Topography of Visuomotor Parameters in the Frontal and Premotor Eye Fields.

To determine whether the periarcuate frontal cortex spatially encodes visual and oculomotor parameters, we trained monkeys to repeatedly execute saccades of the same amplitude and direction toward visual targets and we obtained quantitative images of the distribution of metabolic activity in 2D flattened reconstructions of the arcuate sulcus (As) and prearcuate convexity. We found two topographic maps of contraversive saccades to visual targets, separated by a region representing the vertical meridian: the first region straddled the fundus of the As and occupied areas 44 and 6-ventral, whereas the second one occupied areas 8A and 45 in the anterior bank of the As and the prearcuate convexity. The representation of the vertical meridian runs along the posterior borders of areas 8A and 45 (deep in the As).

The place code of saccade metrics in the lateral bank of the intraparietal sulcus.

The lateral intraparietal area (LIP) of monkeys is known to participate in the guidance of rapid eye movements (saccades), but the means it uses to specify movement variables are poorly understood. To determine whether area LIP devotes neural space to encode saccade metrics spatially, we used the quantitative [(14)C]deoxyglucose method to obtain images of the distribution of metabolic activity in the intraparietal sulcus (IPs) of rhesus monkeys trained to repeatedly execute saccades of the same amplitude and direction for the duration of the experiment. Different monkeys were trained to perform saccades of different sizes and in different directions.

Optimal control of gaze shifts.

To explore the visible world, human beings and other primates often rely on gaze shifts. These are coordinated movements of the eyes and head characterized by stereotypical metrics and kinematics. It is possible to determine the rules that the effectors must obey to execute them rapidly and accurately and the neural commands needed to implement these rules with the help of optimal control theory.

Saccade-related information in the superior temporal motion complex: quantitative functional mapping in the monkey.

Although the role of the motion complex [cortical areas middle temporal (V5/MT), medial superior temporal (MST), and fundus of the superior temporal (FST)] in visual motion and smooth-pursuit eye movements is well understood, little is known about its involvement in rapid eye movements (saccades). To address this issue, we used the quantitative 14C-deoxyglucose method to obtain functional maps of the cerebral cortex lying in the superior temporal sulcus of rhesus monkeys executing saccades to visual targets and saccades to memorized targets in complete darkness. Fixational effects were observed in MT-foveal, FST, the anterior part of V4-transitional (V4t), and temporal-occipital areas.

Control of orienting movements: role of multiple tectal projections to the lower brainstem.

In movement neuroscience this past decade, a conceptual approach that puts emphasis on population coding was clearly dominant. The purpose of numerous studies has been to define presumably homogeneous groups of neurons on the basis of the correlation of their discharges with sensory and motor events. The goal of this chapter is to stress the importance of taking into account individual properties of neurons, this being an essential prerequisite for a biologically meaningful definition of neuron populations.