050629 Kreiter

The Bernstein Center for Computational Neuroscience Freiburg

Announcement for the next

BCCN Seminar

Prof. Dr. Andreas Kreiter

Universitaet Bremen
Germany

Neuronal Mechanisms Implementing Selective Attention

Attention is thought to select individual stimuli from an often complex scene for enhanced processing which may finally result in adaptive behavior. In this lecture I will argue that selective attention is essentially implemented by a fast, task-dependent modulation of the effective interactions between groups of neurons in the cortex. Experimental evidence from macaque monkeys’ visual cortical areas V4 and MT suggests that attention-dependent modulations of neuronal synchronization are strong and may serve to enhance effectively the transmission from local neuronal assemblies engaged in processing of the attended stimulus. A particular direct functional relation between neuronal synchronization and selective attention is indicated by the detailed correspondence between behavioral characteristics of attention and modulations of local synchronization. Neuronal synchronization between separate sites was found to be closely related to cognitive processes, too. For a working-memory task, failures of two separate sites to synchronize during the delay period, predicted failures to remember correctly the sample item. While attention to a target stimulus is associated with enhanced, usually conscious perception, the perception of distracter stimuli is often incomplete and degraded and may in the extreme fail completely (‘inattentional blindness’). These observations on the perceptual level are difficult to explain by the rather limited reductions of the response rate of neurons in the early areas of visual cortex for distracters as compared to a target. However, neurons in area MT suffer from a marked reduction of direction selectivity, if they process a distracter stimulus. This is expected to degrade the information contained in the corresponding population and may explain the reduced perceptual accuracy observed for non-attended stimuli. Selective attention may therefore serve to keep the quality of the target stimulus’ representation in the presence of distracters high and constant.

Host: Dr. Simone Cardoso de Oliveira