Précis of memory: a philosophical study

This is a response to three critical discussions of my book Memory: A Philosophical Study (Oxford University Press 2010): Marya Schechtman, “Memory and Identity”, Fred Adams, “Husker Du?”, and Sanford Goldberg “The Metasemantics of Memory”.     

Correlates of aggressive and delinquent conduct problems in adolescence

The primary purpose of the study was to test a hypothetical model for aggressive and delinquent conduct problems in adolescence. A total of 168 adolescents from 121 families were studied using several questionnaires and a semi‐structured interview. The following factors were considered: obstetric complications, temperament (novelty‐seeking), self‐esteem, family influences (perceived parenting, alcohol abuse/dependence of parents, antisocial personality disorder of the father) and peer‐group characteristics (peer rejection and membership in a deviant peer group). The evaluation methods applied included correlation analyses and testing of two hypothetical models using structural equation modeling. The correlation analyses revealed significant relationships between adolescent aggressive and delinquent behavioral problems and parental antisocial behavior; perceived parental rejection and low emotional warmth; adolescent novelty‐seeking, self‐esteem, peer rejection and peer deviance. The two empirical models, separately for aggressive and delinquent behavior problems, revealed direct relationships between paternal antisocial behavior, parental rejection, adolescent novelty seeking, peer deviance, peer rejection, and offspring aggression and delinquency. There were, however, two differences with respect to the relationships between peer rejection, peer deviance, aggression and delinquency. First, peer rejection was more strongly associated with aggressive behavior and only moderately linked to delinquency. Second, deviance in the peer‐group was found to be closely related with delinquency but only moderately with aggression. Our findings suggest that several pathways for aggressive and delinquent conduct problems are comparable while others were not. Regarding the findings of the empirical models, we conclude that only intervention measures that include parents, peers and individual adolescents may help decrease the incidence of aggressive and delinquent conduct problems. Aggr. Behav. 31:24–39, 2005. © 2005 Wiley‐Liss, Inc.     

Grasping of extrafoveal targets: A robotic model

We present a computational model of grasping of non-fixated (extrafoveal) target objects which is implemented on a robot setup, consisting of a robot arm with cameras and gripper. This model is based on the premotor theory of attention (Rizzolatti et al., 1994) which states that spatial attention is a consequence of the preparation of goal-directed, spatially coded movements (especially saccadic eye movements). In our model, we add the hypothesis that saccade planning is accompanied by the prediction of the retinal images after the saccade. The foveal region of these predicted images can be used to determine the orientation and shape of objects at the target location of the attention shift. This information is necessary for precise grasping. Our model consists of a saccade controller for target fixation, a visual forward model for the prediction of retinal images, and an arm controller which generates arm postures for grasping. We compare the precision of the robotic model in different task conditions, among them grasping (1) towards fixated target objects using the actual retinal images, (2) towards non-fixated target objects using visual prediction, and (3) towards non-fixated target objects without visual prediction. The first and second setting result in good grasping performance, while the third setting causes considerable errors of the gripper orientation, demonstrating that visual prediction might be an important component of eye–hand coordination. Finally, based on the present study we argue that the use of robots is a valuable research methodology within psychology.     

Ontogenetic differences in conditioning of an aversion to a gustatory CS with a peripheral US

Rats 5, 10, or 15 days postnatal were given six pairings of an infused sucrose solution and footshock. Conditioned aversion to the sucrose solution was confirmed for the 5- and 10-day-old pups, but no conditioning was evident for the 15-day-old pups (Experiments 1 and 1A). In Experiment 2 the ventral portion of the rat's body was insulated from the shock source in order to isolate its effect on the feet and minimize visceral consequences of the shock. The sucrose-shock conditioning occurred as before. These results may have implications for the postnatal development of cue-consequence specificity, suggesting that such specificity may in part be learned. The present results also raise the possibility that sources of discomfort may be relatively undifferentiated in the perinatal rat.     

Reduced K+ Channel Inactivation, Spike Broadening, and After-Hyperpolarization in Kvβ1.1-Deficient Mice with Impaired Learning

A-type K⁺ channels are known to regulate neuronal firing, but their role in repetitive firing and learning in mammals is not well characterized. To determine the contribution of the auxiliary K⁺ channel subunit Kvβ1.1 to A-type K⁺ currents and to study the physiological role of A-type K⁺ channels in repetitive firing and learning, we deleted the Kvβ1.1 gene in mice. The loss of Kvβ1.1 resulted in a reduced K⁺ current inactivation in hippocampal CA1 pyramidal neurons. Furthermore, in the mutant neurons, frequency-dependent spike broadening and the slow afterhyperpolarization (sAHP) were reduced. This suggests that Kvβ1.1-dependent A-type K⁺ channels contribute to frequency-dependent spike broadening and may regulate the sAHP by controlling Ca²⁺ influx during action potentials. The Kvβ1.1-deficient mice showed normal synaptic plasticity but were impaired in the learning of a water maze test and in the social transmission of food preference task, indicating that the Kvβ1.1 subunit contributes to certain types of learning and memory.