( Hence ( , ( often ( ( a memory ) ( ( may ( focus ( on ( ( one ( specific impression ) ) ( associated ( with ( the ( ( threat or ) harm ) ) ) ) ) ) ) ) . ) ) ) ) )
(ROOT (S (ADVP (RB Hence)) (, ,) (ADVP (RB often)) (NP (DT a) (NN memory)) (VP (MD may) (VP (VB focus) (PP (IN on) (NP (NP (CD one) (JJ specific) (NN impression)) (VP (VBN associated) (PP (IN with) (NP (DT the) (NN threat) (CC or) (NN harm)))))))) (. .)))
Hence, often a memory may focus on one specific impression associated with the threat or harm.
(ROOT (S (NP (JJ Specific) (NNS scents)) (VP (VBP are) (ADVP (RB often)) (VP (VBN associated) (PP (IN with) (NP (NNS memories))))) (. .)))