Search

Nutrition provides the resources necessary to carry out all the physiological functions organisms require. This has important implications for insect pest management, as polyphagous species can experience considerable nutritional variability, which may impact their response to management tactics.Many studies have shown that dietary protein and carbohydrates play a primary role in insect fitness and that insects regulate their intake of these macronutrients to reach an optimal balance or intake target. Importantly, this intake target can vary across developmental stages, gender, and environmental conditions as physiological requirements change.In this study, we determined the intake target for adult spotted‐wing Drosophila, Drosophila suzukii, an invasive polyphagous fruit pest. We found that adult D. suzukii regulate their intake to meet a 1:4–1:5 protein‐to‐carbohydrate ratio, which is slightly more carbohydrate‐biased than the larval intake target. We also examined the effect of nutritional state on susceptibility to three commonly‐used insecticides by rearing flies on diets with different field‐relevant protein‐to‐carbohydrate ratios and exposing adults to an LC50 dose of zeta‐cypermethrin, spinetoram, or pyrethrin.Overall, female flies had higher survivorship than males, and diet effects varied across insecticides. Diet had no impact in the spinetoram treatments, while the extreme carbohydrate‐ and protein‐biased diets produced the lowest survivorship and reproductive performance in the zeta‐cypermethrin treatments. Survivorship increased with dietary protein in the pyrethrin treatments but reproductive performance did not differ across diets. Our results suggest that tactics, which reduce fly access to dietary protein sources, such as sterilisation, could increase fly susceptibility to insecticides. [ABSTRACT FROM AUTHOR]

Although insecticide formulations and spray rates are optimized to achieve lethal exposure, there are many factors in agricultural settings that can reduce the effective exposure of insect pests. These include weather patterns, timing of application, chemical degradation/volatilization, plant structural complexity, and resistant populations. While sub-lethal exposure to insecticides can still have negative impacts on pest populations, they can also lead to stimulatory, or hormetic, responses that can increase the fitness of surviving insects. Sub-lethal concentrations may also produce increased tolerance in the offspring of surviving adults through transgenerational effects. Sub-lethal effects are pertinent for the invasive fruit pest, spotted-wing Drosophila, Drosophila suzukii (Matsumura), because its small size, diurnal movement patterns, and utilization of hosts with complex plant structures, such as caneberries and blueberries, make effective insecticide applications tenuous. In this study, we measured spotted-wing Drosophila survivorship, reproductive performance, and offspring tolerance in flies exposed to sub-lethal concentrations of three commonly-used insecticides (zeta-cypermethrin, spinetoram, and pyrethrin). We found some evidence for hormesis, with survival effects being sex- and concentration-dependent for all insecticides. Males were far more susceptible to insecticides than females, which in some cases exhibited higher eclosion success and reproductive rates when exposed to sub-lethal doses. We did not observe significant transgenerational effects at sub-lethal concentrations, despite trends of increased offspring viability for zeta-cypermethrin and spinetoram. More research, however, is needed to fully understand the role that sub-lethal effects may play in pest population dynamics, insecticide efficacy, and the development of genetic resistance. [ABSTRACT FROM AUTHOR]

Engineered Genetic Incompatibility (EGI) is an engineered extreme underdominance genetic system wherein hybrid animals are not viable, functioning as a synthetic speciation event. There are several strategies in which EGI could be leveraged for genetic biocontrol of pest populations. We used an agent-based model of Drosophila suzukii (Spotted Wing Drosophila) to determine how EGI would fare with high rates of endemic genetic resistance alleles. We discovered a surprising failure mode wherein field-generated females convert an incompatible male release program into a population replacement gene drive. Local suppression could still be attained in two seasons by tailoring the release strategy to take advantage of this effect, or alternatively in one season by altering the genetic design of release agents. We show in this work that data from modeling can be utilized to recognize unexpected emergent phenomena and a priori inform genetic biocontrol treatment design to increase efficacy. [ABSTRACT FROM AUTHOR]

Modern functional neurosurgery for movement disorders such as Parkinson's disease, tremor, and dystonia involves the placement of focal lesions or the application of deep brain stimulation (DBS) within circuits that modulate motor function. Precise targeting of these motor structures can be further refined by the use of electrophysiological approaches. In particular, microelectrode recordings enable the delineation of neuroanatomic structures. In the course of these operations, there is an opportunity not only to map basal ganglia structures but also to gain insights into how disturbances in neural activity produce movement disorders. In this review, we aim to highlight what the field has uncovered thus far about movement disorders through DBS. The work to date lays the foundation for future studies that will shed further light on dysfunctional circuits mediating diseases of the nervous system and how we might modulate these circuits therapeutically. [ABSTRACT FROM AUTHOR]

Associative plasticity is hypothesized to be an important neurophysiological correlate of memory formation and learning with potentials for applications in neurorehabilitation and for the development of new electrophysiological measures to study disorders of cortical plasticity. We hypothesized that the magnitude of the paired associative stimulation (PAS)-induced long-term potentiation (LTP)-like effect depends on the number of pairs in the PAS protocol. We also hypothesized that homeostatic interaction of PAS with subsequent motor learning is related to the magnitude of the PAS-induced LTP-like effect. We studied 10 healthy subjects. In experiment 1a, subjects received 90 (PAS90), 180 (PAS180), or 270 (PAS270) pairs of stimuli, followed by a dynamic motor practice (DMP) 1 h after the end of the PAS protocols. In experiment 1b, the DMP preceded the PAS protocol. In experiment 2, the time course of PAS270 was studied. We found that PAS270 resulted in greater increase in motor evoked potential (MEP) amplitude compared with protocols with fewer pairs of stimuli. Moreover, the interaction between PAS protocols with motor learning differed depending on the number of stimulus pairs used to induce PAS. While DMP alone increased MEP amplitudes, DMP during the LTP-like effects induced by PAS270 led to a long-term depression (LTD)-like effect (homeostatic interaction). This homeostatic interaction did not occur after PAS90 and PAS180. In conclusion, we found a dose-dependent effect of the number of stimulus pairs used in the PAS protocol on cortical plasticity. Homeostatic interaction between PAS and DMP was observed only after PAS270. [ABSTRACT FROM AUTHOR]

