Step 1: Create a new 500px by 500px document with a transparent background, and reset your background & foreground colours to default (i.e. black & white). Add a new layer on top, select the gradient tool, and set it to use a  radial gradient with blending mode to difference.

Now go crazy with your gradient tool, drawing as many swirls as you like in many different colours.  Once you get fed up or bored, repeat the process with the linear gradient.  You should end up with something that resembles my image on the left.

Step 2: Now Layer > Duplicate the background layer, set the new layer's blending mode to screen, and Layer > Merge visible to recombine them.

Tweak the colour to your own personal taste using Image > Adjustments > Hue/Saturation with the colorize box checked. I chose a blue (220 Hue 75 Sat).

Step 3: Ok, that's the hard part done, so now onto the fun bits!  Click Layer > Duplicate and select the top-most layer in the layers palette. Run Filter > Sketch > Chrome, with the following settings:

Detail: 3
Smoothness: 7

Now select the layer without the chrome effect (i.e. the one at the bottom of the layer palette), set its blending mode to colour, and Layer > Merge visible the two layers. Duplicate the layer a third time, set the top layer's blending mode to multiply, and merge them together again.

Step 4: Are you getting the idea yet?   No?    Well, just in case, Duplicate the layer, set the top layer's blending mode to screen, and merge them together one final time. Make the whole image more appealing by running Image > Adjustments > Invert.  Et voila, a weird plasmid-type effect!