PSYC 2800 Lecture Notes - Substantia Nigra, Tissue Plasminogen Activator, Vascular Dementia

33 views10 pages
20 Apr 2012
of 10
Lecture 3b *final+
Risk factors: Age
Stroke: An interruption of blood flow either from the blockage of a blood
vessel or from bleeding of a vessel
Lack of blood to the brain as a result of stroke. Blood important to
nourish brain.
Sets off a cascade of cellular events that cause the real damage to the
initial site (where blood vessels feeding onto) and surrounding areas
Change gene expression, protein expression, inflammation, lot of
recovery early on
Neural shock that follows brain damage in which areas connected to
the site of damage show temporary arrest of function
Not initial stroke region but associated regions?
Stroke - Treatment
Administer anti-clot drugs
E.g., t-PA (tissue plasminogen activator)
Prevent further incidents of stroke
Must be administered within 3 h of stroke! So need to get to hospital
right away.
Drug used to try to block the cascade of post stroke neural events
No good ones available yet
Behavioral therapies (e.g., speech or physical) are often used to facilitate
plastic changes in the brain following a stroke
Force bad side of body into use
Recurrent seizures accompanied by loss of consciousness
Symptomatic Seizure
Identified with a specific cause, such as infection, trauma, tumor,
vascular formation, toxic chemicals, very high fever, or other
neurological disorders
Idiopathic Seizure
Appears spontaneously and in the absence of other diseases of the
central nervous system
A variety of factors may precipitate a seizure: Stress, fatigue, alcohol
Three common symptoms of seizures
An aura, or warning of impending seizure – a sensation (odor –
“burnt toast” or noise) or a “feeling. Feel like something is off.
Dogs trained to detect these aura’s, even before person does and
guides person to safe place
Loss of consciousness often followed by a period of amnesia that can
include the seizure itself
A motor component that can vary in severity from shaking to
automatic movements such as hand-rubbing or chewing
Two Types of Epileptic Seizures
1. Focal Seizure
Category of seizure that begins locally (at a focus) and then spreads
out to adjacent areas
Start focused area of brain (somatosensory motor areas)
Jacksonian march”: Seizure is neuron firing randomly without input.
Start one part then spreads out
Complex Partial Seizure
Type of focal seizure
Originate mostly in the temporal lobe
Not necessarily accompanied by loss of consciousness
Characterized by:
Subjective experiences that presage the attack (e.g.,
hallucinations so visual cortex firing to produce image not
Automatisms or repetitive stereotyped movements (e.g., lip
Postural changes (e.g., catatonic or frozen posture)
2. Generalized Seizures
Lack focal onset; occur on both sides of the body. Focal start on one
Grand mal Seizure (big bad)
Characterized by loss of consciousness and stereotyped motor
activity; 3 stages:
tonic stage: body stiffens and breathing stops
clonic stage: rhythmic shaking
Postictal depression: post seizure state of confusion, can
see brain wave activity changed on a EEG
Petit mal Seizure
Of brief duration, characterized by loss of awareness with no
motor activity except for blinking, turning the head, or rolling
the eyes
Common in children
Past interpreted in possession by devil
Epilepsy: Treatment
Anticonvulsant medications
Examples: diphenylhydantoin or phenobarbital. Lower activity of CNS
(seizure thought to be over excitation of CNS). GABA is main inhibitor.
Work by stabilizing the neuronal membrane, especially inhibitory
Surgical removal of the abnormal tissue that is the focus of the seizures is
sometimes performed in severe cases, can affect circuitry of brain (ex: HM)
Multiple Sclerosis
Disease characterized by a loss of myelin, largely in the motor tracts but
also sensory nerves
Relapses and remissions (not symptomatic) are common, can also have
chronic MS
Brain imaging reveals discrete lesions, showing areas of damage
Cause is unknown, but proposed causes include: bacterial infection, a virus,
environmental factors (e.g., pesticides), and an immune response of the
central nervous system (most accepted, auto immune disorder)