Add an adjustment layer (whichever works best for you - curves, levels, exposure, brightness/contrast) and clip that adjustment layer to the specific PSB layer that needs the adjustment. Clipping the adjustment to the specified PSB layer confines the adjustment to just that layer and not the entire layer stack. After you add the adjustment layer above the PSB layer you want to affect, place your cursor over the border between the two layers in the Layers panel with the ALT or OPTION key pressed - the cursor will change to an icon that looks like a square with a down-pointing arrow next to it - click and the adjustment layer will become indented in the layer stack with a down-pointing arrow to the left of it, indicating that the layer is now clipped to the layer below it, meaning it will only affect the single layer below it and not the entire layer stack below it.
You can clip any number of layers to a specific layer - for example, if you wanted to adjust the brightness and the warmth of a layer, you could clip brightness/contrast and a photo filter adjustment layers to that single PSB layer in the pano. Etc.
I hope this is what you are trying to accomplish - sorry if I misunderstood the request.
I would use either a levels or curves adjustment layer to best control the specific tonal range you are trying to match with the rest of the area in the pano.
Kirk
