Short training is often sufficient for human individuals to become adept at performing a complex new task. However, the precise nature of the changes in cortical activity during short-term training of under an hour is still not fully understood. In this study, we have examined the effects of such short training in a visual recognition task on cortical activity using functional imaging (BOLD fMRI). Participants performed a gender/age discrimination task on face images for 28min, preceded and followed by resting state scans. Our results reveal a consistent and progressive signal reduction during stimuli presentation compared to a fixation baseline, which was reflected in participant’s subjective experience as evaluated by post-scan questionnaires. The BOLD reduction surprisingly included both task-positive and task-negative regions. While higher order face-selective regions showed a reduced positive peak response, negatively-responding areas – including the peripheral visual representations as well as the Default Mode Network – showed deeper negative BOLD responses during the visual stimulation periods. Interestingly, these training effects have left significant traces in the spontaneous resting-state fluctuations following the training period in areas that partially correspond to those that showed response changes during task performance. The results reveal the widespread cortical changes underlying short-term training.