Laminar Dynamics of Target Selection in the Posterior Parietal Cortex of the Common Marmoset.

The lateral intraparietal area (LIP) plays a crucial role in target selection and attention in primates, but the laminar microcircuitry of this region is largely unknown. To address this, we used ultra-high density laminar electrophysiology with Neuropixels probes to record neural activity in the posterior parietal cortex (PPC) of two adult marmosets while they performed a simple visual target selection task. Our results reveal neural correlates of visual target selection in the marmoset, similar to those observed in macaques and humans, with distinct timing and profiles of activity across cell types and cortical layers.

A ubiquitous spectrolaminar motif of local field potential power across the primate cortex.

The mammalian cerebral cortex is anatomically organized into a six-layer motif. It is currently unknown whether a corresponding laminar motif of neuronal activity patterns exists across the cortex. Here we report such a motif in the power of local field potentials (LFPs).

Delay-related activity in marmoset prefrontal cortex.

Persistent delay-period activity in prefrontal cortex (PFC) has long been regarded as a neural signature of working memory (WM). Electrophysiological investigations in macaque PFC have provided much insight into WM mechanisms; however, a barrier to understanding is the fact that a portion of PFC lies buried within the principal sulcus in this species and is inaccessible for laminar electrophysiology or optical imaging. The relatively lissencephalic cortex of the New World common marmoset (Callithrix jacchus) circumvents such limitations.

Simultaneous functional MRI of two awake marmosets.

Social cognition is a dynamic process that requires the perception and integration of a complex set of idiosyncratic features between interacting conspecifics. Here we present a method for simultaneously measuring the whole-brain activation of two socially interacting marmoset monkeys using functional magnetic resonance imaging. MRI hardware (a radiofrequency coil and peripheral devices) and image-processing pipelines were developed to assess brain responses to socialization, both on an intra-brain and inter-brain level.

Interspecies activation correlations reveal functional correspondences between marmoset and human brain areas.

The common marmoset has enormous promise as a nonhuman primate model of human brain functions. While resting-state functional MRI (fMRI) has provided evidence for a similar organization of marmoset and human cortices, the technique cannot be used to map the functional correspondences of brain regions between species. This limitation can be overcome by movie-driven fMRI (md-fMRI), which has become a popular tool for noninvasively mapping the neural patterns generated by rich and naturalistic stimulation.

Ketamine disrupts gaze patterns during face viewing in the common marmoset.

Faces are stimuli of critical importance for primates. The common marmoset () is a promising model for investigations of face processing, as this species possesses oculomotor and face-processing networks resembling those of macaques and humans. Face processing is often disrupted in neuropsychiatric conditions such as schizophrenia (SZ), and thus, it is important to recapitulate underlying circuitry dysfunction preclinically.

A Novel Three-Choice Touchscreen Task to Examine Spatial Attention and Orienting Responses in Rodents.

Mammalian orienting behavior consists of coordinated movements of the eyes, head, pinnae, vibrissae, or body to attend to an external stimulus. The present study aimed to develop a novel operant task using a touch-screen system to measure spatial attention. In this task, rats were trained to nose-poke a light stimulus presented in one of three locations.

Face selective patches in marmoset frontal cortex.

In humans and macaque monkeys, socially relevant face processing is accomplished via a distributed functional network that includes specialized patches in frontal cortex. It is unclear whether a similar network exists in New World primates, who diverged ~35 million years from Old World primates. The common marmoset is a New World primate species ideally placed to address this question given their complex social repertoire.

Single-unit activity in marmoset posterior parietal cortex in a gap saccade task.

Abnormal saccadic eye movements can serve as biomarkers for patients with several neuropsychiatric disorders. The common marmoset () is becoming increasingly popular as a nonhuman primate model to investigate the cortical mechanisms of saccadic control. Recently, our group demonstrated that microstimulation in the posterior parietal cortex (PPC) of marmosets elicits contralateral saccades.

Functional Localization of the Frontal Eye Fields in the Common Marmoset Using Microstimulation.

The frontal eye field (FEF) is a critical region for the deployment of overt and covert spatial attention. Although investigations in the macaque continue to provide insight into the neural underpinnings of the FEF, due to its location within a sulcus, the macaque FEF is virtually inaccessible to electrophysiological techniques such as high-density and laminar recordings. With a largely lissencephalic cortex, the common marmoset () is a promising alternative primate model for studying FEF microcircuitry.

Electrical microstimulation evokes saccades in posterior parietal cortex of common marmosets.