Since the most significant ischemic sequelae occur within hours of stroke, it is necessary to understand how neuronal function changes during this time. While histologic and behavioral models show the extent of stroke-related damage, only in vivo recordings can illustrate changes in brain activity during stroke and validate effectiveness of neuroprotective compounds. Spontaneous and evoked field potentials (fEPs) were recorded in the deep layers of the cortex with a linear microelectrode array for 3 hours after focal stroke in anesthetized rats. Tat-NR2B9c peptide, which confers neuroprotection by uncoupling the PSD-95 protein from N-methyl-D-aspartate receptor (NMDAR), was administered 5 minutes before ischemia. Evoked field potentials were completely suppressed within 3 minutes of infarct in all ischemic groups. Evoked field potential recovery after stroke in rats treated with Tat-NR2B9c (83% of baseline) was greater compared with stroke-only (61% of baseline) or control peptide (Tat-NR2B-AA; 67% of baseline) groups (P<0.001). Electroencephalography (EEG) power was higher in Tat-NR2B9c-treated animals at both 20 minutes and 1 hour (50% and 73% of baseline, respectively) compared with stroke-only and Tat-NR2B-AA-treated rats (P<0.05). Tat-NR2B9c significantly reduces stroke-related cortical dysfunction as evidenced by greater recovery of fEPs and EEG power; illustrating the immediate effects of the compound on poststroke brain function. [ABSTRACT FROM AUTHOR]

Increased oscillations in the beta band are thought to be related to motor symptoms of Parkinson's disease (PD). Previous studies have shown that beta-band desynchronization in the subthalamic nucleus (STN) is reduced just before and during limb movements. While the STN is part of the basal ganglia (BG)-thalamocortical circuit controlling limb movements, it is also part of the BG-brainstem projection controlling saccadic eye movements. Late-stage PD patients have deficits in saccades in addition to difficulties with limb movements arising from impaired functions of the BG. We investigated saccade-related changes in beta-band (15-30 Hz) oscillatory activities in the human STN while PD patients performed visually guided prosaccades and antisaccades, the latter requiring suppression of reflexive responses and volitional initiation of saccades. We recorded local field potentials from deep brain stimulation electrodes implanted in the STN in human PD patients 1 -5 d after surgery and compared prosaccades and antisaccades with these and with limb movements. Saccade-related beta-band desynchronizations were observed just before and during saccades in all subjects, suggesting that reduction of beta-band oscillatory activity in the STN is related to preparation and execution of saccades. Furthermore, beta-band desynchronizations for antisaccades started earlier, were sustained for longer periods, were of greater magnitude, and were observed more often than prosaccades. Beta-band desynchronization in the STN may reflect the additional processes associated with suppression of reflexive responses and volitional execution of saccades in the opposite direction. [ABSTRACT FROM AUTHOR]

Tethered flight mills and free‐flight studies are two common approaches for examining insect flight behavior in the laboratory. Flight behavior studies are significant because they provide information with understanding dispersal and range expansion. Each approach has advantages and drawbacks and can influence the flight behavior of the study organism. However, tethered and untethered flight studies are rarely performed simultaneously to determine whether one technique is better suited for a particular species. Here, we conducted a tethered and untethered flight study to determine the limitations, benefits, and effects the two methods could have on assessing an insect's flight capacity. We focused the study on the global invasive pest, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). Propensity of flight and flight duration, distance, and velocity were examined for (1) females and males, and (2) summer and winter morphs, as the two morphs differ significantly in body and wing size. The study showed that summer morphs were more likely to fly when untethered than when tethered to a flight mill. Additionally, when comparing the length of time of flight for first take‐off, D. suzukii flew longer when untethered. Outcomes from this study provide information on D. suzukii flight behavior, which could assist with future research on this economically important fruit pest that is rapidly expanding its range. The results also suggest that the flight apparatus can affect D. suzukii flight behaviors, such that future laboratory flight research should be considerate of the flight technique utilized. [ABSTRACT FROM AUTHOR]

Abstract: Objective: Deep brain stimulation in the globus pallidus internus (GPi) is used to alleviate the motor symptoms of both Parkinson’s disease (PD) and dystonia. We tested the hypothesis that PD and dystonia are characterized by different temporal patterns of synchronized oscillations in the GPi, and that the dopaminergic loss in PD makes the basal ganglia more susceptible to oscillatory activity. Methods: Neuronal firing and local field potentials (LFPs) were simultaneously recorded from the GPi in four PD patients and seven dystonia patients using two independently driven microelectrodes. Results: In the PD patients, beta (11–30Hz) oscillations were observed in the LFPs and the firing activity of ∼30% of the neurons was significantly coherent with the LFP. However, in the dystonia group, the peak frequency of LFP oscillations was lower (8–20Hz) and there was a significantly smaller proportion of neurons (∼10%) firing in coherence with the LFP (P <0.001). Conclusions: These findings suggest that synchronization of neuronal firing with LFP oscillations is a more prominent feature in PD than in dystonia. Significance: This study adds to the growing evidence that dopaminergic loss in PD may increase the sensitivity of the basal ganglia network to rhythmic oscillatory inputs. [Copyright &y& Elsevier]

Abstract: There is growing evidence that Parkinson''s disease (PD) is associated with pathological synchronous oscillatory activity in the basal ganglia. These synchronized oscillations primarily occur in the 11–30 Hz range, the so-called beta band. Studies of local field potential activity in the subthalamic nucleus (STN) of PD patients suggest that exaggerated beta band oscillatory activity can disrupt function and, in particular, may contribute to slowness of movement. It has been previously shown that the degree of beta oscillatory activity in the STN of PD patients correlates with the patients'' benefit from dopaminergic medications, but not with baseline motor deficits. In a paper that was recently published in Experimental Neurology, [Kuhn A.A., Tsui A., Aziz T., Ray N., Brucke C., Kupsch A., Schneider G.H., Brown P., 2009. Pathological synchronisation in the subthalamic nucleus of patients with Parkinson''s disease relates to both bradykinesia and rigidity. Exp. Neurol. 215, 380–387.] the authors further establish that the degree of suppression of beta oscillations in the STN by dopaminergic medications can predict the level of improvement in bradykinesia and rigidity but not tremor. This commentary reviews some of the recent findings on beta oscillatory activity in PD and highlights the possible role of these pathological oscillations in mediating PD symptoms. [Copyright &y& Elsevier]

