Spiral waves are a basic feature of excitable systems. Although such waves have been observed in a variety of biological systems, they have not been observed in the mammalian cortex during neuronal activity. Here, we report stable rotating spiral waves in rat neocortical slices visualized by voltage-sensitive dye imaging. Tissue from the occipital cortex (visual) was sectioned parallel to cortical lamina to preserve horizontal connections in layers III-V (500-m-thick, ϳ4 ϫ 6 mm 2 ). In such tangential slices, excitation waves propagated in two dimensions during cholinergic oscillations. Spiral waves occurred spontaneously and alternated with plane, ring, and irregular waves. The rotation rate of the spirals was ϳ10 turns per second, and the rotation was linked to the oscillations in a one-cycle-one-rotation manner. A small (Ͻ128 m) phase singularity occurred at the center of the spirals, about which were observed oscillations of widely distributed phases. The phase singularity drifted slowly across the tissue (ϳ1 mm/10 turns). We introduced a computational model of a cortical layer that predicted and replicated many of the features of our experimental findings. We speculate that rotating spiral waves may provide a spatial framework to organize cortical oscillations.

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Negative emotion influences cognitive control, and more specifically conflict adaptation. However, discrepant results have often been reported in the literature. In this study, we broke down negative emotion into integral and incidental components using a modern motivation-based framework, and assessed whether the former could change conflict adaptation. In the first experiment, we manipulated the duration of the inter-trial-interval (ITI) to assess the actual time-scale of this effect. Integral negative emotion was induced by using loss-related feedback contingent on task performance, and measured at the subjective and physiological levels. Results showed that conflict-driven adaptive control was enhanced when integral negative emotion was elicited, compared to a control condition without changes in defensive motivation. Importantly, this effect was only found when a short, as opposed to long ITI was used, suggesting that it had a short time scale. In the second experiment, we controlled for effects of feature repetition and contingency learning, and replicated an enhanced conflict adaptation effect when integral negative emotion was elicited and a short ITI was used. We interpret these new results against a standard cognitive control framework assuming that integral negative emotion amplifies specific control signals transiently, and in turn enhances conflict adaptation.

Four high resolution depth encoding small animal PET detectors were developed using dual-ended readout of pixelated scintillator arrays with SiPMs. The performance results show that those detectors can be used to build a small animal PET scanner to simultaneously achieve uniform high spatial resolution and high sensitivity.

Background Recent neuroimaging studies have reported grey matter alterations in primary trigeminal neuralgia patients. However, few studies have focused on quantitative measurements of trigeminal nerves and the interaction between trigeminal nerve volume and brain morphology, particularly grey matter volume. In this study, we investigated the link between trigeminal nerves and grey matter volume changes in primary trigeminal neuralgia patients compared to healthy controls. Moreover, we explored the association of structure of trigeminal nerves and grey matter to collected pain clinical variables. Methods Eighty participants (40 patients and 40 controls) were recruited for the study. All participants underwent MRI sessions and clinical pain assessment. Trigeminal nerve volume and whole brain grey matter volume were evaluated using quantitative imaging techniques. Sensory and affective pain rating indices were assessed using the visual analog scale and short-form McGill Pain Questionnaire. Mediation analysis was conducted to investigate the relationship between clinical pain variables and volumetric changes in trigeminal nerves and grey matter. Results Decreased trigeminal nerve volume was detected in primary trigeminal neuralgia patients compared to controls. Additionally, reduced grey matter volume was found in several regions associated with pain in primary trigeminal neuralgia subjects, including the insula, secondary somatosensory cortex, hippocampus, dorsal anterior cingulate cortex, precuneus, and several areas of the temporal lobe. Mediation analysis revealed that decreased trigeminal nerve volume drove grey matter volume abnormality of the left insula, and further led to increased pain ratings. Conclusion This study showed a predominantly direct effect of trigeminal nerve atrophy on clinical pain variables in primary trigeminal neuralgia patients, providing new insight into the pathophysiology of the disease. Trial registration ClinicalTrials.gov ID: NCT02713646.

