What is the function of the PPRF?
The PPRF is a collection of cells lying in the pons adjacent to the nucleus of cranial nerve VI, and is an important center for horizontal gaze. Efferent fibers from the PPRF project to the ipsilateral abducens (VI) nucleus, and to the contralateral oculomotor (III) nucleus through the MLF, stimulating both eyes to move horizontally. 150.
What is the paramedian pontine reticular (PPRF)?
Anatomical terms of neuroanatomy. [edit on Wikidata] The paramedian pontine reticular formation, also known as PPRF or paraabducens nucleus, is part of the pontine reticular formation, a brain region without clearly defined borders in the center of the pons.
Which physical findings are characteristic of peripheral reticular fibrosis (PPRF)?
Unilateral lesions of the PPRF produce characteristic findings: Loss of horizontal saccades directed towards the side of the lesion, no matter the current position of gaze. Contralateral gaze deviation (acute lesions, such as early stroke, only) Gaze-evoked lateral nystagmus on looking away from the side of the lesion.
Are the movement fields in the PPRF topologically organized?
The movement fields are large—their diameter being typically the length of the vector—so that the size and direction of a saccade cannot be predicted from looking at one, or just a few, vector cells. Unlike those in the colliculus, vector cells in the pprf do not appear to be topologically organized. Fig. 2.
What happens in a PPRF lesion?
Lesions of the PPRF cause a saccade palsy to the same side, but may involve all classes of conjugate eye movements when the most caudal portions of the PPRF are affected (Johnston and Sharpe, 1989). Vergence is spared so that adduction of the eyes with a near stimulus can be intact.
What is PPRF full form?
Personality-Related Position Requirements Form (PPRF) is a public-domain job-analysis inventory specifically intended to map on to work-related personality traits.
Is PPRF involved in VOR?
The pathway for the vestibulo- ocular reflex (VOR) passes through the PPRF at the level of the abducens nuclei.
Where is the Paramedian?
ponsThe paramedian reticular formation is adjacent to the abducens (VI)nucleus in the pons and adjacent to the oculomotor nucleus(III) in the midbrain.
Is PPRF in the midbrain?
Gaze Palsies The initiation of eye movements rests to a significant degree with the frontal eye fields (FEF). For horizontal gaze, it is the paramedian pontine reticular formation (PPRF) in the mid-pons region that represents the horizontal gaze center generating conjugate horizontal movements for each eye.
What does the MLF do?
The MLF is a fiber tract located directly ventrolateral to the oculomotor nucleus that interconnects the oculomotor nucleus, trochlear nucleus, and abducens nucleus (Figure 1). The MLF serves to facilitate yoked eye movements (i.e., simultaneous abduction of the right eye and adduction of the left or vice versa).
What are the 3 types of VOR?
There are three types of VOR navigational stations: VOR (just the VOR), VOR-DME (VOR plus distance measuring equipment), and vortac (VOR plus the military's tactical air navigation system).
What are the two VOR signals?
How a VOR works. The ground station transmits two radio signals: The first – master signal – is transmitted in all directions. The second is a directional signal transmitted in sequence from a series of antenna that are spaced out in a circle.
What is the VOR instrument called?
A VHF Omnidirectional Range (VOR) beacon is a short-range radio-navigation system enabling aircraft with a receiving unit to determine their position and stay on a given course. A VOR receiver enables the aircraft to determine its bearing with respect to the beacon (the position of which is known).
Where is the Pprf located?
The PPRF is located anterior and lateral to the medial longitudinal fasciculus (MLF). It receives input from the superior colliculus via the predorsal bundle and from the frontal eye fields via frontopontine fibers.
What does Paramedian mean?
para·me·di·an -ˈmēd-ē-ən. : situated adjacent to the midline.
What is the paramedian approach?
The paramedian approach allows for faster catheter insertion, fewer attempts at needle insertion, and a lower incidence of post lumbar puncture headache. 4-5. This approach can be performed in the neutral spine position.