Abstract: Local field potentials (LFPs) were recorded in 13 patients from pairs of microelectrodes driven through thalamus during functional localization prior to implantation of a thalamic deep brain stimulation electrode for treatment of tremor or pain. Six patients had a history of essential tremor (ET), 3 of multiple sclerosis, and the remaining 4 had symptoms of chronic pain. Specific to the ET group was the observation that oscillatory field potentials recorded from the two microelectrodes in the motor thalamus (ventralis intermedius — Vim, ventralis oralis posterior — Vop) were highly coherent at frequencies characteristic of pathological tremor (4–7 Hz). This stands in contrast to the significantly more desynchronized state observed in the somatosensory thalamus (ventralis caudalis — Vc) for that frequency band. In addition, higher frequency coherent oscillations typically associated with physiological tremor (8–12 Hz) were observed in the ET patients in motor thalamus and Vc and in motor thalamus of pain patients. An examination of the inter-frequency correlation of the LFPs in Vim and Vop showed that the low frequency theta waves correlated with high frequency oscillations in the beta and gamma ranges. These findings are consistent with and extend those of other studies suggesting that alterations in thalamic oscillatory activity are involved in the pathophysiology of ET and furthermore suggest that increased synchronization in the 4–7 Hz range is related to the occurrence of tremor in the ET patient group. Furthermore, they support the idea that therapies such as lesions and high frequency stimulation of the motor thalamus are effective in reducing tremor symptoms since they destroy the abnormal low frequency synchronization in motor thalamus. [Copyright &y& Elsevier]

The subthalamic nucleus (STN) is an important component of the basal ganglia (BG) and plays a major role in the pathogenesis of Parkinson’s disease (PD). Hyperactivity of STN as a consequence of the loss of dopaminergic inputs to the BG is believed to be a major factor in producing the motor symptoms of PD. High-frequency (HF) deep brain stimulation (DBS) of the STN has recently become an important treatment in PD patients where medications no longer provide satisfactory therapy. However, the mechanisms underlying DBS therapy are unknown, and there is seemingly conflicting data suggesting inhibition or excitation of STN neurons. This study directly examined the effects of stimulation in STN on the activity of STN neurons in PD patients during functional stereotactic mapping prior to insertion of DBS electrodes. Electrical stimulation in STN was investigated in twelve PD patients by recording the neural activity of a cell in STN with one electrode while applying current pulses through a second electrode located about 600 µm away. Stimulation at high frequencies (100–300 Hz) was found to produce inhibition following the stimulus train in 42% of the 60 cells tested. Inhibition during the train was seen in 13 of 15 neurons where it was possible to detect such activity. Furthermore, in 44% of the cases where HF stimulation produced inhibition there was an early inhibition followed by rebound excitation and a further inhibitory period, suggesting that the inhibitions observed are due to hyperpolarization. In eight of the 25 neurons inhibited by HF stimulation, the effects of single stimuli were determined and revealed that in seven of these there was an inhibitory period of 15–20 ms following each stimulus. Thus, the present findings suggest that local HF stimulation inhibits many STN neurons. However, these studies could not determine whether the stimulus also directly excited the cell and/or its axon, but other recent findings suggest that this is likely the case. Therefore, the overall effects of DBS stimulation in STN are likely to be inhibition of intrinsic and synaptically mediated activity, and its replacement by regular high-frequency firing. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is caused by the degeneration of the dopaminergic neurons in the substantia nigra. Loss of dopaminergic innervation leads to hyperactivity in the internal segment of the globus pallidus (GPi), the main output nucleus of the basal ganglia and to a profound disturbance in the function of motor circuits. Lesions of the GPi (or in its upstream modulator, the subthalamic nucleus) can greatly improve the motor symptoms of PD presumably by reducing this pathological activity. Paradoxically, high-frequency electrical stimulation of the GPi (deep brain stimulation, DBS) mimics the effects of pallidotomy and has become an accepted therapeutic technique. The mechanisms underlying the beneficial effects of pallidal DBS are not known. Various mechanisms that might account for inhibiting or disrupting the pathological pallidal outflow by high-frequency DBS have been proposed ranging from depolarization block to stimulation-evoked release of GABA, and these are discussed. [ABSTRACT FROM AUTHOR]

Evaluates maize for allelochemicals that affect European corn borer (ECB) larval development. Association of the high performance liquid chromatography absorption peaks with biological activity; Determination of the influence of ferulic and p-coumaric acid on ECB larvae; Decrease of larval weight.

Temperature is a critical single factor influencing insect population dynamics, and is foundational for improving our understanding of the phenology of invasive species adapting to new agroecosystems or in the process of range expansion. An age-stage, two-sex life table was therefore developed to analyze fundamental demographic features such as development, survival, and reproduction of a Minnesota-acclimated population of the invasive brown marmorated stink bug (Halyomorpha halys), in the north central USA. All salient life history parameters were estimated to better understand the population growth potential of H. halys at the current limit of its northern range in North America. We examined the effect of selected constant temperatures on immature development and survival (15–39 °C), adult reproduction and longevity (17–36 °C) of H. halys in the laboratory. The Minnesota population developed faster and survived at higher rates relative to a population that had previously established in Pennsylvania, USA. Mean generation time for the Minnesota population was minimized at 30 °C, while survival and fecundity were maximized at 27 and 23 °C, respectively. Given these findings, we assessed the effect of temperature on the intrinsic rate of increase ( r m ), the life table parameter that integrates the effects of temperature on development, survival, and reproduction. A Ratkowsky model predicted r m was maximized (0.0899) at 27.5 °C. We discuss the implications of our findings for understanding population growth rates for H. halys in the context of a warming climate, and potential to emerge as a serious crop pest in the Midwest U.S. region. [ABSTRACT FROM AUTHOR]

It is commonly perceived that early defoliation of maize (Zea mays L.) is a significant risk for maximum grain yields. However, several studies designed to assess biotic and abiotic factors that reduce leaf area reported contrasting results. When maize suffers defoliation before developing its seventh leaf (V7 stage), plants can often compensate without impacting grain production. Seventy-five percent of 20 reviewed publications that offer empirical information indicated severe defoliation did not affect maize yield when plants were less than V7. We present field results for six maize hybrids, lines, and a landrace with severe (75%) defoliation one, two, or three times before reaching V7, in Maryland. Results showed that despite multiple, severe defoliation, there were no significant differences in grain yield (P > 0.05). Despite seven amounts of defoliation, yields for each defoliation amount did not differ from yields for intact plants. One early defoliation at V2 significantly produced more grain than did the nondefoliated check (P < 0.05). Results confirm the ability of maize to compensate or over-compensate for vegetative-stage defoliation. Results are also discussed in relation to recent reviews of previous studies. It is imperative to reconsider unnecessary recommendations to apply insecticide against maize defoliators when maize plants have yet to develop the seventh leaf. [ABSTRACT FROM AUTHOR]

