An oculomotor representation area within the ventral premotor cortex

155

171

Our present understanding of the neural mechanisms and sensorimotor transformations that govern the planning of arm and eye movements predominantly come from invasive parieto-frontal neural recordings in nonhuman primates. While functional MRI (fMRI) has motivated investigations on much of these same issues in humans, the highly distributed and multiplexed organization of parietofrontal neurons necessarily constrain the types of intention-related signals that can be detected with traditional fMRI analysis techniques. Here we employed multivoxel pattern analysis (MVPA), a multivariate technique sensitive to spatially distributed fMRI patterns, to provide a more detailed understanding of how hand and eye movement plans are coded in human parieto-frontal cortex. Subjects performed an event-related delayed movement task requiring that a reach or saccade be planned and executed toward one of two spatial target positions. We show with MVPA that, even in the absence of signal amplitude differences, the fMRI spatial activity patterns preceding movement onset are predictive of upcoming reaches and saccades and their intended directions. Within certain parieto-frontal regions we show that these predictive activity patterns reflect a similar spatial target representation for the hand and eye. Within some of the same regions, we further demonstrate that these preparatory spatial signals can be discriminated from nonspatial, effector-specific signals. In contrast to the largely graded effector-and direction-related planning responses found with fMRI subtraction methods, these results reveal considerable consensus with the parieto-frontal network organization suggested from primate neurophysiology and specifically show how predictive spatial and nonspatial movement information coexists within single human parieto-frontal areas.

Section: Frontal Cortex Decodingsupporting

confidence: 79%

Decoding Effector-Dependent and Effector-Independent Movement Intentions from Human Parieto-Frontal Brain Activity

Gallivan

McLean

Smith³

et al. 2011

155

171

“…Another approach was to compare the neural activity during the CD task and the control task, and the results suggest that (1) the majority of choice-related neurons were not modulated by the movement, and (2) for the remainder of neurons is the decision to move rather than the movement itself that drives them. In fact, goal-directed saccades are sparsely represented in the PMv (Fujii et al, 1998), suggesting an intermediate representation of directional information.…”

Section: Neural Correlates Of the Decisionmentioning

confidence: 99%

Neural Correlates of Decisions and Their Outcomes in the Ventral Premotor Cortex

Pardo-Vázquez¹,

Leborán²,

Acuña³

2008

105

Selection of the appropriate action in a changing environment involves a chain of events that goes from perception through decision to action and evaluation of the outcomes. What and where in the brain are the correlates of these events? The ventral premotor cortex (PMv) is a candidate because (1) it is involved in sensory transformations for visually guided actions and in perceptual decisions, and (2) it is connected with sensory, motor, and high-level cognitive areas related to performance monitoring. Therefore, we hypothesized that it would be the site for representing sensory perception for action and for evaluating the decision consequences. Trained monkeys were required to discriminate the orientation of two lines showed in sequence and separated by a delay. Monkeys compared the orientation of the second line with the memory trace of the first and communicated whether the second was to the left or to the right of the first. Here we show that the activity of PMv neurons reflected (1) the first stimuli and its memory trace during the delay and comparison periods, (2) its comparison with the second stimuli, including the strength of the evidence, and (3) the result of the discrimination (choice). After the monkeys reported the choice, there were neurons that only encoded the choices, others only the outcomes, and others the choices and outcomes together. The representation of task cues, decision variables, and their outcomes suggest a role of PMv as part of a supervisory network involved in shaping future behavior and in learning.

“…Near the fundus of the posterior bank of the AS, a small region sandwiched between the small saccade area of the FEF and the somatic premotor cortex is involved in smooth pursuit MacAvoy et al, 1991). Behind it, a region near the arcuate spur contains cells discharging in relation to saccades, eye position, and smooth pursuit (Fukushima et al, 2002;Tanaka and Lisberger, 2002), whereas microstimulation of a restricted part of the ventral premotor cortex in the postarcuate convexity has been shown to evoke saccades (Fujii et al, 1998).…”

Section: The Arcuate Sulcusmentioning

confidence: 99%

Oculomotor Areas of the Primate Frontal Lobes: A Transneuronal Transfer of Rabies Virus and [¹⁴C]-2-Deoxyglucose Functional Imaging Study

Moschovakis¹,

Gregoriou²,

Ugolini³

et al. 2004

We used the [14 C]-2-deoxyglucose method to study the location and extent of primate frontal lobe areas activated for saccades and fixation and the retrograde transneuronal transfer of rabies virus to determine whether these regions are oligosynaptically connected with extraocular motoneurons. Fixation-related increases of local cerebral glucose utilization (LCGU) values were found around the fundus of the inferior limb of the arcuate sulcus (AS) just ventral to its genu, in the dorsomedial frontal cortex (DMFC), cingulate cortex, and orbitofrontal cortex. Significant increases of LCGU values were found in and around both banks of the AS, DMFC, and caudal principal, cingulate, and orbitofrontal cortices of monkeys executing visually guided saccades. All of these areas are oligosynaptically connected to extraocular motoneurons, as shown by the presence of retrogradely transneuronally labeled cells after injection of rabies virus in the lateral rectus muscle. Our data demonstrate that the arcuate oculomotor cortex occupies a region considerably larger than the classic, electrical stimulation-defined, frontal eye field. Besides a large part of the anterior bank of the AS, it includes the caudal prearcuate convexity and part of the premotor cortex in the posterior bank of the AS. They also demonstrate that the oculomotor DMFC occupies a small area straddling the ridge of the brain medial to the superior ramus of the AS. Our results support the notion that a network of several interconnected frontal lobe regions is activated during rapid, visually guided eye movements and that their output is conveyed in parallel to subcortical structures projecting to extraocular motoneurons.