34,341 research outputs found
Transcranial magnetic stimulation reveals two cortical pathways for visual body processing
No full textVisual recognition of human bodies is more difficult for upside down than upright presentations. This body inversion effect implies that body perception relies on configural rather than local processing. Although neuroimaging studies indicate that the visual processing of human bodies engages a large fronto-temporo-parietal network, information about the neural underpinnings of configural body processing is meager. Here, we used repetitive transcranial magnetic stimulation (rTMS) to study the causal role of premotor, visual, and parietal areas in configural processing of human bodies. Eighteen participants performed a delayed matching-to-sample task with upright or inverted static body postures. Event-related, dual-pulse rTMS was applied 150 ms after the sample stimulus onset, over left ventral premotor cortex (vPMc), right extrastriate body area (EBA), and right superior parietal lobe (SPL) and, as a control site, over the right primary visual cortex (V1). Interfering stimulation of vPMc significantly reduced accuracy of matching judgments for upright bodies. In contrast, EBA rTMS significantly reduced accuracy for inverted but not for upright bodies. Furthermore, a significant body inversion effect was observed after interfering stimulation of EBA and V1 but not of vPMc and SPL. These results demonstrate an active contribution of the fronto-parietal mirror network to configural processing of bodies and suggest a novel, embodied aspect of visual perception. In contrast, the local processing of the body, possibly based on the form of individual body parts instead of on the whole body unit, appears to depend on EBA. Therefore, we propose two distinct cortical routes for the visual processing of human bodies
Transcranial magnetic stimulation reveals two cortical pathways for visual body processing
No full textVisual recognition of human bodies is more difficult for upside down than upright presentations. This body inversion effect implies that body perception relies on configural rather than local processing. Although neuroimaging studies indicate that the visual processing of human bodies engages a large fronto-temporo-parietal network, information about the neural underpinnings of configural body processing is meager. Here, we used repetitive transcranial magnetic stimulation (rTMS) to study the causal role of premotor, visual, and parietal areas in configural processing of human bodies. Eighteen participants performed a delayed matching-to-sample task with upright or inverted static body postures. Event-related, dual-pulse rTMS was applied 150 ms after the sample stimulus onset, over left ventral premotor cortex (vPMc), right extrastriate body area (EBA), and right superior parietal lobe (SPL) and, as a control site, over the right primary visual cortex (V1). Interfering stimulation of vPMc significantly reduced accuracy of matching judgments for upright bodies. In contrast, EBA rTMS significantly reduced accuracy for inverted but not for upright bodies. Furthermore, a significant body inversion effect was observed after interfering stimulation of EBA and V1 but not of vPMc and SPL. These results demonstrate an active contribution of the fronto-parietal mirror network to configural processing of bodies and suggest a novel, embodied aspect of visual perception. In contrast, the local processing of the body, possibly based on the form of individual body parts instead of on the whole body unit, appears to depend on EBA. Therefore, we propose two distinct cortical routes for the visual processing of human bodies
Action observation and acquired motor skills: An fMRI study with expert dancers
No full textWhen we observe someone performing an action, do our brains simulate making that action? Acquired motor skills offer a unique way to test this question, since people differ widely in the actions they have learned to perform. We used functional magnetic resonance imaging to study differences in brain activity between watching an action that one has learned to do and an action that one has not, in order to assess whether the brain processes of action observation are modulated by the expertise and motor repertoire of the observer. Experts in classical ballet, experts in capoeira and inexpert control subjects viewed videos of ballet or capoeira actions. Comparing the brain activity when dancers watched their own dance style versus the other style therefore reveals the influence of motor expertise on action observation. We found greater bilateral activations in premotor cortex and intraparietal sulcus, right superior parietal lobe and left posterior superior temporal sulcus when expert dancers viewed movements that they had been trained to perform compared to movements they had not. Our results show that this 'mirror system' integrates observed actions of others with an individual's personal motor repertoire, and suggest that the human brain understands actions by motor simulation