Population responses to environmental extremes often dictate the bounds to species' distributions. However, population dynamics at, or near, those range limits may also be affected by sublethal effects. We exposed late instars and pupae of an invasive leafroller, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), to cold temperatures and measured the effects of exposure on subsequent survivorship, development, and reproduction. Cold temperature was applied as acute exposure to –10 °C (a low, but not immediately lethal temperature for this species) or the onset of freezing (the peak of the supercooling point exotherm). Survival was defined as the ability to successfully eclose as an adult. We measured immature development times, pupal mass, and adult longevity as proxies of fitness in survivors. Additionally, surviving insects were mated with individuals that had not been exposed to cold to measure fertility. There was no difference between the proportion of larvae or pupae that survived acute exposure to –10 °C and those exposed to the control temperature. Approximately 17% of larvae and 8% of pupae survived brief periods with internal ice formation and continued development to become reproductively viable adults. Importantly, surviving the onset of freezing came with significant fitness costs but not to exposure to –10 °C; most insects that survived partial freezing had lower fertility and shorter adult lifespans than either the –10 °C or control group. These results are discussed within the context of forecasting invasive insect distributions. [ABSTRACT FROM AUTHOR]

Spotted-wing drosophila (Drosophila suzukii; SWD) is an invasive pest in the United States that is responsible for significant economic damage to soft-skinned fruit and berries worldwide. SWD uses a wide variety of cultivated and wild fruit for reproduction. Host suitability may depend on physical and chemical factors of the fruit, with a positive correlation of SWD oviposition and larval development generally associated with soluble sugar content, softer fruit, and higher pH, and a negative correlation of oviposition with fruit firmness. Variety selection is an important tool for integrated pest management, but few studies have reported host suitability across varieties within a single cultivated crop species for SWD. In this study, we investigated SWD oviposition and larval development in five half-high blueberry cultivars, Chippewa, Northblue, Northland, Patriot, and Polaris, using no-choice and two-choice laboratory bioassays. Using a host potential index, our results showed that Chippewa was the most preferred cultivar for oviposition as measured in the number of eggs laid per fruit, and Polaris was the least preferred. The inverse was true for larval development, with a higher survival rate and adult emergence in 'Polaris' than in 'Chippewa'. There was a negative relationship between fruit firmness and oviposition and a positive correlation between pH and larval development. The results of this study indicate that cultivar selection for half-high blueberries may be a promising integrated pest management (IPM) tool, although further research under field conditions is needed for validation. [ABSTRACT FROM AUTHOR]

Stem borers (Lepidoptera) are common cereal pests. In many parts of the world, the species Ostrinia nubilalis and Sesamia nonagrioides stand out as important insect pests of economically important crops such as maize. Their management relied mainly on transgenic host plant resistance over the last 25 years. Technologies based on the insecticidal properties of Bacillus thuringiensis-derived proteins allowed widespread pest population suppression, especially for O. nubilalis. However, the recent discovery of Bt resistance, which has revitalized interest in both pests' biology and management, may jeopardize the effectiveness of such transgenic technologies. Historical information on O. nubilalis bionomy may need to be reassessed in light of changing climate conditions and changing agricultural practices, as well as increased production of alternate host crops across its distribution range. The current paper examines the bioecology and historical research that has been conducted to manage these two important maize-boring pests. [ABSTRACT FROM AUTHOR]

Background: Local field potentials (LFPs) represent the summation of periodic (oscillations) and aperiodic (fractal) signals. Although previous studies showed changes in beta band oscillations and burst characteristics of the subthalamic nucleus (STN) in Parkinson's disease (PD), how aperiodic activity in the STN is related to PD pathophysiology is unknown. Objectives: The study aimed to characterize the long‐term effects of STN–deep brain stimulation (DBS) and dopaminergic medications on aperiodic activities and beta bursts. Methods: A total of 10 patients with PD participated in this longitudinal study. Simultaneous bilateral STN‐LFP recordings were conducted in six separate visits during a period of 18 months using the Activa PC + S device in the off and on dopaminergic medication states. We used irregular‐resampling auto‐spectral analysis to separate oscillations and aperiodic components (exponent and offset) in the power spectrum of STN‐LFP signals in beta band. Results: Our results revealed a systematic increase in both the exponent and the offset of the aperiodic spectrum over 18 months following the DBS implantation, independent of the dopaminergic medication state of patients with PD. In contrast, beta burst durations and amplitudes were stable over time and were suppressed by dopaminergic medications. Conclusions: These findings indicate that oscillations and aperiodic activities reflect at least partially distinct yet complementary neural mechanisms, which should be considered in the design of robust biomarkers to optimize adaptive DBS. Given the link between increased gamma‐aminobutyric acidergic (GABAergic) transmission and higher aperiodic activity, our findings suggest that long‐term STN‐DBS may relate to increased inhibition in the basal ganglia. © 2022 International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

The article presents information on the past situation and future prospective of Bacillus thuringiensis (Bt) crops and insect pest. It informs that one of the major advantages of Bt crop is that it helps in controlling some specific insect pests and thereby reduces the use of insecticides. The Bt crop covered 66 million hectares of area in the U.S. by 2011 in which maize and cotton were the major parts of Bt agriculture.

Background: Patients with essential tremor (ET), Parkinson's disease (PD) and dystonic tremor (DT) can be difficult to classify and often share similar characteristics. Objectives: To use ubiquitous smartphone accelerometers with and without clinical features to automate tremor classification using supervised machine learning, and to use unsupervised learning to evaluate if natural clusterings of patients correspond to assigned clinical diagnoses. Methods: A supervised machine learning classifier was trained to classify 78 tremor patients using leave-one-out cross-validation to estimate performance on unseen accelerometer data. An independent cohort of 27 patients were also studied. Next, we focused on a subset of 48 patients with both smartphone-based tremor measurements and detailed clinical assessment metrics and compared two separate machine learning classifiers trained on these data. Results: The classifier yielded a total accuracy of 74.4% and F1-score of 0.74 for a trinary classification with an area under the curve of 0.904, average F1-score of 0.94, specificity of 97% and sensitivity of 84% in classifying PD from ET or DT. The algorithm classified ET from non-ET with 88% accuracy, but only classified DT from non-DT with 29% accuracy. A poorer performance was found in the independent cohort. Classifiers trained on accelerometer and clinical data respectively obtained similar results. Conclusions: Machine learning classifiers achieved a high accuracy of PD, however moderate accuracy of ET, and poor accuracy of DT classification. This underscores the difficulty of using AI to classify some tremors due to lack of specificity in clinical and neuropathological features, reinforcing that they may represent overlapping syndromes. [ABSTRACT FROM AUTHOR]

