Making developmental sense of the senses, their origin and function.

The primary senses-touch, taste, sight, smell, and hearing-connect animals with their environments and with one another. Aside from the eyes, the primary sense organs of vertebrates and the peripheral sensory pathways that relay their inputs arise from two transient stem cell populations: the neural crest and the cranial placodes. In this chapter we consider the senses from historical and cultural perspectives, and discuss the senses as biological faculties. We begin with the embryonic origin of the neural crest and cranial placodes from within the neural plate border of the ectodermal germ layer. Then, we describe the major chemical (i.e. olfactory and gustatory) and mechanical (i.e. vestibulo-auditory and somatosensory) senses, with an emphasis on the developmental interactions between neural crest and cranial placodes that shape their structures and functions.

Autonomous Sensory Meridian Response (ASMR) and the Functions of Consciousness.

"Autonomous Sensory Meridian Response" (ASMR) refers to a sensory-emotional experience that was first explicitly identified and named within the past two decades in online discussion boards. Since then, there has been mounting psychological and neural evidence of a clustering of properties common to the phenomenon of ASMR, including convergence on the set of stimuli that trigger the experience, the properties of the experience itself, and its downstream effects. Moreover, psychological instruments have begun to be developed and employed in an attempt to measure it. Based on this empirical work, we make the case that despite its nonscientific origins, ASMR is a good candidate for being a real kind in the cognitive sciences. The phenomenon appears to have a robust causal profile and may also have an adaptive evolutionary history. We also argue that a more thorough understanding of the distinctive type of phenomenal experience involved in an ASMR episode can shed light on the functions of consciousness, and ultimately undermine certain "cognitive" theories of consciousness. We conclude that ASMR should be the subject of more extensive scientific investigation, particularly since it may also have the potential for therapeutic applications.

The influence of a previous implant-based breast reconstruction on postoperative sensation of the deep inferior epigastric artery perforator flap.

BACKGROUND: Implants and DIEP flaps have different outcomes regarding postoperative breast sensation. When compared to the preoperative healthy breast, implant-based breast reconstruction (IBBR) negatively influences postoperative breast sensation. However, it is currently unknown whether a prior IBBR also influences postoperative sensation of a replacing DIEP flap. The goal of this cohort study is to evaluate the influence of an IBBR on the postoperative sensation of a replacing DIEP flap. METHODS: Women were included if they received a DIEP flap reconstruction after mastectomy, with or without prior tissue expander (TE) and/or definitive breast implant. Sensation was measured at four intervals in 9 areas of the breast with Semmes-Weinstein monofilaments: T0 (preoperative, implant/no reconstruction), T1 (2-7 months postoperative, DIEP), T2 (± 12 months postoperative, DIEP), Tmax (maximum follow-up, DIEP). Linear mixed-effects models were used to investigate the relationship between an implant/TE prior to the DIEP flap and recovery of breast sensation. RESULTS: 142 women comprising 206 breasts were included. 48 (23.3%) breasts did, and 158 (76.7%) breasts did not have a TE/IBBR prior to their DIEP. No statistically significant or clinically relevant relationships were found between a prior implant/TE and recovery of DIEP flap breast sensation for the flap skin, native skin, or total breast skin at T1, T2, or Tmax. There were also no relationships found after adjustment for the confounders radiation therapy, BMI, diabetes, age, flap weight, follow-up, and nerve coaptation. CONCLUSIONS: An implant/TE prior to a DIEP flap does not influence the recovery of postoperative breast sensation of the DIEP flap.

Illusory Directional Sensation Induced by Asymmetric Vibrations Influences Sense of Agency and Velocity in Wrist Motions.

Illusory directional sensations are generated through asymmetric vibrations applied to the fingertips and have been utilized to induce upper-limb motions in the rehabilitation and training of patients with visual impairment. However, its effects on motor control remain unclear. This study aimed to verify the effects of illusory directional sensations on wrist motion. We conducted objective and subjective evaluations of wrist motion during a motor task, while inducing an illusory directional sensation that was congruent or incongruent with wrist motion. We found that, when motion and illusory directional sensations were congruent, the sense of agency for motion decreased. This indicates an induction sensation of the hand being moved by the illusion. Interestingly, although no physical force was applied to the hand, the angular velocity of the wrist was higher in the congruent condition than that in the no-stimulation condition. The angular velocity of the wrist and electromyography signals of the agonist muscles were weakly positively correlated, suggesting that the participants may have increased their wrist velocity. In other words, the congruence between the direction of motion and illusory directional sensation induced the sensation of the hand being moved, even though the participants' wrist-motion velocity increased. This phenomenon can be explained by the discrepancy between the sensation of active motion predicted by the efferent copy, and that of actual motion caused by the addition of the illusion. The findings of this study can guide the design of novel rehabilitation methods.

