Source Of Stimulus Research Articles

Assaying Nociception Behaviors in Drosophila Larvae During Parasitoid Wasp Attacks.

Nociception in fruit fly (Drosophila melanogaster) larvae is characterized by a stereotyped escape behavior. When a larva encounters a noxious (potentially harmful) stimulus, it responds by curving its body into a c-shape and rolling in a corkscrew-like manner around its long-body axis. This rolling behavior may serve to quickly remove the larva from the source of the noxious stimulus, and is particularly adaptive to escape from a common natural predator of fruit fly larvae: parasitoid wasps (Leptopilina boulardi). L. boulardi completes its life cycle by using fruit fly larvae as hosts for its offspring. Female wasps sting fly larvae with an ovipositor and lay an egg within the larva. The wasp offspring hatches inside the fly larva, consumes the fly tissues during pupation, and eventually emerges from the pupal case as an adult wasp. Fruit fly larvae respond to oviposition attacks by rolling, which causes the long flexible ovipositor to be wound around the larval body like a spool. This dislodges the wasp and allows the larva to attempt to escape by crawling. Rolling behavior is triggered by the activation of sensory neurons (nociceptors) whose function can inform our understanding of the mechanisms of nociception. In this protocol, we describe a simple behavioral assay to test and measure nociceptive responses in Drosophila larvae during oviposition attacks by female parasitoid wasps. First, we discuss parasitoid wasp husbandry and culturing methods in the laboratory. We then describe how to perform the wasp nociception assay on third-instar fruit fly larvae.

Writing the mire – ‘for we are loom’

ABSTRACT In this essay, I am in-conversation with Proust was a Neuroscientist, by Jonah Lehrer [2008, Proust was a Neuroscientist. New York: Houghton Mifflin Company]. I engage with Lehrer’s chapters focusing Marcel Proust, Virginia Woolf and Paul Cézanne. This essay is a contribution to an ongoing conversation with Professors Kate Coles and Jen Webb regarding the distinctions, or lack thereof, between narrative and the lyric, within the context of broader discussions about genre classifications (Great Writing 2023, 2024). In this essay, I respond to Coles and Webb’s provocative question: What is it you mean, they ask, when you use the term realism? I consider this question from a practice-led perspective, as a writer who loves to read, and a writer-researcher who is drawn to neuro-psychoanalytic approaches to writing and creativity. I’m drawn to the quagmire of memory, as a primary source of stimulus for creative practice. My understanding of what I have come to call narrative lyricism is that it is a form of writing in which narrative may exist in ghost. Its incompleteness (if evaluated within traditional expectations of complication and dénouement) reflects the complicated (which is to say entangled) nature of the operations of memory.

Implicit Selective Attention: The Role of the Mesencephalic-basal Ganglia System.

The ability of the brain to recognize and orient attention to relevant stimuli appearing in the visual field is highlighted by a tuning process, which involves modulating the early visual system by both cortical and subcortical brain areas. Selective attention is coordinated not only by the output of stimulus-based saliency maps but is also influenced by top-down cognitive factors, such as internal states, goals, or previous experiences. The basal ganglia system plays a key role in implicitly modulating the underlying mechanisms of selective attention, favouring the formation and maintenance of implicit sensory-motor memories that are capable of automatically modifying the output of priority maps in sensory-motor structures of the midbrain, such as the superior colliculus. The article presents an overview of the recent literature outlining the crucial contribution of several subcortical structures to the processing of different sources of salient stimuli. In detail, we will focus on how the mesencephalic- basal ganglia closed loops contribute to implicitly addressing and modulating selective attention to prioritized stimuli. We conclude by discussing implicit behavioural responses observed in clinical populations in which awareness is compromised at some level. Implicit (emergent) awareness in clinical conditions that can be accompanied by manifest anosognosic symptomatology (i.e., hemiplegia) or involving abnormal conscious processing of visual information (i.e., unilateral spatial neglect and blindsight) represents interesting neurocognitive "test cases" for inferences about mesencephalicbasal ganglia closed-loops involvement in the formation of implicit sensory-motor memories.

Purinergic Ca2+ Signaling as a Novel Mechanism of Drug Tolerance in BRAF-Mutant Melanoma.

