Unsupervised functional neurocartography of the Aplysia buccal ganglion

A major limitation of large-scale neuronal recordings is the difficulty in locating the same neuron in different subjects, referred to as the "correspondence" issue. This issue stems, at least in part, from the lack of a unique feature that unequivocally identifies each neuron. One promising approach to this problem is the functional neurocartography framework developed by Frady et al. (2016), in which neurons are identified by a semi-supervised machine learning algorithm using a combination of multiple selected features. Here, the framework was adapted to the buccal ganglia of Aplysia. Multiple features were derived from neuronal activity during motor pattern generation, responses to peripheral nerve stimulation, and the spatial properties of each cell. The feature set was optimized based on its potential usefulness in discriminating neurons from each other, and then used to match putatively homologous neurons across subjects with the functional neurocartography software. A matching method was developed based on a cyclic matching algorithm that allows for unsupervised extraction of groups of neurons, thereby enhancing scalability of the analysis. Cyclic matching was also used to automate the selection of high-quality matches, which allowed for unsupervised implementation of the machine learning algorithm. This study paves the way for investigating the roles of both well-characterized and previously uncharacterized neurons in Aplysia, as well as helps to adapt this framework to other systems.

Territorial Displays of the Ctenophorus decresii Complex: A Story of Local Adaptations

Closely related species make for interesting model systems to study the evolution of signaling behavior because they share evolutionary history but have also diverged to the point of reproductive isolation. This means that while they may have some behavioral traits in common, courtesy of a common ancestor, they are also likely to show local adaptations. The Ctenophorus decresii complex is such a system, and comprises six closely related agamid lizard species from Australia: C. decresii, C. fionni, C. mirrityana, C. modestus, C. tjanjalka, and C. vadnappa. In this study, we analyze the motion displays of five members of the C. decresii complex in the context of their respective habitats by comparing signal structure, habitat characteristics and signal contrast between all species. Motor pattern use and the temporal sequence of motor patterns did not differ greatly, but the motion speed distributions generated during the displays were different for all species. There was also variation in the extent to which signals contrasted with plant motion, with C. vadnappa performing better than the other species at all habitats. Overall, this study provides evidence that members of the C. decresii complex exhibit local adaptations in signaling behavior to their respective habitat, but they also maintain some morphological and behavioral traits in common, which is likely a consequence from the ancestral state.

The role of neuronal excitation and inhibition in the pre-Bötzinger complex on the cough reflex in the cat

Brainstem respiratory neuronal network significantly contributes to cough motor pattern generation. Neuronal populations in the pre-Bötzinger complex (PreBötC) represent a substantial component for respiratory rhythmogenesis. We studied the role of PreBötC neuronal excitation and inhibition on mechanically induced tracheobronchial cough in 15 spontaneously breathing, pentobarbital anesthetized adult cats (35 mg/kg i.v. initially). Neuronal excitation by unilateral microinjection of glutamate analog D,L-homocysteic acid resulted in mild reduction of cough abdominal electromyogram (EMG) amplitudes and very limited temporal changes of cough compared to effects on breathing (very high respiratory rate, high amplitude inspiratory bursts with a short inspiratory phase and tonic inspiratory motor component). Mean arterial blood pressure temporarily decreased. Blocking glutamate related neuronal excitation by bilateral microinjections of non-specific glutamate receptor antagonist kynurenic acid reduced cough inspiratory and expiratory EMG amplitude and shortened most cough temporal characteristics similarly to breathing temporal characteristics. Respiratory rate decreased and blood pressure temporarily increased. Limiting active neuronal inhibition by unilateral and bilateral microinjections of GABAA receptor antagonist gabazine resulted in lower cough number, reduced expiratory cough efforts, and prolongation of cough temporal features and breathing phases (with lower respiratory rate). The PreBötC is important for cough motor pattern generation. Excitatory glutamatergic neurotransmission in the PreBötC is involved in control of cough intensity and patterning. GABAA receptor related inhibition in the PreBötC strongly affects breathing and coughing phase durations in the same manner, as well as cough expiratory efforts. In conclusion, differences in effects on cough and breathing are consistent with separate control of these behaviors.

