Attention is a fundamental cognitive process that attempts to select relevant stimuli from among irrelevant distractors. Attention is altered in several neuro-psychiatric conditions such as anxiety and trauma-related disorders, in which fear also plays an important role. Thus, the study of the interaction between attention and fear could help us to understand the pathophysiology of highly prevalent and disabling conditions such as posttraumatic stress disorder (PTSD). For many years, the neural mechanisms of visuo-spatial attention have been studied by measuring the N2pc component of the event-related potential (ERP) waveform. A newer attention-related neural signal is lateralized alpha-band activity. Although both the N2pc component and lateralized alpha-band activity are considered markers of attention and are obtained by examining lateralizations in electroencephalographic signals, no prior research has examined whether these two measures reflect the same or different neural mechanisms of visuo-spatial attention. In a series of experiments, we found that the N2pc and the lateralized alpha-band are separate, dissociable signatures of visual attention. To begin to link attention and fear using ERPs, we conducted a study to develop a new ERP approach to measuring fear learning using the late positive potential (LPP). We found that the LPP was a sensitive marker of fear conditioning and that it has several advantages over the traditional measure, the skin conductance response (SCR). Finally, using an attentional paradigm in which targets and distractors were associated with fear, we provided evidence supporting the hypothesis that fear-induced arousal modulates spatial attention in a generalized manner. These results not only provide new insights for understanding the basic neural processes underlying visuo-spatial attention but also allow us to have better models of the interaction between attention and fear, which may someday will be useful to help patients suffering from anxiety and trauma-related disorders.PFCHA-BecasPFCHA-Becas