Long-term sensorimotor adaptation in the ocular following system of primates.

The sudden movement of a wide-field image leads to a reflexive eye tracking response referred to as short-latency ocular following. If the image motion occurs soon after a saccade the initial speed of the ocular following is enhanced, a phenomenon known as post-saccadic enhancement. We show in macaque monkeys that repeated exposure to the same stimulus regime over a period of months leads to progressive increases in the initial speeds of ocular following.

Sensory experience modifies feature map relationships in visual cortex.

The extent to which brain structure is influenced by sensory input during development is a critical but controversial question. A paradigmatic system for studying this is the mammalian visual cortex. Maps of orientation preference (OP) and ocular dominance (OD) in the primary visual cortex of ferrets, cats and monkeys can be individually changed by altered visual input.

Contrast and response gain control depend on cortical map architecture.

Visual cortical neurons are sensitive to visual stimulus contrast and most cells adapt their sensitivity to the prevailing visual environment. Specifically, they match the steepest region of their contrast response function to the prevailing contrast (contrast gain control), and reduce spike rates to limit saturation (response gain control). Most neurons are also tuned for stimulus orientation, and neurons with similar orientation preference are clustered together into iso-orientation zones arranged around pinwheels, i.

The relative contributions of global and local acceleration components on speed perception and discriminability following adaptation.

The perception of speed is dependent on the history of previously presented speeds. Adaptation to a given speed regularly results in a reduction of perceived speed and an increase in speed discriminability and in certain circumstances can result in an increase in perceived speed. In order to determine the relative contributions of the local and global speed components on perceived speed, this experiment used expanding dot flow fields with accelerating (global), decelerating (global) and mixed accelerating/decelerating (local) speed patterns.

Focal activation of primary visual cortex following supra-choroidal electrical stimulation of the retina: Intrinsic signal imaging and linear model analysis.

Unlabelled: We performed optical intrinsic signal imaging of cat primary visual cortex (Area 17 and 18) while delivering bipolar electrical stimulation to the retina by way of a supra-choroidal electrode array. Using a general linear model (GLM) analysis we identified statistically significant (p < 0.01) activation in a localized region of cortex following supra-threshold electrical stimulation at a single retinal locus.

Differential changes in human perception of speed due to motion adaptation.

Visual systems adapt to the prevailing image conditions. This improves the ability to discriminate between two similar stimuli but has the side effect that veridical perception is degraded. For example, prolonged driving at 100 km/h may reduce the perceived speed to 80 km/h but improve the sensitivity to changes in the prevailing speed.