Differential Role of Left and Right Hemispheres for Recovery from Aphasia. Evidence from SPECT Studies.

AbstractThe present study is interested in the role of the corpus callosum in the development of the language network. We, therefore, investigated language abilities and the language network using task-based fMRI in three cases of complete agenesis of the corpus callosum (ACC), three cases of partial ACC and six controls. Although the children with complete ACC revealed impaired functions in specific language domains, no child with partial ACC showed a test score below average. As a group, ACC children performed significantly worse than healthy controls in verbal fluency and naming. Furthermore, whole-brain ROI-to-ROI connectivity analyses revealed reduced intrahemispheric and right intrahemispheric functional connectivity in ACC patients as compared to controls. In addition, stronger functional connectivity between left and right temporal areas was associated with better language abilities in the ACC group. In healthy controls, no association between language abilities and connectivity was found. Our results show that ACC is associated not only with less interhemispheric, but also with less right intrahemispheric language network connectivity in line with reduced verbal abilities. The present study, thus, supports the excitatory role of the corpus callosum in functional language network connectivity and language abilities.

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The role of visual experience for spatial numerical associations

Seeing and Perceiving ◽

10.1163/187847612x648486 ◽

2012 ◽

Vol 25 (0) ◽

pp. 222 ◽

Cited By ~ 1

Author(s):

Michael J. Proulx ◽

Achille Pasqualotto ◽

Shuichiro Taya

Keyword(s):

Visual Experience ◽

Opposite Effect ◽

Random Number Generation ◽

Number Line ◽

Mental Number Line ◽

Generation Task ◽

Congenitally Blind ◽

Left And Right ◽

The Right

The topographic representation of space interacts with the mental representation of number. Evidence for such number–space relations have been reported in both synaesthetic and non-synaesthetic participants. Thus far most studies have only examined related effects in sighted participants. For example, the mental number line increases in magnitude from left to right in sighted individuals (Loetscher et al., 2008, Curr. Biol.). What is unclear is whether this association arises from innate mechanisms or requires visual experience early in life to develop in this way. Here we investigated the role of visual experience for the left to right spatial numerical association using a random number generation task in congenitally blind, late blind, and blindfolded sighted participants. Participants orally generated numbers randomly whilst turning their head to the left and right. Sighted participants generated smaller numbers when they turned their head to the left than to the right, consistent with past results. In contrast, congenitally blind participants generated smaller numbers when they turned their head to the right than to the left, exhibiting the opposite effect. The results of the late blind participants showed an intermediate profile between that of the sighted and congenitally blind participants. Visual experience early in life is therefore necessary for the development of the spatial numerical association of the mental number line.

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La sinistra e la destra nella Francia politica

MEMORIA E RICERCA ◽

10.3280/mer2012-041002 ◽

2013 ◽

pp. 13-22

Author(s):

Vincent Duclert

Keyword(s):

French Revolution ◽

Presidential Elections ◽

The State ◽

Political Life ◽

Role Of The State ◽

Political Forces ◽

The Future ◽

Left And Right ◽

The Republic

The recent presidential elections in 2012 have shown that left-right cleavage was still dominant in France. The redistribution of political forces, strongly awaited by the center (but also by the extremes) did not take place. At the same time, the major issues, such the European unification, the future of the nation, the future of the Republic, the role of the state, continue to cross left and right fields, revealing other cleavages that meet other historical or philosophical contingencies. However, the left-right opposition in France structured contemporary political life, organizing political families, determining the meaning and practice of institutions. Thence, the question is to understand what defines these two political fields and what history brings to their knowledge since the French Revolution, or they are implemented

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Bihemispheric Language: How the Two Hemispheres Collaborate in the Processing of Language

The Speciation of Modern Homo Sapiens ◽

10.5871/bacad/9780197263112.003.0010 ◽

2004 ◽

Author(s):

Norman D. Cook

Keyword(s):

Language Processing ◽

Right Hemisphere ◽

Central Question ◽

Linguistic Processing ◽

Figures Of Speech ◽

Language Functions ◽

Left And Right ◽

Level Of Understanding ◽

The Right

Speech production in most people is strongly lateralized to the left hemisphere (LH), but language understanding is generally a bilateral activity. At every level of linguistic processing that has been investigated experimentally, the right hemisphere (RH) has been found to make characteristic contributions, from the processing of the affective aspects of intonation, through the appreciation of word connotations, the decoding of the meaning of metaphors and figures of speech, to the understanding of the overall coherency of verbal humour, paragraphs and short stories. If both hemispheres are indeed engaged in linguistic decoding and both processes are required to achieve a normal level of understanding, a central question concerns how the separate language functions on the left and right are integrated. This chapter reviews relevant studies on the hemispheric contributions to language processing and the role of interhemispheric communications in cognition.

