I think of apples now, not because I am surrounded by many visible signs of it, and not because of many childhood memories of it, but because I know the apple season is around the corner, and because I have a few memories of how appealing the fruit can be.
I think of apples and the thoughts present themselves as snapshots or fleeting images: warm golden crust encasing slices of baked, crunchy, glistening apples, overlaid against each other; streaks of caramelization on the edges of the fruit; sweet, tart, caramel, buttery smells and flavor; soft, yellowish-orange lighting; forks and pastry crumbs; people and conversation.
Here is a method to make an apple tart:
Tart dough (pâte brisée) molded into a tart ring
Core and peel the apples. Cut some of them into slices and store in a bowl with some lemon juice. Cut the remaining apples into medium size pieces and cook them covered until soft. Add sugar and lemon juice to taste, and some butter before making a purée. Blind bake the tart shell and then add a thin layer of the apple sauce to it. Spread the sauce with a spatula, and then arrange the cut apple slices in an overlapping pattern. Dot the pastry with butter, sprinkle with some sugar and bake in a 375˚F oven until the crust and apple turn shades of golden brown.
If I think harder, details emerge of the apple tart or people with whom I ate it, but not the two together. The images I recall seem distilled from many apple tart memories, not just one. As I think harder still, I begin to recall other memories of apples, non-tart memories, including memories that distantly remind me of having had apples as a child, but nothing much else. It seems that the ability to vividly recall a food memory is independent of the time since it was formed because the apple memories I remember in detail are relatively recent, unlike, for instance, a similar memory of mangoes that goes far back into childhood.
So, what then determines vivid recall of food memories?
In a study1, subjects were first presented with a series of smells, followed by a series of objects. As the objects were being presented, the subjects were asked to make a story that connected the object to one of the smells they were exposed to earlier. Later, the subjects were placed in a brain scanner that monitors blood flow to various parts of the brain - a brain area that is active receives increased blood flow which can be monitored by the scanner. The subjects were now presented with the objects they had seen earlier. As the objects were being recognized, not surprisingly, the scanner detected blood flow to the region of the brain responsible for object recognition, but interestingly, it also detected blood flow to the region of the brain responsible for smell (despite the absence of any smell being presented to the subjects in the scanner).
Memories may be registered in the brain as associations, a series of associations distributed across the various sensory and motor regions in the brain, including the regions for emotion.
However, how the brain might encode memory does not necessarily answer why certain food memories can be recalled in vivid detail while many others cannot.
Maybe the strength of the associations determines how vividly memory is recalled. But what determines the strength?
Does involuntary recall of food memory, one where a memory forms effortlessly and rises to the surface as the first thing that comes to mind, mean anything different from those that are voluntary and take more effort to form?
1. Remembrance of odors past. Human olfactory cortex in cross-modal recognition memory. Gottfried JA et al. Neuron Volume 42, Issue 4, p687–695, 27 May 2004