Drug tolerance is a major cause of relapse after cancer treatment. Despite intensive efforts, its molecular basis remains poorly understood, hampering actionable intervention. We report a previously unrecognized signaling mechanism supporting drug tolerance in BRAF-mutant melanoma treated with BRAF inhibitors that could be of general relevance to other cancers. Its key features are cell-intrinsic intracellular Ca2+ signaling initiated by P2X7 receptors (purinergic ligand-gated cation channels) and an enhanced ability for these Ca2+ signals to reactivate ERK1/2 in the drug-tolerant state. Extracellular ATP, virtually ubiquitous in living systems, is the ligand that can initiate Ca2+ spikes via P2X7 channels. ATP is abundant in the tumor microenvironment and is released by dying cells, ironically implicating treatment-initiated cancer cell death as a source of trophic stimuli that leads to ERK reactivation and drug tolerance. Such a mechanism immediately offers an explanation of the inevitable relapse after BRAFi treatment in BRAF-mutant melanoma and points to actionable strategies to overcome it.

Unsupervised separation of nonlinearly mixed event-related potentials using manifold clustering and non-negative matrix factorization

Event-related potentials (ERPs) can quantify brain responses to reveal the neural mechanisms of sensory perception. However, ERPs often reflect nonlinear mixture responses to multiple sources of sensory stimuli, and an accurate separation of the response to each stimulus remains a challenge. This study aimed to separate the ERP into nonlinearly mixed source components specific to individual stimuli. We developed an unsupervised learning method based on clustering of manifold structures of mixture signals combined with channel optimization for signal source reconstruction using non-negative matrix factorization (NMF). Specifically, we first implemented manifold learning based on Local Tangent Space Alignment (LTSA) to extract the spatial manifold structure of multi-resolution sub-signals separated via wavelet packet transform. We then used fuzzy entropy to extract the dynamical process of the manifold structures and performed a k-means clustering to separate different sources. Lastly, we used NMF to obtain the optimal contributions of multiple channels to ensure accurate source reconstructions. We evaluated our developed approach using a simulated ERP dataset with known ground truth of two components of ERP mixture signals. Our results show that the correlation coefficient between the reconstructed source signal and the true source signal was 92.8 % and that the separation accuracy in ERP amplitude was 91.6 %. The results show that our unsupervised separation approach can accurately separate ERP signals from nonlinear mixture source components. The outcomes provide a promising way to isolate brain responses to multiple stimulus sources during multisensory perception.

Relationship between Femur Mineral Content and Local Muscle Strength and Mass.

Among the stimuli able to prevent early decreases in bone mineralization, exercise has a noticeable role per se as the source of mechanical stimulus or through lean tissue enlargement by its increasing of tensional stimulus. However, prevention strategies, including exercise, generally do not establish the moment in life when attention should begin to be paid to bone integrity, according to age group- and sex-related differences. Thus, this study analyzed the relationship between variables from the diagnosis of total and regional body composition, muscle strength, and bone mineral content (BMC) of femurs in young adult males. Thirty-four young Caucasian men (24.9 ± 8.6 years) had their body composition and bone density assessed by dual X-ray absorptiometry. The subjects performed a one-repetition maximum test (1-RM) in a bench press, front pulley, seated-row, push press, arm curl, triceps pulley, leg flexion, leg extension, and 45° leg press for the assessment of muscle strength in upper and lower limbs in single- and multi-joint exercises. Lean tissue mass in the trunk and upper and lower limbs were related to femoral BMC (Pearson coefficient ranging from 0.55 to 0.72, p < 0.01), and 1-RM values for different exercises involving both upper and lower limbs also correlated with femoral BMC (Pearson coefficients ranging from 0.34 to 0.46, p < 0.05). Taken together, these correlations suggest that muscle mass and strength are positively linked with the magnitude of femoral mass in men, even in early adulthood. Hence, the importance of an enhanced muscle mass and strength to the health of femoral bones in young adults was highlighted.

Detriments and Benefits in Collaborative Memory of Social Information: Insight From Gender Stereotypes

Abstract Stereotypes are well documented to elicit stereotype-consistent effects in individual memory. Additionally, collaborative memory can result in detrimental collaborative inhibition and 2 beneficial effects: error pruning and postcollaborative memory benefit. We examined whether the stereotype-consistent effect can be expanded to the context of collaborative memory. Additionally, we examined whether the effects observed in collaborative memory also apply to the memory for social stereotypes. This study applied positive, neutral, and negative gender stereotype words and engaged participants in an individual study and 2 recall tests. Recall 1 was completed either individually or collaboratively, whereas Recall 2 was always performed individually. The recall was to remember both the studied words and the speaker's gender associated with them, testing both item memory and source memory. (a) We expanded the stereotype-consistent effect to both ongoing and postcollaboration situations, affecting both item memory and source memory. Additionally, in the word gender–speaker inconsistent situations, there was an involuntary bias to remember the sources of own-gender stimuli. (b) We extended the detrimental and beneficial effects of collaboration into the domain of gender stereotypes. The detrimental effect of collaborative inhibition was sensitive to both memory tasks and the emotional valence of stimuli. This indicates that when dealing with social stimuli, the disruption of preferential strategies is not confined. The beneficial effects acted as a function of the memory task, providing evidence for the conditional application of the mechanisms of the retrieval strategy disruption hypothesis and the processes of dual process theory in social memory processing.