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Independent Coding of Wind Direction in Cockroach Giant Interneurons

Journal of Neurophysiology ◽

10.1152/jn.1997.78.5.2655 ◽

1997 ◽

Vol 78 (5) ◽

pp. 2655-2661 ◽

Cited By ~ 2

Author(s):

Adi Mizrahi ◽

Frederic Libersat

Keyword(s):

Sensory Processing ◽

Wind Direction ◽

Information Transfer ◽

Cell Interactions ◽

Synaptic Activity ◽

Cercal System ◽

Giant Interneurons ◽

Before And After ◽

Left And Right

Mizrahi, Adi and Frederic Libersat. Independent coding of wind direction in cockroach giant interneurons. J. Neurophysiol. 78: 2655–2661, 1997. In this study we examined the possible role of cell-to-cell interactions in the localization processing of a wind stimulus by the cockroach cercal system. Such sensory processing is performed primarily by pairs of giant interneurons (GIs), a group of highly directional cells. We have studied possible interactions among these GIs by comparing the wind sensitivity of a given GI before and after removing another GI with the use of photoablation. Testing various combinations of GI pairs did not reveal any suprathreshold interactions. This was true for all unilateral GI pairs on the left or right side as well as all the bilateral GI pairs (left and right homologues). Those experiments in which we were able to measure synaptic activity did not reveal subthreshold interactions between the GIs either. We conclude that the GIs code independently for a given wind direction without local GI–GI interactions. We discuss the possible implications of the absence of local interactions on information transfer in the first station of the escape circuit.

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Role of angiotensin and adrenoceptors in hemodynamic response to aortic cross-clamping

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1993.264.1.h14 ◽

1993 ◽

Vol 264 (1) ◽

pp. H14-H20

Author(s):

S. Gelman ◽

S. E. Curtis ◽

W. E. Bradley ◽

C. T. Henderson ◽

D. A. Parks ◽

...

Keyword(s):

Inferior Vena Cava ◽

Vascular Resistance ◽

Inferior Vena ◽

Enzyme Inhibitor ◽

Vena Cava ◽

Alpha Adrenoceptors ◽

Beta Adrenoceptor ◽

Adrenergic Antagonist ◽

Left And Right

An earlier study has shown that angiotensin and catecholamines were responsible for the vasoconstriction observed in the isolated hindlimb preparation during aortic cross-clamping. That study also demonstrated that when vasoconstriction was blocked with an alpha-adrenergic antagonist, phenoxybenzamine, vasodilation was elicited by aortic cross-clamping. The present study tested the hypothesis that this vasodilation was mediated via beta-adrenergic receptors. Eighteen dogs had their hindlimb denervated, vascularly isolated, and pump perfused with blood drained from the inferior vena cava, after passing through a gas-exchanging membrane where oxygen and carbon dioxide tensions were normalized. Left and right thoracotomies were performed, and the aorta and inferior vena cava were cross-clamped. The cross-clamping was associated with 29-37% increase in limb vascular resistance in control dogs (n = 6), in animals pretreated with propranolol (2 mg/kg, n = 6), and in dogs pretreated with a combination of phenoxybenzamine (3 mg/kg) and propranolol (2 mg/kg, n = 6). In animals pretreated with a combination of phenoxybenzamine, propranolol, and enalaprilat (2 mg/kg, n = 6), an angiotensin-converting enzyme inhibitor, limb vascular resistance did not change. This study has confirmed that aortic cross-clamping is associated with vasoconstriction induced by angiotensin and activation of alpha-adrenoceptors and has further demonstrated that vasodilation is attributable to beta-adrenoceptor activation.

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Mechanisms of antifibrillatory effect of acidic reperfusion: role of perfusate bicarbonate concentration

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1993.264.3.h783 ◽

1993 ◽

Vol 264 (3) ◽

pp. H783-H790 ◽

Cited By ~ 2

Author(s):

C. Ibuki ◽

D. J. Hearse ◽

M. Avkiran

Keyword(s):

Heart Rate ◽

Ventricular Fibrillation ◽

Rat Heart ◽

Coronary Flow ◽

Isolated Rat Heart ◽

Acidic Ph ◽

Bicarbonate Concentration ◽

Left And Right ◽

Isolated Rat

Transient (2 min) acidic (pH 6.6) reperfusion with low [HCO3-] solution suppresses reperfusion-induced ventricular fibrillation (VF) in the isolated rat heart. Using this preparation, we tested whether the effect was mediated by the high [H+] or the low [HCO3-] of perfusate. Left and right coronary beds were independently perfused with HCO3(-)-containing (25.0 mmol/l) solution at pH 7.4. Regional ischemia was then induced by stopping flow to the left coronary bed for 10 min. Hearts were subsequently assigned to four groups (n = 12 hearts/group), and the left coronary bed was reperfused with either HCO3(-)-containing (25.0 or 4.0 mmol/l) or HCO3(-)-free (5.0 mmol/l HEPES) solution, at pH 7.4 throughout (control reperfusion) or at pH 6.6 for the first 2 min and at pH 7.4 from 2 to 5 min (acidic reperfusion). Regardless of the buffer, controls exhibited a high (92 and 100%) incidence of VF; this was reduced to 42% in both of the acidic reperfusion groups (P < 0.05). There were no intergroup differences in heart rate, coronary flow, or size of ischemic zone. Thus high [H+], rather than low [HCO3-], appears to mediate the antifibrillatory effect of transient acidic reperfusion.