Locomotion Control With Frequency and Motor Pattern Adaptations

Existing adaptive locomotion control mechanisms for legged robots are usually aimed at one specific type of adaptation and rarely combined with others. Adaptive mechanisms thus stay at a conceptual level without their coupling effect with other mechanisms being investigated. However, we hypothesize that the combination of adaptation mechanisms can be exploited for enhanced and more efficient locomotion control as in biological systems. Therefore, in this work, we present a central pattern generator (CPG) based locomotion controller integrating both a frequency and motor pattern adaptation mechanisms. We use the state-of-the-art Dual Integral Learner for frequency adaptation, which can automatically and quickly adapt the CPG frequency, enabling the entire motor pattern or output signal of the CPG to be followed at a proper high frequency with low tracking error. Consequently, the legged robot can move with high energy efficiency and perform the generated locomotion with high precision. The versatile state-of-the-art CPG-RBF network is used as a motor pattern adaptation mechanism. Using this network, the motor patterns or joint trajectories can be adapted to fit the robot's morphology and perform sensorimotor integration enabling online motor pattern adaptation based on sensory feedback. The results show that the two adaptation mechanisms can be combined for adaptive locomotion control of a hexapod robot in a complex environment. Using the CPG-RBF network for motor pattern adaptation, the hexapod learned basic straight forward walking, steering, and step climbing. In general, the frequency and motor pattern mechanisms complement each other well and their combination can be seen as an essential step toward further studies on adaptive locomotion control.

Validity of the Perceived Physical Ability Scale for Children: An Actigraphic Study

This study aimed to provide evidence of the validity of the Perceived Physical Ability Scale for Children against an external-objective criterion of the 24 h motor activity pattern assessed through actigraphy. A total of 107 children (60 females; mean age 10.25 ± 0.48) were originally enrolled. Children wore the actigraph model Actiwatch AW64 (Cambridge Neurotechnology Ltd., Fenstanton, UK) for seven days, 24 h per day, around the non-dominant wrist. At the beginning of the actigraphic recording, participants filled in the Perceived Physical Ability Scale for Children. Functional Linear Modeling was used to examine variation in the 24 h motor activity pattern according to the total score in the Perceived Physical Ability Scale for Children. Higher physical self-efficacy was significantly related to greater levels of motor activity in the afternoon. Overall, this pattern of results supports the validity of the Perceived Physical Ability Scale for Children against the external-objective criterion of the 24 h motor pattern. The Perceived Physical Ability Scale for Children could represent a promising endpoint for studies assessing the effectiveness of physical activity promotion interventions.

Weakness and Dysarthria After Radiosurgery

A 60-year-old woman with a history of Sjögren syndrome had an episode of painful left eye vision loss. Brain magnetic resonance imaging showed an arteriovenous malformation adjacent to the left ventricular atrium. Although this was considered an asymptomatic lesion, the patient underwent stereotactic radiosurgery to reduce the risk of future growth and hemorrhage. Within days of the surgery, speech disturbance and weakness of the right arm and leg developed. Examination indicated a subcortical language deficit and an upper motor pattern of paresis of right-sided limbs. Considered in the differential diagnosis were new hemorrhage from the arteriovenous malformation, ischemic stroke, radiation-induced necrosis, abscess, and demyelinating disease. Magnetic resonance imaging of the head with and without gadolinium contrast was used to evaluate for these possibilities. Brain magnetic resonance imaging after onset of speech and motor symptoms demonstrated new areas of confluent T2 signal abnormality in the brainstem and deep white matter of the left hemisphere, with some accompanying enhancement but without evidence of hemorrhage or acute stroke. Slow conduction was noted in the left optic nerve on visual evoked potentials. The patient was diagnosed with optic neuritis, with subsequent evolution to multiple sclerosis in the setting of radiosurgery. The patient received intravenous methylprednisolone with full recovery of language function and partial recovery of the hemiparesis, which improved with rehabilitation such that she could walk without a gait aid. Because the patient had more than 1 episode, she was treated with interferon beta-1a for further prevention of multiple sclerosis relapse. Chronic neurotoxicity leading to subcortical dementia occurs in approximately 25% of patients undergoing whole-brain radiotherapy. Histologically, demyelination, as well as necrosis, can be a prominent feature. Among patients with multiple sclerosis or a clinically isolated syndrome, the risk of demyelinating events appears to increase after brain radiotherapy, within the field of treatment.

