When I was eight years old, my family moved out of our 100-year-old house in the Netherlands. Its ivy-covered brick walls, dark green door and matching window shutters remain vivid to me. I still keep a framed photo of my golden retriever and me scampering down the pebble driveway, which led past rhododendrons to a separate garage. Behind it rose a majestic dune.

The passing of decades inevitably weakens the brain connections that hold such slices of time in place. Yet as I learned in this issue's special report, “How We Remember,” revisiting one's recollections helps the brain rebuild aging neural links. In “The Engine of Memory,” psychologist Donald G. MacKay describes his discovery of several ways the mind repairs and strengthens reminiscences.

Also in the report, cognitive scientist Felipe De Brigard delves into the mystery of the hippocampus, a brain region viewed as the seat of memory. People with damage to this area develop amnesia—but also suffer deficits of imagination, sight and other core mental functions. Connecting with our past makes it easier to envision the future, it seems. See “The Anatomy of Amnesia.”

Memory is not the only faculty vulnerable to the ravages of time and disease. New hope for treating disorders in which brain cells perish, such as Parkinson's, is now emerging in the form of stem cell therapies. Journalist Lydia Denworth reports on stunning progress in cultivating replacement neurons. The advances she describes in “The Regenerating Brain” demanded many years of painstaking research—a reminder that the passage of time also brings us breakthroughs that improve human lives.

Last October, I paid a brief visit to the house in the Netherlands, my first trip back in decades. I recognized the facade, but gone were the green shutters and the ivy, as well as the detached garage. The gardens had been transformed. The building was a stranger now, not a friend. Yet it dawned on me that my beloved childhood home still stood safely in my memories. By carrying the past forward with us, our present and future become all the richer.