Where is the lesion in one and half syndrome?
One-and-a-half syndrome is a disorder of horizontal ocular movement characterized by a lateral gaze palsy on looking toward the side of the lesion and INO on looking in the other direction. The location of the lesion is the paramedian pontine reticular formation or VI nerve nucleus.
What is the medial longitudinal fasciculus?
The medial longitudinal fasciculus (MLF) is a specialized and heavily myelinated nerve bundle adjacent to the cranial nerve III and IV nuclei in the midbrain. It extends in a craniocaudad dimension to the level of the cranial nerve VI nuclei in the inferior and dorsal pons.
What is internuclear ophthalmoplegia?
INTRODUCTION. Internuclear ophthalmoparesis (INO), also commonly referred to as internuclear ophthalmoplegia, is a specific gaze abnormality characterized by impaired horizontal eye movements with weak and slow adduction of the affected eye, and abduction nystagmus of the contralateral eye.
What is a PPRF?
Personality-Related Position Requirements Form (PPRF) is a public-domain job-analysis inventory specifically intended to map on to work-related personality traits. The goal of the PPRF was to allow one to establish the job-relatedness of personality assessment by having job experts determine whether effective performance on a specific job requires people to engage in various behaviors (e.g., interact with clients, customers, or coworkers). These behaviors are rated by job experts as not required, helpful, or essential to performance on the job in question.
What is PPRF in psychology?
The PPRF was designed to be a public-domain job analysis instrument that could be used by both researchers and practitioners to make better decisions about matching personality dimensions to the specific needs of the job. According to the authors: “At this point, the PPRF is offered to researchers and practitioners so that improvements, refinements, and additional tests of the efficacy of the instrument in generating hypotheses can be conducted on a broad front” (Raymark et al., 1997; p. 735).
What is the purpose of the PPRF?
The goal of the PPRF was to allow one to establish the job-relatedness of personality assessment by having job experts determine whether effective performance on a specific job requires people to engage in various behaviors (e.g., interact with clients, customers, or coworkers).
What causes slow saccades in the PPRF?
Damage to excitatory burst neurons in the PPRF or to inhibitory burst neurons or to omnipause neurons ( Figure 38.1) causes slow saccades. 18,47 Lesions in the pontine tegmentum such as infarcts, tumors, degenerations such as PSP, Huntington's disease, 48 and variants of spinocerebellar degenerations, 8 multiple sclerosis, lipid storage diseases, and infections (e.g., acquired immunodeficiency syndrome (AIDS), Whipple disease) cause slowing of voluntary and reflex saccades and of the fast phases of vestibular and optokinetic nystagmus.
What is the PPRF?
The PPRF is the premotor structure of all ipsilateral saccades (including quick phases of nystagmus) and the generator of horizontal saccadic pulse.
How does the cerebral gaze center work?
Each cerebral gaze center normally produces conjugate eye movements by stimulating a contralateral pontine gaze center, which neurologists also call the pontine paramedian reticular formation ( PPRF ). In contrast to the movement generated by the cerebral center, each pontine center pulls the eyes toward its own side ( Fig. 12.11 ). A lesion on one side of the pons thus allows the eyes to be pulled toward the opposite side. For example, if a stroke damages the right pontine gaze center, the eyes would deviate to the left. Also, because this stroke would damage the corticospinal tract in the right pons, the left arm and leg would be paralyzed. With a pontine lesion, the eyes look toward the paralyzed side of the body.
What happens to the ipsilateral saccades after a PPRF lesion?
