How do memories come up for no apparent reason? Is this evidence that we remember everything? As I was driving, all of a sudden the name "Holden Caufield" came to my mind. It sounded really familiar. I googled the name and it was the main character in The Catcher in the Rye. The last time I even read that book was in 2005. I had no reason to even remember this book because I thought it was boring. 


Yet how did I seem to recall the name "Holden Caufield?" 
Is this proof that we basically remember everything, we just have to find ways to access the memories?
Within the limbic system the hippocampus and  amygdala processes  memory. The hippocampus processes declarative memory, the memory  recalled in the form of thought.  The amygdala processes emotional memory.

hippocampus


  Hippocampal integrity plays a crucial role in intact memory functioning. Research has demonstrated that normal hippocampal development continues into early adulthood . Investigators specifically examining the development of the hippocampus have suggested that the hippocampal formation undergoes a steep increase in volume until approximately the second year of life, then the volume slowly increases throughout adolescence. 1


amygdala


  ...here is extensive evidence that the amygdala is involved in affectively influenced memory. The central hypothesis guiding the research reviewed in this paper is that emotional arousal activates the amygdala and that such activation results in the modulation of memory storage occurring in other brain regions. 
  2


involuntary memory


  Involuntary autobiographical memories are conscious and unintended recollections of personal ex- periences.  ...
  involuntary retrieval, more fre- quently than word-cued memories, accesses memories of specific episodes and involves more mood impact and bodily reaction to the remembered events...
  Using a double-cuing methodology, Chu and Downes (2002) found that memories cued by smells were more vivid and detailed than memories cued by verbal labels
  and photographs of the sources of the odors. Herz and Schooler (2002) found that odor cues yielded more emo- tional memories than did verbal and visual cues
  3


Many cues can trigger involuntary memory. Memories triggered by smell, general evoke a larger emotional response with that memory as opposed to visual or verbal cues.

1. Abnormal Hippocampal Development in Children with Medulloblastoma Treated with Risk-Adapted Irradiation
Bonnie J. Nagela,g, Shawna L. Palmera, Wilburn E. Reddickb,f, John O. Glassb, Kathleen J. Heltonb, Shengjie Wuc, Xiaoping Xiongc, Larry E. Kunb, Amar Gajjard,e and Raymond K. Mulherna
2. Involvement of the amygdala in memory storage: Interaction with other brain systems
James L. McGaugh, Larry Cahill, and Benno Roozendaal
3. Memory &amp; Cognition 2004, 32 (5), 789-803
The episodic nature of involuntary autobiographical memories
DORTHE BERNTSEN and NICOLINE MARIE HALL
University of Aarhus, Aarhus, Denmark