Bioinspired Dynamic Matrix Based on Developable Structure of MXene‐Cellulose Nanofibers (CNF) Soft Actuators

AbstractInspired by natural organisms, soft actuators can convert environmental stimuli into mechanical deformation, making them indispensable for applications in a variety of fields such as soft robotics. MXene, displaying exceptional attributes in conductivity, thermal efficiency, good dispersibility etc., has emerged as a preferred material for high‐performance thermal actuators. However, single actuators struggle to achieve complex tasks realized by intelligent robotic systems. Herein, a bioinspired dynamic matrix is presented utilizing the developable structure of MXene‐cellulose nanofibers (CNF) soft actuators. The inclusion of CNF considerably bolsters the mechanical properties of MXene. The MXene‐CNF film possessed a higher working strain range (≈14%) than pure MXene film (≈2%). The designed developable structures complete the actuating movements. The sensing layer integration with the actuating layer led to an extremely low touch detection limit (0.3 kPa) and expedited actuating‐feedback due to the interaction between contact charging and electrostatic induction. A responsive dynamic matrix containing 3 × 3 soft actuators, completed with a close‐looped sensing‐feedback function, is developed similar to the behavior of the mimosa plant. This mimosa‐inspired dynamic matrix is capable of identifying the source of touch stimuli and providing immediate feedback. This research broadens the potential for enhancing adaptability and intelligence of soft robotic system.

Electrically/Magnetically Dual‐Driven Shape Memory Composites Fabricated by Multi‐Material Magnetic Field‐Assisted 4D Printing

AbstractShape memory polymers (SMPs) are smart materials that enable to transform back to their original shape from the deformed state when subjected to external stimuli. They have shown great potential used as sensors and actuators in diverse applications. However, current research on SMPs primarily focuses on the utilization of a single source of stimuli (e.g., electricity, magnetism, light, etc.), which heavily restricts their potential in complex circumstances. In this study, a novel approach is developed to fabricate multi‐layer electrically/magnetically dual‐driven shape memory composites (ML‐EMSMCs) based on a magnetic field‐assisted digital light processing (MF‐DLP) 4D printing technique. The fabricated ML‐EMSMCs contain alternating high electric conductive layers (up to 5.37 × 10−3 S cm−1) and magnetic responsive layers (10.7 emu g−1), enabling Joule heat‐based and high‐frequency magnetic field induction‐based stimuli. Furthermore, the ML‐EMSMCs exhibited excellent shape memory behavior, good formability, and magnetic properties. The developed 4D printing techniques allows for the alignment of magnetic particles with a unidirectional magnetic field, significantly improving their shape recovery speed. The developed electrically/magnetically dual‐driven and photocurable SMP composites shed light on the development of actuators and sensors with multiple functionalities.

Human and animal intestinal commensals and probiotics vs modern challenges of biosafety: problems and prospects.

The appearance of an array of data on the study of the intestinal microbiota in Metazoa has significantly expanded our understanding of the role of commensals in the control of a wide range of physiological functions in higher organisms in norm and pathology. In the intestine, where the microbial load significantly exceeds the number of microorganisms of other ecosystems, the components of the intestinal microbiota are a constant source of stimuli that induce activation of the host immune system. The introduction into practice of biomedical research of innovative high-resolution methods, includingmulti-omics technologies, has brought data that change our understanding of intestinal commensals, including probiotics with GRAS status, widely used in medicine, agriculture and biotechnology. The ability of these bacteria to induce negative processes in the host body that are beneficial for bacterial proliferation and expansion revealed a clear lack of our knowledge about the logic of their life and the mechanisms of interaction with eukaryotic cells. This determines the urgent need for comprehensive research of probiotics and the development of standardization of their safety assessment. Apriori's confidence in the exceptional benefit of the bacteria widely used in medicine, agriculture and biotechnology has determined the seriously omission in our control system today - the lack of standardization of studies for the safety assessment of bacteria with GRAS status . The moment has come when it became clear that this gap should be promptly filled and that only exact understanding the molecular base of interacting the microbes with eukaryotic cells can provide the foundation for effective practical developments in controlling the evolution of bacterial virulence and probiotic safety strategy, as well as the competent use of genetic technologies for monitoring the environment and managing infectious processes, thus avoiding the dramatic consequences of large-scale interventions in the micro and macro worlds.