Deep brain stimulation procedures offer an invaluable opportunity to study disease through intracranial recordings from awake patients. Here, we address the relationship between single-neuron and aggregate-level (local field potential; LFP) activities in the subthalamic nucleus (STN) and thalamic ventral intermediate nucleus (Vim) of patients with Parkinson's disease (n = 19) and essential tremor (n = 16), respectively. Both disorders have been characterized by pathologically elevated LFP oscillations, as well as an increased tendency for neuronal bursting. Our findings suggest that periodic singleneuron bursts encode both pathophysiological beta (13 to 33 Hz; STN) and tremor (4 to 10 Hz; Vim) LFP oscillations, evidenced by strong time-frequency and phasecoupling relationships between the bursting and LFP signals. Spiking activity occurring outside of bursts had no relationship to the LFP. In STN, bursting activity most commonly preceded the LFP oscillation, suggesting that neuronal bursting generated within STN may give rise to an aggregate-level LFP oscillation. In Vim, LFP oscillations most commonly preceded bursting activity, suggesting that neuronal firing may be entrained by periodic afferent inputs. In both STN and Vim, the phase-coupling relationship between LFP and high-frequency oscillation (HFO) signals closely resembled the relationships between the LFP and single-neuron bursting. This suggests that periodic single-neuron bursting is likely representative of a higher spatial and temporal resolution readout of periodic increases in the amplitude of HFOs, which themselves may be a higher resolution readout of aggregate-level LFP oscillations. Overall, our results may reconcile "rate" and "oscillation" models of Parkinson's disease and shed light on the single-neuron basis and origin of pathophysiological oscillations in movement disorders. [ABSTRACT FROM AUTHOR]

This paper presents a novel model of tremor in Parkinson's disease (PD) based on extensive literature review as well as novel results stemming from functional stereotactic neurosurgery for the alleviation of tremor in PD. Specifically, evidence that suggests the basal ganglia induces PD tremor via excessive inhibitory output to the thalamus and altered firing patterns which in turn generate rhythmic bursting activity of thalamic cells is presented. Then, evidence that the thalamus generates PD tremor by facilitating the generation and consolidation of rhythmic bursting activity of neurons within its nuclei is also offered. Finally, evidence that the cerebellum may modulate characteristics of PD tremor by treating it as if it was a voluntary motor behavior is presented. Accordingly, the current paper proposes that PD tremor is induced by abnormal basal ganglia activity; it is generated by the thalamus, and modulated or reinforced by the cerebellum. [ABSTRACT FROM AUTHOR]

A farmer’s decision on whether to control a pest is usually based on the perceived threat of the pest locally and the guidance of commercial advisors. Therefore, farmers in a region are often influenced by similar circumstances, and this can create a coordinated response for pest control that is effective at a landscape scale. This coordinated response is not intentional, but is an emergent property of the system. We propose a framework for understanding the intrinsic feedback mechanisms between the actions of humans and the dynamics of pest populations and demonstrate this framework using the European corn borer, a serious pest in maize crops. We link a model of the European corn borer and a parasite in a landscape with a model that simulates the decisions of individual farmers on what type of maize to grow. Farmers chose whether to grow Bt-maize, which is toxic to the corn borer, or conventional maize for which the seed is cheaper. The problem is akin to the snow-drift problem in game theory; that is to say, if enough farmers choose to grow Bt maize then because the pest is suppressed an individual may benefit from growing conventional maize. We show that the communication network between farmers’ and their perceptions of profit and loss affects landscape scale patterns in pest dynamics. We found that although adoption of Bt maize often brings increased financial returns, these rewards oscillate in response to the prevalence of pests. [ABSTRACT FROM AUTHOR]

The auditory oddball is a mainstay in research on attention, novelty, and sensory prediction. How this task engages subcortical structures like the subthalamic nucleus and substantia nigra pars reticulata is unclear. We administered an auditory OB task while recording single unit activity (35 units) and local field potentials (57 recordings) from the subthalamic nucleus and substantia nigra pars reticulata of 30 patients with Parkinson's disease undergoing deep brain stimulation surgery. We found tone modulated and oddball modulated units in both regions. Population activity differentiated oddball from standard trials from 200 ms to 1000 ms after the tone in both regions. In the substantia nigra, beta band activity in the local field potential was decreased following oddball tones. The oddball related activity we observe may underlie attention, sensory prediction, or surprise-induced motor suppression. • Population activity and single units in the STN and SNr distinguish infrequent from frequent tones. • OB + TM units distinguish infrequent from frequent tones earlier in time compared to pure OB units. • A model-switching analysis suggests that the population code changes over time. • Beta power decreases following oddball tones in the SNr, but not STN. [ABSTRACT FROM AUTHOR]

The fall armyworm, Spodoptera frugiperda (J.E. Smith), now is arguably the most important global insect pest of maize, Zea mays L., in the world. Maize growers in the Americas have battled the pest for centuries, and control recommendations have been adapted for Africa and Asia, based on contrasting results of the impact on yield when the pest infests young maize plants. Important control decision-making tools such as action thresholds, or economic thresholds, are not completely developed to control fall army worms, and insecticide applications are still recommended at low levels of infestation on young plants. To further assess the damage-yield relationship for fall armyworm, we manually removed 0, 33, and 66% of foliage when maize had 1-2 (V1-V2), and 3-4 (V3-V4) fully developed leaves. The amount of defoliation did not reduce maize yield potential when compared with nondefoliated plants, regardless of the defoliation timing: V1-V2 or V3-V4. Fertilizing defoliated plants significantly yielded more grain than non-fertilized plants, and these obvious results showed that smallholder maize growers that can afford investing in either fertilizer or insecticide will benefit more from the former. Our results add to the number of reports that indicate young maize plants can compensate for large amounts of defoliation without reducing yields. [ABSTRACT FROM AUTHOR]

Background: Patients with Parkinson's disease might develop treatment‐resistant axial dysfunction after bilateral subthalamic stimulation. Objectives: To study whether lateralized stimulation (unilateral 50% amplitude reduction) for ≥21 days results in ≥0.13 m/s faster gait velocity in the dopaminergic ON state in these patients, and its effects on motor and axial function, quantitative gait and speech measures, quality of life, and selected cognitive tasks. Methods: Randomized, double‐blinded, double‐crossover trial. Results: In 22 participants (51–79 years old, 15 women), there were no significant changes in gait velocity, quality of life, cognitive, and speech measures. Reducing left‐sided amplitude resulted in a 2.5‐point improvement in axial motor Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS‐UPDRS) (P = 0.005, uncorrected) and a 1.9‐point improvement in the Freezing of Gait Questionnaire (P = 0.024, uncorrected). Conclusions: Lateralized subthalamic stimulation does not result in meaningful improvement in gait velocity in patients with Parkinson's disease who develop treatment‐resistant axial dysfunction after bilateral subthalamic stimulation. Left subthalamic overstimulation may contribute to axial deterioration in these patients. © 2022 International Parkinson and Movement Disorder Society [ABSTRACT FROM AUTHOR]

