Brain-wide functional connectivity of face patch neurons during rest.

The brain is a highly organized, dynamic system whose network architecture is often assessed through resting functional magnetic resonance imaging (fMRI) functional connectivity. The functional interactions between brain areas, including those observed during rest, are assumed to stem from the collective influence of action potentials carried by long-range neural projections. However, the contribution of individual neurons to brain-wide functional connectivity has not been systematically assessed.

Cortical microcircuitry of performance monitoring.

The medial frontal cortex enables performance monitoring, indexed by the error-related negativity (ERN) and manifested by performance adaptations. We recorded electroencephalogram over and neural spiking across all layers of the supplementary eye field, an agranular cortical area, in monkeys performing a saccade-countermanding (stop signal) task. Neurons signaling error production, feedback predicting reward gain or loss, and delivery of fluid reward had different spike widths and were concentrated differently across layers.

Microcircuitry of agranular frontal cortex: contrasting laminar connectivity between occipital and frontal areas.

Neocortex is striking in its laminar architecture. Tracer studies have uncovered anatomical connectivity among laminae, but the functional connectivity between laminar compartments is still largely unknown. Such functional connectivity can be discerned through spontaneous neural correlations during rest.

Microsaccade production during saccade cancelation in a stop-signal task.

We obtained behavioral data to evaluate two alternative hypotheses about the neural mechanisms of gaze control. The "fixation" hypothesis states that neurons in rostral superior colliculus (SC) enforce fixation of gaze. The "microsaccade" hypothesis states that neurons in rostral SC encode microsaccades rather than fixation per se.

Microcircuitry of agranular frontal cortex: testing the generality of the canonical cortical microcircuit.

We investigated whether a frontal area that lacks granular layer IV, supplementary eye field, exhibits features of laminar circuitry similar to those observed in primary sensory areas. We report, for the first time, visually evoked local field potentials (LFPs) and spiking activity recorded simultaneously across all layers of agranular frontal cortex using linear electrode arrays. We calculated current source density from the LFPs and compared the laminar organization of evolving sinks to those reported in sensory areas.

Current advances and pressing problems in studies of stopping.

The stop-signal task probes agents' ability to inhibit responding. A well-known race model affords estimation of the duration of the inhibition process. This powerful approach has yielded numerous insights into the neural circuitry underlying response control, the specificity of inhibition across effectors and response strategies, and executive processes such as performance monitoring.

Event-related potentials elicited by errors during the stop-signal task. I. Macaque monkeys.

The error-related negativity (ERN) and positivity (Pe) are components of event-related potential (ERP) waveforms recorded from humans and are thought to reflect performance monitoring. Error-related signals have also been found in single-neuron responses and local-field potentials recorded in supplementary eye field and anterior cingulate cortex of macaque monkeys. However, the homology of these neural signals across species remains controversial.

Measurement of the extraocular spike potential during saccade countermanding.

The stop signal task is used to investigate motor inhibition. Several groups have reported partial electromyogram (EMG) activation when subjects successfully withhold manual responses and have used this finding to define the nature of response inhibition properties in the spinal motor system. It is unknown whether subthreshold EMG activation from extraocular muscles can be detected in the saccadic response version of the stop signal task.

Anorexigenic effects of central neuropeptide S involve the hypothalamus in chicks (Gallus gallus).

Neuropeptide S (NPS) affects appetite-related processes in mammals. However, its role in avian biology is unreported. We hypothesized that intracerebroventricular (ICV) NPS would cause anorexigenic effects in chicks (Gallus gallus).