Distinct pattern separation related transfer functions in human CA3/dentate and CA1 revealed using high-resolution fMRI and variable mnemonic similarity

Producing and maintaining distinct (orthogonal) neural representations for similar events is critical to avoiding interference in long-term memory. Recently, our laboratory provided the first evidence for separation-like signals in the human CA3/dentate. Here, we extended this by parametrically varying the change in input (similarity) while monitoring CA1 and CA3/dentate for separation and completion-like signals using high-resolution fMRI. In the CA1, activity varied in a graded fashion in response to increases in the change in input. In contrast, the CA3/dentate showed a stepwise transfer function that was highly sensitive to small changes in input.     

Negative emotional processing induced by spoken scenarios modulates corticospinal excitability

Emotion is assumed to facilitate the preparation of behavioral responses to environmental stimuli. In the present study, we examined whether emotional processing induced by spoken scenarios of positive and negative content, related to the self or to other people, modulates corticospinal excitability. Motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) in 20 volunteers indicated that processing of negative emotional content increased MEP amplitude, regardless of the perspective taken in the scenario. By contrast, positive emotional processing did not reliably alter MEP amplitude. These results provide the first TMS evidence that the auditory processing of emotionally negative information triggers action preparation.     

The extent of the present

One of the principal objections to a tensed or dynamic theory of time is the ancient puzzle about the extent of the present. Three alternative conceptions of the extent of the present are considered: an instantaneous present, an atomic present, and a non-metrical present. The first conception is difficult to reconcile with the objectivity of temporal becoming posited by a dynamic theory of time. The second conception solves that problem, but only at the expense of making change discontinuous. The third conception is the most plausible: that "the present" is a non-metrical notion which must be completed by the mention of some event or interval in order to have a measure, in which case what is present varies with one's context.     

Factor structure of the Hare Psychopathy Checklist: Youth Version (PCL: YV) in incarcerated adolescents

Two studies are reported on the underlying dimensions of the psychopathy construct in adolescents as measured by the Hare Psychopathy Checklist-Youth Version (PCL: YV; Forth, Kosson, & Hare, 2003). In Study 1, the PCL: YV item ratings for 505 male adolescents incarcerated in 5 different settings in North America were used to test the fit of 3 models that have been hypothesized to represent the structure of psychopathy in adults. A 4th model based on parceling PCL: YV items was also tested. In Study 2, these models were tested with a sample of 233 male adolescents incarcerated in 2 facilities in the United Kingdom. Model fit results indicated that the 18-item 4-factor model developed by Hare (2003) and a modified version of a 13-item 3-factor model developed by Cooke and Michie (2001) were associated with generally good fit. Because the 4-factor model is a less saturated model than the 3-factor model (better parameter to data point ratio), it survived a riskier test of disconfirmation. Implications for the nature of psychopathy in youth are discussed.     

Dynamic shifts in corticostriatal expression patterns of the immediate early genes Homer 1a and Zif268 during early and late phases of instrumental training

Adaptive motor actions require prior knowledge of instrumental contingencies. With practice, these actions can become highly automatic in nature. However, the molecular and anatomical substrates mediating these related forms of learning are not understood. In the present study, we used in situ hybridization to measure the mRNA levels of two immediate early genes (IEGs) in an instrumental paradigm where rats learned to lever-press for food. We report that after three training sessions, Homer 1a and Zif268 (an effector and regulatory IEG, respectively) were significantly induced within an extensive corticostriatal network relative to untrained controls. With extended training (23 sessions), however, a shift in the expression patterns of the two genes was evident. Expression of Homer 1a (official symbol Homer1) decreased significantly in frontal and cingulate cortices, whereas striatal expression was generally maintained. Interestingly, Homer 1a expression markedly increased with extensive training in the ventrolateral region of the striatum (VLS) relative to early learners, suggesting that plasticity in the VLS is required for the efficient production of the learned behavior or in habit formation. Zif268 (official symbol Egr1) expression generally decreased with extensive training; however, these changes were not significant. These results demonstrate for the first time, on a molecular level, a dynamic shift in the contribution of corticostriatal systems mediating the early acquisition and consolidation of goal-directed responses to those engaged after extensive training.     