Transgenic maize MON88017, expressing the Cry3Bb1 toxin from Bacillus thuringiensis (Bt maize), confers resistance to corn rootworms (Diabrotica spp.) and provides tolerance to the herbicide glyphosate. However, prior to commercialization, substantial assessment of potential effects on non-target organisms within agroecosystems is required. The MON88017 event was therefore evaluated under field conditions in Southern Bohemia in 2009–2011, to detect possible impacts on the above-ground arthropod species. The study compared MON88017, its near-isogenic non-Bt hybrid DK315 (treated or not treated with the soil insecticide Dursban 10G) and two non-Bt reference hybrids (KIPOUS and PR38N86). Each hybrid was grown on five 0.5 ha plots distributed in a 14-ha field with a Latin square design. Semiquantitative ELISA was used to verify Cry3Bb1 toxin levels in the Bt maize. The species spectrum of non-target invertebrates changed during seasons and was affected by weather conditions. The thrips Frankliniella occidentalis was the most abundant species in all three successive years. The next most common species were aphids Rhopalosiphum padi and Metopolophium dirhodum. Frequently observed predators included Orius spp. and several species within the Coccinellidae. Throughout the three-year study, analysis of variance indicated some significant differences (P<0.05). Multivariate analysis showed that the abundance and diversity of plant dwelling insects was similar in maize with the same genetic background, for both Bt (MON88017) and non-Bt (DK315) untreated or insecticide treated. KIPOUS and PR38N86 showed some differences in species abundance relative to the Bt maize and its near-isogenic hybrid. However, the effect of management regime on arthropod community was insignificant and accounted only for a negligible portion of the variability. [ABSTRACT FROM AUTHOR]

High-frequency deep brain stimulation ( HFS- DBS) of the subcallosal cingulate ( SCC) region has been investigated as a treatment for refractory forms of depression with a ~50% remission rate in open label studies. However, the therapeutic mechanisms of DBS are still largely unknown. Using anaesthetized Sprague Dawley rats, we recorded neuronal spiking activity in 102 neurons of the dorsal raphe ( DR) before, during and after the induction of a 5-min HFS train in the infralimbic region ( IL) of the medial prefrontal cortex ( mPFC), the rodent homologue of the human SCC. The majority of DR cells (82%) significantly decreased firing rate during HFS ( P < 0.01, 55.7 ± 4.5% of baseline, 35 rats). To assess whether mPFC- HFS mediates inhibition of DR cellular firing by stimulating local GABAergic interneurons, the GABAA antagonist bicuculline ( Bic, 100 μ m) was injected directly into the DR during HFS. Neurons inhibited by HFS recovered their firing rate during Bic+ HFS ( P < 0.01, n = 15, seven rats) to levels not different from baseline. Cells that were not affected by HFS did not change firing rate during Bic+ HFS ( P = 0.968, n = 7, three rats). These results indicate that blocking GABAA reverses HFS-mediated inhibition of DR neurons. As the cells that were not inhibited by HFS were also unaffected by HFS+ Bic, they are probably not innervated by local GABA. Taken together, our results suggest that mPFC- HFS may exert a preferential effect on DR neurons with GABAA receptors. [ABSTRACT FROM AUTHOR]

Helicoverpa armigera has recently invaded South and Central America, and appears to be spreading rapidly. We update a previously developed potential distribution model to highlight the global invasion threat, with emphasis on the risks to the United States. The continued range expansion of H. armigera in Central America is likely to change the invasion threat it poses to North America qualitatively, making natural dispersal from either the Caribbean islands or Mexico feasible. To characterise the threat posed by H. armigera, we collated the value of the major host crops in the United States growing within its modelled potential range, including that area where it could expand its range during favourable seasons. We found that the annual value of crops that would be exposed to H. armigera totalled approximately US$78 billion p.a., with US$843 million p.a. worth growing in climates that are optimal for the pest. Elsewhere, H. armigera has developed broad-spectrum pesticide resistance; meaning that if it invades the United States, protecting these crops from significant production impacts could be challenging. It may be cost-effective to undertake pre-emptive biosecurity activities such as slowing the spread of H. armigera throughout the Americas, improving the system for detecting H. armigera, and methods for rapid identification, especially distinguishing between H. armigera, H. zea and potential H. armigera x H. zea hybrids. Developing biological control programs, especially using inundative techniques with entomopathogens and parasitoids could slow the spread of H. armigera, and reduce selective pressure for pesticide resistance. The rapid spread of H. armigera through South America into Central America suggests that its spread into North America is a matter of time. The likely natural dispersal routes preclude aggressive incursion responses, emphasizing the value of preparatory communication with agricultural producers in areas suitable for invasion by H. armigera. [ABSTRACT FROM AUTHOR]

Minnesota is the state with the strongest winter warming in the contiguous United States. We performed regional climate projections at 10 km horizontal resolution using the Weather Research Forecasting model forced with eight CMIP5 GCMs. The selected GCMs have previously been found to be in relatively good agreement with observations over Minnesota compared to other members of the CMIP5 model ensemble. Our projections suggest ongoing warming in all seasons, especially in winter, as well as shallower snow depth and fewer days with snow cover. We expect significant increases in spring and early summer heavy precipitation events. Our comparisons between different time slices and two different emission scenarios indicate a climate for the state of Minnesota near the end of the 21st century that is significantly different from what has been observed by the end of the 20th century. Winters and summers are expected to be up to 6 and 4°C warmer, respectively, over northern and central Minnesota, and spring precipitation may increase by more than 1 mm d−1 over northern Minnesota. Especially over the central part of the state, winter snow depth is projected to decrease by more than 12 cm, and the number of days per year with snow depth of more than 2.54 cm (one inch) is expected to decrease by up to 55. Plain Language Summary: Minnesota is the state with the strongest winter warming in the contiguous United States. We performed regional projections of the climate across Minnesota for the middle and end of the 21st century. We selected the results from eight recent global climate model projections to calculate climate data over an area of 10 km by 10 km with a regional climate model. Our results indicate that the future climate for the state of Minnesota is likely to be significantly different from what has been observed near the end of the 20th century. Over northern and central Minnesota, winters and summers are expected to be up to 6 and 4°C warmer, respectively, near the end of the 21st century. Spring precipitation may increase by more than 1 mm d−1 over northern Minnesota. Over the central part of the state, winter snow depth is suggested to decrease by more than 12 cm. The number of days per year with snow depth of more than 2.54 cm (one inch) is expected to decrease by up to 55. These results are expected to influence regional decision‐making related to agriculture, infrastructure, water resources, and other sectors. Key Points: Over northern and central Minnesota, winters and summers may be up to 6 and 4°C warmer, respectively, at the end of the 21st centurySpring precipitation may increase by more than 1 mm per day over northern MinnesotaSnow depth may decrease by more than 12 cm. Number of snow days per year may decrease by up to 55 [ABSTRACT FROM AUTHOR]

