P02.04: Axial and coronal views of the vermian primary fissure assist in the diagnosis of vermian dysgenesis

The cerebellum is crucial for planning, executing, terminating, and learning movements. The cerebellum compares actual with intended motor performance and optimizes the timing of motor function. Thus, it is important in the adaptation of movement and posture. In addition, the cerebellum contributes to cognition and behavior. The primary fissure divides the cerebellum anatomically into anterior and posterior lobes. The posterior lobe is divided from the flocculonodular lobe by the posterolateral fissure. The cerebellum may also be divided into functional zones, including the vermis (midline), paravermal region, and hemispheres (most lateral).

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Cerebellar cortical activity during antagonist cocontraction and reciprocal inhibition of forearm muscles

Journal of Neurophysiology ◽

10.1152/jn.1984.51.1.32 ◽

1984 ◽

Vol 51 (1) ◽

pp. 32-49 ◽

Cited By ~ 77

Author(s):

R. C. Frysinger ◽

D. Bourbonnais ◽

J. F. Kalaska ◽

A. M. Smith

Keyword(s):

Purkinje Cells ◽

Cerebellar Cortex ◽

Discharge Frequency ◽

Wrist Movement ◽

Movement Velocity ◽

Wrist Position ◽

Forearm Muscles ◽

Antagonist Muscles ◽

Primary Fissure ◽

Flexion And Extension

Monkeys were trained to perform a maintained isometric grip of the thumb and forefinger that elicited a simultaneous cocontraction of the antagonist muscles of the forearm. The same monkeys were also trained to flex and extend the wrist against a stop with the fingers extended and to maintain an isometric wrist position for 1.0-1.5 s. During wrist movement, some of the synergist forearm muscles contracted during both flexion and extension. However, during the maintained isometric wrist position, the prime mover and synergist muscles were reciprocally active or silent. In the culmen-simplex region of the cerebellar cortex bordering on the primary fissure, 62% of the Purkinje cells that were identified by the climbing fiber discharge and that changed firing frequency decreased activity during maintained prehension. Almost all of these same Purkinje cells were reciprocally active during isometric wrist flexion and extension, although three neurons had similar discharge patterns during movements in both directions. In contrast, 79% of the unidentified neurons recorded from the same region of the cerebellar cortex increased discharge frequency during prehension. In general, most of these same neurons had reciprocal patterns of discharge during wrist movement even though a few cells were active during the dynamic phase in both directions. Together, the Purkinje cells and the unidentified neurons with bidirectional response patterns were thought to be related to muscles active during both flexion and extension wrist movements. No cells were found that increased discharge with the static isometric wrist torque exerted in both directions. The discharge frequency of some Purkinje and some unidentified neurons could be shown to be related to prehensile force as well as wrist movement velocity and isometric wrist torque. These data suggest that the discharge of about two-thirds of the Purkinje cells related to forearm muscles located along the borders of the primary fissure may depend on whether antagonist muscles are activated reciprocally or coactively. As a consequence, these cells may play a role in the selection or alternation between either of these two modes of muscular contraction. The increased discharge of the remaining one-third of the Purkinje cells excited during antagonist coactivation may provide inhibition of nuclear cells to stabilize the posture at joints other than the wrist and fingers or, alternatively, they may act to reduce nuclear cell discharge in proportion to the intensity of cutaneous stimulation.

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Study on the dominant factors for primary fissure form in the process of hydraulic fracturing in coal rock

Boundaries of Rock Mechanics ◽

10.1201/9780203883204.ch28 ◽

2008 ◽

pp. 151-155

Author(s):

Y Wang ◽

B Yan ◽

Q Hu ◽

X Ni

Keyword(s):

Hydraulic Fracturing ◽

Coal Rock ◽

Primary Fissure

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Cerebellar Cortex Contributions to the Expression and Timing of Conditioned Eyelid Responses

Journal of Neurophysiology ◽

10.1152/jn.00033.2010 ◽

2010 ◽

Vol 103 (4) ◽

pp. 2039-2049 ◽

Cited By ~ 27

Author(s):

Brian E. Kalmbach ◽

Tobin Davis ◽

Tatsuya Ohyama ◽

Frank Riusech ◽

William L. Nores ◽

...

Keyword(s):

