RT Journal Article
SR Electronic
T1 Selective Modulation of the Pupil Light Reflex by Prefrontal Cortex Microstimulation
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 2433-16
DO 10.1523/JNEUROSCI.2433-16.2017
A1 R. Becket Ebitz
A1 Tirin Moore
YR 2017
UL http://www.jneurosci.org/content/early/2017/05/02/JNEUROSCI.2433-16.2017.abstract
AB The prefrontal cortex (PFC) is thought to flexibly regulate sensorimotor responses. One way the PFC regulates sensorimotor transformations is to modulate activity in other circuits. However, the scope of that control remains unknown: it remains unclear whether the prefrontal cortex can modulate basic reflexes. One canonical example of a central reflex is the pupil light reflex (PLR): the automatic constriction of the pupil in response to luminance increments. Unlike pupil size, which depends the interaction of multiple physiological and neuromodulatory influences, the PLR reflects the action of a simple brainstem circuit. However, emerging behavioral evidence suggests that the PLR may be modulated by cognitive processes. Although the neural basis of these modulations remains unknown, one possible source is the PFC, particularly the frontal eye field (FEF), an area of the PFC implicated in the control of attention. We show that microstimulation of the rhesus macaque FEF alters the magnitude of the PLR in a spatially-specific manner. FEF microstimulation enhanced the PLR to probes presented within the stimulated visual field, but suppressed the PLR to probes at non-overlapping locations. The spatial specificity of this effect parallels the effect of FEF stimulation on attention and suggests that FEF is capable of modulating visuomotor transformations carried out at a lower level than was previously known. These results provide evidence of the selective regulation of a basic brainstem reflex by the PFC.Significance Statement:The pupil light reflex (PLR) is our brain's first and most fundamental mechanism for light adaptation. Though it is often described in textbooks as an immutable reflex, converging evidence suggests that the magnitude of the PLR is modulated by cognitive factors. The neural bases of these modulations are unknown. Here, we report that microstimulation in the prefrontal cortex modulates the gain of the pupil light reflex—changing how a simple reflex circuit responds to physically identical probes. These results suggest that control structures such as the prefrontal cortex can add complexity and flexibility to even a basic brainstem circuit.