We artificially selected for increased freeze tolerance in the invasive light brown apple moth. Our results suggest that, by not accounting for adaptation to cold, current models of potential geographic distributions could underestimate the areas at risk of exposure to this species. [ABSTRACT FROM AUTHOR]

External sensory cues can reduce freezing of gait in people with Parkinson's disease (PD), yet the role of the basal ganglia in these movements is unclear. We used microelectrode recordings to examine modulations in single unit (SU) and oscillatory local field potentials (LFP) during auditory-cued rhythmic pedaling movements of the feet. We tested five blocks of increasing cue frequencies (1 Hz, 1.5 Hz, 2 Hz, 2.5 Hz, and 3 Hz) in 24 people with PD undergoing deep brain stimulation surgery of the subthalamic nucleus (STN) or globus pallidus internus (GPi). Single unit firing and beta band LFPs (13–30 Hz) in response to movement onsets or cue onsets were examined. We found that the timing accuracy of foot pedaling decreased with faster cue frequencies. Increasing cue frequencies also attenuated firing rates in both STN and GPi neurons. Peak beta power in the GPi and STN showed different responses to the task. GPi beta power showed persistent suppression with fast cues and phasic modulation with slow cues. STN beta power showed enhanced beta synchronization following movement. STN beta power also correlated with rate of pedaling. Overall, we showed task-related responses in the GPi and STN during auditory-cued movements with differential roles in sensory and motor control. The results suggest a role for both input and output basal ganglia nuclei in auditory rhythmic pacing of gait-like movements in PD. • Single neurons in STN (72%) and GPi (52%) responded to auditory cued foot pedaling at rates from 1 to 3 Hz in awake PD persons OFF-drug • Accuracy of pedaling with respect to cues progressively decreased as cue frequencies increased, particularly above 1.5 Hz. • GPi showed decrease in tonic beta LFP power with fast auditory cues. STN showed tonic increases in beta power after onset of foot movement. • STN is involved in motor aspects of auditory cued pedaling while the GPi may play a role in sensory processing of the task. [ABSTRACT FROM AUTHOR]

Deep brain stimulation of the basal ganglia and other brain regions has been used successfully to treat a variety of neurological disorders. However, the mechanisms by which it works, remain unclear. In a previous study, we showed that locally delivered single current pulses delivered from a nearby microelectrode are sufficient to inhibit firing in the internal globus pallidus for tens of milliseconds. The GPi and the substantia nigra pars reticulata are the output nuclei of the basal ganglia and share many anatomical and physiological features. The goal of the current study was to examine the after-effects of trains of high-frequency microstimulation on neuronal firing in the GPi of Parkinson’s disease and dystonia patients as well as in the SNr of PD patients. Microelectrode recordings and microstimulation were performed in a total of 57 patients during stereotactic surgery. We found that firing in the GPi and SNr is inhibited for several hundreds of milliseconds following the end of a short, 200 Hz high-frequency train delivered through the recording electrode (e.g., on average 618 ms when stimulating in the SNr with a 0.5 s train of 4 μA pulses at 200 Hz). Inhibition duration usually increased with increasing current intensity, train frequency and generally peaked for trains of 1–2 s, while it decreased with increasing train durations. Statistical analysis with general linear models revealed a significant linear relationship between current intensity and inhibition duration in all nuclei and patient groups. There was also a significant relationship between train frequency and inhibition duration in the SNr and GPi of PD patients and between train duration and inhibition duration in the GPi of PD patients. There was no significant difference in inhibition duration across patient groups but the current threshold for inhibition was significantly different in the SNr compared to the GPi. The characteristics of the inhibition observed are consistent with stimulation-induced GABA release following activation of the GABAergic afferents in the SNr and GPi. The findings suggest that high-frequency microstimulation of the GPi and SNr depresses local neuronal activity and synaptic transmission, and such mechanisms may contribute to the therapeutic effects of DBS. [ABSTRACT FROM AUTHOR]

The establishment of the multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), in North America has resulted in negative impacts on fruit production. We investigated the overwintering survival of H. axyridis after feeding on four diets: injured wine grape berries, 25% sucrose solution, water, and a control containing no food or water. After being exposed to these diets for 6 days, live individuals were transferred to clean plastic Petri dishes, and held at 5 ± 1 °C in growth chambers throughout the winter. Survival was recorded every month. Adult lady beetles collected during the overwintering flight in mid-October had higher survival rates than beetles collected from soybean fields in mid-August. These results suggest that an adaptation period prior to diapause increases the chances of lady beetle survival over the winter. In addition, injured wine grape berries, sugar, and water decreased beetle mortality during the overwintering months. Our results also showed that under similar conditions, females have higher survival during the winter than males. The importance of sugar and water on winter survival may drive H. axyridis adults to vineyards for feeding on wine grapes. Finally, we tested if adults of H. axyridis and the European paper wasp, Polistes dominulus Christ (Hymenoptera: Vespidae), were able to break the grape skin. Harmonia axyridis adults and paper wasps were not able to cause the primary injury to berries of Frontenac grapes under laboratory conditions. These results suggest that control of paper wasps in vineyards may not affect H. axyridis aggregations, and that H. axyridis feeding on wine grapes depends on previous injury to grape berries. [ABSTRACT FROM AUTHOR]

The pedunculopontine nucleus (PPN) lies within the brainstem reticular formation and is involved in the motor control of gait and posture. Interest has focused recently on the PPN as a target for implantation of chronic deep brain stimulation (DBS) electrodes for Parkinson’s disease (PD) and progressive supranuclear palsy (PSP) therapy. The aim of this study was to examine the neurophysiology of the human PPN region and to identify neurophysiological landmarks that may aid the proper placement of DBS electrodes in the nucleus for the treatment of PD and PSP. Neuronal firing and local field potentials were recorded simultaneously from two independently driven microelectrodes during stereotactic neurosurgery for implantation of a unilateral DBS electrode in the PPN in five PD patients and two PSP patients. Within the PPN region, the majority (57%) of the neurons fired randomly while about 21% of the neurons exhibited ‘bursty’ firing. In addition, 21% of the neurons had a long action potential duration and significantly lower firing rate suggesting they were cholinergic neurons. A change in firing rate produced by passive and/or active contralateral limb movement was observed in 38% of the neurons that were tested in the PPN region. Interestingly, oscillatory local field potential activity in the beta frequency range (∼25 Hz) was also observed in the PPN region. These electrophysiological characteristics of the PPN region provide further support for the proposed role of this region in motor control. It remains to be seen to what extent the physiological characteristics of the neurons and the stimulation-evoked effects will permit reliable identification of PPN and determination of the optimal target for DBS therapy. [ABSTRACT FROM AUTHOR]