Human feelings: why are some more aware than others?

A recent article reports that human perception of heartbeat timing is mediated by right (non-dominant) anterior insular cortex, and that the activity and the size of this region is directly correlated with individuals' subjective awareness of inner body feelings and emotionality. These results support the somatic-marker hypothesis of consciousness (a modern successor to the James-Lange theory of emotion) and the neuroanatomical concept that human awareness is based on a phylogenetically distinct interoceptive pathway.     

A behavior-analytic conceptualization of the side effects of psychotropic medication

A range of behavior-much deemed problematic by society-is treated with behavioral methods or psychotropic medications. Although the processes associated with behavioral interventions have been investigated using conceptual, experimental, and applied analyses, less is known about the behavioral processes associated with the use of psychotropic medication. Psychotropic drugs produce at least two types of effects of behavioral interest: (a) primary effects of drug action on target behaviors and (b) side effects that change the target or other behavior. Although an empirical literature exists regarding the former effects, little attention has been given to the latter topic. In this paper we offer a conceptual analysis of the side effects of psychotropic medication. We propose that the side effects of various drugs can influence behavior by functioning as motivating operations, conditional or discriminative stimuli, or by establishing new response-reinforcer relations. This conceptualization may facilitate the empirical analysis of how psychotropic drugs change behavior.     

The effect of hand position and pattern motion on temporal order judgments

Subjects made temporal order judgments (TOJs) of tactile stimuli presented to the fingerpads. The subjects judged which one of two locations had been stimulated first. The tactile stimuli were patterns that simulated movement across the fingerpads. Although irrelevant to the task, the direction of movement of the patterns biased the TOJs. If the pattern at one location moved in the direction of the second location, the subjects tended to judge the first location as leading the second location. If the pattern moved in the opposite direction, that location was judged as trailing. In a series of experiments, the effect of the spatial position of the hands and fingers on TOJs and the perception of the direction of pattern movement were examined. Changing the position of the hands so that the patterns no longer moved directly toward each other reduced or eliminated the effect of motion on TOJs. In a variation of Aristotle's illusion, the moving patterns were presented to crossed and uncrossed fingers. The results indicated that, contrary to Aristotle's illusion, the subjects processed the moving patterns relative to an environmental framework, rather than to the local direction of motion on the fingerpads. Presenting the patterns to crossed hands produced results similar to those obtained with crossed fingers: The subjects processed the patterns according to an environmental framework.     

ESID,Dissemination, and Community Psychology: A Case of Partial Implementation?

Dissemination, the second stage of Experimental Social Innovation and Dissemination (ESID) is a critical, if not defining, element of this social change model. This paper attempts to assess the extent to which community psychology has adopted and implemented ESID's dissemination focus in its training and publications. We identify four levels of commitment to dissemination: dissemination advocate, dissemination activist, dissemination researcher, and experimental dissemination researcher. Content analyses of textbooks, journal publications, and conference papers and a brief survey of doctoral training in the field were conducted. Findings suggest that the dissemination aspects of ESID have been modestly and partially implemented within the field. That is, although there is some evidence of a commitment to dissemination practice (advocate, activist), there is much less evidence of a commitment to dissemination research. The implications of these findings for the effectiveness of the ESID model and for training and practice in community psychology are discussed.     

Information used in detecting upcoming collision

In four experiments we examined the nature of the information used in judging whether events would or would not give rise to a collision in the near future. Observers were tested in situations depicting approaches between two objects (lateral approaches) and approaches between an object and the point of observation (head-on approaches), with objects moving according to constant deceleration or sinusoidal deceleration patterns. Judgments were found to be based, to a large extent, on the (in)sufficiency of current deceleration to avoid upcoming collision, as specified optically by tau-dot (tau). However, the information specified by tau (tau), that is the current (first-order) time remaining until contact, was also found to play a significant role. We deduce that judgment of upcoming collision is based on the detection of tau and its evolution over time, suggesting that observers are sensitive to delta(tau) rather than to tau itself.