brain lesions and chemical control

Question 1

Conduction aphasia

Answer 1

Inability to repeat sentences/phrases and a defective ability to identify/name objects and people

Question 2

Unilateral frontal lobe disorders

Answer 2

• Contralateral spastic paraplegia if big enough to press on motor cortex
• Mood elevation
• Anosmia (if anterior and inferior)
• Entirely prefrontal: no hemiplegia, grasp reflex regained
• Frontal dysexecutive function: talkative, loss of initiative, difficulty adapting, tendency to joke, gregarious

Question 3

Bilateral frontal lobe disorders

Answer 3

• Bilateral plegia
• Early: frontal dysexecutive features
• Late: abulia, akinetic, socially inept, disordered gait, apathetic

Question 4

Cholinergic system

Answer 4

• Cholinergic nerve cell bodies and projections contain ACh
• Initial projections from nucleus basalis
• ACh from nerve ending - travels to post-synaptic neurone and causes signal transduction
• Can be broken down by AChE or recycled
• Binds to nicotinic receptors
• Pyridostigmine
• NMJ disorders: Myasthenia gravis, lambert eaton, botulism,

Question 5

Dopaminerhic pathways

Answer 5

• Dopamine enters cleft and binds to downstream receptors (d1 and d2)
• When bound, G protein signalling causes downstream transduction
• Some reabsorbed via dopamine transporter to be recycled
• MAO breaks down dopamine
• Dopamine transporter studied using DAT scan

Question 6

mesolimbic dopaminergic system

Answer 6

• Start in ventral tegmental area
• Involve amygdala and cingulate cortices
• Dopaminergic system regulates emotions, rewards and pleasure - addictive behaviours

Question 7

Why do you get positive and negative sx of schizophrenia

Answer 7

+ve due to overactive mesolimbic pathway - hallucinations, delusions, thought disorders
-ve due to mesocortical pathway dysfunction - withdrawal, minimal conversation etc

Question 8

Noradrenaline

Answer 8

• tarts in basal brain stem nucleus
• Sleep-wake patterns, PTSD, panic disorders,
• Depression when suppressed
• SNRI improves mood - allows noradrenaline to be reabsorbed via receptors
• Duloxetine and venlafaxine
• Cocaine stops re-uptake through dopamine receptor - more in cleft - can be useful initially when treating parkinsons