The cortical mechanisms and substrates of cognitive and emotional demands are poorly understood. Lesion studies and functional imaging implicate the anterior cingulate cortex (ACC). The caudal ACC (cACC) has been implicated in cognitive processes such as attention, salience, interference, and response competition, mostly on the basis of neuroimaging results. To test the hypothesis that individual cACC neurons subserve these functions, we monitored neuronal activity from single cells in the cACC while subjects were engaged in a mental arithmetic task, the cognitively demanding counting Stroop task, and/or the emotional Stroop interference task. We now report the first direct measures of single neurons in humans identifying a population of cACC neurons that respond differentially or in a graded manner to cognitively demanding high- and low-conflict Stroop tasks, including those with emotional valence. These data indicate that cACC neurons may be acting as salience detectors when faced with conflict and difficult or emotional stimuli, consistent with neuroimaging results of cACC responses to abrupt sensory, novel, task-relevant, or painful stimuli. [ABSTRACT FROM AUTHOR]

Demographic matrix models are standard tools for analyzing the dynamics of age- or stage-structured populations. Here, we present a method for estimating the average vital rates that parameterize a demographic matrix using a series of measurements of population size and structure (an "inverse problem" of demographic analysis). We join a deterministic, density-independent demographic matrix model with a stochastic observation model to write a likelihood function for the matrix parameters given the data. Adopting a Bayesian perspective, we combine this likelihood function with prior distributions for the model parameters to produce a joint posterior distribution for the parameters. We use a numerical technique (Markov chain Monte Carlo) to estimate and analyze the posterior distribution, and from this we calculate posterior distributions for functions of the demographic matrix, such as the population multiplication rate, stable stage distribution, and matrix sensitivities. Although measurements of population size and structure rarely contain enough information to estimate all the parameters in a matrix precisely, our analysis sheds light on the information that the data do contain about the vital rates by quantifying the precision of the parameter estimates and the correlations among them. Moreover, we show that matrix functions such as the population multiplication rate and matrix sensitivities can still be estimated precisely despite sizable uncertainty in the estimates of individual parameters, permitting biologically meaningful inference. We illustrate our approach for three populations of pea aphids (Acyrthosiphon pisum). [ABSTRACT FROM AUTHOR]

Discusses the strategies and statistics of sampling for rare insects. Errors in the detection of rare insects; Sampling for exotic pests during quarantine inspections; Sampling for pathogens in veterinary and medical entomology.

Parkinson's disease is a neurodegenerative disease affecting the supply of dopamine to basal ganglia nuclei, leading to pathological beta band (13–35 Hz) oscillations in the subthalamic nucleus (STN). STN and beta activity are recognized in motoric functions but their role in cognitive functions remains elusive. We examined single unit and beta local field potential (LFP) activity in the STN during a visual choice preference task in PD patients (n = 12) undergoing deep brain stimulation surgery. Patients viewed 2 of 5 possible animal picture‐pairs and were instructed to choose their favorite ("fav") picture by clicking the left or right mouse key. A block of trials consisted of 50–75 picture‐pair presentations. Single unit histograms and LFP spectrograms were aligned to picture presentation and point of decision for pairs that included the fav and non‐fav pictures, respectively. A total of 58 neurons from 26 blocks of trials were analyzed. Thirty of 58 neurons showed a selective change in spiking activity 0.20–0.65 s to fav picture presentation, which preceded the shortest recorded reaction time (=0.7 s), and 17/58 neurons showed no significant response in our task. Beta LFP significantly desynchronized in response to fav but not non‐fav pictures in all trials, and in 14/26 blocks of trials, the desynchronization was followed by a "beta burst" and ramp‐up to baseline activity. Neurons with choice preference responses were found throughout the dorsoventral extent of the STN. STN single units and beta activity are modulated during visual choice preference, and this suggests a role for STN beta activity in cognitive processing. [ABSTRACT FROM AUTHOR]

Introduction: Freezing of gait (FOG) is a complex symptom in Parkinson's disease (PD) that manifests during walking as limited forward progression despite the intention to walk. It is unclear if lower limb motor blocks (LLMB) that occur independently from FOG are related to overground FOG and the effects of dopaminergic medications.Methods: Nineteen patients with PD were tested on two separate days in the dopaminergic medication "on" and "off" states. The patients completed a series of freezing-provoking tasks while videotaped. Raters assessed videos for FOG presence using Movement Disorders Society Unified Parkinson's Disease Rating Scale item 3.11 score greater than or equal to 1 and FOG severity using the standardized FOG score. Whilst seated in a virtual environment, patients and 20 healthy controls stepped in right-left sequence on foot pedals. Frequency and percent time in LLMB were assessed for accurate classification of FOG presence and correlation to the FOG score.Results: Frequency and percent time spent in LLMB predicted the presence of FOG in both medication states. Percent time spent in LLMB correlated with FOG severity in both medication states. LLMB frequency predicted FOG severity in the "off" state only.Conclusions: LLMB during bilateral stepping in a virtual environment predicted the presence and severity of FOG in PD in both "on" and "off" medication states. These findings support the use of this non-walking paradigm to detect and assess FOG in PD patients unable or unsafe to walk. [ABSTRACT FROM AUTHOR]

Tremor is a well-known side effect from many psychiatric medications, including lithium and dopamine antagonists. In patients whose psychiatric symptoms are stabilized and only respond to certain medications, deep brain stimulation may offer relief of the consequent motor complications. We report the case of an elderly male with disabling tremor related to lithium therapy for bipolar affective disorder, who was subsequently treated with deep brain stimulation. In this patient, we obtained recordings from the substantia nigra pars reticulata and performed a high-frequency stimulation protocol that robustly elicits long-term potentiation (LTP)-like changes in patients with Parkinson's disease. We hypothesized that in this patient, who did not have Parkinson's disease, the levels of inhibitory plasticity would be much greater. However, we found an unanticipated lack of plasticity in the patient with lithium-induced tremor, compared with two de novo control patients with Parkinson's disease. This patient was successfully treated with deep brain stimulation in the vicinity of the ventral oral posterior nucleus, an area of the thalamus that receives inputs from the basal ganglia. We postulate that the lithium-induced blockade of LTP may bring about motor complications such as tremor while simultaneously contributing to the therapeutic mechanism for treating the symptoms of psychiatric disorders such as bipolar affective disorder. [ABSTRACT FROM AUTHOR]