Deep neural network models reveal interplay of peripheral coding and stimulus statistics in pitch perception.

Perception is thought to be shaped by the environments for which organisms are optimized. These influences are difficult to test in biological organisms but may be revealed by machine perceptual systems optimized under different conditions. We investigated environmental and physiological influences on pitch perception, whose properties are commonly linked to peripheral neural coding limits. We first trained artificial neural networks to estimate fundamental frequency from biologically faithful cochlear representations of natural sounds. The best-performing networks replicated many characteristics of human pitch judgments. To probe the origins of these characteristics, we then optimized networks given altered cochleae or sound statistics. Human-like behavior emerged only when cochleae had high temporal fidelity and when models were optimized for naturalistic sounds. The results suggest pitch perception is critically shaped by the constraints of natural environments in addition to those of the cochlea, illustrating the use of artificial neural networks to reveal underpinnings of behavior.

Subtle predictive movements reveal actions regardless of social context.

Humans have a remarkable ability to predict the actions of others. To address what information enables this prediction and how the information is modulated by social context, we used videos collected during an interactive reaching game. Two participants (an "initiator" and a "responder") sat on either side of a plexiglass screen on which two targets were affixed. The initiator was directed to tap one of the two targets, and the responder had to either beat the initiator to the target (competition) or arrive at the same time (cooperation). In a psychophysics experiment, new observers predicted the direction of the initiators' reach from brief clips, which were clipped relative to when the initiator began reaching. A machine learning classifier performed the same task. Both humans and the classifier were able to determine the direction of movement before the finger lift-off in both social conditions. Further, using an information mapping technique, the relevant information was found to be distributed throughout the body of the initiator in both social conditions. Our results indicate that we reveal our intentions during cooperation, in which communicating the future course of actions is beneficial, and also during competition despite the social motivation to reveal less information.

Across-species differences in pitch perception are consistent with differences in cochlear filtering.

Pitch perception is critical for recognizing speech, music and animal vocalizations, but its neurobiological basis remains unsettled, in part because of divergent results across species. We investigated whether species-specific differences exist in the cues used to perceive pitch and whether these can be accounted for by differences in the auditory periphery. Ferrets accurately generalized pitch discriminations to untrained stimuli whenever temporal envelope cues were robust in the probe sounds, but not when resolved harmonics were the main available cue. By contrast, human listeners exhibited the opposite pattern of results on an analogous task, consistent with previous studies. Simulated cochlear responses in the two species suggest that differences in the relative salience of the two pitch cues can be attributed to differences in cochlear filter bandwidths. The results support the view that cross-species variation in pitch perception reflects the constraints of estimating a sound's fundamental frequency given species-specific cochlear tuning.

Consumer-based technology for distribution of surgical videos for objective evaluation.

BACKGROUND: The Global Operative Assessment of Laparoscopic Skill (GOALS) is one validated metric utilized to grade laparoscopic skills and has been utilized to score recorded operative videos. To facilitate easier viewing of these recorded videos, we are developing novel techniques to enable surgeons to view these videos. The objective of this study is to determine the feasibility of utilizing widespread current consumer-based technology to assist in distributing appropriate videos for objective evaluation. METHODS: Videos from residents were recorded via a direct connection from the camera processor via an S-video output via a cable into a hub to connect to a standard laptop computer via a universal serial bus (USB) port. A standard consumer-based video editing program was utilized to capture the video and record in appropriate format. We utilized mp4 format, and depending on the size of the file, the videos were scaled down (compressed), their format changed (using a standard video editing program), or sliced into multiple videos. Standard available consumer-based programs were utilized to convert the video into a more appropriate format for handheld personal digital assistants. In addition, the videos were uploaded to a social networking website and video sharing websites. RESULTS: Recorded cases of laparoscopic cholecystectomy in a porcine model were utilized. Compression was required for all formats. All formats were accessed from home computers, work computers, and iPhones without difficulty. Qualitative analyses by four surgeons demonstrated appropriate quality to grade for these formats. CONCLUSIONS: Our preliminary results show promise that, utilizing consumer-based technology, videos can be easily distributed to surgeons to grade via GOALS via various methods. Easy accessibility may help make evaluation of resident videos less complicated and cumbersome.

Technical skills rotation for general surgery residents.

BACKGROUND: Technical skills are an important part of any general surgery residency curriculum. With the demands of limited work weeks, it is imperative that educators create novel methods of teaching technical skills to their residents. Our program utilizes a dedicated month to help accomplish this. This study hypothesized that general surgery residents would report a positive effect of a dedicated technical skills rotation. METHODS: Residents who had undergone a 1 mo rotation in technical skills during their first year were asked to fill out a survey concerning their experience. During the 1-mo rotation, the residents had almost no clinical responsibilities. Teaching of technical skills was performed with various activities, including video content (VC), virtual reality simulators (VR), open foam procedures (OF), laparoscopic box trainers (BT), surgical equipment in-service (SE), and animate sessions (AS). Responses were given on a Likert scale (1-10) with higher numbers being more positive responses. RESULTS: There were seven residents in this study. The residents gave a very positive response to the overall rotation (9.4) and exposure to laparoscopic procedures (9.6). The other responses were enthusiastic as well: exposure to open procedures (8.9) and preparation for operative room (9.4). After their rotation, the residents were comfortable performing a laparoscopic cholecystectomy (9.2), a hand-sewn anastomosis (8.7), and a stapled anastomosis (9.4). The residents found theses activities helpful in increasing order: VC (7.8), VR (8.0), BT (9.0), ES (9.7), OF (9.8), and AS (9.8). CONCLUSIONS: A 1-mo dedicated technical skills rotations was perceived to be extremely positive by the residents. The residents felt very comfortable performing a laparoscopic cholecystectomy, a hand-sewn anastomosis, and a stapled anastomosis. With the 80-h work week, alternatives to learning technical skills in the operating room are essential. Further studies need to be performed to determine if this rotation aids in accomplishing this goal.