a lot of what we’re going to be now talking about on a great work by Joseph LeDoux from NYU.
... He had shown that the amygdala has two tracks going to it. One is the fast track and one is the slow track.
The fast track is stronger than the slow track. So the fast track goes something like this. I’m walking down a trail in the Grand Canyon and out of the corner of my eye I see a very large long object. My retina picks it up. My retina is part of my brain, signals directly to the central switch board of the brain which is the thalamus. Then goes directly to the amygdala and my amygdala got a response as if that long object is a snake. That fast track kept our species and many other species alive. We need a fast track.
The slow track goes something like this. The retina picks up that information and signals to the thalamus which again is the central switchboard. It goes then to the cortex and I looked at the snake and right now I’m thinking about the snake because my cortex is involved “Well look at that. Oh look at that nice looking snake there. Oh my God and it’s looking at me.” Now I’m incorporating a lot of cognition here and then I send the information to the amygdala.
Now sometimes we need the slow track when there’s nothing to be fearful of. Sometimes we need the fast track when we step off a curve and we see a semi truck heading toward us but unfortunately people with anxiety disorders have their fast-track on too often and their slow track is hardly operable.
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Explicit memory sometimes called declarative memory is what you and I think about when we talk about memory “Oh yes I remember that event and that situation.” They are facts and figures, situations, and autobiographical information and all that.
It’s largely a hippocampal driven process. Whereas with implicit memory you can think of in terms of it being nondeclarative or nonconscious and nonconscious memory can be procedural as you mentioned earlier which is more body memory, riding a bicycle, the tennis swing, typing, or driving a car. We do it without thinking about it. Once you get it down, you’ve mentioned how neuroplasticity and procedural memory work together and how I was using the tennis swing as an example earlier, once you sort of get it down, you just repeat it over and over again like driving a car.
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In addition to procedural memory being part of the nondeclarative implicit memory category of type of memory, there’s also emotional memory, just having an emotional feel for something and that’s largely amygdala driven. It is something that is roughly nonconscious, as well. We might just have a feeling about something without having any idea as to why we have that feeling.
As therapists and as health professionals whether you’re a nurse, a physician, psychologist, occupational therapist or whatever, we are helping people often learn to change their nondeclarative memory, either their procedural memories or their implicit memories by helping them learn new skills. But it takes some time because unlike explicit memory that is more fact and context-based, more hippocampal driven, you need to have repetition, exposure, and repetition over and over again to create a new emotional base memory or a new procedural memory, such as the tennis swing, the typing or the exercise. I just thought that before we get into the different memory enhancement techniques that differentiation between explicit and implicit memory was important to make.
--- source NICABM "New Brain Science" 2011 webinar series interview with Dr. John Arden