Cigarette smoking : During pregnancy cigarette smoking produce lasting arousal,
attentional and cognitive deficits in humans.
The pedunculopontine nucleus (PPN),
as the cholinergic arm of the reticular activating system (RAS),
is known to modulate arousal,
waking and rapid eye movement (REM) sleep.
Prenatal exposure to cigarette smoke induces marked changes in cells in the cholinergic arm of the RAS,
making them more excitable.
Preterm birth induces persistent deleterious effects on arousal and sleep wake cycle and cortical mechanisms throughout development
In the pontine tegmentum, there is an important center for horizontal gaze.
The coordination of for lateral conjugate gaze is carried out at the pontine level by the paramedian pontine reticular formation (PPRF). This nucleus,
which also has ipsilateral connections to the abducent (VI) nucleus.
These PPRF fibers then ascend in the MLF to the contralateral oculomotor (cranial nerve III) nucleus.
If a lesion extends into the dorsal–medial aspect of the upper pons,
it may interrupt these ascending fibers in the MLF,
resulting in difficulties with conjugate gaze to the side opposite the lesion.
Horner’s syndrome-involvement of descending sympathetic pathway in reticular formation
Coma is a state of unconsciousness- due to inactivity of RAS
In Parkinsonism - Parkinson's disease have significant loss of PPN neurones,
the degeneration of PPN neurones or their dysfunction may be important in the pathophysiology of locomotor and postural disturbances of parkinsonism.
REM sleep behaviour disorder:Studies conducted showed pedunculopontine nucleus ,
latero dorso tegmental nucleus (LDTN) and several pontine nuclei influence wake-sleep states .In REM sleep without atonia,
lesions to locus ceruleus disrupt the excitatory connection to mangocellular column disable the hyperpolarization of the alpha spinal motorneurons.
In humans after extensive neurologic evaluations who have suffering from both idiopathic and symptomatic forms have not identified specific lesions.
,
The findings in some patients suggest that diffuse lesions of the hemispheres,
bilateral thalamic abnormalities,
or primary brain-stem lesions may result in the RBD.
Schizophrenia : it is characterized by severe sleep wake cycle which includesdecreased slow wave sleep (SWS),increased rapid eye movement (REM) sleep,
fragmented sleep etc.
These abnormalities reflects an overactivity of pendunculopontine nucleus (PPN) of reticular activating system.
Many studies emphasized the relationship of increased cholinergic output of PPN and the negative symptoms in schizophrenia.
Post traumatic stress syndrome: Patients with this syndrome have significant 50% decrease in the number of locus coeruleus (LC) neurons,which results in increased disinhibition of the PPN.
Depression,
autism,
attention deficit disorder : The exact role of the RAS in the above mentioned disorders are not identified so far.
However,
it is said that any neurological or psychiatric disease that manifests disturbances in arousal and sleep-wake cycle regulation,
there will be a corresponding dysregulation of some elements of the RAS.
Alzheimer's disease : Reduction of cholinergic neurons observed in Alzheimer’s disease with dementia
Narcolepsy : Clinically,
disturbances in electrical coupling have a effect with a decrement in synchronization,
especially of gamma oscillations,
leading to decreased alertness in narcolepsy.
There is significant inhibition of PPN and loss of orein peptides,
which induces daytime sleepiness in narcolepsy.
Normal 0 false false false EN-US X-NONE X-NONE