***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The dentate gyrus ( DG ) is a region in the hippocampal formation whose function declines in association with human aging and is therefore considered to be a possible source of age-related memory decline . Causal evidence is needed , however , to show that DG-associated memory decline in otherwise healthy elders can be improved by interventions that enhance DG function . We addressed this issue by first using a high-resolution variant of functional magnetic resonance imaging ( fMRI ) to map the precise site of age-related DG dysfunction and to develop a cognitive task whose function localized to this anatomical site . Then , in a controlled r and omized trial , we applied these tools to study healthy 50–69-year-old subjects who consumed either a high or low cocoa flavanol – containing diet for 3 months . A high-flavanol intervention was found to enhance DG function , as measured by fMRI and by cognitive testing . Our findings establish that DG dysfunction is a driver of age-related cognitive decline and suggest non-pharmacological means for its amelioration Axon-sparing  neurotoxic lesions of CA1 or CA3 were produced in the dorsal hippocampus to test dissociative lesion effects on spatial working memory for sequential items . Rats were required to remember  four different sections sequentially presented on a newly devised maze ( i.e. , Tulum maze ) during a study phase . Each section was cued by a unique object that was specifically associated with each location within the section during the study phase . Following a 15-s delay and during the test phase , rats were required to revisit the location within a section r and omly chosen among the previously visited sections in the absence of the cued object . Both CA1 and CA3 lesions similarly disrupted accurate relocation of a previously visited place . However , differential effects of the CA1 and CA3 lesions were observed in serial position curves . CA3-lesions disrupted performance for the first three serial positions , but did not disrupt performance for the last serial position ( recency ) . In contrast , CA1-lesions disrupted performance for all serial positions . The results suggest that temporal separation of spatial memory may depend on the conjoint function of CA1 and CA3 of the hippocampus with a disruption of a spatial pattern completion process following CA3 lesions and a disruption of a temporal pattern separation process following a CA1 lesion Two experiments tested the effect of temporal interference on order memory for fixed and r and om sequences in young adults and nondemented older adults . The results demonstrate that temporal order memory for fixed and r and om sequences is impaired in nondemented older adults , particularly when temporal interference is high . However , temporal order memory for fixed sequences is comparable between older adults and young adults when temporal interference is minimized . The results suggest that temporal order memory is less efficient and more susceptible to interference in older adults , possibly due to impaired temporal pattern separation 
    Output:
    
Pattern separation and pattern completion were most frequently tested during a retrieval task using familiar or recognizable visual stimuli and cues .
This review found evidence that some of the parameters for task validity have been followed in some human studies of pattern separation and pattern completion , but no study was judged to have adequately met all the parameters for task validity .