A computational model of Parkinsonian handwriting that highlights the role of the indirect pathway in the basal ganglia

Parkinsonian handwriting is typically characterized by micrographia, jagged line contour, and unusual fluctuations in pen velocity. In this paper we present a computational model of handwriting generation that highlights the role of the basal ganglia, particularly the indirect pathway. Whereas reduced dopamine levels resulted in reduced letter size, transition of STN–GPe dynamics from desynchronized (normal) to synchronized (PD) condition resulted in increased fluctuations in velocity in the model. We also present handwriting data from PD patients (n = 34) who are at various stages of disease and had taken medication various lengths of time before the handwriting sessions. The patient data are compared with those of age-matched controls. PD handwriting statistically exhibited smaller size and larger velocity fluctuation compared to normal handwriting.     

Culture and the role of choice in agency

Three cross-cultural studies conducted among U.S. and Indian adults compared perceptions of helping friends in strongly versus weakly expected cases, views of helping family versus strangers, and responses to a self-determination motivation scale. Expectations to help family and friends were positively correlated with satisfaction and choice only among Indians and not among Americans. Also, whereas U.S. respondents associated lesser satisfaction and choice with strongly versus weakly socially expected helping, Indian respondents associated equal satisfaction and choice with the 2 types of cases. Providing evidence of the importance of choice in collectivist cultures, the results indicate that social expectations to meet the needs of family and friends tend to be more fully internalized among Indians than among Americans. Methodologically, the results also highlight the need to incorporate items that tap more internalized meanings of role-related social expectations on measures of motivation in the tradition of self-determination theory.