Time Course Emotional Prosody Table 1. Reaction times during triple-pulse rTMS for the three conditions 400 ms 700 ms 1000 ms 1300 ms 1600 ms 1900 ms aSTG (n = 14) fearful 2264 (461) 2295 (449) 2618 (537) 2687 (398) 2381 (497) 2518 (552) sad 2037 (570) 1923 (519) 2293 (669) 2490 (741) 2215 (527) 2428 (592) happy 2051 (391) 2195 (412) 2268 (506) 2186 (399) 2256 (432) 2207 (532) FPO (n = 14) fearful 2347 (537) 2358 (615) 2571 (648) 2793 (636) 2415 (530) 2528 (595) sad 2198 (549) 2102 (497) 2323 (655) 2660 (732) 2334 (519) 2583 (681) happy 2152 (364) 2238 (461) 2320 (421) 2309 (467) 2339 (556) 2176 (454) POz (n = 10) fearful 2100 (444) 1919 (514) 2212 (643) 2295 (623) 2024 (513) 2182 (568) sad 1837 (561) 1790 (516) 1875 (605) 2107 (695) 1998 (601) 1919 (634) happy 1760 (430) 1970 (566) 1848 (434) 1732 (421) 2080 (566) 1940 (617) No significant differences were observed between fronto-parietal operculum (FPO) and anterior superior temporal gyrus (aSTG) with regard to reaction times. Reaction times on POz were significantly different from both FPO and aSTG. Reaction times after triple-pulse rTMS at 1300ms after onset of the sentence were significantly higher than at all other time-points. doi:10.1371/journal.pone.0002244.t001 study found that TMS over that area interfered with the recognition of fear (a withdrawal emotion), but not with the recognition of happy (approach emotion) facial expressions [26]. Our findings are also a replication and extension of the study by Van Rijn and colleagues, who targeted the right fronto-parietal operculum with TMS and measured the effect on emotional prosody perception. They also found an effect on the recognition of withdrawal emotions (fear and sadness) but the performance on approach emotions (happiness and anger) was unaffected [23]. We have replicated the findings of these TMS studies on the effects of TMS at the right fronto-parietal operculum for detection of withdrawal emotions in emotional prosody [23]. In addition, however, we investigated the time course of the TMS interference. Given previous evidence for the time course of emotional prosody recognition, 1300 ms after sentence onset seems rather late. However, the earlier studies used single words and syllables as stimuli. Results from an event-related potential study revealed that P200 is an event-related potential correlate of vocal emotional processing. Vocal emotions elicited a P200 smaller than neutral expressions, representing early differentiation of basic vocal emotional expressions and neutral vocal expressions [34]. In another event-related potential study that tested pre-attentive, vocal emotion processing using an oddball paradigm, emotionally (angry and happy) and neutrally spoken syllables ‘dada’ were presented as standards and deviants [35]. The difference in mismatch negativity amplitude between emotional and neutral vocalizations peaked around 350 ms, suggesting that at this time point the primary acoustic information and derived emotional significance had been integrated. In an event-related potential study using words, results suggested that emotional prosody is processed around 360 ms [36]. In this study, the duration of the stimuli was around 761 ms on average, and there were only two emotional categories spoken by one female actress. It is expected that under natural circumstances, as in the present study, the time window is prolonged. We used complete sentences with a mean duration of 2042 ms, three emotional categories and spoken by multiple male and female actors. It is noteworthy that in both studies, the peak of the process takes place halfway through the stimuli. Our results did not reveal different time patterns of involvement of both brain areas, i.e., right anterior superior temporal gyrus and right fronto-parietal operculum. One possible explanation is that the processes ‘extraction of slow acoustic elements’ and ‘simulation of the perceived emotion’, ascribed to the right anterior superior temporal gyrus and the right fronto-parietal operculum respec- tively, take place at the same time. These processes then interact with the putatively more frontal process of categorization. Stimulation of one site would result in widespread activation along the functional network and thus in activation of the other site as well. ‘Recurrent neural networks’ have been found for visual information processing [37] and consist of a feed-forward-system, e.g. anterior superior temporal gyrus to fronto-parietal operculum, and a feedback system, e.g. fronto-parietal operculum to anterior superior temporal gyrus. Auditory information can be exchanged very quickly between the anterior superior temporal gyrus and the fronto-parietal operculum. In this way both areas can be crucially Table 2. Emotion identified correctly (%) during triple-pulse rTMS for the three conditions 400 ms 700 ms 1000 ms 1300 ms 1600 ms 1900 ms aSTG (n = 14) fearful 75.1 (24.9) 64.5 (15.3) 60.1 (14.8) 69.4 (15.4) 75.2 (25.3) 75.2 (21.8) sad 96.9 (7.2) 90.4 (12.9) 92.1 (10.5) 92.9 (8.0) 87.9 (6.9) 94.7 (9.4) happy 95.4 (9.4) 84.7 (12.4) 89.4 (8.3) 85.6 (10.1) 84.9 (14.8) 96.6 (5.6) FPO (n = 14) fearful 78.0 (14.1) 70.9 (13.6) 62.7 (15.4) 65.7 (22.3) 81.4 (18.8) 72.4 (18.3) sad 89.0 (9.9) 92.1 (9.2) 93.0 (9.4) 96.6 (5.6) 84.1 (13.3) 99.1 (3.2) happy 96.1 (6.3) 86.6 (11.4) 90.4 (10.0) 86.7 (11.4) 82.9 (17.5) 97.3 (5.4) POz (n = 10) fearful 76.6 (21.6) 69.5 (18.8) 66.5 (11.9) 71.5 (18.6) 85.3 (14.1) 74.9 (22.8) sad 93.9 (8.7) 86.4 (13.7) 91.4 (10.2) 95.2 (6.2) 81.4 (12.1) 97.6 (5.1) happy 97.6 (5.1) 95.2 (6.2) 90.2 (9.8) 85.0 (12.8) 83.6 (14.7) 95.2 (6.2) No significant differences were found on percentages correct between the three sites, fronto-parietal operculum (FPO), anterior superior temporal gyrus (aSTG) and POz (EEG electrode site). doi:10.1371/journal.pone.0002244.t002 PLoS ONE | www.plosone.org 4 May 2008 | Volume 3 | Issue 5 | e2244