Designs on consciousness: literature and predictive processing.

Predictive processing is a recent approach in cognitive science that describes the brain as an engine of probabilistic hierarchical inference. Initially proposed as a general theory of brain function, predictive processing has recently been expanding to account for questions of consciousness in philosophy and neuroscience. In my previous work (Kukkonen 2020 Probability designs: literature and predictive processing. New York, NY: Oxford University Press), I have shown how predictive processing can also be used to model our engagement with literary texts. In this article, I use my account of our engagement with literature in predictive processing terms, as well as recent work on predictive processing and consciousness, to explore how literature can shed light on various aspects of conscious experience, including qualia, counterfactual depth in conscious experience and sense of self. In the final section, I propose a number of theoretical questions that could be addressed by drawing on literature as a source of hypotheses and stimuli for possible experimental designs. The upshot is a picture where literature is not just a source of illustrative examples about conscious experience, but a designer environment through which we can explore and rethink consciousness. This article is part of the theme issue 'Art, aesthetics and predictive processing: theoretical and empirical perspectives'.

Delving into Hearing Threshold of the Delay Gap of Initial Reflection in a Room by Using the Response of Cortical Brainwaves

In this study, the apparent variation ranges of acoustical parameters were investigated in a concert hall. The initial time delay gap (ITDG) was evaluated in terms of its just noticeable difference (JND) through two instruments, the cello and the trumpet. Even though the IDTG values were prolonged over the measurements and were not significantly varied, an ITDG range of 22–220 ms in increments of 91 steps was produced electro-acoustically in an anechoic chamber. The result of JNDc (Δgap/gap) was rated by 50% “different” judgement ranges for the cello and trumpet tracks, respectively. The effective duration of the autocorrection function (ACF) of the continuous brainwaves (CBWs) within the alpha (8–13 Hz) frequency range in the left hemisphere responding to 91-step ITDG increments revealed that the continuous ratios of τe_min ((τe_min_rear − τe_min_front)/τe_min_front) of CBWs were constantly on the trumpet. Furthermore, a homologous period of resonance between the subjective JNDc and τe values of the ACF of CBWs in the alpha range allowed us to conclude that the subjective JND of the ITDG in a room was related to the W_IACC value of the interaural cross-correlation function, which reflected the characteristics of source signals themselves and aroused the activities of the brain in the right hemisphere (p &lt; 0.01). The dry sources of sound stimuli were first used to link the psychological preference and the neurophysiological activation of the room acoustics.

Plant structural and storage glucans trigger distinct transcriptional responses that modulate the motility of Xanthomonas pathogens.

Some phytopathogens are outfitted with a broad and diverse repertoire of enzymatic systems that enable the breakdown and utilization of host polysaccharides as a source of carbon, energy, and stimuli. However, the functional assignment of these enzymatic systems and the influence of their products on modulating pathogen behavior during host colonization are yet poorly comprehended. In this study, we performed RNA-seq analyses to provide a comprehensive, genome-wide view of the transcriptional response of the model phytopathogen Xanthomonas citri pv. citri 306 (known as X. citri 306) to cellobiose, a component of structural β-1,4-glucans (majorly cellulose), and storage α-glucans, seeking to better understand how they are assimilated and the impacts of their sensing on bacterial behavior and physiology. Structural β-1,4-glucans and storage α-glucans (starch) are spatially discretized in the plant cell, therefore representing spatiotemporal references for the bacterium during host colonization. Combining transcriptional and genome mining analyses with gene knockout and cell motility assays, we show that X. citri 306 harbors molecular systems for the breakdown and assimilation of these carbohydrates, revealing that cellobiose upregulates genes related to flagellum assembly and type IV pili, inducing a higher motility state. In contrast, starch suppresses genes related to chemotaxis, flagellum assembly, and biofilm dispersion, decreasing motility. Taken together, these results unravel that, besides using structural β-glucans and storage α-glucans as sources of carbon and energy, Xanthomonas bacteria also sense them, adapting their metabolism and controlling transitions between higher and lower motility states for successful host colonization. IMPORTANCE Pathogenic Xanthomonas bacteria can affect a variety of economically relevant crops causing losses in productivity, limiting commercialization and requiring phytosanitary measures. These plant pathogens exhibit high level of host and tissue specificity through multiple molecular strategies including several secretion systems, effector proteins, and a broad repertoire of carbohydrate-active enzymes (CAZymes). Many of these CAZymes act on the plant cell wall and storage carbohydrates, such as cellulose and starch, releasing products used as nutrients and modulators of transcriptional responses to support host colonization by mechanisms yet poorly understood. Here, we reveal that structural and storage β-glucans from the plant cell function as spatial markers, providing distinct chemical stimuli that modulate the transition between higher and lower motility states in Xanthomonas citri, a key virulence trait for many bacterial pathogens.

