Generation of co-speech gestures based on spatial imagery from the right-hemisphere: Evidence from split-brain patients

Cortex ◽  
2008 ◽  
Vol 44 (2) ◽  
pp. 131-139 ◽  
Author(s):  
Sotaro Kita ◽  
Hedda Lausberg
Keyword(s):  
Right Hemisphere ◽  
Spatial Imagery ◽  
Split Brain ◽  
The Right

Dual Intentional Agency

2018 ◽  
Author(s):  
Elizabeth Schechter
Keyword(s):  
Left Hemisphere ◽  
Practical Reasoning ◽  
Right Hemisphere ◽  
Brain Surgery ◽  
Experimental Conditions ◽  
Split Brain ◽  
Intentional Agency ◽  
Intentional Agents ◽  
Experimental Findings ◽  
The Right

This chapter defends the 2-agents claim, according to which the two hemispheres of a split-brain subject are associated with distinct intentional agents. The empirical basis of this claim is that, while both hemispheres are the source or site of intentions, the capacity to integrate them in practical reasoning no longer operates interhemispherically after split-brain surgery. As a result, the right hemisphere-associated agent, R, and the left hemisphere-associated agent, L, enjoy intentional autonomy from each other. Although the positive case for the 2-agents claim is grounded mainly in experimental findings, the claim is not contradicted by what we know of split-brain subjects’ ordinary behavior, that is, the way they act outside of experimental conditions.

scholarly journals Moral judgement by the disconnected left and right cerebral hemispheres: a split-brain investigation

2017 ◽  
Vol 4 (7) ◽  
pp. 170172 ◽  
Author(s):  
Conor M. Steckler ◽  
J. Kiley Hamlin ◽  
Michael B. Miller ◽  
Danielle King ◽  
Alan Kingstone
Keyword(s):  
Brain Research ◽  
Right Hemisphere ◽  
Mental States ◽  
Brain Regions ◽  
Moral Judgement ◽  
Temporoparietal Junction ◽  
Split Brain ◽  
Moral Judgements ◽  
The Right ◽  
Necessary And Sufficient

Owing to the hemispheric isolation resulting from a severed corpus callosum, research on split-brain patients can help elucidate the brain regions necessary and sufficient for moral judgement. Notably, typically developing adults heavily weight the intentions underlying others' moral actions, placing greater importance on valenced intentions versus outcomes when assigning praise and blame. Prioritization of intent in moral judgements may depend on neural activity in the right hemisphere's temporoparietal junction, an area implicated in reasoning about mental states. To date, split-brain research has found that the right hemisphere is necessary for intent-based moral judgement. When testing the left hemisphere using linguistically based moral vignettes, split-brain patients evaluate actions based on outcomes, not intentions. Because the right hemisphere has limited language ability relative to the left, and morality paradigms to date have involved significant linguistic demands, it is currently unknown whether the right hemisphere alone generates intent-based judgements. Here we use nonlinguistic morality plays with split-brain patient J.W. to examine the moral judgements of the disconnected right hemisphere, demonstrating a clear focus on intent. This finding indicates that the right hemisphere is not only necessary but also sufficient for intent-based moral judgement, advancing research into the neural systems supporting the moral sense.

Split brains

2018 ◽  
Author(s):  
Elizabeth Schechter
Keyword(s):  
Visual Field ◽  
Information Exchange ◽  
Visual Information ◽  
Right Hemisphere ◽  
The Other ◽  
Brain Surgery ◽  
Interhemispheric Interaction ◽  
Split Brain ◽  
The One ◽  
The Right

