Mockingbird Morphing Music: Structured Transitions in a Complex Bird Song.

The song of the northern mockingbird, Mimus polyglottos, is notable for its extensive length and inclusion of numerous imitations of several common North American bird species. Because of its complexity, it is not widely studied by birdsong scientists. When they do study it, the specific imitations are often noted, and the total number of varying phrases. What is rarely noted is the systematic way the bird changes from one syllable to the next, often with a subtle transition where one sound is gradually transformed into a related sound, revealing an audible and specific compositional mode. It resembles a common strategy in human composing, which can be described as variation of a theme. In this paper, we present our initial attempts to describe the specific compositional rules behind the mockingbird song, focusing on the way the bird transitions from one syllable type to the next. We find that more often than chance, syllables before and after the transition are spectrally related, i.e., transitions are gradual, which we describe as morphing. In our paper, we categorize four common modes of morphing: timbre change, pitch change, squeeze (shortening in time), and stretch (lengthening in time). This is the first time such transition rules in any complex birdsong have been specifically articulated.

Temporal regularity increases with repertoire complexity in the Australian pied butcherbird's song.

Music maintains a characteristic balance between repetition and novelty. Here, we report a similar balance in singing performances of free-living Australian pied butcherbirds. Their songs include many phrase types. The more phrase types in a bird's repertoire, the more diverse the singing performance can be. However, without sufficient temporal organization, avian listeners may find diverse singing performances difficult to perceive and memorize. We tested for a correlation between the complexity of song repertoire and the temporal regularity of singing performance. We found that different phrase types often share motifs (notes or stereotyped groups of notes). These shared motifs reappeared in strikingly regular temporal intervals across different phrase types, over hundreds of phrases produced without interruption by each bird. We developed a statistical estimate to quantify the degree to which phrase transition structure is optimized for maximizing the regularity of shared motifs. We found that transition probabilities between phrase types tend to maximize regularity in the repetition of shared motifs, but only in birds of high repertoire complexity. Conversely, in birds of low repertoire complexity, shared motifs were produced with less regularity. The strong correlation between repertoire complexity and motif regularity suggests that birds possess a mechanism that regulates the temporal placement of shared motifs in a manner that takes repertoire complexity into account. We discuss alternative musical, mechanistic and ecological explanations to this effect.

Investigation of musicality in birdsong.

Songbirds spend much of their time learning, producing, and listening to complex vocal sequences we call songs. Songs are learned via cultural transmission, and singing, usually by males, has a strong impact on the behavioral state of the listeners, often promoting affiliation, pair bonding, or aggression. What is it in the acoustic structure of birdsong that makes it such a potent stimulus? We suggest that birdsong potency might be driven by principles similar to those that make music so effective in inducing emotional responses in humans: a combination of rhythms and pitches-and the transitions between acoustic states-affecting emotions through creating expectations, anticipations, tension, tension release, or surprise. Here we propose a framework for investigating how birdsong, like human music, employs the above "musical" features to affect the emotions of avian listeners. First we analyze songs of thrush nightingales (Luscinia luscinia) by examining their trajectories in terms of transitions in rhythm and pitch. These transitions show gradual escalations and graceful modifications, which are comparable to some aspects of human musicality. We then explore the feasibility of stripping such putative musical features from the songs and testing how this might affect patterns of auditory responses, focusing on fMRI data in songbirds that demonstrate the feasibility of such approaches. Finally, we explore ideas for investigating whether musical features of birdsong activate avian brains and affect avian behavior in manners comparable to music's effects on humans. In conclusion, we suggest that birdsong research would benefit from current advances in music theory by attempting to identify structures that are designed to elicit listeners' emotions and then testing for such effects experimentally. Birdsong research that takes into account the striking complexity of song structure in light of its more immediate function - to affect behavioral state in listeners - could provide a useful animal model for studying basic principles of music neuroscience in a system that is very accessible for investigation, and where developmental auditory and social experience can be tightly controlled.

Neuro-critical care skills training using a human patient simulator.

BACKGROUND: Neurosurgical trainees regularly encounter critical care situations. Traditionally, education was accomplished through lecture and experience. Increasingly, human patient simulators (HPS) are employed, allowing trainees to sharpen skills in a safe and realistic environment. We describe our experience using HPS in neurosurgical training. METHODS: We developed a critical care training program for residents and medical students using HPS. We used a hi-fidelity, lifelike Human Patient Simulator™ (HPS™) produced by Medical Education Technologies, Inc.™ to simulate realistic scenarios for trainee education. Topics included spinal shock, closed head injury, and cerebral vasospasm. A three-way evaluation model was employed to test validity, including pre- and post-exercise testing, survey feedback, and videotaped replay. The simulation exercises were conducted by a neuro-critical care attending, a senior neurosurgical resident, and a HPS technician. RESULTS: We currently have 29 participants. On a 20-point critical care multiple-choice exam for these participants, average improvement has been 4.5 points or 25%. In subgroup analysis, average improvement was 4.75 points (24%) amongst neurosurgery residents, 3.07 points (18%) amongst neurology residents, 7 points (38%) amongst general surgery residents, and 7 points (38%) amongst senior medical students. Post-exercise evaluations were overwhelmingly positive. CONCLUSIONS: Neurosurgical critical care education is important for safe and effective care for patients. Clinical experience and didactic lectures help trainees obtain a solid knowledge base, but do not provide the benefit for learning in a fail-safe environment. Through the use of HPS, we have enhanced the critical care education of our trainees.

Unusual presentation of perioperative ischemic optic neuropathy following major spine surgery.

Perioperative visual loss following spinal surgery has become of increasing concern among anesthesiologists, surgeons, and patients alike. Perioperative ischemic optic neuropathy often occurs in patients greater than 50 years of age, in association with a number of presumed risk factors, including diabetes, hypertension, small cup-to-disc ratio, preoperative anemia, intraoperative hypotension, prolonged operative time in the prone position, and significant blood loss during surgery. The visual loss is notably devastating, and generally leads to permanent disability. A 44-year-old man whose central visual acuity was completely preserved is presented.

Education of trainees in the intensive care unit.

The focus on improving education in critical care medicine must begin early in medical school training and further be promoted during residency if there is to be an increase in intensivists in the hospital workforce. This is "critical" to healthcare reform movements that are endorsing full-time critical care coverage in U.S. urban intensive care units. There is, therefore, a need for more novel approaches in educating trainees in critical care medicine to better prepare future physicians to manage acutely ill patients and improve patient safety. This article will review methods to improve educational designs in teaching critical care medicine to medical students, residents, and fellows, including the use of simulation technology to enhance cognition and procedural skills.