A comparison of donepezil and galantamine in the treatment of cognitive symptoms of Alzheimer's disease: a meta-analysis.

This review was conducted in order to determine the efficacy of donepezil and galantamine in the treatment of cognitive symptoms of Alzheimer's disease, and also to determine whether galantamine was a superior pharmacological intervention. Meta-analytic methods were used to analyse the data from eight empirical studies which met the inclusion criteria specified. By finding the mean effect sizes of the treatment on the outcome measures of cognition, it was determined that neither drug was greatly efficacious. However, this result does not necessarily diminish the practical value of the drug. It was also found that galantamine was no better than donepezil at treating cognitive decline in AD.

Proximodistal structure of early reaching in human infants.

Nine infants were tested, at the age of onset of reaching, seated on their parent's lap and reaching for a small plastic toy. Kinematic analysis revealed that infants largely used shoulder and torso rotation to move their hands to the toy. Many changes in hand direction were observed during reaching, with later direction changes correcting for earlier directional errors. Approximately half of the infants started many reaches by bringing their hands backward or upward to a starting location that was similar across reaches. Individual infants often achieved highly similar peak speeds across their reaches. These results support the hypothesis that infants reduce the complexity of movement by using a limited number of degrees-of-freedom, which could simplify and accelerate the learning process. The proximodistal direction of maturation of the neural and muscular systems appears to restrict arm and hand movement in a way that simplifies learning to reach.

Midreach correction in 7-month-olds.

In recent work, it has been suggested that infant reaching is composed of a sequence of perception-action cycles in which the positions of the hand and the target are assessed and actions are generated that bring the hand to the target. In the present work, the author examined the ability of 7-month-old infants (N = 12) to correct reaches in midflight when a target location was shifted. The results showed that on the majority of shift trials, the infants corrected hand direction in midreach and that the latency of correction was 200-400 ms. Although the present results are limited to the case of the infant's response to a target shift, they are consistent with the hypothesis that infants monitor the positions of the hand and the target during the reach and are able to adjust for any errors of movement.

Visual Information and Object Size in the Control of Reaching.

The role of vision in the control of reaching and grasping was investigated by varying the available visual information. Adults (N = 7) reached in conditions that had full visual information, visual information about the target object but not the hand or surrounding environment, and no visual information. Four different object diameters were used. The results indicated that as visual information and object size decreased, subjects used longer movement times, had slower speeds, and more asymmetrical hand-speed profiles. Subjects matched grasp aperture to object diameter, but overcompensated with larger grasp apertures when visual information was reduced. Subjects also qualitatively differed in reach kinematics when challenged with reduced visual information or smaller object size. These results emphasize the importance of vision of the target in reaching and show that subjects do not simply scale a command template with task difficulty.

Multimodal perception in the control of infant reaching.

Six-month-old infants were presented with sounding objects under 3 conditions of illumination: in full vision, in the dark with target location specified by a glowing and sounding object, and in the dark with location specified by sound alone. Reaching behavior was videotaped with an infrared camera, and hand movement was measured by infrared-emitting diodes on the hand that were tracked by a motion analysis system. No differences were found in reaching behavior for objects in the light and glowing objects in the dark. Reaches for sounding objects in the dark had higher speeds, shorter durations, and more errors compared to the other 2 conditions. These findings indicate that vision of the hand did not appear to affect infants' reaching in this situation, whereas vision of the target did.