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发表于 2008-10-18 21:05:59
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Much of the research on hallucinogenic drugs such
as LSD has focused on the neurotransmitter serotonin,
a chemical that when released from a presynaptic
serotonin-secreting neuron causes the transmission of
(5) a nerve impulse across a synapse to an adjacent
postsynaptic, or target, neuron. There are two major
reasons for this emphasis. First, it was discovered
early on that many of the major hallucinogens have a
molecular structure similar to that of serotonin. In
(10) addition, animal studies of brain neurochemistry
following administration of hallucinogens invariably
reported changes in serotonin levels.
Early investigators correctly reasoned that the
structural similarity to the serotonin molecule might
(15) imply that LSD’s effects are brought about by an
action on the neurotransmission of serotonin in the
brain. Unfortunately, the level of technical expertise
in the field of brain research was such that this
hypothesis had to be tested on peripheral tissue
(20) (tissue outside the brain). Two different groups of
scientists reported that LSD powerfully blockaded
serotonin’s action. Their conclusions were quickly
challenged, however. We now know that the action
of a drug at one site in the body does not necessarily
(25) correspond to the drug’s action at another site,
especially when one site is in the brain and the other
is not.
By the 1960’s, technical advances permitted the
direct testing of the hypothesis that LSD and related
(30) hallucinogens act by directly suppressing the activity
of serotonin-secreting neurons themselves—the so-
called presynaptic hypothesis. Researchers reasoned
that if the hllucinogenic drugs act by suppressing the
activity of serotonin-secreting neurons, then drugs
(35) administered after these neurons had been destroyed
should have no effect on behavior, because the
system would already be maximally suppressed.
Contrary to their expectations, neuron destruction
enhanced the effect of LSD and related hallucinogens
(40) on behavior. Thus, hallucinogenic drugs apparently
do not act directly on serotonin-secreting neurons.
However, these and other available data do support
an alternative hypothesis, that LSD and related drugs
act directly at receptor sites on serotonin target
(45) neurons (the postsynaptic hypothesis). The fact that
LSD elicits “serotonin syndrome” —that is, causes
the same kinds of behaviors as does the adminis-
tration of serotonin—in animals whose brains are
depleted of serotonin indicates that LSD acts directly
(50)on serotonin receptors, rather than indirectly through
the release of stores of serotonin. The enhanced effect
of LSD reported after serotonin depletion could be
due to a proliferation of serotonin receptor sites on
serotonin target neurons. This phenomenon often
(55) follows neuron destruction or neurotransmitter
depletion; the increase in the number of receptor sites
appears to be a compensatory response to decreased
input. Significantly, this hypothesis is supported by
data from a number of different laboratories.
17. According to the passage, which of the
following is one of the primary factors that led
researchers studying hallucinogenic drugs to
focus on serotonin?
(A) The suppression of the activity of serotonin-
secreting neurons by the administration of
hallucinogens
(B) The observed similarities in the chemical
structures of serotonin and hallucinogens
(C) The effects the administration of
hallucinogens has on serotonin production
in the human brain
(D) Serotonin-induced changes in the effects of
hallucinogens on behavior
(E) Hallucinogen-induced changes in the effects
of serotonin on behavior
18. It can be inferred that researchers abandoned the
presynaptic hypothesis because
(A) a new and more attractive hypothesis was
suggested
(B) no research was reported that supported the
hypothesis
(C) research results provided evidence to
counter the hypothesis
(D) the hypothesis was supported only by
studies of animals and not by studies of
human beings
(E) the level of technical expertise in the field of
brain research did not permit adequate
testing of the hypothesis
19. Which of the following best expresses the main
idea of the passage?
(A) Research has suggested that the
neurotransmitter serotonin is responsible for
the effects of hallucinogenic drogs on the
brain and on behavior.
(B) Researchers have spent an inadequate amount
of time developing theories concerning the way
in which the effects of hallucinogenic drugs occur.
(C) Research results strongly suggest that
hallucinogenic drugs create their effects by
acting on the serotonin receptor sites located
on target neurons in the brain.
(D) Researchers have recently made valuable
discoveries concerning the effects of
depleting the amount of serotonin in the
brain.
(E) Researchers have concluded that hallucinogenic
drugs suppress the activity of serotonin-secreting
neurons.
20. The research described in the passage is
primarily concerned with answering which of
the following questions?
(A) How can researchers control the effects that
LSD has on behavior?
(B) How are animals’ reactions to LSD different
from those of human beings?
(C) What triggers the effects that LSD has on
human behavior?
