Detection of hydrodynamic stimuli by the postcranial body of Florida manatees (Trichechus manatus latirostris) A Neuroethology, sensory, neural, and behavioral physiology

Manatees live in shallow, frequently turbid waters. The sensory means by which they navigate in these conditions are unknown. Poor visual acuity, lack of echo- location, and modest chemosensation suggest that other modalities play an important role. Rich innervation of sen- sory hairs that cover the entire body and enlarged soma- tosensory areas of the brain suggest that tactile senses are good candidates. Previous tests of detection of underwater vibratory stimuli indicated that they use passive movement of the hairs to detect particle displacements in the vicinity of a micron or less for frequencies from 10 to 150 Hz. In the current study, hydrodynamic stimuli were created by a sinusoidally oscillating sphere that generated a dipole field at frequencies from 5 to 150 Hz. Go/no-go tests of manatee postcranial mechanoreception of hydrodynamic stimuli indicated excellent sensitivity but about an order of magnitude less than the facial region. When the vibrissae were trimmed, detection thresholds were elevated, suggest- ing that the vibrissae were an important means by which detection occurred. Manatees were also highly accurate in two-choice directional discrimination: greater than 90% correct at all frequencies tested. We hypothesize that mana- tees utilize vibrissae as a three-dimensional array to detect and localize low-frequency hydrodynamic stimul

Atraumatic gluteal compartment syndrome.

A case of atraumatic gluteal compartment syndrome complicated by sciatic nerve palsy and acute rhabdomyolysis is presented. A presumed diagnosis of deep venous thrombosis led to a delay in diagnosis. Gluteal compartment syndrome should be considered in the differential diagnosis of the swollen leg