Bridging the gap between physiology and behavior: evidence from the sSoTS model of human visual attention

We present the case for a role of biologically plausible neural network modeling in bridging the gap between physiology and behavior. We argue that spiking-level networks can allow "vertical" translation between physiological properties of neural systems and emergent "whole-system" performance-enabling psychological results to be simulated from implemented networks and also inferences to be made from simulations concerning processing at a neural level. These models also emphasize particular factors (e.g., the dynamics of performance in relation to real-time neuronal processing) that are not highlighted in other approaches and that can be tested empirically. We illustrate our argument from neural-level models that select stimuli by biased competition. We show that a model with biased competition dynamics can simulate data ranging from physiological studies of single-cell activity (Study 1) to whole-system behavior in human visual search (Study 2), while also capturing effects at an intermediate level, including performance breakdown after neural lesion (Study 3) and data from brain imaging (Study 4). We also show that, at each level of analysis, novel predictions can be derived from the biologically plausible parameters adopted, which we proceed to test (Study 5). We argue that, at least for studying the dynamics of visual attention, the approach productively links single-cell to psychological data.     

Where and how does grammatically geared processing take place-and why is Broca's area often involved. A coordinated fMRI/ERBP study of language processing

We address the possibility of combining the results from hemodynamic and electrophysiological methods for the study of cognitive processing of language. The hemodynamic method we use is Event-Related fMRI, and the electrophysiological method measures Event-Related Band Power (ERBP) of the EEG signal. The experimental technique allows us to approach the relation between cortical structure and cognitive function in a sophisticated way. In particular, we can formulate original working hypotheses about the language-induced changes in the ongoing brain dynamics. We show, on the basis of electrophysiological data collected in an experiment on language production, that synchronized cortical networks code cognitive processes induced by language in form of power modulations of specific frequency bands. The hemodynamic (fMRI) data collected in the same task point to the existence of a central processor for the phrase structure assignment. We conceptualize such a central processor as a frequency scanner, a cortical device designed to pick up synchronized brain activity over a specific range of frequencies. We discuss the experimental designs which result from this set of hypotheses and show their relevance for the models of language processing.     

Game Logic is Strong Enough for Parity Games

We investigate the expressive power of Parikh's Game Logic interpreted in Kripke structures, and show that the syntactical alternation hierarchy of this logic is strict. This is done by encoding the winning condition for parity games of rank n. It follows that Game Logic is not captured by any finite level of the modal -calculus alternation hierarchy. Moreover, we can conclude that model checking for the -calculus is efficiently solvable iff this is possible for Game Logic     

Pharmacotherapy of seasonal affective disorder

Seasonal affective disorder is a common variant of recurrent major depressive disorder or bipolar disorder. Treatment with bright artificial light has been found to be effective in this condition. However, for patients who do not respond to light therapy or those who lack compliance, conventional drug treatment with antidepressants also has been proposed. Substances with selective serotonergic or noradrenergic mechanisms should be preferred over older antidepressants. Although there are a number of open and controlled studies evaluating different compounds, these studies were often limited by relatively small sample sizes. Furthermore, there are no studies specifically addressing bipolar seasonal depression. This article will review the published literature on pharmacotherapy of seasonal affective disorder.     

Early, involuntary top-down guidance of attention from working memory

Four experiments explored the interrelations between working memory, attention, and eye movements. Observers had to identify a tilted line amongst vertical distractors. Each line was surrounded by a colored shape that could be precued by a matching item held in memory. Relative to a neutral baseline, in which no shapes matched the memory item, search was more efficient when the memory cue matched the shape containing the target, and it was less efficient when the cued stimulus contained a distractor. Cuing affected the shortest reaction times and the first saccade in search. The effect occurred even when the memory cue was always invalid but not when the cue did not have to be held in memory. There was also no evidence for priming effects between consecutive trials. The results suggest that there can be early, involuntary top-down directing of attention to a stimulus matching the contents of working memory.     

Postural control in otolith disorders

It was the aim of the present paper to investigate the influence of otolith disorders on human postural control by different methods. The 33 patients of our study had undergone a minor head injury and suffered subsequently from an utricular or sacculo-utricular disorder as evidenced by vestibular evoked myogenic potential recordings and eccentric rotation recordings of the otolith-ocular responses. Postural control was assessed by performing stance/gait tests (standard balance deficit test, SBDT) and by evaluating trunk sway (using angular velocity sensors). Moreover, classical tests of the posterior column of the spinal tract (Romberg/Unterberger) and the dynamic posturography (sensory organization test, SOT) were included. It could be shown that SBDT tasks with reduced proprioceptive and visual cues (e.g. standing on foam, eyes closed) are most sensitive for an otolith disorder. The patients showed an increased trunk sway in the pitch plane (i.e. linear motion as adequate utricular stimulus) and an increase in sway velocities (i.e. tilting movements as adequate saccular stimulus) compared to controls. The SOT was most sensitive for combined (sacculo-utricular) otolith disorders (78%) while vestibulospinal tests are not enough sensitive. In essence, otolith disorders evidently impair human postural control and have been possibly underestimated as a source of posttraumatic postural imbalance as yet.     

Oedipus and the Oedipus complex: A revision

The authors consider whether those aspects of the Oedipus myths that have been ignored by Freud could improve our knowledge of how the Oedipus complex develops. They conclude that the myths can provide an answer to Freud's question posed on the 25 February 1914 (Nunberg and Federn, 1975, p. 234) concerning “the extent to which the Oedipus complex is a reflection of the sexual behavior of the parents” with Fenichel's (1931, p. 421) view that the “child's Oedipus complex reflects that of his parents”.     

Evidence for graded central processing resources in a sequential movement task

In the present experiment, we examined slowing of the individual key presses of a familiar keying sequence by four different versions of a concurrent tone counting task. This was done to determine whether the same cognitive processor that has previously been assumed by the dual processor model (DPM) to initiate familiar keying sequences and assist in their execution, is involved also in the central processes of a very different task (viz. identifying tones and counting target tones). The present results confirm this hypothesis. They also suggest that in this particular situation the central processing resources underlying the cognitive processor can be distributed across the central processes of different tasks in a graded manner, rather than that they continue to behave like a single, central processor that serially switches between the central processes of the concurrently performed tasks. We argue that the production of highly practiced movement sequences can be considered automatic in the sense that execution of familiar movement sequences can continue without cognitive control once they have been initiated.     

Preparing lane changes while driving in a fixed-base simulator: Effects of advance information about direction and amplitude on reaction time and steering kinematics

Reaction times (RTs) of aiming movements are typically shorter when responses are prepared by informative precues. Aside from RT facilitation, response preparation can also modify the velocity profile of the movement trajectory. In this study we assess the preparatory effects of advance information about direction and number of lanes in a lane change task. Consistent with the findings of previous studies with aiming movements, prior information reduced RT and affected the velocity profile of the steering angle. The velocity profile was mainly shortened around the first peak steering wheel angle, and this finding is in line with the movement integration hypothesis. The results suggest that the findings from basic research can be generalized to driving tasks.