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Changes in left and right atrial size after cardioversion of atrial fibrillation: Role of mitral valve disease

Journal of the American College of Cardiology ◽

10.1016/0735-1097(93)90593-p ◽

1993 ◽

Vol 22 (6) ◽

pp. 1666-1672 ◽

Cited By ~ 66

Author(s):

A.T.Marcel Gosselink ◽

Harry J.G.M. Crijns ◽

Hans P.M. Hamer ◽

Hans Hillege ◽

Kong I. Lie

Keyword(s):

Atrial Fibrillation ◽

Mitral Valve ◽

Mitral Valve Disease ◽

Valve Disease ◽

Right Atrial ◽

Atrial Size ◽

Left And Right

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Cross-modal Processing in the Occipito-temporal Cortex: A TMS Study of the Müller-Lyer Illusion

Journal of Cognitive Neuroscience ◽

10.1162/jocn.2010.21561 ◽

2011 ◽

Vol 23 (8) ◽

pp. 1987-1997 ◽

Cited By ~ 16

Author(s):

Flavia Mancini ◽

Nadia Bolognini ◽

Emanuela Bricolo ◽

Giuseppe Vallar

Keyword(s):

Temporal Cortex ◽

Visual Modality ◽

Lateral Occipital Complex ◽

Lyer Illusion ◽

Superior Parietal Cortex ◽

Left And Right ◽

Neural Underpinnings ◽

The Right ◽

Underlying Processes

The Müller-Lyer illusion occurs both in vision and in touch, and transfers cross-modally from vision to haptics [Mancini, F., Bricolo, E., & Vallar, G. Multisensory integration in the Müller-Lyer illusion: From vision to haptics. Quarterly Journal of Experimental Psychology, 63, 818–830, 2010]. Recent evidence suggests that the neural underpinnings of the Müller-Lyer illusion in the visual modality involve the bilateral lateral occipital complex (LOC) and right superior parietal cortex (SPC). Conversely, the neural correlates of the haptic and cross-modal illusions have never been investigated previously. Here we used repetitive TMS (rTMS) to address the causal role of the regions activated by the visual illusion in the generation of the visual, haptic, and cross-modal visuo-haptic illusory effects, investigating putative modality-specific versus cross-modal underlying processes. rTMS was administered to the right and the left hemisphere, over occipito-temporal cortex or SPC. rTMS over left and right occipito-temporal cortex impaired both unisensory (visual, haptic) and cross-modal processing of the illusion in a similar fashion. Conversely, rTMS interference over left and right SPC did not affect the illusion in any modality. These results demonstrate the causal involvement of bilateral occipito-temporal cortex in the representation of the visual, haptic, and cross-modal Müller-Lyer illusion, in favor of the hypothesis of shared underlying processes. This indicates that occipito-temporal cortex plays a cross-modal role in perception both of illusory and nonillusory shapes.

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High variability impairs motor learning regardless of whether it affects task performance

Journal of Neurophysiology ◽

10.1152/jn.00158.2017 ◽

2018 ◽

Vol 119 (1) ◽

pp. 39-48 ◽

Cited By ~ 17

Author(s):

Marco Cardis ◽

Maura Casadio ◽

Rajiv Ranganathan

Keyword(s):

Motor Learning ◽

Task Performance ◽

Null Space ◽

Motor Task ◽

Task Space ◽

Movement Variability ◽

Motor Variability ◽

Different Dimensions ◽

Left And Right

Motor variability plays an important role in motor learning, although the exact mechanisms of how variability affects learning are not well understood. Recent evidence suggests that motor variability may have different effects on learning in redundant tasks, depending on whether it is present in the task space (where it affects task performance) or in the null space (where it has no effect on task performance). We examined the effect of directly introducing null and task space variability using a manipulandum during the learning of a motor task. Participants learned a bimanual shuffleboard task for 2 days, where their goal was to slide a virtual puck as close as possible toward a target. Critically, the distance traveled by the puck was determined by the sum of the left- and right-hand velocities, which meant that there was redundancy in the task. Participants were divided into five groups, based on both the dimension in which the variability was introduced and the amount of variability that was introduced during training. Results showed that although all groups were able to reduce error with practice, learning was affected more by the amount of variability introduced rather than the dimension in which variability was introduced. Specifically, groups with higher movement variability during practice showed larger errors at the end of practice compared with groups that had low variability during learning. These results suggest that although introducing variability can increase exploration of new solutions, this may adversely affect the ability to retain the learned solution.NEW & NOTEWORTHY We examined the role of introducing variability during motor learning in a redundant task. The presence of redundancy allows variability to be introduced in different dimensions: the task space (where it affects task performance) or the null space (where it does not affect task performance). We found that introducing variability affected learning adversely, but the amount of variability was more critical than the dimension in which variability was introduced.

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