Structure and Function of Neural Circuits

Our decisions, which are often based on sensory information, are ultimately manifested as behaviours, such as our eye movements (e.g., shifting one's gaze to the stimulus of interest). The goal of the proposed research is to uncover the structure and function of neural circuits that convert visual information into motor commands. The oculomotor system is an ideal model for investigating this question because eye movements are easy to quantify and the cortical areas involved in visuomotor transformation have been well identified.

The Frontal Eye Field

The frontal eye field (FEF) is one such area that is involved in this process. First, the role of the FEF in producing saccadic eye movements is well established. Anatomically, the FEF send efferents to oculomotor structures including the superior colliculus and brainstem oculomotor centres (Fries, 1984; Huerta et al., 1986; Collins et al., 2005).  Electrical stimulation in the FEF elicits saccadic eye movements (Blum et al., 1982; Bruce et al., 1985), and reversible inactivation of the FEF severely disrupts saccades and fixations (Sommer and Tehovnik, 1997; Dias and Segraves, 1999). In addition to its role in saccades, the FEF receives afferents from extrastriate visual areas (Schall et al., 1995), and has been shown to play an important role in visual information processing (Sato et al., 2001; Sato and Schall, 2003; Awh et al., 2006).

Visual Information Processing

Consistent with the role of the FEF in visuomotor transformations, neurons in the FEF exhibit diverse activity patterns ranging from visual responses to saccade-related bursts of activity (Bruce and Goldberg, 1985). I have previously shown that, for some neurons, the activity can be associated with visual information processing rather than saccadic eye movements (Sato and Schall, 2003).  Although a number of models have been proposed on information processing in the FEF, without clear understanding of how the activity patterns of neurons relate to information processing by the neural circuit, the models remains speculative.