Cortical Response to Acute Implantation of the Utah Optrode Array in Macaque Cortex.

Optogenetics has transformed the study of neural circuit function, but limitations in its application to species with large brains, such as non-human primates (NHPs), remain. A major challenge in NHP optogenetics is delivering light to sufficiently large volumes of deep neural tissue with high spatiotemporal precision, without simultaneously affecting superficial tissue. To overcome these limitations, we recently developed and tested in NHP cortex, the Utah Optrode Array (UOA).

optogenetics using a Utah Optrode Array with enhanced light output and spatial selectivity.

Optogenetics allows the manipulation of neural circuitswith high spatial and temporal precision. However, combining this precision with control over a significant portion of the brain is technologically challenging (especially in larger animal models).Here, we have developed, optimised, and tested, the Utah Optrode Array (UOA), an electrically addressable array of optical needles and interstitial sites illuminated by 181LEDs and used to optogenetically stimulate the brain.

optogenetics using a Utah Optrode Array with enhanced light output and spatial selectivity.

Optogenetics allows manipulation of neural circuits with high spatial and temporal precision. However, combining this precision with control over a significant portion of the brain is technologically challenging (especially in larger animal models). Here, we have developed, optimised, and tested in vivo, the Utah Optrode Array (UOA), an electrically addressable array of optical needles and interstitial sites illuminated by 181 µLEDs and used to optogenetically stimulate the brain.

An optrode array for spatiotemporally-precise large-scale optogenetic stimulation of deep cortical layers in non-human primates.

Optogenetics has transformed studies of neural circuit function, but remains challenging to apply to non-human primates (NHPs). A major challenge is delivering intense, spatiotemporally-precise, patterned photostimulation across large volumes in deep tissue. Such stimulation is critical, for example, to modulate selectively deep-layer corticocortical feedback circuits.

A neural correlate of perceptual segmentation in macaque middle temporal cortical area.

High-resolution vision requires fine retinal sampling followed by integration to recover object properties. Importantly, accuracy is lost if local samples from different objects are intermixed. Thus, segmentation, grouping of image regions for separate processing, is crucial for perception.

Distinct Laminar Processing of Local and Global Context in Primate Primary Visual Cortex.

Visual perception is affected by spatial context. In visual cortex, neuronal responses to stimuli inside the receptive field (RF) are suppressed by stimuli in the RF surround. To understand the circuits and cortical layers processing spatial context, we simultaneously recorded across all layers of macaque primary visual cortex while presenting stimuli at increasing distances from the recorded cells' RF.

Interaction between orbital prefrontal and rhinal cortex is required for normal estimates of expected value.

Predicting and valuing potential rewards requires integrating sensory, associative, and contextual information with subjective reward preferences. Previous work has identified regions in the prefrontal cortex and medial temporal lobe believed to be important for each of these functions. For example, activity in the orbital prefrontal cortex (PFo) encodes the specific sensory properties of and preferences for rewards, while activity in the rhinal cortex (Rh) encodes stimulus-stimulus and stimulus-reward associations.

Reward processing: a global brain phenomenon?

Rewards and punishments (reinforcement) powerfully shape behavior. Accordingly, their neuronal representation is of significant interest, both for understanding normal brain-behavior relationships and the pathophysiology of disorders such as depression and addiction. A recent article by Vickery and colleagues (Neuron 72: 166-177, 2011) provides evidence that the neural response to rewards and punishments is surprisingly widespread, suggesting the need for examination of the specific roles of areas not commonly included in the canonical reward circuitry in processing reinforcement.

Intersection of reward and memory in monkey rhinal cortex.

In humans and other animals, the vigor with which a reward is pursued depends on its desirability, that is, on the reward's predicted value. Predicted value is generally context-dependent, varying according to the value of rewards obtained in the recent and distant past. Signals related to reward prediction and valuation are believed to be encoded in a circuit centered around midbrain dopamine neurons and their targets in the prefrontal cortex and basal ganglia.

Stimulus onset quenches neural variability: a widespread cortical phenomenon.

Neural responses are typically characterized by computing the mean firing rate, but response variability can exist across trials. Many studies have examined the effect of a stimulus on the mean response, but few have examined the effect on response variability. We measured neural variability in 13 extracellularly recorded datasets and one intracellularly recorded dataset from seven areas spanning the four cortical lobes in monkeys and cats.