Purkinje Cells ◽

Cerebellar Cortex ◽

Local Anesthetic ◽

Eyelid Conditioning ◽

Trace Conditioning ◽

Anterior Lobe ◽

Short Latency ◽

Delay Conditioning ◽

Conditioned Responses ◽

Primary Fissure

We used micro-infusions during eyelid conditioning in rabbits to investigate the relative contributions of cerebellar cortex and the underlying deep nuclei (DCN) to the expression of cerebellar learning. These tests were conducted using two forms of cerebellum-dependent eyelid conditioning for which the relative roles of cerebellar cortex and DCN are controversial: delay conditioning, which is largely unaffected by forebrain lesions, and trace conditioning, which involves interactions between forebrain and cerebellum. For rabbits trained with delay conditioning, silencing cerebellar cortex by micro-infusions of the local anesthetic lidocaine unmasked stereotyped short-latency responses. This was also the case after extinction as observed previously with reversible blockade of cerebellar cortex output. Conversely, increasing cerebellar cortex activity by micro-infusions of the GABAA antagonist picrotoxin reversibly abolished conditioned responses. Effective cannula placements were clustered around the primary fissure and deeper in lobules hemispheric lobule IV (HIV) and hemispheric lobule V (HV) of anterior lobe. In well-trained trace conditioned rabbits, silencing this same area of cerebellar cortex or reversibly blocking cerebellar cortex output also unmasked short-latency responses. Because Purkinje cells are the sole output of cerebellar cortex, these results provide evidence that the expression of well-timed conditioned responses requires a well-timed decrease in the activity of Purkinje cells in anterior lobe. The parallels between results from delay and trace conditioning suggest similar contributions of plasticity in cerebellar cortex and DCN in both instances.

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Embriologia e genetica dello sviluppo cerebellare

Rivista di Neuroradiologia ◽

10.1177/197140090301600305 ◽

2003 ◽

Vol 16 (3) ◽

pp. 349-357

Author(s):

M. Gallucci ◽

F. Iannessi ◽

E. Puglielli ◽

A. Splendiani ◽

R. Russo

Keyword(s):

Proliferative Activity ◽

Cerebellar Nuclei ◽

Tissue Interactions ◽

Proliferation And Differentiation ◽

Genetic Clusters ◽

Development And Differentiation ◽

Cervical Flexure ◽

Genetic And Environmental Factors ◽

Primary Fissure ◽

Rhombic Lip

During the fourth week of development, the mesencephalic flexure and cervical flexure appear in the cranial region of the neural tube, delimiting three neural vescicles: the prosencephalon, mesencephalon and rhomboencephalon. During the fifth week, the pontine flexure forms in the roof of the rhomboencephalon, marking the division between the metencephalon and myeloencephalon, the future medulla oblongata. The dorsal part of the metencephalon (alar plate), between the mesencaphalic isthmus and the pontine flexure, will give rise to the cerebellum, whereas its ventral part (basal plate) will give rise to the pons. The alar plates, lateral to the deepening pontine fissure and the hindbrain cavity, present an intense proliferative activity with the formation of two extensions which fuse just behind the isthmus to form the cerebellar plate. During the sixth week of development, the rhombic lips appear in the posterolateral regions of this strip and after persistent proliferative activity they fuse along the median line. Median thickening of this region will give rise to the vermis, while the two lateral masses become the lateral lobes. During the seventh week, the flocculonodular lobe will form. Between the eighth and ninth weeks, the vermis expands caudally with progressive dilatation of the fourth ventricle whose Luschka and Magendie foramina are still unperforated. The cerebellar proliferation and differentiation processes are correlated to the activity of two separate germinal areas: the ependymal ventricle and the rhombic lip. From the eighth week, neuroblastic migration starts from the rhombic lip which in successive genetically controlled steps leads to the formation of the external granular layer of the cerebellar cortex. From the ventriculo-ependymal zone cells migrate to form the cerebellar nuclei destined to differentiate into Purkinje cells. The cerebellar recess starts to develop around the twelfth week with the formation of the primary fissure separating the anterior and posterior parts of the cerebellum to end with the complete formation of all cerebellar lobes at around the twenty-fourth week of development. The foliation process starts when the recess has formed and continues in the first months of life after birth. The processes of cell development and differentiation are genetically programmed and the outcome of an interaction between genetic and environmental factors. The different stages of embryonic development are thought to be controlled by sequential ordered activation of genetic clusters (homeotypic genes) which in turn encode for a series of molecules directly involved in the regulation of cell and tissue interactions. There is increasing evidence of genetic involvement in the different types of cerebellar malformation whose expression and association with other extracerebellar malformations depends on the developmental age at which the genetic change occurred.

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Palestinians Sidelined in Saudi-Emirati Rapprochement with Israel

Journal of Palestine Studies ◽

10.1525/jps.2018.47.4.79 ◽

2018 ◽

Vol 47 (4) ◽

pp. 79-89 ◽

Cited By ~ 2

Author(s):

Kristian Coates Ulrichsen

Keyword(s):

Saudi Arabia ◽

United Arab Emirates ◽

Arab Spring ◽

Middle Eastern ◽

Abu Dhabi ◽

Threat Perceptions ◽

Gulf States ◽

Middle Eastern Politics ◽

Primary Fissure ◽

The Arab Spring

This essay examines how and why Saudi Arabia and the United Arab Emirates (UAE) have pursued policies that have aligned closer to Israel since 2011. The disruptive impact of the Arab Spring and its turbulent aftermath altered threat perceptions in Riyadh and Abu Dhabi, which increasingly saw Islamism and Iran as the major sources of regional instability. For Saudi and Emirati leaders committed to adopting a more forceful approach to shaping the post-Arab Spring landscape, Israel no longer represented the primary fissure in Middle Eastern politics. Although the process of creating informal ties between the Gulf states and Israel has been decades in the making, the nature of the post-2011 connections between Saudi Arabia and the UAE with Israel have greater strategic depth and are taking place in a far more open setting than ever before.

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