The common marmoset () is a small-bodied New World primate increasing in prominence as a model animal for neuroscience research. The lissencephalic cortex of this primate species provides substantial advantages for the application of electrophysiological techniques such as high-density and laminar recordings, which have the capacity to advance our understanding of local and laminar cortical circuits and their roles in cognitive and motor functions. This is particularly the case with respect to the oculomotor system, as critical cortical areas of this network such as the frontal eye fields (FEF) and lateral intraparietal area (LIP) lie deep within sulci in macaques.

Task-based fMRI of a free-viewing visuo-saccadic network in the marmoset monkey.

Saccadic tasks are often used to index aberrations of cognitive function in patient populations, with several neuropsychiatric and neurologic disorders characterized by saccadic dysfunction. The common marmoset (Callithrix jacchus) has received recent attention as an additional primate model for studying the neural basis of these dysfunctions - marmosets are amenable to a host of genetic manipulation techniques and have a lissencephalic cortex, which is well suited for a variety of recording techniques (e.g.

In vivo manganese tract tracing of frontal eye fields in rhesus macaques with ultra-high field MRI: Comparison with DWI tractography.

The saccadic eye movement system has emerged as a valuable model for studying neural circuitry related to flexible control of behavior. Although connections of the saccadic circuitry are well documented via histochemical tracers, these methods require fixed tissue and thus cannot provide longitudinal assessments of connectivity. To circumvent this, diffusion weighted imaging (DWI) is often used as a proxy for connectivity in vivo, allowing for the tracing of connections longitudinally and noninvasively.

Methods for chair restraint and training of the common marmoset on oculomotor tasks.

The oculomotor system is the most thoroughly understood sensorimotor system in the brain, due in large part to electrophysiological studies carried out in macaque monkeys trained to perform oculomotor tasks. A disadvantage of the macaque model is that many cortical oculomotor areas of interest lie within sulci, making high-density array and laminar recordings impractical. Many techniques of molecular biology developed in rodents, such as optogenetic manipulation of neuronal subtypes, are also limited in this species.

Looking beyond 5-HT(3) receptors: a review of the wider role of serotonin in the pharmacology of nausea and vomiting.

The concept that 5-hydroxytryptamine (5-HT; serotonin) is involved in the emetic reflex was revealed using drugs that interfere with its synthesis, storage, release and metabolism ahead of the discovery of selective tools to modulate specific subtypes of receptors. This review comprehensively examines the fundamental role of serotonin in emesis control and highlights data indicating association of 5-HT1-4 receptors in the emetic reflex, whilst leaving open the possibility that 5-HT5-7 receptors may also be involved. The fact that each receptor subtype may mediate both emetic and anti-emetic effects is discussed in detail for the first time.

Conscious sedation for awake fibreoptic intubation: a review of the literature.

Purpose: Awake fibreoptic intubation (AFOI) is the gold standard of management of the predicted difficult airway. Sedation is frequently used to make the process more tolerable to patients. It is not always easy to strike a balance between patient comfort and good intubating conditions on the one hand and maintaining ventilation and a patent airway on the other.

The effect of anesthetic technique on recovery after orthognathic surgery: a retrospective audit.

We audited the recovery characteristics of 51 patients who had undergone orthognathic maxillofacial surgery at a single center. Patients whose anesthesia had been maintained with intravenous propofol and remifentanil (n  =  21) had significantly higher pain scores during the first 4 hours after surgery than those whose anesthesia was maintained with volatile inhalational agents and longer-acting opioids (n  =  30) (P  =  .016).

The potential for mu-opioid receptor agonists to be anti-emetic in humans: a review of clinical data.

In animal models of vomiting, mu-opioid (MOP, OP(3)) receptors mediate both emesis and anti-emesis. mu-receptors within the blood-brain barrier, mediating anti-emesis, are more rapidly accessible to lipid-soluble mu-opioid receptor agonists such as fentanyl than to morphine, and fentanyl has broad-spectrum anti-emetic effects in a number of species. Whether a similar situation exists in humans is not known.

Effects of acute ethyl alcohol consumption on a psychophysical measure of lateral inhibition in human vision.

Acute consumption of ethyl alcohol affects a variety of visual functions. However, there have been few systematic attempts to investigate the neural mechanisms underlying these effects. Here, we employed the Westheimer paradigm to investigate the hypothesis that alcohol reduces lateral inhibition within human "perceptive fields", the psychophysical analogue of physiological receptive fields.

Action of 5-HT3 receptor antagonists and dexamethasone to modify cisplatin-induced emesis in Suncus murinus (house musk shrew).

Ondansetron (1-3 mg/kg), granisetron (0.3-1 mg/kg) and dexamethasone (0.3-1 mg/kg), administered at 12-h intervals, were investigated for their potential to prevent cisplatin (30 mg/kg, i.