What's the best way to detect small moving black blobs in a noisy grayscale image?

I am trying to achieve detection and tracking of certain 'markers' in a series of very noisy grayscale images. The blobs are very small, and because of the nature of the images, there is not a lot of contrast with the surroundings. I have tried some contour based methods to isolate the blobs but the results were somewhat inconsistent. I was wondering if I could get some suggestions as to what would be some effective techniques to get more accurate detection? A couple of sample images that contain four black blobs (seen near the center) are shown below.

Thank you!