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Question

Difficulty: MediumNecessary Assumption

Cognitive Neuroscientist: During slow-wave sleep, hippocampal neural replay is observed, wherein patterns of brain activity from daytime maze-learning tasks are rapidly reactivated. When researchers pharmacologically suppressed this replay in laboratory rodents without disrupting the overall duration or depth of their slow-wave sleep, the rodents performed significantly worse on spatial recall tests the following day compared to control rodents whose replay activity was uninhibited. Therefore, hippocampal neural replay during slow-wave sleep is essential for the consolidation of spatial memories.

Which of the following are assumptions on which the cognitive neuroscientist's argument depends? (Select all that apply.)

  1. The pharmacological substance administered to the experimental rodents did not degrade their spatial recall performance through some physiological effect other than the suppression of replay.Answer
  2. B
    Hippocampal neural replay during slow-wave sleep is sufficient on its own to ensure long-term retention of spatial memories.
  3. The disparity in spatial recall between the experimental and control rodents was not entirely attributable to pre-existing differences in their baseline navigational capabilities.Answer
  4. D
    Reactivating daytime neural patterns during slow-wave sleep always results in superior recall compared to any form of waking rehearsal.
  5. E
    If a rodent exhibits successful spatial memory consolidation, that rodent must have engaged in higher rates of neural replay than any rodent that failed the recall test.

Answer

The argument depends on the assumptions that the pharmacological agent did not cause the performance deficit through an unrelated mechanism and that the difference between the groups was not entirely due to pre-existing baseline navigation differences.
Both required statements protect the causal connection between replay suppression and memory deficit. If the pharmacological intervention impaired recall through an unrelated physiological mechanism, or if the experimental and control groups differed completely in baseline ability prior to the test, the observed recall deficit cannot be attributed to the lack of replay during sleep. Negating either statement destroys the conclusion.

Step-by-Step Solution

1
Analyze the core argument structure
Premises: Suppressing hippocampal replay during slow-wave sleep without altering sleep duration/depth led to worse next-day recall in rodents compared to uninhibited controls. Conclusion: Hippocampal replay during slow-wave sleep is essential (necessary) for spatial memory consolidation.
Identifying the exact premises and conclusion isolates the gap between the experimental observation and the causal claim.
2
Apply the Negation Test to potential Defender assumptions
Negating the statement about side effects shows that if the drug caused deficits via an unrelated pathway, the conclusion collapses. Negating the statement about pre-existing differences shows that if baseline disparities explained the entire performance gap, the experimental intervention was not the cause.
A necessary assumption must fatally undermine the conclusion when logically negated.
3
Evaluate and eliminate distractors
Claims asserting sufficiency, extreme universal superiority, or rigid individual comparative rankings are not strictly required for the author's necessary relationship to hold.
Assumptions that go beyond what is logically required are invalid for necessary assumption tasks.

Key Concept

Identifying necessary foundational assumptions (both supporter bridges and defender exclusions) required to validate a causal conclusion drawn from an experimental study.
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Topics

Necessary Assumption

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