Perceptual learning with perceptions.

Unlabelled: In this work we present an approach to understand neuronal mechanisms underlying perceptual learning. Experimental results achieved with stimulus patterns of coherently moving dots are considered to build a simple neuronal model. The design of the model is made transparent and underlying behavioral assumptions made explicit.

The neurodynamics underlying attentional control in set shifting tasks.

In this work we address key phenomena observed with classical set shifting tasks as the "Wisconsin Card Sorting Test" or the "Stroop" task: Different types of errors and increased response times reflecting decreased attention. A component of major importance in these tasks is referred to as the "attentional control" thought to be implemented by the prefrontal cortex which acts primarily by an amplification of task relevant information. This mode of operation is illustrated by a neurodynamical model developed for a new kind of set shifting experiment: The Wisconsin-Delayed-Match-to-Sample task combines uninstructed shifts as investigated in Wisconsin-like tasks with a Delayed-Match-to-Sample paradigm.

The neuronal dynamics underlying cognitive flexibility in set shifting tasks.

The ability to switch attention from one aspect of an object to another or in other words to switch the "attentional set" as investigated in tasks like the "Wisconsin Card Sorting Test" is commonly referred to as cognitive flexibility. In this work we present a biophysically detailed neurodynamical model which illustrates the neuronal base of the processes related to this cognitive flexibility. For this purpose we conducted behavioral experiments which allow the combined evaluation of different aspects of set shifting tasks: uninstructed set shifts as investigated in Wisconsin-like tasks, effects of stimulus congruency as investigated in Stroop-like tasks and the contribution of working memory as investigated in "Delayed-Match-to-Sample" tasks.

Neurons and the synaptic basis of the fMRI signal associated with cognitive flexibility.

The Wisconsin Card Sorting Test (WCST) is well known to test cognitive flexibility in terms of set-shifting capabilities. Many fMRI studies with behaving monkeys as well as human subjects have shown transient neural activity in the Prefrontal Cortex (PFC), as indicated by an increase in the fMRI signal, following a rule change in the WCST or when using a WCST-like paradigm. We present a computational model, covering a limited number of PFC neurons and using precise biophysical descriptions, which is able to simulate WCS-like tests.