Developing PFC representations using reinforcement learning

From both functional and biological considerations, it is widely believed that action production, planning, and goal-oriented behaviors supported by the frontal cortex are organized hierarchically [Fuster (1991); Koechlin, E., Ody, C., & Kouneiher, F. (2003). Neuroscience: The architecture of cognitive control in the human prefrontal cortex. Science, 424, 1181-1184; Miller, G. A., Galanter, E., & Pribram, K. H. (1960). Plans and the structure of behavior. New York: Holt]. However, the nature of the different levels of the hierarchy remains unclear, and little attention has been paid to the origins of such a hierarchy. We address these issues through biologically-inspired computational models that develop representations through reinforcement learning. We explore several different factors in these models that might plausibly give rise to a hierarchical organization of representations within the PFC, including an initial connectivity hierarchy within PFC, a hierarchical set of connections between PFC and subcortical structures controlling it, and differential synaptic plasticity schedules. Simulation results indicate that architectural constraints contribute to the segregation of different types of representations, and that this segregation facilitates learning. These findings are consistent with the idea that there is a functional hierarchy in PFC, as captured in our earlier computational models of PFC function and a growing body of empirical data.     

Learning as a possible sign of non-reflective consciousness in persons with a diagnosis of vegetative state and pervasive motor impairment

A diagnosis of vegetative state represents a serious predicament, which basically precludes/minimizes rehabilitation perspectives. Reliability of the assessment approach in these situations is of paramount importance, but not easy to achieve. In recent studies, a learning assessment procedure has been suggested as a supplement in the diagnostic process and assessed with eight patients. The procedure involves an ABABCB sequence in which A represents baseline phases with no stimulation available, B intervention phases with stimuli delivered contingently on target responses, and C a control condition. This condition involves stimulation presented non-contingently. The patients’ ability to associate responding with environmental stimuli and thus increase such responding during the B phases, and reduce it during the A and C phases, may be considered a sign of learning. Learning might be viewed as representative of forms of concrete knowledge and presumably basic levels of consciousness. Preliminary results indicate that (a) signs of learning may appear in patients with a previous diagnosis of vegetative state and (b) the presence of those signs may require a revision of their diagnostic label and a reappraisal of their rehabilitation perspectives.     

A Behavior Analytically Modified Implicit Association Test for Measuring Sexual Categorization of Children

The Psychological Record - The current study assessed the sexual categorization of children among a random sample of adults from the general population. Twenty-seven males and 27 females (N = 54)...     

Cognitive vulnerability to depression: a comparison of the weakest link, keystone and additive models

Multiple theories of cognitive vulnerability to depression have been proposed, each focusing on different aspects of negative cognition and utilising different measures of risk. Various methods of integrating such multiple indices of risk have been examined in the literature, and each demonstrates some promise. Yet little is known about the interrelations among these methods, or their incremental validity in predicting changes in depression. The present study compared three integrative models of cognitive vulnerability: the additive, weakest link, and keystone models. Support was found for each model as predictive of depression over time, but only the weakest link model demonstrated incremental utility in predicting changes in depression over the other models. We also explore the correlation between these models and each model's unique contribution to predicting onset of depressive symptoms.     

Selective nontarget inhibition in Multiple Object Tracking

We previously reported that in the Multiple Object Tracking (MOT) task, which requires tracking several identical targets moving unpredictably among identical nontargets, the nontargets appear to be inhibited, as measured by a probe-dot detection method. The inhibition appears to be local to nontargets and does not extend to the space between objects—dropping off very rapidly away from targets and nontargets. In the present three experiments we show that (1) nontargets that are identical to targets but remain in a fixed location are not inhibited and (2) moving objects that have a different shape from targets are inhibited as much as same-shape nontargets, and (3) nontargets that are on a different depth plane and so are easily filtered out are not inhibited. This is consistent with a task-dependent view of item inhibition wherein nontargets are inhibited if (and only if) they are likely to be mistaken for targets.     

Doing and Redoing Emphasized Femininity: How Women Use Emotion Work to Manage Competing Expectations in College Hookup Culture

Sex Roles - Emphasized femininity plays a key role in maintaining gender inequality. Yet, classic conceptualizations of emphasized femininity render it static and inflexible, and obscure...