Both eyes remain on the midline in attempted ipsilateral saccades, because of the absence of phasic excitation of excitatory burst neurons and agonist muscles, and, when eyes are in a position contralateral to the lesion, they return to the midline with a very slow movement ( Pierrot-Deseilligny et al., 1982b; Leigh and Zee, 2006 ). The absence of ipsilateral saccades in the return movement from the contralateral position to the midline is explained by impairment of the pathway controlling phasic inhibition of antagonist muscles (inhibitory burst neurons) (see Fig. 12.3 ). The VOR ipsilateral to the lesion is preserved after a PPRF lesion ( Pierrot-Deseilligny et al., 1982b ), as is also, on occasion, ipsilateral smooth pursuit ( Kommerell et al., 1987; Pierrot-Deseilligny et al., 1989 ), since the pathways involved in these slow eye movements do not pass through the PPRF. If the lesion affects the caudal part of the PPRF (in the lower pons), an ipsilateral sixth-nerve palsy is usually associated (see Fig. 12.1, syndrome 5) since the abducens nerve fascicles pass through this part of the PPRF (see Fig. 12.2 ), whereas lesions of the rostral part of the PPRF (in the upper pons) result in an isolated paralysis of all ipsilateral saccades ( Johnston and Sharpe, 1989 ). In the case of a bilateral PPRF lesion, there is a total loss of horizontal saccades, and, at times, a slight slowing of vertical saccades ( Pierrot-Deseilligny et al., 1984; Hanson et al., 1986 ). The latter may result from damage to the OPN, which are located between the PPRFs. The OPN project to both the PPRFs and the premotor midbrain reticular formations involved in vertical saccades, i.e., the rostral interstitial nucleus of the MLF ( Kaneko, 1989) (see below). OPN tonically inhibit excitatory burst neurons of these reticular formations, except during saccades, and the abrupt suspension of their activity could be necessary to trigger a saccade with normal high velocity ( Miura and Optican, 2006 ). Lastly, degenerative damage to the OPN or the PPRF could account for the horizontal saccade slowing observed in spinocerebellar atrophy (SCA) 2 ( Horn et al., 1996 ), SCA3 ( Rüb et al., 2004 ), and progressive supranuclear palsy (PSP) ( Malessa et al., 1991 ).
Why do saccades slow down?
Slow saccades are also caused by peripheral neuromuscular disease (ocular myopathy and nerve palsies). 49 Involvement of cerebral projections to the brainstem by strokes, and degenerations such as Parkinson's disease and Alzheimer's disease, causes mild, but clinically imperceptible slowing. 34,35 Mental fatigue, reduced vigilance, and ingestion of sedative drugs cause slight slowing of saccades.
What is horizontal gaze palsy?
For horizontal gaze, it is the paramedian pontine reticular formation (PPRF) in the mid-pons region that represents the horizontal gaze center generating conjugate horizontal movements for each eye.21 For example, a horizontal right conjugate gaze palsy would involve the left FEF sending a signal via the superior colliculus to the right PPRF. For a horizontal right conjugate gaze palsy, the right PPRF would be affected preventing transmission of the neural signal to the right CN VI for innervation of the right lateral rectus muscle and the left CN III for innervation of the left medial rectus muscle. Therefore, the patient would present with complete abduction deficit of the right eye and complete adduction deficit of the left eye upon attempted conjugate rightward movement of both eyes. This results in a horizontal right conjugate gaze palsy, or an inability to move both eyes rightward under binocular viewing conditions. 21
What is the body part that controls horizontal eye movements?
Horizontal eye movements are controlled in the pontine tegmentum. The pontine tegmentum contains the abducens nucleus, pontine paramedian reticular formation (PPRF), medial longitudinal fasciculus (MLF), and facial nucleus and fascicle. The final common pathway being the abducens nucleus, which contains the motor neurons for ...
Troy Derek Holan
I'm not sure what PPRF stands for in LA, but RPT means report and CLK means clerk. Reading between the lines, I am guessing there was some type of report that the clerk entered into the court file. Likely not a big deal in the grand scope of things given the 8 year prison sentence. More
Jay Scott Finnecy
If you believe he's been sentenced to 8 years in prison, none of that really matters much. Could be something regarding restitution or who knows? I'm certain your friend's attorney is aware of the case status.
