RESUMEN
We introduce a large-scale neurocomputational model of spatial cognition called 'Spacecog', which integrates recent findings from mechanistic models of visual and spatial perception. As a high-level cognitive ability, spatial cognition requires the processing of behaviourally relevant features in complex environments and, importantly, the updating of this information during processes of eye and body movement. The Spacecog model achieves this by interfacing spatial memory and imagery with mechanisms of object localisation, saccade execution, and attention through coordinate transformations in parietal areas of the brain. We evaluate the model in a realistic virtual environment where our neurocognitive model steers an agent to perform complex visuospatial tasks. Our modelling approach opens up new possibilities in the assessment of neuropsychological data and human spatial cognition.
Asunto(s)
Cognición , Memoria Espacial , Humanos , Visión Ocular , Percepción Espacial , Atención , Percepción VisualRESUMEN
While we are scanning our environment, the retinal image changes with every saccade. Nevertheless, the visual system anticipates where an attended target will be next and attention is updated to the new location. Recently, two different types of perisaccadic attentional updates were discovered: predictive remapping of attention before saccade onset (Rolfs, Jonikaitis, Deubel, & Cavanagh, 2011) and lingering of attention after saccade (Golomb, Chun, & Mazer, 2008; Golomb, Pulido, Albrecht, Chun, & Mazer, 2010). We here propose a neuro-computational model located in lateral intraparietal cortex based on a previous model of perisaccadic space perception (Ziesche & Hamker, 2011, 2014). Our model can account for both types of updating of attention at a neural-systems level. The lingering effect originates from the late updating of the proprioceptive eye-position signal and the remapping from the early corollary-discharge signal. We put these results in relationship to predictive remapping of receptive fields and show that both phenomena arise from the same simple, recurrent neural circuit. Thus, together with the previously published results, the model provides a comprehensive framework for discussing multiple experimental observations that occur around saccades.
Asunto(s)
Atención/fisiología , Movimientos Oculares/fisiología , Percepción Espacial/fisiología , Corteza Cerebral/fisiología , Simulación por Computador , Humanos , Orientación Espacial/fisiología , Estimulación Luminosa/métodos , Propiocepción/fisiología , Movimientos Sacádicos/fisiologíaRESUMEN
When the target of a saccadic eye movement is displaced while the eyes move this displacement is often not noticed (saccadic suppression of displacement, SSD). We present a neurobiologically motivated, computational model of SSD and compare its simulation results to experimental data. The model offers a simple explanation of the effects of pre- and post-saccadic stimulus blanking on SSD in terms of peri-saccadic network dynamics. Under normal peri-saccadic conditions pre-and post-saccadic stimulus traces are recurrently integrated with reference to present and future eye position, whereas blanking diminishes the pre-saccadic stimulus trace and thus leads to an uninfluenced integration of the post-saccadic stimulus trace. We show that part of the intersubject variability in SSD can be explained by differences in decision thresholds of this integration process.
Asunto(s)
Parpadeo/fisiología , Simulación por Computador , Párpados/fisiología , Fijación Ocular/fisiología , Movimientos Sacádicos/fisiología , Humanos , Factores de TiempoRESUMEN
Understanding the subjective experience of a visually stable world during eye movements has been an important research topic for many years. Various studies were conducted to reveal fundamental mechanisms of this phenomenon. For example, in the paradigm saccadic suppression of displacement (SSD), it has been observed that a small displacement of a saccade target could not easily be reported if this displacement took place during a saccade. New results from Zimmermann et al. (J Neurophysiol 112(12):3066-3076, 2014) show that the effect of being oblivious to small displacements occurs not only during saccades, but also if a mask is introduced while the target is displaced. We address the question of how neurons in the parietal cortex may be connected to each other to account for the SSD effect in experiments involving a saccade and equally well in the absence of an eye movement while perception is disrupted by a mask.