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Your sentence is a bit awkward. I think I know what you want to say:
You are driving along in your car, and an unpleasant memory springs to mind--a memory that is firmly etched in your mind. Suddenly you tense up and unconsciously grasp the steering wheel tightly as your emotions take over.
If so, perhaps you could reword your sentence to make the thought clearer.
As the memory of that day enters my mind once again, I find myself tensing up and grasping the steering wheel tightly.
People do not grasp at memories. Memories spring to mind, they pop into our minds, they revisit us, they intrude in our thoughts, they focus our attention, they distract us, and much more. They do not, however, grasp.
You can cling to a pleasant memory, or you can try to repress a bad memory. When a bad memory comes to mind or "sneaks up on you," you sometimes find yourself feeling angry, upset, embarrassed, or any number of emotions. These emotions may cause you to react physically by gripping tightly something you are holding when the memory intrudes in your mind.