Analysis of sequence-dependent interactions between transient calcium and transmitter stimuli in activating adenylyl cyclase in Aplysia: possible contribution to CS--US sequence requirement during conditioning

An important recent insight in a number of neurobiological systems is that during learning, individual dually regulated proteins with associative properties function as critical sites of stimulus convergence. During conditioning in Aplysia, the Ca2+ /calmodulin-sensitive adenylyl cyclase (AC) in mechanosensory neurons serves as a molecular site of interaction between Ca2+ and serotonin [5-hydroxytryptamine (5-HT)]-two signals that represent the CS and US in these cells. Conditioning requires that the CS and US be paired within a narrow time window and in the appropriate sequence. AC shows an analogous sequence preference: It is more effectively activated when a pulse of Ca2+ precedes a pulse of 5-HT than when the 5-HT precedes Ca2+. One mechanism that contributes to this sequence preference is that Ca2+/calmodulin binding to AC accelerates the rate of AC activation by receptor-Gs. We have identified two additional properties of AC activation that would cause pairing with Ca2+ preceding 5-HT to be more effective than simultaneous pairing or pairing with the reciprocal sequence: (1) Activation of Aplysia AC by a Ca2+ pulse rose with a delay compared with activation by a 5-HT pulse. (2) A late pulse of Ca2+, which arrived after 5-HT, acted, via calmodulin, to accelerate the decay of AC activation by receptor-Gs. Together, these activation properties of AC may contribute to the CS-US sequence requirement of classical conditioning.     

Perception of political candidates based on their stand on abortion and taxes.

This study investigated whether young voters would vote for and volunteer to work for the election campaign of a presidential candidate, given the candidate's background and positions on two major campaign issues. Findings indicate that, although voter-candidate agreement on a single issue may be enough for a voter to vote for a candidate, agreement on both issues may be necessary before a voter agrees to volunteer to work for the candidate's election campaign.     

Risky aggression in individuals and groups.

This study set out to investigate whether the risky shaft found in group consensus decisions as compared to group members' personal decisions extends to situations that combine risk and aggression. In a between-subjects design, subjects were exposed, either alone or as members of unisex triads, to an experimental task in which the risk entailed severe noxious consequences. The findings show that for both sexes, groups take significantly greater risks than individuals even when risk taking is mediated by aggressive means. The results are seen and discussed as limiting the explanatory scope of the risk-as-a-value hypothesis and as more consistent with the diffusion of responsibility hypothesis.     

Validity of a group measure of individual associative domains

FlekkØy, K. Validity of a group measure of individual associative domains. Scand. J. Psychol., 1973, 14, 96–98.-Number of different responses given to a stimulus word by a group of subjects in a single-word free-association situation (D) has been presumed to be a measure of the magnitude of the associative potential connected with the stimulus word in the individual subject. The study compares D with mean number of different responses given to each stimulus word in a continued association situation (m), and finds no significant correlation (r=-0.04), which is interpreted to mean that D is not a valid measure of individual associative domains.     

Associative frequency and response latency

FlekkØy, K. Associative frequency and response latency. Scand. J. Psychol., 1973, 14, 199–202.MdashWith 176 Norwegian subjects in a single-word free-association experiment, latency of response was found to relate more highly to the number of different words associated with a stimulus word (D), than to the response frequency of the words involved. D is therefore assumed to reflect a basic characteristic of the associative relationship between the stimulus and response words. The inverse relationship between associative frequency and latency is interpreted to mean that frequency reflects some relatively frequent order of preference of possible response words for individual subjects.