(D) What technical advances would permit
researchers to predict more accurately the
effects of LSD on behavior?
(E) What relationship does the suppression of
neuron activity have to the occurrence of
“serotonin syndrome”?
21. Which of the following best defines “serotonin
syndrome” (line 46) as the term is used in the
passage?
(A) The series of behaviors, usually associated
with the administration of serotonin, that also
occurs when LSD is administered to animals
whose brains are depleted of serotonin
(B) The series of behaviors, usually associated
with the administration of LSD, that also
occurs when the amount of serotonin in the
brain is reduced
(C) The maximal suppression of neuron activity
that results from the destruction of serotonin-
secreting neurons
(D) The release of stores of serotonin from
serotonin-secreting neurons in the brain
(E) The proliferation of serotonin receptor sites
that follows depletion of serotonin supplies in
the brain
22. Which of the following best describes the
organization of the argument that the author of
the passage presents in the last two paragraphs?
(A) Two approaches to testing a hypothesis are
described, and the greater merits of one
approach are indicated.
(B) The assumptions underlying two hypotheses
are outlined, and evidence for and against
each hypothesis is discussed.
(C) A phenomenon is described, and hypotheses
concerning its occurrence are considered and
rejected.
(D) The reasoning behind a hypothesis is
summarized, evidence supporting the
hypothesis is presented, and research that
counters the supporting evidence is
described.
(E) A hypothesis is discussed, evidence
undermining the hypothesis is revealed, and a
further hypothesis based on the undermining
evidence is explained
23. The author’s attitude toward early researchers’
reasoning concerning the implications of
similarities in the structures of serotonin and
LSD molecules can best be described as one of
(A) complete agreeement
(B) reluctant support
(C) subtle condescension
(D) irreverent dismissal
(E) strong opposition
When literary periods are defined on the basis of
men’s writing, women’s writing must be forcibly
assimilated into an irrelevant grid: a Renaissance that
is not a renaissance for women, a Romantic period in
(5) which women played very little part, a modernism
with which women conflict. Simultaneously, the
history of women’s writing has been suppressed,
leaving large, mysterious gaps in accounts of the
development of various genres. Feminist criticism is
(10) beginning to correct this situation. Margaret Anne
Doody, for example, suggests that during “the period
between the death of Richardson and the appearance
of the novels of Scott and Austen,” which has “been
regarded as a dead period.” Late-eighteenth-century
(15) women writers actually developed “the paradigm
for women’s fiction of the nineteenth century—
something hardly less than the paradigm of the
nineteenth-century novel itself.” Feminist critics have
also pointed out that the twentieth-century writer
(20) Virginia Woolf belonged to a tradition other than
modernism and that this tradition surfaces in her
work precisely where criticism has hitherto found
obscurities, evasions, implausibilities, and
imperfections.
24. It can be inferred from the passage that the
author views the division of literature into
periods based on men’s writing as an approach
that
(A) makes distinctions among literary periods
ambiguous
(B) is appropriate for evaluating only premodern
literature
(C) was misunderstood until the advent of
feminist criticism
(D) provides a valuable basis from which
feminist criticism has evolved
(E) obscures women’s contributions to literature
25. The passage suggests which of the following
about Virginia Woolf’s work?
Ⅰ. Nonfeminist criticism of it has been flawed.
Ⅱ. Critics have treated it as part of modernism.
Ⅲ. It is based on the work of late-eighteenth-
century women writers.
(A) Ⅰonly
(B) Ⅱonly
(C) Ⅰand Ⅱ only
(D) Ⅱand Ⅲ only
(E) Ⅰ, Ⅱand Ⅲ
26. The author quotes Doody most probably in order
to illustrate
(A) a contribution that feminist criticism can
make to literary criticism
(B) a modernist approach that conflicts with
women’s writing
(C) writing by a woman which had previously
been ignored
(D) the hitherto overlooked significance of Scott’s
and Austen’s novels
(E) a standard system of defining literary periods
27. The passage provides information that answers
which of the following questions?
(A) In what tradition do feminist critics usually
place Virginia Woolf?
(B) What are the main themes of women’s fiction
of the nineteenth century?
(C) What events motivated the feminist
reinterpretation of literary history?
(D) How has the period between Richardson’s
death and Scott’s and Ansten’s novels
traditionally been regarded by critics?
(E) How was the development of the nineteenth-
century novel affected by women’s fiction in
the same century?
[ 本帖最后由 草木也知愁 于 2008-10-18 21:09 编辑 ] |
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