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Published in Terence R. Anthoney, Neuroanatomy and the Neurologic Exam, 2017
Though the term “sulcus” suggests a singular structure, many a named sulcus is sometimes discontinuous, being made up of two or more grooves which are not connected to each other. Some sulci, in fact, are usually discontinuous. Examples mentioned in recent textbooks of basic neuroanatomy include the “precentral sulcus” (e.g., B&K, p. 216; W&W, p. 986; M&M, p. 52; chus, p. 19), the “postcentral sulcus” (e.g., M&M, p. 52; chus, p. 19–20), the “inferior temporal sulcus” (e.g., B&K, p. 216; W&W, p. 986; MarMar, p. 58), and the “occipitotemporal sulcus” (e.g., W&W, p. 990; M&M, p. 56).
ENTRIES A–Z
Published in Philip Winn, Dictionary of Biological Psychology, 2003
The primary somatosensory cortex (SI) is the portion of the CEREBRAL CORTEX that receives the most direct input from SOMATOSENSORY systems. It is located around the POSTCENTRAL GYRUS and can be divided into three (mostly) parallel strips designated SI1, SI2 and SI3. SI1 is closest to the CENTRAL SULCUS, SI3 to the postcentral sulcus, with SI2 in between them. The body is represented somatotopically through this tissue: the various parts of the body trunk, the various parts of the face, genitalia, limbs, hands and feet are all represented in the primary somatosensory cortex. The SECONDARY SOMATOSENSORY CORTEX (SII) is much smaller, receives a smaller volume of direct somatosensory input (it is principally concerned with information from the throat, tongue teeth and jaws—see MOUTH) and is located in the LATERAL FISSURE.
Somatosensory Evoked Magnetic Fields in Humans
Published in Mark J Rowe, Yoshiaki Iwamura, Somatosensory Processing: From Single Neuron to Brain Imaging, 2001
For summarizing these previous studies, we mapped a complete homunculus in 5 normal subjects (Nakamura et al., 1998). We stimulated 19 sites, tongue, lower lip, upper lip, thumb, index finger, middle finger, ring finger, little finger, radial palm, ulnar palm, forearm, elbow, upper arm, chest, thigh, ankle, big toe, second toe and five toe. After measuring the location of single ECD of the primary component for each stimulus site, we put them on the MRI of each subject (Fig. 14.2). Then, we could map a large part of the somatosensory receptive fields (topography) on SI, including tongue, lips, finger, palm, arm and toes. These representation areas were generally arranged in the above order from inferior to superior, lateral to medial, and anterior to posterior. These coordinates were compatible with the anatomy of the central sulcus and the homunculus. ECD location to the upper lip could be distinguished from that to the lower lip, the former located more superior than the latter in all subjects. Each finger representation area of the thumb, index finger, middle finger, ring finger and little finger was also distinguishable from the others and was represented sequentially from thumb to little finger, ascending the postcentral sulcus.
Deficits underlying handgrip performance in mildly affected chronic stroke persons
Published in Topics in Stroke Rehabilitation, 2021
Esther Prados-Román, Irene Cabrera-Martos, Laura López-López, Janet Rodríguez-Torres, Irene Torres-Sánchez, Araceli Ortiz-Rubio, Marie Carmen Valenza
Jung et al.4 demonstrated that persons with weakness of the ipsilesional upper limb maximally recovered within 1-month poststroke but remained impaired in comparison with controls. Persistent impaired reaction time within the first year poststroke has been shown, indicating that ipsilesional upper limbs deficits might not be a temporary event.39,40 It has been shown that both the precision- and power-grip tasks activated the primary sensorimotor cortex contralateral to the grasping hand. The activations extended into the dorsal premotor cortex and the postcentral sulcus. Furthermore, the ventral premotor cortex showed bilateral activation with peaks of activity in the inferior part of the precentral gyrus.41 Among common assumptions motor deficits caused by disruption of ipsilesional projections of the corticospinal tract42 and changes in ipsilesional motor performance after nonaffected primary motor cortex disinhibition43 are included. However, little is known about the time course evolution of ipsilesional handgrip assessment, and even less about its implications for rehabilitation.40,44 Previous studies45,46 have reported difficulties in most clinical tests to detect fine changes in motor performance, specially the subtle ipsilesional motor deficits. Our study found significant differences on grip and pinch resistance to fatigue in the ipsilesional hand in comparison with controls. Moreover, significant differences were found on flexor digitorum superficialis muscle fatigue during a sustained handgrip contraction.
Central Sulcus Misfolding: Polarity Reversal of SSEP N20 Potential in “Layered” Polymicrogyria
Published in The Neurodiagnostic Journal, 2019
Tyson Hale, Aaron Knecht, Kristiana Barbarevech, Qing Yue
We propose that our PMG patient might have suffered a misfolding in the central sulcus secondary to the premature differentiation during brain development that moves area 3b from postcentral sulcus to postcentral gyrus. As the model is shown in Figure 4, the tangential thalamocortical input in the area 3b produces a net downward dipole designated as N20 potential when registered on C4ʹ of the normal side of cortex (Figure 4 left). On the PMG side of cortex, the posteriorly shifting of area 3b from postcentral sulcus to postcentral gyrus converts the dipole to a net upward “positive” N20 when recorded on C3ʹ-Fpz and C3ʹ-C4ʹ montages (Figure 4 right), akin to Brodmann area 1 derived P25 in the subdural recordings (Allison et al. 1991). In contrast, the cortical potential of lower SSEPs has a positive (P37) polarity by default and, according to the model, a move of area 3b from postcentral sulcus to postcentral gyrus should not reverse the orientation of the P37 polarity.
Seizure and cognitive outcomes of posterior quadrantic disconnection: a series of 12 pediatric patients
Published in British Journal of Neurosurgery, 2020
Yao Wang, Chao Zhang, Xiu Wang, Lin Sang, Feng Zhou, Jian-Guo Zhang, Wen-Han Hu, Kai Zhang
After this procedure, the following connections were retained: 1) the association fibres from the posterior parietal and occipital lobes to the frontal cortex; 2) the uncinate fascicle; 3) the anatomic integrity of the cingulate gyrus; and 4) the corpus callosum.(2) Stage II: Parietooccipital disconnection: The parietal cortex and white matter were disconnected along the postcentral sulcus. The white matter incision reached the interior and inferior boundaries ending at the falx and corpus callosum, respectively. Then, the posterior corpus callosum was disconnected, and the lateral ventricle was opened.