The mirage of floating exchange rates
No full textThis note summarizes some of the highlights of my longer paper with Guillermo Calvo”Fear of Floating.” Many emerging market countries have suffered financial crises. One view blames soft pegs for these crises. Adherents to that view suggest that countries move to corner solutions--hard pegs or floating exchange rates. We analyze the behavior of exchange rates, reserves, and interest rates to assess whether there is evidence that country practice is moving toward corner solutions. We focus on whether countries that claim they are floating are indeed doing so. We find that countries that say they allow their exchange rate to float mostly do not--there seems to be an epidemic case of “fear of floating.”fear of floating fixed exchange rates interest rates reserves
Extrastriate body area underlies aesthetic evaluation of body stimuli
No full textHumans appear to be the only animals to have developed the practice and culture of art. This practice presumably relies on special processing circuits within the human brain associated with a distinct subjective experience, termed aesthetic experience, and preferentially evoked by artistic stimuli. We assume that positive or negative aesthetic judgments are an important function of neuroaesthetic circuits. The localization of these circuits in the brain remains unclear, though neuroimaging studies have suggested several possible neural correlates of aesthetic preference. We applied repetitive transcranial magnetic stimulation (rTMS) over candidate brain areas to disrupt aesthetic processing while healthy volunteers made aesthetic preference judgments between pairs of dance postures, or control non-body stimuli. Based on evidence from visual body perception studies, we targeted the ventral premotor cortex (vPMC) and extrastriate body area (EBA), in the left and right hemispheres. rTMS over EBA reduced aesthetic sensitivity for body stimuli relative to rTMS over vPMC, while no such difference was found for non-body stimuli. We interpret our results within the framework of dual routes for visual body processing. rTMS over either EBA or vPMC reduced the contributions of the stimulated area to body processing, leaving processing more reliant on the unaffected route. Disruption of EBA reduces the local processing of the stimuli, and reduced observers’ aesthetic sensitivity. Conversely, disruption of the global route via vPMC increased the relative contribution of the local route via EBA, and thus increased aesthetic sensitivity. In this way, we suggest a complementary contribution of both local and global routes to aesthetic processing
Selection for growth, muscling and fatness alters the maternal performance and intermediary metabolism of Merino ewes
No full textThere is growing interest in selectively breeding Merinos with higher growth and muscling and lower fatness. The effects of selection for these traits on ewe intermediary metabolism, body composition, reproduction and milk production and on lamb birthweight, survival and growth were studied in a series of experiments and analyses.
Ewes with higher genetic propensity for early growth had higher mature weight, reproductive rate, lamb birthweight, ewe milk production and lamb growth rate. Ewes with higher growth also had a higher circulating level of growth hormone during lactation.
Ewes with higher genetic propensity for muscling had a higher reproductive rate and produced lambs that were lighter at birth, but this did not result in lower lamb survival. Ewes with higher muscling maintained a higher condition score which may be at least partly attributed to a lower response to adrenaline at the level of the muscle in these higher muscled ewes. Similarly higher muscled ewes had lower growth hormone concentration in lactation which would result in lower mobilisation of tissues. In addition peripheral tissues were less responsive to insulin in high muscled ewes and blood glucose levels were also higher during the non-breeding state in high muscled ewes.