Does movement preparation enhance attending to bodily sensations in the back in people with persistent low back pain?

Attention has been proposed to play an important role in persisting pain, with excessive attentional processes towards pain information leading to worse pain outcomes and maladaptive behaviors. Nevertheless, research on somatosensory attending during the anticipation of pain-related movements is still scarce. This study investigated if individuals with chronic and recurrent lower back pain compared to pain-free controls, show enhanced attending to somatosensory information in the back while anticipating back-recruiting movements. 43 healthy control, 33 recurrent (RLBP) and 33 chronic low back (CLBP) pain sufferers were asked to perform back-recruiting movements. Before the movement initiation cue, a task-irrelevant tactile stimulus was administered to participants' lower back to elicit somatosensory evoked potentials (SEPs), used as an index of somatosensory attending. In contrast to our hypothesis, most identified SEP components did not differ across groups. The only exception was the P175 amplitude which was larger for the CLBP group compared to individuals with RLBP and healthy controls. The current study did not find robust evidence of enhanced somatosensory attending to the back in people with persisting lower back pain. The finding that CLBP, but not RLBP individuals, had larger amplitudes to the P175 component, is discussed as possibly reflecting a higher state of emotional arousal in these patients when having to prepare the back-recruiting movements.

Tension activation of mechanosensitive two-pore domain K+ channels TRAAK, TREK-1, and TREK-2.

TRAAK, TREK-1, and TREK-2 are mechanosensitive two-pore domain K+ (K2P) channels that contribute to action potential propagation, sensory transduction, and muscle contraction. While structural and functional studies have led to models that explain their mechanosensitivity, we lack a quantitative understanding of channel activation by membrane tension. Here, we define the tension response of mechanosensitive K2Ps using patch-clamp recording and imaging. All are low-threshold mechanosensitive channels (T10%/50% 0.6-2.7 / 4.4-6.4 mN/m) with distinct response profiles. TRAAK is most sensitive, TREK-1 intermediate, and TREK-2 least sensitive. TRAAK and TREK-1 are activated broadly over a range encompassing nearly all physiologically relevant tensions. TREK-2, in contrast, activates over a narrower range like mechanosensitive channels Piezo1, MscS, and MscL. We further show that low-frequency, low-intensity focused ultrasound increases membrane tension to activate TRAAK and MscS. This work provides insight into tension gating of mechanosensitive K2Ps relevant to understanding their physiological roles and potential applications for ultrasonic neuromodulation.

Gross, organoleptic and histologic assessment of cadaveric equine heads preserved using chemical methods for veterinary surgical teaching.

BACKGROUND: Preservation of biological tissues has been used since ancient times. Regardless of the method employed, tissue preservation is thought to be a vital step in veterinary surgery teaching and learning. OBJECTIVES: This study was designed to determine the usability of chemically preserved cadaveric equine heads for surgical teaching in veterinary medicine. METHODS: Six cadaveric equine heads were collected immediately after death or euthanasia and frozen until fixation. Fixation was achieved by using a hypertonic solution consisting of sodium chloride, sodium nitrite and sodium nitrate, and an alcoholic solution containing ethanol and glycerin. Chemically preserved specimens were stored at low temperatures (2°C to 6°C) in a conventional refrigerator. The specimens were submitted to gross and organoleptic assessment right after fixative solution injection (D0) and within 10, 20, and 30 days of fixation (D10, D20, and D30, respectively). Samples of tissue from skin, tongue, oral vestibule, and masseter muscle were collected for histological evaluation at the same time points. RESULTS: Physical and organoleptic assessments revealed excellent specimen quality (mean scores higher than 4 on a 5-point scale) in most cases. In some specimens, lower scores (3) were assigned to the range of mouth opening, particularly on D0 and D10. A reduced the range of mouth opening may be a limiting factor in teaching activities involving structures located in the oral cavity. CONCLUSIONS: The excellent physical, histologic, and organoleptic characteristics of the specimens in this sample support their usability in teaching within the time frame considered. Appropriate physical and organoleptic characteristics (color, texture, odor, and flexibility) of the specimens in this study support the use of the method described for preparation of reusable anatomical specimens.

An Evolving Landscape: Return of Breast Sensation After Mastectomy Varies by Anatomic Region and Reconstructive Method.

