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Stock-Based Compensation
3 Months Ended
Mar. 31, 2012
Stock-Based Compensation [Abstract]  
Stock-Based Compensation

8. Stock-Based Compensation

Employee stock-based compensation expense is calculated based on the grant-date fair value of awards ultimately expected to vest, reduced for estimated forfeitures, and is recorded on a straight-line basis over the vesting period of the awards. Forfeitures are estimated at the time of grant, based on historical option cancellation information, and revised in subsequent periods if actual forfeitures differ from those estimates. The following table summarizes stock-based compensation expense related to the Company's stock-based awards for the periods indicated (in thousands):

 

                 
     Three months ended
March 31,
 
     2012      2011  

Research and development

   $ 226       $ 84   

General and administrative

     317         167   
    

 

 

    

 

 

 

Employee stock-based compensation expense

     543         251   

Non-employee stock-based compensation expense

     25         4   
    

 

 

    

 

 

 

Total stock-based compensation expense

   $ 568       $ 255