scholarly journals The Significance of Chimpanzee Occipital Asymmetry to Hominin Evolution

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1862
Author(s):  
Shawn Hurst ◽  
Ralph Holloway ◽  
Alannah Pearson ◽  
Grace Bocko
Keyword(s):  
Parietal Lobe ◽  
Brain Evolution ◽  
Occipital Lobe ◽  
Relative Reduction ◽  
Complex Phenomenon ◽  
Linear Measurements ◽  
Hominin Evolution ◽  
Human Brain Evolution ◽  
Posterior Parietal ◽  
Posterior Parietal Lobe

Little is known about how occipital lobe asymmetry, width, and height interact to contribute to the operculation of the posterior parietal lobe, despite the utility of knowing this for understanding the relative reduction in the size of the occipital lobe and the increase in the size of the posterior parietal lobe during human brain evolution. Here, we use linear measurements taken on 3D virtual brain surfaces obtained from 83 chimpanzees to study these traits as they apply to operculation of the posterior occipital parietal arcus or bridging gyrus. Asymmetry in this bridging gyrus visibility provides a unique opportunity to study both the human ancestral and human equivalently normal condition in the same individual. Our results show that all three traits (occipital lobe asymmetry, width, and height) are related to this operculation and bridging gyrus visibility but width and not height is the best predictor, against expectations, suggesting that relative reduction of the occipital lobe and exposure of the posterior parietal is a complex phenomenon.

scholarly journals Cerebrovascular Accident Secondary to Paradoxical Embolism Following Arteriovenous Graft Thrombectomy

2012 ◽  
Vol 2012 ◽  
pp. 1-3 ◽  
Author(s):  
Jolina Pamela Santos ◽  
Zaher Hamadeh ◽  
Naheed Ansari
Keyword(s):  
Vascular Access ◽  
Parietal Lobe ◽  
Paradoxical Embolism ◽  
Arteriovenous Graft ◽  
Common Procedure ◽  
Left Posterior ◽  
Posterior Parietal ◽  
Stage Renal Disease ◽  
End Stage ◽  
Posterior Parietal Lobe

Thrombectomy is a common procedure performed to declot thrombosed dialysis arteriovenous fistula (AVF) or arteriovenous graft (AVG). Complications associated with access thrombectomy like pulmonary embolism have been reported, but paradoxical embolism is extremely rare. We report a case of a 74-year-old black man with past medical history significant for end-stage renal disease (ESRD), atrial fibrillation on anticoagulation with warfarin, who presented to our hospital with lethargy, aphasia, and right-sided hemiparesis following thrombectomy of a clotted AVG. Computed tomography (CT) scan of brain showed a hypodensity within the left posterior parietal lobe. INR was 2.0 on admission. Echocardiogram revealed a normal sized left atrium with no intracardiac thrombus, and bubble study showed the presence of right-to-left shunting. These findings suggest that the stroke occurred as a result of an embolus originating from the AVG. Paradoxical cerebral embolism is uncommon but can occur after thrombectomy of clotted vascular access in ESRD patients. Clinicians and patients should be aware of this serious and potentially fatal complication of vascular access procedure.

scholarly journals Coming Unbound: Disrupting Automatic Integration of Synesthetic Color and Graphemes by Transcranial Magnetic Stimulation of the Right Parietal Lobe

2006 ◽  
Vol 18 (9) ◽  
pp. 1570-1576 ◽  
Author(s):  
Michael Esterman ◽  
Timothy Verstynen ◽  
Richard B. Ivry ◽  
Lynn C. Robertson
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Magnetic Stimulation ◽  
Parietal Lobe ◽  
Naming Task ◽  
Color Naming ◽  
Automatic Integration ◽  
Posterior Parietal ◽  
The Right ◽  
Posterior Parietal Lobe ◽  
Stimulation Technique

In some individuals, a visually presented letter or number automatically evokes the perception of a specific color, an experience known as color-grapheme synesthesia. It has been suggested that parietal binding mechanisms play a role in the phenomenon. We used a noninvasive stimulation technique, transcranial magnetic stimulation (TMS), to determine whether the posterior parietal lobe is critical for the integration of color and shape in color-grapheme synesthesia, as it appears to be for normal color-shape binding. Using a color-naming task with colored letters that were either congruent or incongruent with the synesthetic photism, we demonstrate that inhibition of the right posterior parietal lobe with repetitive TMS transiently attenuates synesthetic binding. These findings suggest that synesthesia (the induction of color from shape) relies on similar mechanisms as found in normal perception (where the perception of color is induced by wavelength).

scholarly journals Simultanagnosia: When a Rose Is Not Red

2008 ◽  
Vol 20 (1) ◽  
pp. 36-48 ◽  
Author(s):  
H. Branch Coslett ◽  
Grace Lie
Keyword(s):  
Visual Processing ◽  
Parietal Lobe ◽  
Spatial Location ◽  
Limited Capacity ◽  
Object Identity ◽  
Object Processing ◽  
Preattentive Processing ◽  
Report Data ◽  
Posterior Parietal ◽  
Posterior Parietal Lobe

Information regarding object identity (“what”) and spatial location (“where/how to”) is largely segregated in visual processing. Under most circumstances, however, object identity and location are linked. We report data from a simultanagnosic patient (K.E.) with bilateral posterior parietal infarcts who was unable to “see” more than one object in an array despite relatively preserved object processing and normal preattentive processing. K.E. also demonstrated a finding that has not, to our knowledge, been reported: He was unable to report more than one attribute of a single object. For example, he was unable to name the color of the ink in which words were written despite naming the word correctly. Several experiments demonstrated, however, that perceptual attributes that he was unable to report influenced his performance. We suggest that binding of object identity and location is a limited-capacity operation that is essential for conscious awareness for which the posterior parietal lobe is crucial.

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