[Conductivity fluctuation of lipid bilayer membranes formed on a substrate]. / Fluktuatsii provodimosti visloinykh lipidnykh membran, sformirovannykhna podlozhkakh.

In the range of voltages -0.9-(+)0.9 V the fluctuations of conductivity of bilayer lipid membranes formed on the support (s-BLM) were measured. The new cut of the wire from stainless steel SS-10T served as the support. The similarity of current fluctuations for s-BLM as well as for support-electrolyte interface was observed, some quantitative distinctions are revealed. Three types of fluctuations are observed; 1) large current jumps observed as current steps at DC channel; 2) small current fluctuations near zero line with the spectrum of 1/f alpha type (flicker noise); 3) short current jumps, whose amplitudes are many folds higher than mean noise level, and the density of distribution function falls off as fluctuation magnitude raised to power 2.5 for s-BLM.

[Current-voltage characteristics of bilayer lipid membranes formed on the substrates]. / Vol't-ampernye kharakteristiki bisloinykh lipidnykh membran, sformirovannykh na podlozhkakh.

Current-voltage characteristics (CVC) of bilayer lipid membranes formed on the support (s-BLM) were measured in static mode as well as in cyclic one with the period 33 s. The new cut of the wire from stainless stell SS-10T served as the support. In the range of voltages -0.9-(+)0.9V the similarity of the CVC for s-BLM as well as for support- electrolyte border was observed. Static CVC for both objects satisfy the Tafel's equation with close parameters. If the voltage amplitudes were over 0.3 V, s-BLM specific capacitance approached the same value for the support-electrolyte border. Possible electrical models of s-BLM are discussed.

Integration of visual information and motor output in reaching and grasping: the contributions of peripheral and central vision.

This study examined the contributions made by peripheral and central vision to reaching and grasping. A specially designed contact lens system was used to restrict information to the peripheral retina. Modified goggles were used to restrict information to the central retina. A WATSMART motion analysis system was used to record and reconstruct three dimensional kinematic data. Analyses included an examination of peak kinematic values as well as a qualitative description of the trajectory profiles as related to transport and grasp components. With only peripheral vision, information related to size and shape of an object was inadequate, thus affecting the organization of both the transport and grasp components. With only central vision, information related to the location of an object was inadequate, affecting the organization of the transport but not the grasp component. Implications are discussed relevant to the current models of visuomotor control of reaching and grasping.

Evidence for cerebral asymmetries in a finger sequencing task.

Visual input was lateralized using a specially designed contact lens system. Subjects performed a sequence of two keypresses in response to a light stimulus with either the left or the right hand in a choice reaction time paradigm. Two choice reaction time conditions were used: (A) hand certainty, sequence uncertainty and (B) hand uncertainty, sequence certainty. Reaction time (RT) results indicate that there are no significant differences between the left and right hemisphere in selecting a sequential response in either of the two conditions. Interfinger time (IFT) results show a relative left eye (right hemisphere)-left hand advantage when there was hand certainty, sequence uncertainty and a relative left eye (right hemisphere) disadvantage for both hands when there was hand uncertainty, sequence certainty. The RT results do not support the concept of a center in the left hemisphere for selection of the components of a two-element sequential keypress, prior to movement initiation. However, the IFT results indicate that there are differences in the processing ability of the left and right hemispheres in a sequencing task, after movement initiation.

Manual localization of lateralized visual targets.

The effects of visual field, responding limb and extrapersonal space on the ability to localize visual targets using slow positioning movements of the arm were examined. Special contact lenses were used to lateralize visual information and to make comparisons with localization under monocular control conditions. Subjects made slow positioning movements to place a cursor directly beneath target lights. They saw target lights but not the moving limb during the trial. For directional error, results indicated that subjects were more accurate localizing targets lateralized to the right hemisphere than targets lateralized to the left hemisphere, indicating right hemisphere superiority for localization of visual targets in grasping space. Localization performance was significantly better with the right hand than the left hand. the left hand demonstrated a directional bias to the right of the targets. Responding hand and visual field did not interact. Finally, contrary to subjects' awareness and verbal reports, target localization was not less accurate in lens than in monocular control conditions. This was true for both amplitude and directional error. This is consistent with other studies where visual information about limb position is not available.

Contact lens design for lateralizing visual input.

A contact lens designed for use in lateralizing visual input is described. The design includes a carrier soft contact lens into which a smaller hard contact lens is inserted. The hard lens is partially painted black to obstruct a portion of the visual field, as required for experimental purposes.

A review of proprioception in extraocular muscles.

The controversial literature concerning the presence or absence of extraocular muscle proprioception is reviewed under the headings of anatomical, physiological, and psychophysical evidence. The principal area of confusion, namely whether to expect conscious awareness of proprioceptive information, is a problem also faced by researchers dealing with general skeletal muscle proprioception. It is unlikely that extraocular muscle proprioception will be understood in isolation from the proprioceptive mechanisms of the rest of the body.