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The Missing Female Homunculus
Abstract
The somatosensory homunculus shows a deformed human figure that illustrates the proportion of the brain devoted to the sense of touch in each part of the body. Originally based on Penfield’s brain mapping, it has been presented as a drawing of a human figure along the somatosensory cortex, an independent human figure, and a sculpted figure. Until recently, these homunculi have been male due to the lack of information on the female somatosensory cortex. A few female homunculi have been drawn. Based on more current brain research, the authors present, to our knowledge, the first sculpted 3D female somatosensory homunculus.
... Recently, social criticisms have also been raised concerning male-dominance as manifested by lack of involvement or acknowledgment of women or study of female somatotopic anatomy 5 -Wright recently created a hermunculus to do this. 7 In sum, while Penfield's motor homunculus is imperfect, still today he 'is a [beloved] metaphor for the complex neurological mechanisms that we strive to comprehend in their entirety … [and is] a brilliant aide-mémoire'. 3 One criticism of Penfield's motor homunculus that has not been raised is that he is incomplete, representing only the cerebral level of motor control, the cortico-motor neurons, and leaving spinal and cranial motor neurons-the part of the motor system that executes motor work-unrepresented. In parallel to, but separate from, elu- Sherrington identified integrative properties of motor neurons and referred to them as 'the final common pathway' and along with his mentee Liddell, formulated the concept of 'the motor unit' as the fundamental element of motor physiology comprising a motor neuron and its axon and muscle fibres. ...
... Gower's formulation remains today still essentially unaltered as a fundamental axiom of localization in clinical neurology-'the little old synecdoche that works'. 7 In this context, Penfield's motor homunculus anthropomorphizes the upper motor neuron, the cerebral aspect of the motor system, but leaves the lower motor neuron, the final common pathway, to be so represented. To redress this, we present here a lower motor neuron homunculus, who is shown juxtaposed to his upper motor neuron partner to highlight their relative proportions and differences (Fig. 1). ...
Penfield’s motor homunculus anthropomorphizes the cerebral level of motor control, the upper motor neuron. However, it leaves the cranial and spinal motor neurons unrepresented. Here Ravits and Stack redress the imbalance by presenting a lower motor neuron homunculus.
Recent and rapidly developing movements relating to the increasing awareness and reports of gender bias, discrimination, and abuse have reached the academic environments. The consideration that negative attitudes toward women and abuse of power creates a hostile environment for female scientists, facilitating sexual harassment and driving women out of science, can be easily related to. Rationally inaccessible gender biases are not only evident at the level of the researchers, but are also paralleled by a corresponding imbalance at the level of the research subjects. Here, we focus on the maternal immune activation (MIA) animal model to illustrate exemplarily the current state of ex-/inclusion of female research subjects and the consideration of sex as biological variable in the basic neurosciences. We demonstrate a strong sex disparity with a major emphasis on male animals in studies examining behavioral and neurochemical alterations in MIA offspring. We put forward the hypothesis that this neglect of female subjects in basic research may stem from a hard-wired sex/gender bias, which may also be reflected in a similar attitude toward female scientists. We suggest exploring the possibility that by dismantling sex bias and male dominance in basic research one would get an additional handle on favorably modifying the perception and appreciation for women in science.
We present a new generation tool based of interactive 3D models. This models are based on the radiological two-dimensional images by computed tomography imaging. Our article focuses on the anatomical region of the skull base. These new three-dimensional models offer a wide field of application in the learning, as they offer multiple visualization tools (rotation, scrolling, zoom…). In this way, understanding of the anatomical region is facilitated. A feature to be dismissed is that a professional workstation is not required to work with three-dimensional models, since a personal computer can be viewed and interacted with the models. Educational and clinical applications are also discussed.
Background:
Not including female rats or mice in neuroscience research has been justified due to the variable nature of female data caused by hormonal fluctuations associated with the female reproductive cycle. In this study, we investigated whether female rats are more variable than male rats in scientific reports of neuroscience-related traits.