PURPOSE: Loss of breast sensation after mastectomy has been well documented. Postoperative reinnervation of the breast is influenced by factors including reconstructive technique, patient comorbidities, and adjuvant treatment. However, little attention has been paid to the differences in sensation across regions of the breast and the impact of reconstructive method on these regional differences over time. METHODS: Patients undergoing nipple-sparing mastectomy with immediate autologous or alloplastic reconstruction were prospectively followed. Neurosensory testing was performed in 9 breast regions using a pressure-specified sensory device. Patients were stratified by reconstructive technique, and regional sensation was compared at different preoperative and postoperative time points using Student t tests. RESULTS: One hundred ninety-two patients were included; 106 underwent autologous reconstruction via neurotized deep inferior epigastric artery perforator flap, and 86 underwent 2-stage alloplastic reconstruction. Preoperative sensation thresholds did not differ between reconstructive cohorts in any region and averaged 18.1 g/mm2. In the first year after mastectomy, decreased sensation was most pronounced in the inner breast regions and at the nipple areolar complex (NAC) in both reconstructive cohorts. At 4 years postoperatively, sensation increased the most at the NAC in the alloplastic cohort (34.0 g/mm2 decrease) and at the outer lateral region in the autologous cohort (30.4 g/mm2 threshold decrease). The autologous cohort experienced improved sensation compared with the alloplastic cohort in 5 of 9 regions at 1 year postoperatively, and in 7 of 9 regions at 4 years postoperatively; notably, only sensation at the outer superior and outer medial regions did not differ significantly between cohorts at 4 years postoperatively. CONCLUSIONS: Although patients undergoing breast reconstruction experience increased breast sensation over time, the return of sensation is influenced by type of reconstruction and anatomic region. Regions closer to and at the NAC experience the greatest loss of sensation after mastectomy, although the NAC itself undergoes the most sensation recovery of any breast region in those with alloplastic reconstruction.Autologous reconstruction via a neurotized deep inferior epigastric artery perforator flap results in increased return of sensation compared with alloplastic reconstruction, particularly in the inferior and lateral quadrants of the breast.

Plasma Levels of Interferon Gamma associated with Hearing Loss and Hearing Loss Sensation through the Handicap Questionnaire Inventory for the Elderly Screening Version.

OBJECTIVE: The aim of this study was to verify the association between the auditory handicap found in the Hearing Handicap Inventory for the Elderly-Screening Version (HHIE-S) questionnaire and hearing loss and the plasma levels of inflammatory biomarkers. MATERIALS AND METHODS: Cross-sectional study with 76 participants, 67 (88%) females and 9 (12%) males, with a mean age of 70 years. Tonal threshold audiometry and self-assessment with HHIE-S questionnaire were performed to measure the plasma levels of interleukin-2 (IL-2), IL-4, IL-6, and IL-10; tumor necrosis factor alpha; and interferon gamma (IFN-γ) flow cytometry method. For all data analyzed, the significance level adopted was P < 0.05 and 95% confidence interval. RESULTS: An inverse correlation was observed between the increase in plasma levels of IFN-γ and normal auditory handicap (P = 0.015; rs = -0.280). The severe handicap group showed an increase in the averages I (P = 0.005; rs = 0.350) and II (P = 0.016; rs = 0.368) in the right ear and the light/moderate handicap group increased the means I (P = 0.027; rs = 0.350) and II (P = 0.046; rs = 0.310) of the left ear. A statistically significant association was found between the speech recognition threshold (SRT) test results of the right ear and the severe handicap group (P = 0.002; rs = 0.271). CONCLUSIONS: There was an association between the increase in plasma levels of IFN-γ and normal auditory handicap. Additionally, statistically significant associations were observed between the mild/moderate and severe handicap groups with the increase in hearing means and an increase in SRT associated with the severe handicap group.

Circuit formation and sensory perception in the mouse olfactory system.

In the mouse olfactory system, odor information is converted to a topographic map of activated glomeruli in the olfactory bulb (OB). Although the arrangement of glomeruli is genetically determined, the glomerular structure is plastic and can be modified by environmental stimuli. If the pups are exposed to a particular odorant, responding glomeruli become larger recruiting the dendrites of connecting projection neurons and interneurons. This imprinting not only increases the sensitivity to the exposed odor, but also imposes the positive quality on imprinted memory. External odor information represented as an odor map in the OB is transmitted to the olfactory cortex (OC) and amygdala for decision making to elicit emotional and behavioral outputs using two distinct neural pathways, innate and learned. Innate olfactory circuits start to work right after birth, whereas learned circuits become functional later on. In this paper, the recent progress will be summarized in the study of olfactory circuit formation and odor perception in mice. We will also propose new hypotheses on the timing and gating of olfactory circuit activity in relation to the respiration cycle.

