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deja vu all over again
Jul. 21st, 2004 03:07 pmI was leafing through the current issue of The Chronicle of Higher Education that came to the office today. There was an interesting little bit three modern attempts to explain deja vu:
1. Spontaneous neural activity in the parahippocampal gyrus: According to this theory, the brain suffers a small seizure in the parahippocampal system, which is associated with the spatial processing and our sense of the familiarity.
2. Slowdown in the secondary visual pathway: It is well established that we process visual information through two pathways. One goes directly to the visual cortex,in the occipital lobe. The secondary pathway, which is infinitesimally slower, is routed through various other areas of the brain, notably the parietal cortex, on its way to the occipital lobe. Some researchers believe that a deja vu experience occurs when signals on the secondary pathay move too slowly, and the brain interprets this second wave of data as a second experience.
3. Inattentional blindness: Imagine that you drive through an unfamiliar town but pay it little attention because you are talking on a cellphone. If you then drive back down the same streets a few moments later, this time focusing on the landscape, you might be prone to experience deja vu. During your second pass, the visual information is consciously processed in the hippocampus but feels falsely "old" because the images from the earlier drive still linger in your short-term memory.
I think all three theories are really interesting--especially the second one. I wonder, though, which theory would apply to the not entirely uncommon to me feeling of deja vu about a feeling of deja vu. Seriously, sometimes I have an experience of deja vu where I stop and think "and last time this happened I had a feeling of deja vu too!" It's kind of a freaky feeling.
1. Spontaneous neural activity in the parahippocampal gyrus: According to this theory, the brain suffers a small seizure in the parahippocampal system, which is associated with the spatial processing and our sense of the familiarity.
2. Slowdown in the secondary visual pathway: It is well established that we process visual information through two pathways. One goes directly to the visual cortex,in the occipital lobe. The secondary pathway, which is infinitesimally slower, is routed through various other areas of the brain, notably the parietal cortex, on its way to the occipital lobe. Some researchers believe that a deja vu experience occurs when signals on the secondary pathay move too slowly, and the brain interprets this second wave of data as a second experience.
3. Inattentional blindness: Imagine that you drive through an unfamiliar town but pay it little attention because you are talking on a cellphone. If you then drive back down the same streets a few moments later, this time focusing on the landscape, you might be prone to experience deja vu. During your second pass, the visual information is consciously processed in the hippocampus but feels falsely "old" because the images from the earlier drive still linger in your short-term memory.
I think all three theories are really interesting--especially the second one. I wonder, though, which theory would apply to the not entirely uncommon to me feeling of deja vu about a feeling of deja vu. Seriously, sometimes I have an experience of deja vu where I stop and think "and last time this happened I had a feeling of deja vu too!" It's kind of a freaky feeling.