Attentional disengagement dysfunction following mTBI assessed with the gap saccade task.

Concussion, or mild traumatic brain injury (mTBI), leads to a number of cognitive, attentional, and sensorimotor deficits that can last a surprisingly long time after the initial injury. We have previously shown that the ability to orient visuospatial attention is deficient in participants with mTBI within 2 days of their injury, but then recovers to normal levels within a week. Orienting attention requires disengagement from the point of fixation, movement of attention to the location of interest, and re-engagement at that location.

The contribution of the human FEF and SEF to smooth pursuit initiation.

Smooth pursuit eye movements function to keep moving targets foveated. Behavioral studies have shown that pursuit is particularly effective for predictable target motion. There is evidence that both the frontal eye field (FEF) and supplementary eye field (SEF) (also known as the dorsomedial frontal cortex) contribute to pursuit control.

The contribution of the human PPC to the orienting of visuospatial attention during smooth pursuit.

Smooth pursuit eye movements function to stabilize the retinal image of small moving targets. In order for those targets to be foveated, however, they must first be "captured" by an attentional mechanism which then interacts with the oculomotor system. Cortical sites involved with producing smooth pursuit overlap with areas known to be involved in directing visuospatial attention, particularly the posterior parietal cortex (PPC).

Cancelling planned actions following mild traumatic brain injury.

Mild traumatic brain injury (mTBI) leads to a variety of attentional, cognitive, and sensorimotor deficits. An important aspect of behavior that intersects each of these functions is the ability to cancel a planned action. Thus, the purpose of this study was to determine the effects of mTBI on the ability to perform a countermanding saccade task.

Cortical frames of reference for eye-hand coordination.

To reach for an object the brain must transform visual input from the eye into motor output of the arm. Recent neurophysiological experiments have shown that this transformation maps onto a network of brain areas including the posterior parietal (PPC) and premotor (PMC) cortices. In this chapter, we review evidence from our own experiments which demonstrate that this network can only partially complete the transformation when the eye and limb movement amplitudes are dissociated.

The allocation of attention during smooth pursuit eye movements.

The spatial-temporal allocation of attention during smooth pursuit eye movements is poorly understood. In this chapter we review evidence showing that attention contributes to both saccades and smooth pursuit. We then discuss results from our own recent studies using a dual-task paradigm in which subjects pursued a moving stimulus and pressed a button when targets appeared in the periphery.

Eye-hand interactions differ in the human premotor and parietal cortices.

In order to successfully look at and reach for a visual target the central nervous system must perform a complex sensorimotor transformation. How this transformation is mapped onto relevant brain structures has become the subject of much recent investigation. In the present paper we examined the contribution of the human premotor cortex (PMC) to this transformation process during a task requiring coordinated eye and hand movements.