It's in your eyes--using gaze-contingent stimuli to create truly interactive paradigms for social cognitive and affective neuroscience.

The field of social neuroscience has made remarkable progress in elucidating the neural mechanisms of social cognition. More recently, the need for new experimental approaches has been highlighted that allow studying social encounters in a truly interactive manner by establishing 'online' reciprocity in social interaction. In this article, we present a newly developed adaptation of a method which uses eyetracking data obtained from participants in real time to control visual stimulation during functional magnetic resonance imaging, thus, providing an innovative tool to generate gaze-contingent stimuli in spite of the constraints of this experimental setting.

Minds made for sharing: initiating joint attention recruits reward-related neurocircuitry.

The ability and motivation to share attention is a unique aspect of human cognition. Despite its significance, the neural basis remains elusive. To investigate the neural correlates of joint attention, we developed a novel, interactive research paradigm in which participants' gaze behavior--as measured by an eye tracking device--was used to contingently control the gaze of a computer-animated character.

Comparison of functional and cytoarchitectonic maps of human visual areas V1, V2, V3d, V3v, and V4(v).

Cytoarchitectonic maps of human striate and extrastriate visual cortex based upon post-mortem brains can be correlated with functionally defined cortical areas using, for example, fMRI. We here assess the correspondence of anatomical maps of the visual cortex with functionally defined in vivo visual areas using retinotopic mapping. To this end, anatomical maximum probability maps (aMPM) derived from individual cytoarchitectonic maps of striate and extrastriate visual areas were compared with functional localisers for the early visual areas.

Cognitive subtypes of dyslexia.

Different theories conceptualise dyslexia as either a phonological, attentional, auditory, magnocellular, or automatisation deficit. Such heterogeneity suggests the existence of yet unrecognised subtypes of dyslexics suffering from distinguishable deficits. The purpose of the study was to identify cognitive subtypes of dyslexia.

Ageing-related changes of neural activity associated with spatial contextual memory.

Neuropsychological studies provide evidence for an ageing-related decline of memory for contextual information related to remembered items. Using event-related fMRI we investigated the neural correlates of ageing-related changes during encoding and retrieval of spatial contextual memory. Eighteen young and 17 older subjects were included in the analysis (mean age 24 and 60 years, respectively).

Head motion during overt language production in functional magnetic resonance imaging.

Head motion parameters (translation, rotation) during an event-related functional magnetic resonance imaging experiment of overt picture naming were investigated for two fixation conditions. We compared normal fixation with cushions and belts with the additional use of a bite-bar. Neither mean nor maximum values differed between the two conditions for any of the parameters.

Cytoarchitectonic analysis of the human extrastriate cortex in the region of V5/MT+: a probabilistic, stereotaxic map of area hOc5.

Functional imaging studies identified a motion-sensitive area (V5/MT+) in the vicinity of the posterior branch of the inferior temporal sulcus that has no correlate in any classical cytoarchitectonic map. The aim of the present study was to identify a cytoarchitectonic correlate of this region in 10 human postmortem brains and to provide a probability map of this area. Observer-independent mapping revealed an area, hOc5 (h for human, Oc for occipital lobe), that has a broad layer III, a high cell density in layer II/III, and a low one in layer V.

Visual resolution with retinal implants estimated from recordings in cat visual cortex.

We investigated cortical responses to electrical stimulation of the retina using epi- and sub-retinal electrodes of 20-100 microm diameter. Temporal and spatial resolutions were assessed by recordings from the visual cortex with arrays of microelectrodes and optical imaging. The estimated resolutions were approximately 40 ms and approximately 1 degrees of visual angle.

Human V5/MT+: comparison of functional and cytoarchitectonic data.

To date, the delineation of the human visual "motion area" still relies on functional paradigms originally devised to identify monkey area MT. Using fMRI, we have identified putative human area V5/MT+ in normals by modelling the BOLD responses to alternating radially moving and stationary dot patterns. Functional activations were compared with cytoarchitectonic probability maps of its putative correlate area hOc5, which was calculated based upon data from histological sections of ten human post-mortem brains.

Spatiotemporal receptive field properties of epiretinally recorded spikes and local electroretinograms in cats.

Background: Receptive fields of retinal neural signals of different origin can be determined from extracellular microelectrode recordings at the inner retinal surface. However, locations and types of neural processes generating the different signal components are difficult to separate and identify. We here report epiretinal receptive fields (RFs) from simultaneously recorded spikes and local electroretinograms (LERGs) using a semi-chronic multi-electrode in vivo recording technique in cats.

Retino-cortical information transmission achievable with a retina implant.

Blind subjects with photoreceptor degeneration perceive phosphenes when their intact retinal ganglion cells are stimulated electrically. Is this approach suitable for transmitting enough information to the visual cortex for partially restoring vision? We stimulated the retina of anesthetized cats electrically and visually while recording the responses in the visual cortex. Transmission of retino-cortical information T was quantified by information theory.

Subretinal implantation and testing of polyimide film electrodes in cats.

Background: Progress in the field of microelectronics has led to the development of visual prostheses for the treatment of blinding diseases. One concept under investigation is an electronic subretinal prosthesis to replace the function of lost photoreceptors in degenerative diseases, such as retinitis pigmentosa.

Methods: In the subretinal prosthesis design concept, an array of stimulation electrodes is placed in the subretinal space.

Visual resolution with epi-retinal electrical stimulation estimated from activation profiles in cat visual cortex.

Blinds with receptor degeneration can perceive localized phosphenes in response to focal electrical epi-retinal stimuli. To avoid extensive basic stimulation tests in human patients, we developed techniques for estimating visual spatial resolution in anesthetized cats. Electrical epi-retinal and visual stimulation was combined with multiple-site retinal and cortical microelectrode recordings of local field potentials (LFPs) from visual areas 17 and 18.

Activation zones in cat visual cortex evoked by electrical retina stimulation.

Background: A retina implant for restoring simple basic visual perception in patients who are blind due to photoreceptor loss requires optimisation of stimulation parameters for obtaining high spatio-temporal resolution. We developed effective low-power epi-retinal stimulation and intracortical recording in semichronically prepared cats.

Methods: Individually driveable fibre electrodes were inserted through a small scleral incision and positioned at the area centralis.