Taste dysfunction as a predictor of depression in schizophrenia: A systematic review and meta-analysis.

OBJECTIVE: This study aims to investigate the relationship between taste dysfunction and depression among patients with schizophrenia, to achieve early detection of depression in clinical practice. METHODS: Following PRISMA guidance, a comprehensive literature search was conducted globally, covering papers published from 1961 to June 2023. A total of 17 manuscripts were selected through meta-analysis and sensitivity analysis after examining available materials from seven databases to determine the correlation between depression and taste dysfunction. RESULTS: The comparison of the 17 selected manuscripts revealed that individuals with gustatory dysfunction may be more likely to experience depressive symptoms (SMD, 0.51, 95% CI, 0.08 to 0.93, p = 0.02). Depression is associated with taste dysfunction in certain aspects, as indicated by the pleasantness ratings of sucrose solutions (SMD, -0.53, 95% confidence interval [CI] -1.11 to 0.05, p = 0.08), gustatory identification ability (SMD, 0.96, 95% CI, 0.03 to 1.89, p = 0.04), and the perception threshold of sweet taste (MD, 0.80, 95% CI, 0.79 to 0.81, p < 0.00001). CONCLUSIONS: Due to variations in the methods, designs, and selection criteria employed in the included studies, it is necessary to establish a feasible framework. Future research using detailed and targeted approaches can provide clearer and more unified conclusions on the relationship between taste dysfunction and depression. Moreover, further high-quality research is needed to obtain clearer conclusions and explore the potential of taste dysfunction as an effective tool for early screening of depression. TRIAL REGISTRATION: This review has been registered in the PROSPERO on April 2022 with the identifier CRD42023400172.

Patient-Reported Outcomes on Subjective Nipple Sensation After Double-Incision and Periareolar Mastectomy for Chest Masculinization: Subjective Nipple Sensation After Chest Masculinization.

ABSTRACT: We evaluated patient-reported outcomes to assess for patient and procedural factors associated with postchest masculinization subjective nipple sensation. Patients who underwent double-incision or periareolar mastectomies for chest masculinization by a single senior surgeon (2015-2019) were surveyed at 2 time points regarding postoperative nipple sensation and satisfaction, including patient-reported outcomes using BODY-Q modules (Q-Portfolio.org). Demographic, operative, and postoperative variables were obtained from medical records. Patients were stratified according to survey responses. Univariate and multivariate analyses were performed.Response rate was 42% for survey 1 and 22% for survey 2. Of the 151 survey 1 responders, 138 (91.4%) received double-incision mastectomies and 13 (8.6%) received periareolar mastectomies. Among Survey 1 responders, 84.6% periareolar patients and 69.6% double-incision patients reported "completely" or "a little" nipple sensation preservation, and the difference trended toward significance (P = 0.0719). There was a stepwise increase in proportion of patients reporting sensation with greater recovery time until response to survey 1. Obesity (P = 0.0080) and greater tissue removed (P = 0.0247) were significantly associated with decreased nipple sensation. Nipple satisfaction scores were significantly higher for patients reporting improved nipple sensation (P = 0.0235). Responders to survey 2 who reported greater satisfaction with nipple sensation were significantly more likely to report preserved sensitivity to light touch (P = 0.0277), pressure (P = 0.0046), and temperature (P = 0.0031). Preserved erogenous sensation was also significantly associated with greater satisfaction (P = 0.0018).In conclusion, we found that nipple sensation may be associated with postoperative nipple satisfaction. Operative techniques to optimize nipple sensation preservation may improve this population's postoperative satisfaction.

Sensory neurobiology: Muscles power pheromone sensation.

While we understand how the five main sensory organs enable and facilitate stimulus detection, little is known about how the vomeronasal organ enables pheromone sensation. A new study finds specialized muscles poised to coordinate stimulus delivery, dynamics, and arousal.

Modeling circuit mechanisms of opposing cortical responses to visual flow perturbations.