Energy-based features and bi-LSTM neural network for EEG-based music and voice classification

AbstractThe human brain receives stimuli in multiple ways; among them, audio constitutes an important source of relevant stimuli for the brain regarding communication, amusement, warning, etc. In this context, the aim of this manuscript is to advance in the classification of brain responses to music of diverse genres and to sounds of different nature: speech and music. For this purpose, two different experiments have been designed to acquire EEG signals from subjects listening to songs of different musical genres and sentences in various languages. With this, a novel scheme is proposed to characterize brain signals for their classification; this scheme is based on the construction of a feature matrix built on relations between energy measured at the different EEG channels and the usage of a bi-LSTM neural network. With the data obtained, evaluations regarding EEG-based classification between speech and music, different musical genres, and whether the subject likes the song listened to or not are carried out. The experiments unveil satisfactory performance to the proposed scheme. The results obtained for binary audio type classification attain 98.66% of success. In multi-class classification between 4 musical genres, the accuracy attained is 61.59%, and results for binary classification of musical taste rise to 96.96%.

Helping networks to get synchronized: Effect of external stimulation

The attempts to evaluate the synchronizability of chaotic systems have shown that additive periodic forcing, as a relevant source of stimuli, significantly impacts multiple forms of synchrony. This paper investigates the complete synchronizability of coupled periodically forced chaotic systems using the master stability function method. Three classic chaotic systems, Lorenz, Chen's, and Hindmarsh-Rose models are employed for this study. The numerical simulations supporting master stability function findings are also reported. The impacts of forcing amplitude and frequency on the critical value of coupling strength at which synchronization occurs are determined. Evidence implies that, as the stimulation is amplified, the chaotic forced systems tend to synchronize at weaker couplings than the autonomous versions. In contrast, high-frequency stimulation is entirely ineffective. The required forcing amplitude is also relative to the system's attractor size.

Entrepreneurship in the age of the digital economy.

Entrepreneurship in the age of the digital economy.

The Impact of Plasma Membrane Ion Channels on Bone Remodeling in Response to Mechanical Stress, Oxidative Imbalance, and Acidosis

The extracellular milieu is a rich source of different stimuli and stressors. Some of them depend on the chemical-physical features of the matrix, while others may come from the 'outer' environment, as in the case of mechanical loading applied on the bones. In addition to these forces, a plethora of chemical signals drives cell physiology and fate, possibly leading to dysfunctions when the homeostasis is disrupted. This variety of stimuli triggers different responses among the tissues: bones represent a particular milieu in which a fragile balance between mechanical and metabolic demands should be tuned and maintained by the concerted activity of cell biomolecules located at the interface between external and internal environments. Plasma membrane ion channels can be viewed as multifunctional protein machines that act as rapid and selective dual-nature hubs, sensors, and transducers. Here we focus on some multisensory ion channels (belonging to Piezo, TRP, ASIC/EnaC, P2XR, Connexin, and Pannexin families) actually or potentially playing a significant role in bone adaptation to three main stressors, mechanical forces, oxidative stress, and acidosis, through their effects on bone cells including mesenchymal stem cells, osteoblasts, osteoclasts, and osteocytes. Ion channel-mediated bone remodeling occurs in physiological processes, aging, and human diseases such as osteoporosis, cancer, and traumatic events.

Review on host-pathogen interaction in dermatophyte infections.

