The electrophysiological properties of distinct subpopulations of striatal medium-sized spiny neurons (MSSNs) were compared using enhanced green fluorescent protein as a reporter gene for identification of neurons expressing dopamine D1 and D2 receptor subtypes in mice. Whole-cell patch-clamp recordings in slices revealed that passive membrane properties were similar in D1 and D2 cells. All MSSNs displayed hyperpolarized resting membrane potentials but the threshold for firing action potentials was lower in D2 than in D1 neurons. In voltage clamp, the frequency of spontaneous excitatory postsynaptic currents was higher in D2 than in D1 cells and large-amplitude inward currents (> 100 pA) were observed only in D2 cells. After tetrodotoxin this difference was reduced, suggesting that sodium conductances contribute to the increased frequencies in D2 cells. After pharmacological blockade of GABA(A) receptors, a subset of D2 cells also displayed large spontaneous membrane depolarizations and complex responses to stimulation of the corticostriatal pathway. To further characterize ionotropic glutamate receptor function, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) was applied onto dissociated MSSNs. Application of AMPA alone or in the presence of cyclothiazide (an AMPA receptor desensitization blocker) evoked larger currents in D1 than in D2 cells. Together, these data demonstrate significant differences in electrophysiological properties of subpopulations of MSSNs defined by selective expression of D1 and D2 receptors. D2 cells display increased excitability and reflect ongoing cortical activity more faithfully than D1 cells, an effect that is independent of postsynaptic AMPA receptors and probably results from stronger synaptic coupling. This could help to explain the increased vulnerability of D2 MSSNs in neurodegenerative disorders.

Although people often recognize the moral value of impartial behavior (i.e., not favoring specific individuals), it is unclear when, if ever, people recognize the moral value of partiality. The current studies investigated whether information about special obligations to specific individuals, particularly kin, is integrated into moral judgments. In Studies 1 and 2, agents who helped a stranger were judged as more morally good and trustworthy than those who helped kin, but agents who helped a stranger, instead of kin were judged as less morally good and trustworthy than those who did the opposite. In Studies 3 and 4, agents who simply neglected a stranger were judged as less morally bad and untrustworthy than those who neglected kin. Study 4 also demonstrated that the violation (vs. fulfillment) of perceived obligations underlaid all judgment patterns. Study 5 demonstrated boundary conditions: When occupying roles requiring impartiality, agents who helped a stranger instead of kin were judged as more morally good and trustworthy than agents who did the opposite. These findings illuminate the importance of obligations in structuring moral judgment.

When an automated car harms someone, who is blamed by those who hear about it? Here, we asked human participants to consider hypothetical cases in which a pedestrian was killed by a car operated under shared control of a primary and a secondary driver, and to indicate how blame should be allocated. We find that when only one driver makes an error, that driver is blamed more, regardless of whether that driver is a machine or a human. However, when both drivers make errors in cases of human-machine shared-control vehicles, the blame attributed to the machine is reduced. This finding portends a public under-reaction to the malfunctioning AI components of automated cars and therefore has a direct policy implication: allowing the de-facto standards for shared-control vehicles to be established in courts by the jury system could fail to properly regulate the safety of those vehicles; instead, a top-down scheme (through federal laws) may be called for.