Patients with hippocampal amnesia cannot imagine new experiences
TL;DR: It is revealed that patients with primary damage to the hippocampus bilaterally could construct new imagined experiences in response to short verbal cues that outlined a range of simple commonplace scenarios, but were markedly impaired relative to matched control subjects at imagining new experiences.
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Abstract: Amnesic patients have a well established deficit in remembering their past experiences. Surprisingly, however, the question as to whether such patients can imagine new experiences has not been formally addressed to our knowledge. We tested whether a group of amnesic patients with primary damage to the hippocampus bilaterally could construct new imagined experiences in response to short verbal cues that outlined a range of simple commonplace scenarios. Our results revealed that patients were markedly impaired relative to matched control subjects at imagining new experiences. Moreover, we identified a possible source for this deficit. The patients' imagined experiences lacked spatial coherence, consisting instead of fragmented images in the absence of a holistic representation of the environmental setting. The hippocampus, therefore, may make a critical contribution to the creation of new experiences by providing the spatial context into which the disparate elements of an experience can be bound. Given how closely imagined experiences match episodic memories, the absence of this function mediated by the hippocampus, may also fundamentally affect the ability to vividly re-experience the past.
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Citations
Constructing, Perceiving, and Maintaining Scenes: Hippocampal Activity and Connectivity
TL;DR: The hippocampus is identified as a subregion commonly engaged by scenes, whether perceived or constructed, by separating scene construction from working memory, and by revealing the functional network underlying scene construction, offering new insights into why patients with hippocampus lesions cannot construct scenes.
Remembering what could have happened: neural correlates of episodic counterfactual thinking.
TL;DR: Examination of functional magnetic resonance imaging data suggests that episodic counterfactual thinking engages regions that form the core brain network, and also that the subjective likelihood of the authors' counterfactUAL thoughts modulates the engagement of different areas within this set of regions.
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Lesion Studies in Contemporary Neuroscience.
TL;DR: It is argued that lesion studies are essential to the rigorous assessment of neuroscience theories and should be considered in the context of clinical and ecological relevance.
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Remote Memory and the Hippocampus: A Constructive Critique.
TL;DR: It is proposed that the hippocampus reconstructs remote memories in the absence of the original trace by assembling consolidated neocortical elements into spatially coherent scenes that form the basis of unfolding memory events.
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Hippocampal Contributions to Model-Based Planning and Spatial Memory
Oliver M. Vikbladh,Michael R. Meager,John A. King,Karen Blackmon,Orrin Devinsky,Daphna Shohamy,Neil Burgess,Nathaniel D. Daw +7 more
TL;DR: Investigating model-based planning and place memory in healthy controls and epilepsy patients treated using unilateral anterior temporal lobectomy with hippocampal resection found both functions were impaired in the patient group, consistent with both functions relying on the same structure in the healthy brain.
181
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