Rapid-Onset Hemibody Sensory Loss, Incoordination, and Muscle Jerking

A 61-year-old woman with no pertinent medical history had progressive decline in multiple neurologic domains over the course of 2 months. She had development of progressive sensory loss in her left foot that subsequently spread up the left lower extremity and into the left upper extremity; accompanied by a sense of unsteadiness. Later, jerky movements of the left leg occurred while she was lying supine and sometimes when walking. At times, her left hand would wander involuntarily. Later in the course of her symptoms, mild short-term memory loss was also noted. On examination, she was unable to recall her home address, but findings were otherwise normal. She had mild gaze-evoked nystagmus and significant saccadic intrusion of smooth pursuits. A mild upper motor pattern of weakness, action myoclonus, hyperreflexia, and moderate loss of vibration was present on the left. Gait was markedly ataxic. Repeated magnetic resonance imaging of the brain 2 months after illness onset showed right parietal cortical hyperintense signal on diffusion-weighted imaging consistent with cortical ribboning, a common diagnostic finding early in the course of prion disease. Although characteristic of prion disease, similar imaging findings have been reported in autoimmune encephalitis and in the postictal setting. However, the putamen and caudate nucleus also demonstrated subtle asymmetric diffusion-weighted imaging hyperintense signal, which in the clinicoradiologic context is highly specific for prion disease. Electroencephalography showed frequent sharp wave discharges over right posterior temporal and left occipital head regions, along with frontal intermittent rhythmic delta slowing, consistent with encephalopathy (not otherwise specified). Real-time quaking-induced conversion testing of cerebrospinal fluid was positive for misfolded prion proteins. The positive real-time quaking-induced conversion result confirmed a diagnosis of sporadic Creutzfeldt-Jakob disease. The patient’s treatment was palliative. Hospice services implemented a home palliation program. Clonazepam was prescribed to reduce myoclonus. The patient died 18 weeks after onset of her neurologic symptoms. The differential diagnosis of a rapidly progressive multifocal neurologic syndrome includes many considerations but can be focused in complex situations by first confirming lesion localization and characterization with neuroimaging or other objective studies (eg, electromyography).

Intraoperative serosal extracellular mapping of the human distal colon: a feasibility study

Background Cyclic motor patterns (CMP) are the predominant motor pattern in the distal colon, and are important in both health and disease. Their origin, mechanism and relation to bioelectrical slow-waves remain incompletely understood. During abdominal surgery, an increase in the CMP occurs in the distal colon. This study aimed to evaluate the feasibility of detecting propagating slow waves and spike waves in the distal human colon through intraoperative, high-resolution (HR), serosal electrical mapping. Methods HR electrical recordings were obtained from the distal colon using validated flexible PCB arrays (6 × 16 electrodes; 4 mm inter-electrode spacing; 2.4 cm2, 0.3 mm diameter) for up to 15 min. Passive unipolar signals were obtained and analysed. Results Eleven patients (33–71 years; 6 females) undergoing colorectal surgery under general anaesthesia (4 with epidurals) were recruited. After artefact removal and comprehensive manual and automated analytics, events consistent with regular propagating activity between 2 and 6 cpm were not identified in any patient. Intermittent clusters of spike-like activities lasting 10–180 s with frequencies of each cluster ranging between 24 and 42 cpm, and an average amplitude of 0.54 ± 0.37 mV were recorded. Conclusions Intraoperative colonic serosal mapping in humans is feasible, but unlike in the stomach and small bowel, revealed no regular propagating electrical activity. Although sporadic, synchronous spike-wave events were identifiable. Alternative techniques are required to characterise the mechanisms underlying the hyperactive CMP observed in the intra- and post-operative period. New findings The aim of this study was to assess the feasibility of detecting propagating electrical activity that may correlate to the cyclic motor pattern in the distal human colon through intraoperative, high-resolution, serosal electrical mapping. High-resolution electrical mapping of the human colon revealed no regular propagating activity, but does reveal sporadic spike-wave events. These findings indicate that further research into appropriate techniques is required to identify the mechanism of hyperactive cyclic motor pattern observed in the intra- and post-operative period in humans.