Methods:
PubMed and Web of Science were searched for the period from August 1, 2010, to July 31, 2014, for articles that included both male and female rats and that measured diverse aspects of brain function. Only empirical articles using both male and female gonad-intact adult rats, written in English, and including the number of subjects (or a range) were included. This resulted in 311 articles for analysis. Data were extracted from digital images from article PDFs and from manuscript tables and text. The mean and standard deviation (SD) were determined for each data point and their quotient provided a coefficient of variation (CV) as a measure of trait-specific variability for each sex. Additionally, the results were coded for the type of research being measured (behavior, electrophysiology, histology, neurochemistry, and non-brain measures) and for the strain of rat. Over 6000 data points were extracted for both males and females. Subsets of the data were coded for whether male and female mean values differed significantly and whether animals were grouped or individually housed.
Results:
Across all traits, there were no sex differences in trait variability, as indicated by the CV, and there were no sex differences in any of the four neuroscience categories, even in instances in which mean values for males and females were significantly different. Female rats were not more variable at any stage of the estrous cycle than male rats. There were no sex differences in the effect of housing conditions on CV. On one of four measures of non-brain function, females were more variable than males.
Conclusions:
We conclude that even when female rats are used in neuroscience experiments without regard to the estrous cycle stage, their data are not more variable than those of male rats. This is true for behavioral, electrophysiological, neurochemical, and histological measures. Thus, when designing neuroscience experiments to include both male and female rats, power analyses based on variance in male measures are sufficient to yield accurate numbers for females as well, even when the estrous cycle is not taken into consideration.
Participants in 2 experiments interacted with computer simulations designed to foster understanding of scientific principles governing complex adaptive systems. The quality of participants' transportable understanding was measured by the amount of transfer between 2 simulations governed by the same principle. The perceptual con- creteness of the elements within the first simulation was manipulated. The elements either remained concrete throughout the simulation, remained idealized, or switched midway into the simulation from concrete to idealized or vice versa. Transfer was better when the appearance of the elements switched, consistent with theories pre- dicting more general schemas when the schemas are multiply instantiated. The best transfer was observed when originally concrete elements became idealized. These results are interpreted in terms of tradeoffs between grounded, concrete construals of simulations and more abstract, transportable construals. Progressive idealization ("concreteness fading") allows originally grounded and interpretable principles to become less tied to specific contexts and hence more transferable. Cognitive psychologists and educators have often debated the merits of concrete versus idealized materials for fostering scientific understanding. Should chemical molecules be represented by detailed, shaded, and realistically illuminated balls or by simple ball-and-stick figures? Should a medical illustration of a pancreas in- clude a meticulous rendering of the islets of Langerhans or convey in a more styl- ized manner the organ's general form? Our informal interviews with mycologists at the Royal Kew Gardens (personal communication, Brian Spooner and David Pegler, May 1998) indicate a schism between authors of mushroom field guides.
The representation of the body in the brain, the homunculus, was posited by Wilder Penfield based on his studies of patients with intractable epilepsy. While he mapped both male and female patients, Penfield reports little about the females. The now iconic illustration of the map is clearly male with testicles, penis, and no breasts. In order to bring attention to this omission and to stimulate studies of female somatosensory cortex (SS), we discuss what is known about the map of the female body in the brain, including Penfield's findings in his female patients and subsequent work by others exploring the human female SS. We reveal that there is much we do not know about how the entire female body is represented in the brain or how it might change with different reproductive life stages, hormones, and experiences. Understanding what is and is not currently known about the female SS is a first step toward fully understanding neurological and physiological sex differences, as well as producing better-informed treatments for pain conditions related to mastectomy, hysterectomy, vulvodynia, and fibromyalgia. We suggest that the time is ripe for a full mapping of the female brain with the production of a hermunculus.
The projection of vagina, uterine cervix, and nipple to the sensory cortex in humans has not been reported.
The aim of this study was to map the sensory cortical fields of the clitoris, vagina, cervix, and nipple, toward an elucidation of the neural systems underlying sexual response.
Using functional magnetic resonance imaging (fMRI), we mapped sensory cortical responses to clitoral, vaginal, cervical, and nipple self-stimulation. For points of reference on the homunculus, we also mapped responses to the thumb and great toe (hallux) stimulation.
The main outcome measures used for this study were the fMRI of brain regions activated by the various sensory stimuli.