The largest fibre tract in the human brain connects the two cerebral hemispheres. A ‘split-brain’ surgery severs this structure, sometimes together with other white matter tracts connecting the right hemisphere and the left. Split-brain surgeries have long been performed on non-human animals for experimental purposes, but a number of these surgeries were also performed on adult human beings in the second half of the twentieth century, as a medical treatment for severe cases of epilepsy. A number of these people afterwards agreed to participate in ongoing research into the psychobehavioural consequences of the procedure. These experiments have helped to show that the corpus callosum is a significant source of interhemispheric interaction and information exchange in the ‘neurotypical’ brain. After split-brain surgery, the two hemispheres operate unusually independently of each other in the realm of perception, cognition, and the control of action. For instance, each hemisphere receives visual information directly from the opposite (‘contralateral’) side of space, the right hemisphere from the left visual field and the left hemisphere from the right visual field. This is true of the normal (‘neurotypical’) brain too, but in the neurotypical case interhemispheric tracts allow either hemisphere to gain access to the information that the other has received. In a split-brain subject however the information more or less stays put in whatever hemisphere initially received it. And it isn’t just visual information that is confined to one hemisphere or the other after the surgery. Rather, after split-brain surgery, each hemisphere is the source of proprietary perceptual information of various kinds, and is also the source of proprietary memories, intentions, and aptitudes. Various notions of psychological unity or integration have always been central to notions of mind, personhood, and the self. Although split-brain surgery does not prevent interhemispheric interaction or exchange, it naturally alters and impedes it. So does the split-brain subject as a whole nonetheless remain a unitary psychological being? Or could there now be two such psychological beings within one human animal – sharing one body, one face, one voice? Prominent neuropsychologists working with the subjects have often appeared to argue or assume that a split-brain subject has a divided or disunified consciousness and even two minds. Although a number of philosophers agree, the majority seem to have resisted these conscious and mental ‘duality claims’, defending alternative interpretations of the split-brain experimental results. The sources of resistance are diverse, including everything from a commitment to the necessary unity of consciousness, to recognition of those psychological processes that remain interhemispherically integrated, to concerns about what the moral and legal consequences would be of recognizing multiple psychological beings in one body. On the other hand underlying most of these arguments against the various ‘duality’ claims is the simple fact that the split-brain subject does not appear to be two persons, but one – and there are powerful conceptual, social, and moral connections between being a unitary person on the one hand and having a unified consciousness and mind on the other.

scholarly journals Visuospatial Attention and the Split Brain

Physiology ◽  
1997 ◽  
Vol 12 (5) ◽  
pp. 226-231
Author(s):  
G Berlucchi ◽  
GR Mangun ◽  
MS Gazzaniga
Keyword(s):  
Visual Field ◽  
Left Hemisphere ◽  
Right Hemisphere ◽  
Visuospatial Attention ◽  
Attentional Biases ◽  
Split Brain ◽  
Right Hemisphere Damage ◽  
Entire Visual Field ◽  
The Right

In callosotomy patients, the right hemisphere attends to the entire visual field, whereas the left hemisphere attends to the right field only. The occurence of rightward attentional biases, simulating a hemineglect from right hemisphere damage, suggests that in these patients visuospatial attention tends to be controlled by the left hemisphere.

Right-Hemisphere Memory Superiority: Studies of a Split-Brain Patient

1995 ◽  
Vol 6 (3) ◽  
pp. 157-164 ◽  
Author(s):  
Janet Metcalfe ◽  
Margaret Funnell ◽  
Michael S. Gazzaniga
Keyword(s):  
Corpus Callosum ◽  
Left Hemisphere ◽  
Semantic Priming ◽  
Language Production ◽  
Right Hemisphere ◽  
Split Brain ◽  
Left And Right ◽  
The Right ◽  
Source Of Information

Six experiments explored hemispheric memory differences in a patient who had undergone complete corpus callosum resection The right hemisphere was better able than the left to reject new events similar to originally presented materials of several types, including abstract visual forms, faces, and categorized lists of words Although the left hemisphere is capable of mental manipulation, imagination, semantic priming, and complex language production, these functions are apparently linked to memory confusions—confusions less apparent in the more literal right hemisphere Differences between the left and right hemispheres in memory for new schematically consistent or categorically related events may provide a source of information allowing people to distinguish between what they actually witnessed and what they only inferred

Subjects of Experience and Subjective Perspectives

2018 ◽  
Author(s):  
Elizabeth Schechter
Keyword(s):  
Right Hemisphere ◽  
Single Subject ◽  
Empirical Basis ◽  
Split Brain ◽  
The Right

This chapter offers a preliminary defense of the claim that the two hemispheres of a split-brain subject are associated with distinct subjects of experience. The empirical basis of this 2-subjects claim is that, while both hemispheres are the source or site of elements of experience, these elements are unified only within each hemisphere system, and not across them. In other words, consciousness is unified intrahemispherically, but disunified interhemispherically. A split-brain subject thus has two subjective perspectives, one associated with the right hemisphere and one with the left. Our first-personal way of understanding what it is to be an experiencing subject, however, makes it impossible for a single subject of experience to have multiple subjective perspectives in just the same way that another subject of experience has one. It seems to follow that the two hemispheres of a split-brain subject are associated with distinct subjects of experience, each standing in just the relation to its one perspective that I do to mine.

