Biology

Dr B Suresh Krishna
German Primate Center, Goettingen, Germany

How do humans and rhesus macaques actively view visual scenes ? How are different views stitched together across saccadic eye-movements, and what are some of the cerebral cortical mechanisms that underlie this behavior ? I will describe some of our recent findings in this area based on behavioral measurements in humans, computational modeling and single-neuron recordings from the cerebral cortex in awake, behaving rhesus macaques. We have recently provided the first empirical evidence for the role of inhibitory mechanisms in the selection of targets for visual attention and saccadic eye-movements. We have also shown that visual attention shifts are rapid and well-synchronized with saccades. The locations, but not the features of attended stimuli are remapped across saccades, so that these attended stimuli can be tracked and processed rapidly after each saccade. We find evidence for the presence of fast sequences of eye-movements during naturalistic active vision: these saccade sequences are driven by visual information that is rapidly and accurately transferred across saccades. In addition to effects on neuronal firing-rate, the variability of firing and the temporal patterns of firing are also affected by visual attention.  Our work has been used by modelers (in collaboration with us) to identify novel principles of neural circuit organization. If time permits, I will also briefly cover some of my work in hearing: specifically, the transformation of sound envelopes in the auditory midbrain, and the initial encoding of sound in the auditory nerve.