Clitoral, vaginal, and cervical self-stimulation activated differentiable sensory cortical regions, all clustered in the medial cortex (medial paracentral lobule). Nipple self-stimulation activated the genital sensory cortex (as well as the thoracic) region of the homuncular map.
The genital sensory cortex, identified in the classical Penfield homunculus based on electrical stimulation of the brain only in men, was confirmed for the first time in the literature by the present study in women applying clitoral, vaginal, and cervical self-stimulation, and observing their regional brain responses using fMRI. Vaginal, clitoral, and cervical regions of activation were differentiable, consistent with innervation by different afferent nerves and different behavioral correlates. Activation of the genital sensory cortex by nipple self-stimulation was unexpected, but suggests a neurological basis for women's reports of its erotogenic quality.
Female mammals have long been neglected in biomedical research. The NIH mandated enrollment of women in human clinical trials in 1993, but no similar initiatives exist to foster research on female animals. We reviewed sex bias in research on mammals in 10 biological fields for 2009 and their historical precedents. Male bias was evident in 8 disciplines and most prominent in neuroscience, with single-sex studies of male animals outnumbering those of females 5.5 to 1. In the past half-century, male bias in non-human studies has increased while declining in human studies. Studies of both sexes frequently fail to analyze results by sex. Underrepresentation of females in animal models of disease is also commonplace, and our understanding of female biology is compromised by these deficiencies. The majority of articles in several journals are conducted on rats and mice to the exclusion of other useful animal models. The belief that non-human female mammals are intrinsically more variable than males and too troublesome for routine inclusion in research protocols is without foundation. We recommend that when only one sex is studied, this should be indicated in article titles, and that funding agencies favor proposals that investigate both sexes and analyze data by sex.
Neuroscience research has historically demonstrated sex bias that favors male over female research subjects, as well as sex omission, which is the lack of reporting sex. Here we analyzed the status of sex bias and omission in neuroscience research published across six different journals in 2017. Regarding sex omission, 16% of articles did not report sex. Regarding sex bias, 52% of neuroscience articles reported using both males and females, albeit only 15% of articles using both males and females reported assessing sex as an experimental variable. Overrepresentation of the sole use of males compared to females persisted (26% versus 5%, respectively). Sex bias and omission differed across research models, but not by reported NIH funding status. Sex omission differed across journals. These findings represent the latest information regarding the complex status of sex in neuroscience research and illustrate the continued need for thoughtful and informed action to enhance scientific discovery.
To the Editor I read the recently published Original Investigation by Anderson and colleagues¹ with keen interest. They contributed important findings on outcomes of intensive hypertension control following hospitalization. Observational studies like theirs are vital for building our understanding of for whom and under what circumstances intensive hypertension control can be beneficial. Well-designed observational studies provide meaningful contributions to the literature where gaps in experimental data exist. Despite this contribution, the interpretation of the results and absence of attempts to address potential sex effects are concerning.
Emotional design of multimedia instruction involves making the essential elements in the lesson's graphics more appealing, such as by rendering them with human-like features and with distinct, appealing colors (Um, Plass, Hayward, & Homer, 2012). College students received an 8-slide multimedia lesson on how a virus causes a cold for 5 min (Experiment 1) or for as long as they wanted (Experiment 2). For the control group, the graphics consisted of simple black-and-white drawings in which the host cell was represented as a large circle, and the virus was represented as a small circle with small spikes on the outside and a rectangle on the inside. For the enhanced group, the graphics were redrawn to render the host cell as a red face with expressive eyes (registering surprise, fear, and sickness at various stages in the process), and the virus as a blue face with fierce eyes and with a green dot at the end of each of the blue tentacles surrounding the virus face. The enhanced group performed better than the control group on a subsequent learning test (d = 0.69 in Experiment 1, d = 0.65 in Experiment 2) and gave higher effort ratings in Experiment 1 (d = 0.65) but not in Experiment 2 (d = −0.10). The findings are generally consistent with the cognitive affective theory of learning with media, and point to the importance of incorporating motivation into cognitive theories of multimedia learning.
