scholarly journals Differential Contribution of Right and Left Parietal Cortex to the Control of Spatial Attention: A Simultaneous EEG-rTMS Study

2011 ◽  
Vol 22 (2) ◽  
pp. 446-454 ◽  
Author(s):  
P. Capotosto ◽  
C. Babiloni ◽  
G. L. Romani ◽  
M. Corbetta
Keyword(s):  
Spatial Attention ◽  
Parietal Cortex ◽  
Left Parietal Cortex ◽  
Differential Contribution

scholarly journals Electrophysiological Correlates of Stimulus-driven Reorienting Deficits after Interference with Right Parietal Cortex during a Spatial Attention Task: A TMS-EEG Study

2012 ◽  
Vol 24 (12) ◽  
pp. 2363-2371 ◽  
Author(s):  
Paolo Capotosto ◽  
Maurizio Corbetta ◽  
Gian Luca Romani ◽  
Claudio Babiloni
Keyword(s):  
Spatial Attention ◽  
Parietal Cortex ◽  
Visual Target ◽  
Human Vision ◽  
Attention Task ◽  
Spatial Orienting ◽  
Cueing Task ◽  
Left Parietal Cortex ◽  
Differential Contribution ◽  
Central Arrow

TMS interference over right intraparietal sulcus (IPS) causally disrupts behaviorally and EEG rhythmic correlates of endogenous spatial orienting before visual target presentation [Capotosto, P., Babiloni, C., Romani, G. L., & Corbetta, M. Differential contribution of right and left parietal cortex to the control of spatial attention: A simultaneous EEG-rTMS study. Cerebral Cortex, 22, 446–454, 2012; Capotosto, P., Babiloni, C., Romani, G. L., & Corbetta, M. Fronto-parietal cortex controls spatial attention through modulation of anticipatory alpha rhythms. Journal of Neuroscience, 29, 5863–5872, 2009]. Here we combine data from our previous studies to examine whether right parietal TMS during spatial orienting also impairs stimulus-driven reorienting or the ability to efficiently process unattended stimuli, that is, stimuli outside the current focus of attention. Healthy volunteers (n = 24) performed a Posner spatial cueing task while their EEG activity was being monitored. Repetitive TMS (rTMS) was applied for 150 msec simultaneously to the presentation of a central arrow directing spatial attention to the location of an upcoming visual target. Right IPS-rTMS impaired target detection, especially for stimuli presented at unattended locations; it also caused a modulation of the amplitude of parieto-occipital positive ERPs peaking at about 480 msec (P3) post-target. The P3 significantly decreased for unattended targets and significantly increased for attended targets after right IPS-rTMS as compared with sham stimulation. Similar effects were obtained for left IPS stimulation albeit in a smaller group of volunteers. We conclude that disruption of anticipatory processes in right IPS has prolonged effects that persist during target processing. The P3 decrement may reflect interference with postdecision processes that are part of stimulus-driven reorienting. Right IPS is a node of functional interaction between endogenous spatial orienting and stimulus-driven reorienting processes in human vision.

scholarly journals Left parietal tACS at alpha frequency induces a shift of visuospatial attention

2019 ◽  
Author(s):  
T. Schuhmann ◽  
S. K. Kemmerer ◽  
F. Duecker ◽  
T.A. de Graaf ◽  
S. ten Oever ◽  
...  
Keyword(s):  
Spatial Attention ◽  
Parietal Cortex ◽  
Visuospatial Attention ◽  
High Density ◽  
Exogenous Attention ◽  
Alpha Power ◽  
Endogenous Attention ◽  
Alpha Frequency ◽  
Stimulus Detection ◽  
Left Parietal Cortex

AbstractBackgroundVoluntary shifts of visuospatial attention are associated with a lateralization of occipitoparietal alpha power (7-13Hz), i.e. higher power in the hemisphere ipsilateral and lower power contralateral to the locus of attention. Recent noninvasive neuromodulation studies demonstrated that alpha power can be experimentally increased using transcranial alternating current stimulation (tACS).Objective/HypothesisWe hypothesized that tACS at alpha frequency over the left parietal cortex induces shifts of attention to the left hemifield. However, spatial attention shifts not only occur voluntarily (endogenous), but also stimulus-driven (exogenous). In order to study the task-specificity of the potential effects of tACS on attentional processes, we administered three conceptually different spatial attention tasks.Methods36 healthy volunteers were recruited from an academic environment. In two seperate sessions, we applied either high-density tACS at 10Hz, or sham tACS, for 35-40 minutes to their left parietal cortex. We systematically compared performance on endogenous attention, exogenous attention, and stimulus detection tasks.ResultsIn the Endogenous attention task, we found a greater leftward bias in reaction times during left parietal 10Hz tACS as compared to sham. There were no stimulation effects in the exogenous attention or stimulus detection task.ConclusionThe study shows that high-density tACS at 10Hz can be used to modulate visuospatial attention performance. The tACS effect is task-specific, indicating that not all forms of attention are equally susceptible to the stimulation.

