Effects of Down syndrome on three-dimensional motion during walking at different speeds.

The inherent joint laxity and muscle hypotonia of adults with Down syndrome (DS) may result in reduced gait stability and increased energetic cost. These factors vary as a function of walking speed and may be reflected in gait patterns. The present study therefore examined whether the three-dimensional motion of the body center of mass (COM) and stepping characteristics differ between adults with and without DS as a function of speed.

Attractors: architects of network organization?

An attractor is defined here informally as a state of activity toward which a system settles. The settling or relaxation process dissipates the effects produced by external perturbations. In neural systems the relaxation process occurs temporally in the responses of each neuron and spatially across the network such that the activity settles into a subset of the available connections.

Putative neuroendocrine cells in the Aplysia cerebral ganglion.

We report on a special population of cells in the Aplysia cerebral ganglion that are characterized by several features compatible with neuroendocrine function. These cells can be recognized in living ganglia by their small size, white color and their typical distribution as a compact cluster in the central medial region of the dorsal ganglion surface. Upon intracellular recording, these cells generate action potentials of relatively long duration (about 25 ms), as compared with the faster action potentials of larger white cells or of non-white cells (about 4 ms).

Immunohistochemistry of enkephalins: model studies on hapten-carrier conjugates and fixation methods.

For immunohistochemical demonstration of the enkephalin octapeptide Met5-enkephalin-Arg6-Gly7-Leu8, the peptide was conjugated with a carrier protein using either glutaraldehyde or 1-ethyl-3 (3-dimethylaminopropyl)-carbodiimide as coupling agent. Antisera were raised in rabbits and their specificity was studied using the immunoblotting technique. The results suggest that glutaraldehyde selectively couples the amino terminus of the peptide to the carrier protein, while carbodiimide coupling produces a mixture of specificities.