Short and long-term motor skill learning in an accelerated rotarod training paradigm

Rodent models of motor skill learning include skilled forelimb reaching and acrobatic locomotor paradigms. This study characterizes motor skill learning in the accelerated rotarod task. Thirty Long-Evans rats (300-400 g) were trained on an accelerated rotarod (1cm/s(2)) over eight consecutive sessions (=days, 20 trials each). Improvement in rotarod velocities mastered before falling off the rod was observed within and between sessions (plateau after five sessions). Intrasession improvement was incompletely retained at the beginning of the next day's session. Over several training sessions, intrasession improvement diminished, suggesting a ceiling effect. After 1 week of pause, the rotarod skill was retained. Locomotor exercise in a running wheel for 30 min before the first rotarod session did not affect intrasession improvement. Running-wheel exposure for 6 days did not diminish the rate of rotarod skill learning (steepness of the learning curve) but improved overall performance (upward shift of curve). Video analysis of gait on the rotarod showed that rats developed a motor strategy by modifying their gait patterns during training. The data demonstrate that rotarod improvement is not the result of enhanced general locomotor ability or fitness, which are trained in the running wheel, but requires a change in the motor strategy to master the task. Accelerated rotarod training can be regarded a valid paradigm for motor skill learning over short (intrasession, minutes) and long time frames (intersession, days).     

Husserl's phenomenological discovery of the natural attitude

In this paper I will give a systematic account of Husserl's notion of the natural attitude in the development from its first presentation in Ideas I (1913) until Husserl's last years. The problem of the natural attitude has to be dealt with on two levels. On the thematic level, it is constituted by the correlation of attitude and horizon, both stemming from Husserl's theory of intentionality. On the methodic level, the natural attitude is constituted by three factors: naturalness, naivety and normality. I shall conclude by sketching out a possible motivation for leaving the natural attitude and thus for entering the sphere of phenomenology.     

Effect of initial status and growth in pseudoword reading on Spanish reading comprehension at the end of first grade

This study analyzes the effect of initial status and growth in Spanish pseudoword reading in kindergarten and first grade on reading comprehension in Spanish at the end of first grade. One hundred and sixty-eight Spanish-speaking English learners who were learning to read in Spanish and English in the United States participated in the study. Results of hierarchical linear modeling indicate that students grew, on average, by 95 letter-sounds in Spanish from the middle of kindergarten to the end of first grade. Structural equation modeling indicated that 53% of the variance in Spanish reading comprehension at the end of first grade was explained by Spanish initial status on pseudoword reading, Spanish kindergarten overall reading performance, and growth in Spanish pseudoword reading. Findings are important in a Response to Intervention approach where screening and progress monitoring of pseudoword reading helps educators determine the level of support beginning readers need to acquire the alphabetic principle, an important skill that contributes substantially to Spanish reading comprehension.     

Protein synthesis inhibition blocks consolidation of an acrobatic motor skill

To investigate whether motor skill learning depends on de novo protein synthesis, adult rats were trained in an acrobatic locomotor task (accelerating rotarod) for 7 d. Animals were systemically injected with cycloheximide (CHX, 0.5 mg/kg, i.p.) 1 h before sessions 1 and 2 or sessions 2 and 3. Control rats received vehicle injections before sessions 1, 2, and 3. Although CHX did not affect improvement of performance within session 1, between-session improvement was impaired. In overtrained animals, comparable injections of CHX had no effect on rotarod performance. These findings suggest that consolidation of motor skills requires protein synthesis.