In an ever-changing visual world, animals' survival depends on their ability to perceive and respond to rapidly changing motion cues. The primary visual cortex (V1) is at the forefront of this sensory processing, orchestrating neural responses to perturbations in visual flow. However, the underlying neural mechanisms that lead to distinct cortical responses to such perturbations remain enigmatic. In this study, our objective was to uncover the neural dynamics that govern V1 neurons' responses to visual flow perturbations using a biologically realistic computational model. By subjecting the model to sudden changes in visual input, we observed opposing cortical responses in excitatory layer 2/3 (L2/3) neurons, namely, depolarizing and hyperpolarizing responses. We found that this segregation was primarily driven by the competition between external visual input and recurrent inhibition, particularly within L2/3 and L4. This division was not observed in excitatory L5/6 neurons, suggesting a more prominent role for inhibitory mechanisms in the visual processing of the upper cortical layers. Our findings share similarities with recent experimental studies focusing on the opposing influence of top-down and bottom-up inputs in the mouse primary visual cortex during visual flow perturbations.

Effect of modifying pumpkin preparation on oral processing of breads.

There is an increasing demand for texture sensations of bread during mastication, with reformulation being needed. This study investigated how bread structure influences oral processing behavior and texture perception. Variations in bread structure were created by manipulating ingredient additions, including pumpkin content and pumpkin processing methods. Results indicated that the physical, chemical, and structural properties drove the oral processing behaviors, and texture sensations were highly correlated with bolus properties. At the beginning and middle of the mastication, bolus from breads with low pumpkin-content required more saliva and exhibited greater hardness, lower adhesiveness, and a higher proportion of small-piece particles than the bolus from high pumpkin-content breads. Bolus from pumpkin pulp breads required more saliva, and was softer, stickier, and generated particles with a lower degree of degradation than the bolus from pumpkin puree breads. However, at the end period, the bolus properties tended to change to similar values. Low pumpkin content breads were initially perceived chewy, whereas high pumpkin content, soft. The dominance rate for soft sensation was higher and lasted longer in breads with pumpkin puree than in breads with pumpkin pulp. Finally, six bread samples were all perceived as hydrated, sticky, and crumbly. This study contributes to a better understanding of the impact of reformulation on oral behavior and sensory properties.

Navigation by magnetic signatures in a realistic model of Earth's magnetic field.

Certain animal species use the Earth's magnetic field (i.e. magnetoreception) alongside their other sensory modalities to navigate long distances that include continents and oceans. It is hypothesized that several animals use geomagnetic parameters, such as field intensity and inclination, to recognize specific locations or regions, potentially enabling migration without a pre-surveyed map. However, it is unknown how animals use geomagnetic information to generate guidance commands, or where in the world this type of strategy would maximize an animal's fitness. While animal experiments have been invaluable in advancing this area, the phenomenon is difficult to studyin vivoorin situ, especially on the global scale where the spatial layout of the geomagnetic field is not constant. Alongside empirical animal experiments, mathematical modeling and simulation are complementary tools that can be used to investigate animal navigation on a global scale, providing insights that can be informative across a number of species. In this study, we present a model in which a simulated animal (i.e. agent) navigates via an algorithm which determines travel heading based on local and goal magnetic signatures (here, combinations of geomagnetic intensity and inclination) in a realistic model of Earth's magnetic field. By varying parameters of the navigation algorithm, different regions of the world can be made more or less reliable to navigate. We present a mathematical analysis of the system. Our results show that certain regions can be navigated effectively using this strategy when these parameters are properly tuned, while other regions may require more complex navigational strategies. In a real animal, parameters such as these could be tuned by evolution for successful navigation in the animal's natural range. These results could also help with developing engineered navigation systems that are less reliant on satellite-based methods.

Human sensory adaptation to the ecological structure of environmental statistics.

Humans acquire sensory information via fast, highly specialized detectors: For example, edge detectors monitor restricted regions of visual space over timescales of 100-200 ms. Surprisingly, this study demonstrates that their operation is nevertheless shaped by the ecological consistency of slow global statistical structure in the environment. In the experiments, humans acquired feature information from brief localized elements embedded within a virtual environment. Cast shadows are important for determining the appearance and layout of the environment. When the statistical reliability of shadows was manipulated, human feature detectors implicitly adapted to these changes over minutes, adjusting their response properties to emphasize either "image-based" or "object-based" anchoring of local visual elements. More specifically, local visual operators were more firmly anchored around object representations when shadows were reliable. As shadow reliability was reduced, visual operators disengaged from objects and became anchored around image features. These results indicate that the notion of sensory adaptation must be reframed around complex statistical constructs with ecological validity. These constructs far exceed the spatiotemporal selectivity bandwidth of sensory detectors, thus demonstrating the highly integrated nature of sensory processing during natural behavior.