enable a perceptual
ability
D.
The tendency of infant eyes to gain normal vision
quickly
15.
The author has used the hearing and the seeing
examples to prove the point
A.
That human sensory abilities are inborn
B.
Those human sensory abilities need external
inputs to develop properly.
C.
That they are paramount to an infant’s
development.
D.
That though inbuilt into the neural system, they
need external stimulation to develop fully.
16.
The last paragraph serves to
A.
Counter the cultural dominance viewpoint of
human evolution.
B.
Highlight the significance of culture in shaping
human evolution.
C.
Drive home the importance of relative length of
human childhood.
D.
Strike a compromise between rival viewpoints.
Answer:
12.
C Please refer to the first paragraph.
13.
C The last few lines of the second and third
paragraphs amply bear out this conclusion.
14.
B
Please refer back to the last few lines of the third paragraph.
15.
D
Please refer to the second paragraph and the last few lines of the third
paragraph.
16.
A the
last few lines amply justify the answer given.
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