Diverse Time Encoding Strategies Within the Medial Premotor Areas of the Primate.

The measurement of time in the subsecond scale is critical for many sophisticated behaviors, yet its neural underpinnings are largely unknown. Recent neurophysiological experiments from our laboratory have shown that the neural activity in the medial premotor areas (MPC) of macaques can represent different aspects of temporal processing. During single interval categorization, we found that preSMA encodes a subjective category limit by reaching a peak of activity at a time that divides the set of test intervals into short and long.

Amodal population clock in the primate medial premotor system for rhythmic tapping.

The neural substrate for beat extraction and response entrainment to rhythms is not fully understood. Here we analyze the activity of medial premotor neurons in monkeys performing isochronous tapping guided by brief flashing stimuli or auditory tones. The population dynamics shared the following properties across modalities: the circular dynamics of the neural trajectories form a regenerating loop for every produced interval; the trajectories converge in similar state space at tapping times resetting the clock; and the tempo of the synchronized tapping is encoded in the trajectories by a combination of amplitude modulation and temporal scaling.

The amplitude in periodic neural state trajectories underlies the tempo of rhythmic tapping.

Our motor commands can be exquisitely timed according to the demands of the environment, and the ability to generate rhythms of different tempos is a hallmark of musical cognition. Yet, the neuronal underpinnings behind rhythmic tapping remain elusive. Here, we found that the activity of hundreds of primate medial premotor cortices (MPCs; pre-supplementary motor area [preSMA] and supplementary motor area [SMA]) neurons show a strong periodic pattern that becomes evident when their responses are projected into a state space using dimensionality reduction analysis.

Conversion of failed Roux-en-Y gastric bypass to biliopancreatic diversion with duodenal switch: outcomes of 9 case series.

Introduction: Weight regain after Roux-en-Y gastric bypass (RYGB) is a frustrating long-term complication in some patients. Revision of RYGB to biliopancreatic diversion with duodenal switch (BPD-DS) is an appealing option. There is a paucity of information in literature regarding this type of conversion.

Laparoscopic repair of duodenal atresia in a low birth weight neonate.

The small volume of the infant abdomen limits the application of laparoscopic procedures. We successfully repaired a duodenal atresia in a 2-kg female infant using a standard diamond-shaped anastomosis and intracorporeal suturing and knot-tying techniques. Anesthesia and positive pressure ventilation assured adequate gas exchange during pneumoperitoneum during the procedure.