scholarly journals Right Hemisphere Dominance in Visual Statistical Learning

2011 ◽  
Vol 23 (5) ◽  
pp. 1088-1099 ◽  
Author(s):  
Matthew E. Roser ◽  
József Fiser ◽  
Richard N. Aslin ◽  
Michael S. Gazzaniga
Keyword(s):  
Visual Field ◽  
Statistical Learning ◽  
Conceptual Knowledge ◽  
Right Hemisphere ◽  
Visual Fields ◽  
Activation Patterns ◽  
Split Brain ◽  
Visuospatial Processing ◽  
Hemisphere Dominance ◽  
The Right

Several studies report a right hemisphere advantage for visuospatial integration and a left hemisphere advantage for inferring conceptual knowledge from patterns of covariation. The present study examined hemispheric asymmetry in the implicit learning of new visual feature combinations. A split-brain patient and normal control participants viewed multishape scenes presented in either the right or the left visual fields. Unbeknownst to the participants, the scenes were composed from a random combination of fixed pairs of shapes. Subsequent testing found that control participants could discriminate fixed-pair shapes from randomly combined shapes when presented in either visual field. The split-brain patient performed at chance except when both the practice and the test displays were presented in the left visual field (right hemisphere). These results suggest that the statistical learning of new visual features is dominated by visuospatial processing in the right hemisphere and provide a prediction about how fMRI activation patterns might change during unsupervised statistical learning.

Hemispheric Encoding Asymmetry is More Apparent Than Real

2002 ◽  
Vol 14 (5) ◽  
pp. 702-708 ◽  
Author(s):  
Michael B. Miller ◽  
Alan Kingstone ◽  
Michael S. Gazzaniga
Keyword(s):  
Left Hemisphere ◽  
Right Hemisphere ◽  
Specific Information ◽  
Hemispheric Differences ◽  
Split Brain ◽  
Episodic Encoding ◽  
Processing Material ◽  
The Right ◽  
Unfamiliar Faces ◽  
Hemisphere Specialization

Previous neuroimaging studies have claimed a left hemisphere specialization for episodic “encoding” and a right hemisphere specialization for episodic “retrieval.” Yet studies of split-brain patients indicate relatively minor memory impairment after disconnection of the two hemispheres. This suggests that both hemispheres are capable of encoding and retrieval. In the present experiment, we examined the possible limits on encoding capacity of each hemisphere by manipulating the “depth” of processing during the encoding of unfamiliar faces and familiar words in the left and right hemispheres of two split-brain patients. Results showed that only the left hemisphere benefited from deeper (more elaborate) encoding of familiar words, and only the right hemisphere benefited from deeper encoding of unfamiliar faces. Our findings are consistent with the view that hemispheric asymmetries in episodic encoding are related to hemisphere-specific processing of particular stimuli. Convergent with recent neuroimaging studies, these results with split-brain patients also suggest that these hemispheric differences are not due to unique specializations in each half brain for encoding memories, but rather, are due to preferential recruitment of the synaptically closer prefrontal cortex to posterior regions processing material-specific information.

Investigation of the Effect of Mode and Tempo on Emotional Responses to Music Using EEG Power Asymmetry

2013 ◽  
Vol 27 (3) ◽  
pp. 142-148 ◽  
Author(s):  
Konstantinos Trochidis ◽  
Emmanuel Bigand
Keyword(s):  
Left Hemisphere ◽  
Right Hemisphere ◽  
Emotional Responses ◽  
Interactive Effects ◽  
Eeg Activity ◽  
Musical Excerpt ◽  
Major Mode ◽  
Musical Modes ◽  
Slow Tempo ◽  
The Right

The combined interactions of mode and tempo on emotional responses to music were investigated using both self-reports and electroencephalogram (EEG) activity. A musical excerpt was performed in three different modes and tempi. Participants rated the emotional content of the resulting nine stimuli and their EEG activity was recorded. Musical modes influence the valence of emotion with major mode being evaluated happier and more serene, than minor and locrian modes. In EEG frontal activity, major mode was associated with an increased alpha activation in the left hemisphere compared to minor and locrian modes, which, in turn, induced increased activation in the right hemisphere. The tempo modulates the arousal value of emotion with faster tempi associated with stronger feeling of happiness and anger and this effect is associated in EEG with an increase of frontal activation in the left hemisphere. By contrast, slow tempo induced decreased frontal activation in the left hemisphere. Some interactive effects were found between mode and tempo: An increase of tempo modulated the emotion differently depending on the mode of the piece.

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