The genetic fatness of ewes was positively associated with lamb birthweight but only when nutrition was restricted suggesting that ewes with a higher genetic propensity for fatness can buffer lamb birthweight under periods of poor nutrition. Ewes with higher genetic fatness had lower circulating growth hormone and a greater response to insulin providing potential mechanisms for the observed higher fatness. Furthermore, response to adrenaline at the level of liver was greater in ewes with higher fatness suggestive of a higher capacity for gluconeogenesis. The combined results of this work suggest that actively selecting Merino ewes to have higher growth, muscling and fatness is likely to have positive reproduction and therefore economic outcomes
Welfare implications of Calvo vs. Rotemberg pricing assumptions
No full textThis paper compares the welfare implications of two widely used pricing assumptions in the New-Keynesian literature: Calvo-pricing vs. Rotemberg-pricing. We show that despite the strong similarities between the two assumptions to a first order of approximation, in general they might entail different welfare costs at higher order of approximation. In the special case of non-distorted steady state, the two pricing assumptions imply identical welfare losses to a second order of approximation. JEL Classification: E3, E5Calvo price adjustment, inflation, Rotemberg price adjustment, second-order approximation, Welfare
Somatosensory Evoked Potentials Reveal Reduced Embodiment of Emotions in Autism
No full textConsistent with current models of embodied emotions, this study investigates whether the somatosensory system shows reduced sensitivity to facial emotional expressions in autistic compared with neurotypical individuals, and whether these differences are independent from between-group differences in visual processing of facial stimuli. To investigate the dynamics of somatosensory activity over and above visual carryover effects, we recorded EEG activity from two groups of autism spectrum disorder (ASD) or typically developing (TD) humans (male and female), while they were performing a facial emotion discrimination task and a control gender task. To probe the state of the somatosensory system during face processing, in 50% of trials we evoked somatosensory activity by delivering task-irrelevant tactile taps on participants' index finger, 105 ms after visual stimulus onset. Importantly, we isolated somatosensory from concurrent visual activity by subtracting visual responses from activity evoked by somatosensory and visual stimuli. Results revealed significant task-dependent group differences in mid-latency components of somatosensory evoked potentials (SEPs). ASD participants showed a selective reduction of SEP amplitudes (P100) compared with TD during emotion task; and TD, but not ASD, showed increased somatosensory responses during emotion compared with gender discrimination. Interestingly, autistic traits, but not alexithymia, significantly predicted SEP amplitudes evoked during emotion, but not gender, task. Importantly, we did not observe the same pattern of group differences in visual responses. Our study provides direct evidence of reduced recruitment of the somatosensory system during emotion discrimination in ASD and suggests that this effect is not a byproduct of differences in visual processing.
SIGNIFICANCE STATEMENT The somatosensory system is involved in embodiment of visually presented facial expressions of emotion. Despite autism being characterized by difficulties in emotion-related processing, no studies have addressed whether this extends to embodied representations of others' emotions. By dissociating somatosensory activity from visual evoked potentials, we provide the first evidence of reduced recruitment of the somatosensory system during emotion discrimination in autistic participants, independently from differences in visual processing between typically developing and autism spectrum disorder participants. Our study uses a novel methodology to reveal the neural dynamics underlying difficulties in emotion recognition in autism spectrum disorder and provides direct evidence that embodied simulation of others' emotional expressions operates differently in autistic individuals
GARCIA CALVO, M. y Genaro B. ESQUIVEL
No full textTelegram from Misters M. García Calvo and Genaro B. Esquivel, President and Vice-Secretary, respectively, of the Benito Juárez Liberal Center of Oaxaca to Gen. Alvaro Obregón, requesting that the Governor of the state of Oaxaca, Mr. Carlos Bravo, be removed from his position. Response indicating that the petition has been transcribed to the President of the Republic. / Telegrama de los Srs. M. García Calvo y Genaro B. Esquivel, Presidente y Prosecretario respectivamente, del Centro Liberal Benito Juárez de Oaxaca al Gral. Alvaro Obregón, solicitándole sea removido de su cargo el Sr. Carlos Bravo, Gobernador del estado de Oaxaca. Respuesta indicando que ha transcrito su petición al Presidente de la República
GARCIA CALVO, M. y Genaro B. ESQUIVEL
No full textTelegram from Misters M. García Calvo and Genaro B. Esquivel, President and Vice-Secretary, respectively, of the Benito Juárez Liberal Center of Oaxaca to Gen. Alvaro Obregón, requesting that the Governor of the state of Oaxaca, Mr. Carlos Bravo, be removed from his position. Response indicating that the petition has been transcribed to the President of the Republic. / Telegrama de los Srs. M. García Calvo y Genaro B. Esquivel, Presidente y Prosecretario respectivamente, del Centro Liberal Benito Juárez de Oaxaca al Gral. Alvaro Obregón, solicitándole sea removido de su cargo el Sr. Carlos Bravo, Gobernador del estado de Oaxaca. Respuesta indicando que ha transcrito su petición al Presidente de la República
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