Bypassing use-dependent plasticity in the primary motor cortex to preserve adaptive behavior

Behavioral adaptation, a central feature of voluntary movement, is known to rely on top-down cognitive control. For example, the conflict-adaptation effect on tasks such as the Stroop task leads to better performance (e.g. shorter reaction time) for incongruent trials following an already incongruent one. The role of higher-order cortices in such between-trial adjustments is well documented, however, a specific involvement of the primary motor cortex (M1) has seldom been questioned. Here we studied changes in corticospinal excitability associated with the conflict-adaptation process. For this, we used single-pulse transcranial-magnetic stimulation (TMS) applied between two consecutive trials in an interference flanker task, while measuring motor-evoked potentials (MEPs) after agonistic and antagonistic voluntary movements. In agonist movement, MEP amplitude was modulated by recent movement history with an increase favoring movement repetition, but no significant change in MEP size was observed whether a previous trial was incongruent or congruent. Critically, for an antagonist movement, the relative size of MEPs following incongruent trials correlated positively with the strength of behavioral adaptation measured as the degree of RT shortening across subjects. This post-conflict increase in corticospinal excitability related to antagonist muscle recruitment could compensate for a potential deleterious bias due to recent movement history that favors the last executed action. Namely, it prepares the motor system to rapidly adapt to a changing and unpredictable context by equalizing the preparation for all possible motor responses.

THE BENEFITS OF TEACHING #METOO IN THE CONTEXT OF WOMEN’S LIBERATION HISTORY

This essay acknowledges the importance of examining the #metoo movement in global, cross-cultural, international contexts as scholars. Yet it also argues for teaching the social media (SM) movement in a grounded historical context as growing out of other moments of women’s liberation movement history in which women came together to tell their story, sharing their personal experiences that led to political action, particularly when teaching the hashtag movement in introductory women and gender studies courses. The author shares her efforts to do so online at a south-eastern technical university in the United States in the Spring of 2019. Not as part of evaluations but as part of a teaching unit within the course, she asked her nearly 50 students, both male and female, to compare and contrast the SM movement to consciousness-raising groups in which women had met face-to-face to share their experiences in an earlier time in movement history. All 300 student posts and reflections posted in the week under examination were scrutinized by the instructor, and their thoughts and conclusions analyzed. In this article, a sample of four is explored.

Epilogue

The epilogue ponders the space created by a study of New Afrikan Independence Movement history for further exploration and analysis. Taking seriously Marilyn Preston Killingham’s perspective about racial terrorism, it reminds readers that historical state violence and ongoing repression against the activist left create archival silences that the small but growing body of scholarship about this movement has yet to fully explore. The production of geographies, economic studies, cultural analysis, and biographies associated with the NAIM will help scholars and activists continue to reveal and learn from the lessons of this dynamic political struggle. Therefore, the epilogue encourages further research as students of New Afrikan history continue to reveal archival silences and use them to generate the production of new ideas and more activism.

Age has no effect on ankle proprioception when movement history is controlled

It is generally accepted that proprioceptive ability deteriorates with age, although not all data support this view. We tested proprioception using three reliable tests at the ankle in 80 adults (19–80 yr). For all tests, the effects of muscle thixotropy were controlled. Under these conditions, we found no difference in proprioceptive acuity between young and old people.