Cerebral mycetoma with cranial osteomyelitis

2008 ◽  
Vol 1 (6) ◽  
pp. 493-495 ◽  
Author(s):  
Vamseemohan Beeram ◽  
Sundaram Challa ◽  
Prasad Vannemreddy
Keyword(s):  
Computed Tomography ◽  
Cerebral Cortex ◽  
Parietal Cortex ◽  
Subcutaneous Tissue ◽  
Young Male ◽  
Ct Scanning ◽  
Parietal Bone ◽  
Total Excision ◽  
Farm Laborer ◽  
Left Parietal Cortex

✓ Craniocerebral maduromycetoma is extremely rare. The authors describe a case of maduromycetoma involving the left parietal cortex, bone, and subcutaneous tissue in a young male farm laborer who presented with left parietal scalp swelling that had progressed into a relentlessly discharging sinus. Computed tomography (CT) scanning of his brain revealed osteomyelitis of the parietal bone with an underlying homogeneously enhancing tumor. Intraoperatively, the mass was revealed to be a black lesion involving the bone, dura mater, and underlying cerebral cortex. It was friable and separated from the surrounding brain by a thick gliotic scar. Gross-total excision was performed, and the patient was placed on a 6-week regimen of itraconazole. To the authors' knowledge, this is the first instance of cerebral mycetoma with CT findings reported in the literature.

Cortical control of Inhibition of Return: Exploring the causal contributions of the left parietal cortex

Cortex ◽  
2013 ◽  
Vol 49 (10) ◽  
pp. 2927-2934 ◽  
Author(s):  
Alexia Bourgeois ◽  
Ana B. Chica ◽  
Antoni Valero-Cabré ◽  
Paolo Bartolomeo
Keyword(s):  
Parietal Cortex ◽  
Inhibition Of Return ◽  
Cortical Control ◽  
Left Parietal Cortex

Mechanisms of Spatial Attention: The Relation of Macrostructure to Microstructure in Parietal Neglect

1994 ◽  
Vol 6 (4) ◽  
pp. 377-387 ◽  
Author(s):  
Jonathan D. Cohen ◽  
Richard D. Romero ◽  
David Servan-Schreiber ◽  
Martha J. Farah
Keyword(s):  
Computational Model ◽  
Spatial Attention ◽  
Parietal Cortex ◽  
Emergent Property ◽  
Normal Brain

Parietal-damaged patients respond abnormally slowly to targets presented in the affected hemifield when preceded by cues in the intact hemifield. This inability to disengage attention from the ipsilesional field to reengage it in the contralesional field has been interpreted as evidence for a distinct “disengage” mechanism, localized in parietal cortex. We present a computational model that accounts for normal attentional effects by interactivity and competition among representations of different locations in space, without a dedicated “disengage” mechanism. We show that when the model is lesioned, it produces the “disengage deficit” shown by parietal-damaged patients. This suggests that the deficit observed in such patients can be understood as an emergent property of interactions among the remaining parts of the system, and need not imply the existence of a dedicated “disengage” mechanism in the normal brain.

The anatomic organization of evoked potentials in rat parietal cortex: electrically evoked commissural responses

1994 ◽  
Vol 72 (1) ◽  
pp. 139-149 ◽  
Author(s):  
D. S. Barth ◽  
J. Kithas ◽  
S. Di
Keyword(s):  
Spatial Distribution ◽  
Parietal Cortex ◽  
Evoked Potential ◽  
Sensory Information ◽  
Electrode Array ◽  
Maximum Amplitude ◽  
Temporal Distribution ◽  
Diagonal Band ◽  
Sensory Information Processing ◽  
Left Parietal Cortex

1. Two 8 x 8 channel microelectrode arrays were positioned over 3.5 x 3.5 mm2 areas in homologous regions of right and left parietal cortex of four rats. Potentials were evoked by delivering epicortical electrical stimulation to each electrode on one hemisphere while mapping the commissural response from the contralateral array. Spatial distributions of the electrically evoked potential (EECP) complex were compared directly with cytochrome oxidase-stained sections of the recorded region. 2. Electrode sites most capable of eliciting a commissural EECP were arranged along a diagonal band extending medially from the rostral to caudal region of each electrode array, approximating the pattern of dysgranular cortex separating primary auditory (Te1) from primary somatosensory (Par1) cortex. Electrode sites in the rostromedial and caudolateral region were ineffectual in eliciting an EECP in either hemisphere. Stimulation sites within secondary visual cortex (Oc2L) also produced strong responses. Only weak responses were elicited from stimulation of Te1 and no EECP could be evoked when stimulating within Par1. 3. When an EECP in the maximally sensitive diagonal region was elicited, its spatial distribution was typically asymmetrical throughout the recording array; the response was largest along a diagonal region also extending medially from the rostral to caudal area of each electrode array. Thus the pattern of EECP in each hemisphere closely matched the pattern of electrically excitable regions in the contralateral hemisphere. 4. The EECP was usually heterogeneous. EECP distributions within the strongly responding diagonal area often formed two regions of maximum amplitude separated by a less active zone. Although responses in Te1 were significantly weaker than those in the adjacent dysgranular cortex, they also revealed a heterogeneous spatial distribution with multiple closely spaced maxima. Only responses in Oc2L appeared consistently homogeneous, with a single maximum representing the EECP. 5. These results provide functional evidence supporting a model of parietal cortex in which there are two basic types of recipient regions, densely granular regions, which are the termination sites of specific thalamocortical fibers, and dysgranular or agranular regions, which receive both ipsilateral and contralateral projections. The functional parceling of rodent parietal cortex on the basis of the spatial and temporal distribution of the epicortical evoked potential complex may be superimposed onto the anatomic parceling into granular and dysgranular zones. Implications for stages of sensory information processing are discussed.

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