Paramedian pontine reticular formation

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The paramedian pontine reticular formation, or PPRF, is a brain region, without clearly defined borders, in the center of the pons. It is involved in the coordination of eye movements, particularly saccades.

Contents 1 Inputs, outputs, functions 2 Lesions 3 See also 4 References 5 External links

[edit] Inputs, outputs, functions

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. The rostral PPRF probably coordinates horizontal saccades; the caudal PPRF may be the generator of both horizontal and vertical saccades. In particular, activity of the excitatory burst neurons (EBNs) in the PPRF generates the "pulse" movement that initiates a saccade. In the case of horizontal saccades the "pulse" information is conveyed via axonal fibers to the abducens nucleus, initiating lateral eye movements. The angular velocity of the eye during horizontal saccade ranges from 100 to 700 degrees per second. Larger saccades have faster pulses; the PPRF is involved in this determination.^[1]

[edit] Lesions

Unilateral lesions of the PPRF produce characteristic findings:^[2]

• 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
• Bilateral lesions produce horizontal gaze palsy and slowing of vertical saccades

[edit] See also

• Ophthalmoparesis
• Internuclear ophthalmoplegia
• One and a half syndrome
• Multiple sclerosis
• Stroke

[edit] References

1. ^  Brazis, P.W., Masdeu, J.C., and Biller, J. Localization in Clinical Neurology, 4th edition. Lippincott, Williams, and Wilkins, Philadelphia, 2001; pp. 213-216. ISBN 0-7817-2843-6
2. ^  Adapted from Leigh, R.J., and Zee, D.S. The Neurology of Eye Movements, 3rd edition. Oxford University Press, Oxford, England, 1999; p. 499. ISBN 0-19-512-972-5

[edit] External links

• BrainInfo at the University of Washington ancil-479

v·d·e Brain: rhombencephalon (hindbrain)
Metencephalon/ pons	{| class="navbox collapsible nowraplinks" style="margin:auto; background:white;background:white;"
[[[:Template:Fullurl:Template:]] v]·[[[:Template:Fullurl:Template talk:]] d]·[[[:Template:Fullurl:Template:]] e]
Dorsal/ (tegmentum)	surface: Locus ceruleus Trigeminal lemniscus (Dorsal trigeminal tract, Ventral trigeminal tract) cranial nuclei: GSA: Principal V/Spinal V - VIII-c (Dorsal, Anterior)/VIII-v (Lateral, Superior, Medial, Inferior) - SVE: Motor V - VII - GSE: VI - GVE: VII: Superior salivary nucleus MLF, III, IV and VI (vestibulo-oculomotor fibers, medial vestibulospinal tract) sensory/ascending: Trapezoid body/VIII - Superior olivary nucleus Inferior cerebellar peduncle (Vestibulocerebellar tract) motor/descending: Apneustic center • Pneumotaxic center (Medial parabrachial nucleus) - Lateral parabrachial nucleus
Ventral/ (base)	Middle cerebellar peduncles (Pontocerebellar fibers) - Pontine nuclei motor/descending: Corticospinal tract - Corticobulbar tract - Corticopontine fibers
Raphe/reticular	Reticular formation (Caudal, Oral, Tegmental, Paramedian) • Raphe nuclei (Median)

|- style="white-space:nowrap;background:#ddddff;text-align:right;background-color: LightYellow" ! Myelencephalon/
medulla | colspan="1" style="text-align:left;width:100%;font-size:95%;background:#f7f7f7;" | {| class="navbox collapsible nowraplinks" style="margin:auto; background:white;background:white;" |- style="text-align:center;width:100%;"

!colspan="2" |

|- |- style="white-space:nowrap;background:#ddddff;text-align:right;padding-left:0em;padding-right:0em;background-color: LightYellow"

!

| colspan="1" style="text-align:left;width:100%;font-size:95%;" | surface: Posterior median sulcus - Postero-lateral sulcus - Area postrema

cranial nuclei: GVA: VII,IX,X: Solitary/tract • SVA: Gustatory nucleus • GSE: XII  • GVE: IX,X,XI: Ambiguus • SVE: X: Dorsal • IX: Inferior salivatory nucleus - MLF, III, IV and VI

sensory/ascending: Gracile nucleus • Cuneate nucleus (Accessory cuneate nucleus) • Sensory decussation  • Medial lemniscus

motor/descending: Dorsal respiratory group
|- style="white-space:nowrap;background:#ddddff;text-align:right;padding-left:0em;padding-right:0em;background-color: LightYellow"

!

| colspan="1" style="text-align:left;width:100%;font-size:95%;background:#f7f7f7;" | motor/descending: Ventral respiratory group - Pyramid (Motor decussation) - Inferior olivary nucleus (Olivocerebellar tract, Rubro-olivary tract)
surface: Anterior median fissure - Antero-lateral sulcus - Arcuate nucleus of medulla - Olivary body
|- style="white-space:nowrap;background:#ddddff;text-align:right;padding-left:0em;padding-right:0em;background-color: LightYellow"

!

| colspan="1" style="text-align:left;width:100%;font-size:95%;" | Reticular formation (Gigantocellular, Parvocellular, Ventral, Lateral, Paramedian) • Raphe nuclei (Obscurus, Magnus, Pallidus) |} |}

This page uses content from the English-language version of Wikipedia. The original article was at Paramedian pontine reticular formation. The list of authors can be seen in the page history. As with Psychology Wiki, the text of Wikipedia is available under the GNU Free Documentation License.