Yes, that's something that you can do in After Effects.
The jargon for this currently very popular technique is 'tilt-shift'.
One component of a common approach is the Lens Blur effect. See the
"Lens Blur effect" page; at the bottom of the page, there's a link to a tutorial on how to do this.
Here's an
After Effects Community Help search that pulls up many more useful resources on this technique.
---------------------------------------------------------------------------------------------------------
Todd Kopriva, Adobe Systems Incorporated
putting the 'T' back in 'RTFM' :
After Effects Help on the Web
---------------------------------------------------------------------------------------------------------
If a page of After Effects Help answers your question, please consider rating it. If you have a tip, technique, or link to share---or if there is something that you'd like to see added or improved---please leave a comment.