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  3. Alison Preston of the University of Texas at Austin’s Center for Learning and Memory explains: A short-term memory’s conversion

Alison Preston of the University of Texas at Austin’s Center for Learning and Memory explains: A short-term memory’s conversion

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问题     Alison Preston of the University of Texas at Austin’s Center for Learning and Memory explains: A short-term memory’s conversion to a long-term memory requires changes within the brain that protect the memory from interference from competing stimuli or disruption from injury or disease. This time-dependent process of stabilization, whereby our experiences achieve a permanent record in our memory, is referred to as "consolidation".
    Memory consolidation can occur at many organizational levels in the brain. The cellular and molecular portions of memory consolidation typically take place within the first minutes or hours of learning and result in changes to neurons (nerve cells) or sets of neurons. Systems-level consolidation, involving the reorganization of brain networks that handle the processing of individual memories can then happen on a much slower time frame of days or even years.
    The consolidation process that affects declarative memories-recollections of general facts and specific events—relies on the function of some specific structures in the brain. At the cellular level, memory is expressed as changes to the structure and function of neurons. For example, new synapses—the connections between neurons through which they exchange information—can form to allow for communication between new networks of neurons. Alternatively, existing synapses can be strengthened to allow for increased sensitivity in the communication between two neurons.
    Consolidating such synaptic changes requires the synthesis of new RNA and proteins in the structures, which transform temporary alterations in synaptic transmission into persistent modifications of synaptic architecture. With time, the brain systems also change. Initially, the specific structure works in concert with sensory-processing regions distributed in the neo-cortex (the outermost layer of the brain) to form the new memories. Within the neo-cortex, representations of the elements that constitute an event in our life are distributed across multiple brain regions according to their content.
    When a memory is first formed, the specific structure rapidly combines this distributed information into a single memory, thus acting as an index of representations in the sensory-processing regions. As time passes, cellular and molecular changes allow for the strengthening of direct connections among the neocortical regions, enabling access to the memory independent of the structure. Thus, while damage to the structure from injury or particular disorder hampers the ability to form new declarative memories, such a disruption may not impair memories for facts and events that have already been consolidated. Thus, an amnesiac with hippocampal damage would not be able to learn the names of current presidential candidates but would be able to recall the identity of our 16th president.
According to the passage, the declarative memories could be
选项 A、affected by the memory of general facts and specific events.
B、determined by some specific structures in the brain.
C、expressed as changes to the structure and function of neurons.
D、communicated to create new connections of neurons.
答案C
解析 根据declarative memories可定位至第三段。第三段提到，“在细胞层面，记忆表现为神经元结构和功能的改变”，陈述性记忆是记忆的一种，因此C项正确。
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