We have examined the spatiotemporal properties of ensemble activity, an evoked all-or-none polysynaptic activity in rat neocortical slices. Ensemble activity occurred in cortical slices bathed in normal artificial cerebrospinal fluid (ACSF) and was evoked by a single electrical shock either to the white matter or directly to the cortical tissue. This activity was seen in slices of somatosensory and auditory cortices; in other cortical areas we have not been able to evoke it. The activity developed 10 to 250 ms poststimulus and lasted 280 +/- 120 ms in local field potential (LFP) recordings. Voltage-sensitive dye imaging showed that this activity was an area of activation 0.8 +/- 0.4 mm wide that propagated slowly (11.4 +/- 6.2 mm/s, n = 60, 6 animals) in the horizontal direction. Due to this propagation, the actual duration in the whole tissue may be longer (approximately 400 ms) than that recorded by a single LFP electrode. Ensemble activity produced a low-amplitude optical signal (7-14% of the interictal-like spikes in the same tissue), suggesting a moderate net depolarization of the population. These were very different from hyperexcitable (epileptiform) events in the same tissue that had about 10 times the optical signal amplitude and propagated at 125 +/- 24 mm/s (n = 21, 6 animals). On a global spatial scale (approximately 0.8 mm wide in layers II-III) ensemble activity had a smooth waveform in voltage-sensitive dye signals (population transmembrane potential). On a local scale, field potential recordings showed large fluctuations with complex oscillations and substantial trial-to-trial variation. This suggests that oscillations in cortical circuits occurred only in small clusters of correlated neurons. Ensemble activity was sensitive to the excitation-inhibition balance of the local network. Antagonists of N-methyl-D-aspartate, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, and GABAa receptors, and muscarinic agonists and other modest manipulations such as increasing bath concentration of Mg(2+) to 2.5-4 mM (normally at 2 mM), or K(+) to 5-7 mM (normally 3 mM), all significantly reduced the probability of evoking the activity. The metabotropic glutamate receptor agonist, aminocyclopentane-1,3-dicarboxylic acid, blocked the activity at a low concentration (10-15 microM), while the antagonist (R,S)-alpha-methyl-4-carboxyphenylglycine had no effect even at high concentration (240 microM). Our data suggest that locally organized neuronal clusters may play a role in the organization of oscillatory activities in the gamma band and may participate in cortical integration/amplification occurring on a scale of approximately 1 mm x 300 ms.

PET scanners using SiPMs as photodetectors could have tens of thousands of SiPMs. To simplify the readout electronics, analog signal multiplexing readouts are always preferred to be used as early as possible. In this paper, two simple analog signal multiplexing readouts, a capacitive charge-division readout, and a resistive charge-division readout were evaluated and compared using dual-ended readout detectors based on 10  ×  10 arrays of SensL MicroFJ-30035 SiPMs coupled to both ends of a 20  ×  20 LYSO array with a pitch size of 1.5 mm and a length of 20 mm. The performance of the detectors were evaluated at different bias voltages (from 27.0 V to 30.5 V with an interval of 0.5 V) and a temperature of 22.8 °C. The flood histograms show that all the crystals in the LYSO array were clearly identified, whilst better flood histogram was obtained using the resistive charge-division readout. At a bias voltage of 29.5V, the flood histogram quality, energy resolution, DOI resolution, and timing resolution of the detector obtained using the capacitive charge-division readout were 3.28  ±  0.85, 18.9%  ±  6.2%, 1.93  ±  0.20 mm, 1.25  ±  0.11 ns respectively, and those obtained using the resistive charge-division readout were 3.57  ±  0.81, 16.9%  ±  6.5%, 1.96  ±  0.23 mm and 1.23  ±  0.07 ns, respectively. Overall, the detector with the resistive charge-division readout provided better performance.

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