Fast spiking interneuron activity in primate striatum tracks learning of attention cues.

Cognitive flexibility depends on a fast neural learning mechanism for enhancing momentary relevant over irrelevant information. A possible neural mechanism realizing this enhancement uses fast spiking interneurons (FSIs) in the striatum to train striatal projection neurons to gate relevant and suppress distracting cortical inputs. We found support for such a mechanism in nonhuman primates during the flexible adjustment of visual attention in a reversal learning task.

Multineuromodulator measurements across fronto-striatal network areas of the behaving macaque using solid-phase microextraction.

Different neuromodulators rarely act independent from each other to modify neural processes but are instead coreleased, gated, or modulated. To understand this interdependence of neuromodulators and their collective influence on local circuits during different brain states, it is necessary to reliably extract local concentrations of multiple neuromodulators in vivo. Here we describe results using solid-phase microextraction (SPME), a method providing sensitive, multineuromodulator measurements.

Solid Phase Microextraction-Based Miniaturized Probe and Protocol for Extraction of Neurotransmitters from Brains in Vivo.

Despite the importance of monitoring and correlating neurotransmitter concentrations in the brain with observable behavior and brain areas in which they act, in vivo measurement of multiple neurochemicals in the brain remains a challenge. Here, we propose an alternative solid phase microextraction-based (SPME) chemical biopsy approach as a viable method for acquirement of quantitative information on multiple neurotransmitters by one device within a single sampling event, with multisite measurement capabilities and minimized invasiveness, as no tissue is removed. The miniaturized SPME probe developed for integrated in vivo sampling/sample preparation has been thoroughly optimized with respect to probe shape, desorption solvent, and extracting phase tailored for extraction of small hydrophilic molecules via synthesis and functionalization of the SPME coating.

Feature-specific prediction errors and surprise across macaque fronto-striatal circuits.

To adjust expectations efficiently, prediction errors need to be associated with the precise features that gave rise to the unexpected outcome, but this credit assignment may be problematic if stimuli differ on multiple dimensions and it is ambiguous which feature dimension caused the outcome. Here, we report a potential solution: neurons in four recorded areas of the anterior fronto-striatal networks encode prediction errors that are specific to feature values of different dimensions of attended multidimensional stimuli. The most ubiquitous prediction error occurred for the reward-relevant dimension.

Asymmetric effective connectivity between primate anterior cingulate and lateral prefrontal cortex revealed by electrical microstimulation.

The dorsal anterior cingulate cortex (dACC) and lateral prefrontal cortex (lPFC) of the non-human primate show neural firing correlations and synchronize at theta and beta frequencies during the monitoring and shifting of attention. These functional interactions might be based on synaptic connectivity that is equally efficacious in both directions, but it might be that there are systematic asymmetries in connectivity consistent with reports of more effective inhibition within the dACC than lPFC, or with a preponderance of dACC projections synapsing onto inhibitory neurons in the lPFC. Here, we tested effective dACC-lPFC connectivity in awake monkeys and report systematic asymmetries in the temporal patterning and latencies of effective connectivity as measured using electrical microstimulation.