Dermatophytosis is a common superficial fungal infection of the skin and its appendages caused by dermatophytes. Recent times have witnessed a dynamic evolution of dermatophytes driven by their ecology, reproduction, pathogenicity and host immune response, influenced by population migration and socioeconomic status. Dermatophytes establish infection following successful adherence of arthroconidia to the surface of keratinized tissues. The proteolytic enzymes released during adherence and invasion not only ascertain their survival but also allow the persistence of infection in the host. While the cutaneous immune surveillance mechanism, after antigen exposure and presentation, leads to activation of T lymphocytes and subsequent clonal expansion generating effector T cells that differentially polarize to a predominant Th17 response, the response fails to eliminate the pathogen despite the presence of high levels of IFN-γ. In chronic dermatophytosis, antigens are a constant source of stimulus promoting a dysregulated Th17 response causing inflammation. The host-derived iTreg response fails to counterbalance the inflammation and instead polarizes to Th17 lineage, aggravating the chronicity of the infection. Increasing antifungal resistance and recalcitrant dermatophytosis has impeded the overall clinical remission. Human genetic research has the potential to generate knowledge to explore new therapeutic targets. The review focuses on understanding specific virulence factors involved in pathogenesis and defining the role of dysregulated host immune response against chronic dermatophytic infections for future management strategies.

Neurodevelopment in the Congenital Heart Disease Population as Framed by the Life Course Health Development Framework.

Adverse neurodevelopment is a common comorbidity associated with congenital heart disease (CHD). The consequences of adverse neurodevelopment are seen across the life course. The cause of adverse neurodevelopment is multifactorial, and use of a life course perspective can assist with understanding and enhancing neurodevelopment in individuals with CHD. The purposes of this article are to (1) apply the Life Course Health Development framework to neurodevelopment in the population with CHD and (2) discuss how exposure to the pediatric cardiac intensive care unit (PCICU) environment during infancy is a point of intervention for improving neurodevelopmental outcomes. Individuals with CHD are at an increased risk for adverse neurodevelopment across the life course. The PCICU environment is a point of intervention for improving neurodevelopmental outcomes. Stress can lead to changes in brain structure and function that are associated with negative outcomes in terms of outward behavioral and functional capacity, and the PCICU environment is a source of stressful stimuli. Infancy is a period of rapid brain growth, and the brain is more susceptible to stress during this period of the life course, putting infants receiving care in the PCICU at an increased risk of adverse neurodevelopment. Interventions to support optimal neurodevelopment should focus on the PCICU environment during infancy. Developmentally supportive care models should be explored as a means of modifying the PCICU environment. In addition, more research is needed on the relationship between the PCICU and neurodevelopment. The conceptual model introduced can serve as a starting point for this research.

Host assessment and feeding behaviour of adult female Glycaspis brimblecombei on preferred and non‐preferred eucalypts

AbstractInsect herbivores assess plants by integrating responses elicited by a variety of external and internal cues and signals mediated by physical and chemical traits. We investigated host assessment behaviours of adult females of the Eucalyptus‐feeding psyllid, Glycaspis brimblecombei Moore (Hemiptera: Aphalaridae), on 10 species and subspecies (comprising preferred and non‐preferred hosts) using video recordings, electrical penetration graph (EPG) technology, and histological examination of tissues surrounding secondary veins. Our video recordings indicated that the shortest first searching time (mean 7.5 s) occurred on preferred hosts. Females placed on novel (non‐preferred) hosts jumped off leaves in &lt;10 s. We found that host acceptance occurred surprisingly rapidly after stylet penetration, e.g., between 7 and 11 s on preferred eucalypts, suggesting a strong role for gustatory cues. Our histological studies provided no evidence of physical barriers to phloem access. Females produced eight EPG waveforms, as observed for other psyllids and aphids, but the durations of PG (xylem activity) and PE2 (phloem ingestion), in particular, were unlike those recorded for any other hemipteran. On preferred hosts, phloem ingestion represented 21.5% (mean duration 4 h 18 min) of individual feeding bouts, whereas on non‐preferred hosts, there was almost no ingestion from phloem. Xylem ingestion on non‐preferred hosts represented 20.1% (mean duration 4 h 1 min) of feeding bouts, presumably to imbibe water. Thus, contrary to widespread belief, female G. brimblecombei did not feed exclusively from phloem even on preferred hosts, but also regularly ingested from the xylem. This is surprising considering that nymphs construct lerps consisting of approximately 16% sugars, and suggests that adults feed from phloem for shorter periods than offspring. Rapid assessment of hosts could also mean that positive stimuli induced by sugars are opposed by negative gustatory stimuli experienced in non‐vascular tissues. The most likely source of such stimuli are water‐soluble polyphenolic compounds that are widespread in cell vacuoles.