Brain scan data backs up what women have been telling men for decades: stimulating the vagina is not the same as stimulating the clitoris
We studied a detailed somatosensory representation map of the human primary somatosensory cortex using magnetoencephalography. Somatosensory-evoked magnetic fields following tactile stimulation of multiple points in the right hemibody (including the tongue, lips, fingers, arm, trunk, leg, and foot) were analyzed in five normal subjects. We were able to estimate equivalent current dipoles (ECDs) following stimulation of the tongue, lips, fingers, palm, forearm, elbow, upper arm, and toes in most subjects and those following the stimulation of the chest, ankle, and thigh in one subject. The ECDs were located in the postcentral gyrus and generally arranged in order along the central sulcus, which is compatible with the somatosensory “homunculus.” Linear distances, averaged in five subjects, from the receptive area of the thumb to that of the tongue, little finger, forearm, upper arm, and toes were estimated to be 2.42 ± 0.28, 1.25 ± 0.28, 2.21 ± 0.72, 2.75 ± 0.63, and 5.29 ± 0.48 cm, respectively. The moment of each ECD, which suggested the size of the cortical areas responsive to the stimulation, was also compatible with the bizarre proportion of the homunculus with a large tongue, lips, and fingers. According to these results, we were able to reproduce a large part of the somatosensory homunculus quantitatively on an individual brain MRI.
This book is based on the Lane Medical Lectures which Penfield gave in 1947. Four hundred craniotomies performed between 1928 and 1947 presented the opportunity to stimulate various parts of the cerebral cortex with electrical currents and to record the objective (movements) and subjective effects. The results of these studies are presented clearly and with the necessary details. Objective results and interpretation are sharply separated. The investigations give a very complete description of the organization of the sensorimotor cortex. The primitive character of the movements is emphasized. They are "not more complicated than those the newborn infant is able to perform." Evidence of the existence of a secondary motor cortex is also presented. A certain muscle may show widely separated cortical foci when it is used in different functional groupings. Central overlap exists clearly in precentral and postcentral gyrus. The authors assume that the diencephalon plays an important role in
In Promethean Ambitions, William R. Newman uses alchemy as a means to discuss the thinning boundary between the natural and the artificial. Focusing primarily on the period between 1200 and 1700, Newman examines the labors of pioneering alchemists and the impassionedâand often negativeâresponses to their efforts. Newman also shows that alchemy was not an unformed and capricious precursor to chemistry; it was an art founded on coherent philosophical and empirical principlesâwith vocal supporters and even louder criticsâthat attracted individuals of first-rate intellect. The historical relationship that he charts here between human creation and nature has innumerable implications today. Promethean Ambitions ably imbues a millennium-old scientific and ethical debate with modern relevance. "With close attention to historical and textual detail that is never less than engaging, Newman unpacks the historical accidents and political machinations that led to alchemy's marginalization, bringing sympathy, wit and imagination to his account."âSimon Ings, New Scientist "Newman chooses the fascinating topic of alchemy as his case study in the long history of human efforts to breach the barriers between nature and human artifice. . . . A thought-provoking book."âIwan Rhys Morus, Science
We studied the central representation of pudendal afferents arising from the clitoral nerves in 15 healthy adult female subjects using electrical dorsal clitoral nerve stimulation and fMRI. As a control body region, we electrically stimulated the right hallux in eight subjects. In a block design experiment, we applied bilateral clitoral stimulation and unilateral (right) hallux stimulation. Activation maps were calculated for the contrasts 'electrical dorsal clitoral nerve stimulation versus rest' and 'electrical hallux stimulation versus rest'. A random-effect group analysis for the clitoral stimulation showed significant activations bilateral in the superior and inferior frontal gyri, insulae and putamen and in the postcentral, precentral and inferior parietal gyri (including the primary and secondary somatosensory cortices). No activation was found on the mesial surface of the postcentral gyrus. For the hallux, activations occurred in a similar neuronal network but the activation in the primary somatosensory cortex was localized in the inter-hemispheric fissure. The results of this study demonstrate that the central representation of pudendal afferents arising from the clitoral nerves and sensory inputs from the hallux can be studied and distinguished from each other by fMRI. From the somatotopic order described in the somatosensory homunculus one would expect for electrical clitoral nerve stimulation activation of the mesial wall of the postcentral gyrus. In contrast, we found activations on the lateral surface of the postcentral gyrus.
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