Brainstem Modulation

What is the function of the modulatory system of the brainstem

Optimize brainstem activity controlled by many neurons

What neurotransmitters are involved in the modulatory system

Acetylcholine, norepinephrine, epinephrine, serotonin, dopamine, histamine

What is arousal and consciousness

Arousal → state of alertness, consciousness → state of awareness of self surrounding

What are the components of consiousness

Level of consciousness (alert, drowsy, stupor, coma), content of consciousness (cognitive and mental status)

What does stupor mean

Patient needs vigorous and repeated stimulus to arouse patient

What is the reticular formation

Set of many nuclei in the brainstem

Which part of the reticular formation is responsible for arousal

Pontomesencephalic reticular formation

Pontomesencephalic reticular formation dorsal pathway

Send signal to thalamus → Cortex

Pontomesencephalic reticular formation ventral pathway

Send signal to basal forebrain and hypothalamus → Cortex

What is ascending arousal system

Merging of ARAS with thalamus that control consciousness and arousal

What neuron is found in locus ceruleus and lateral tegmental

Noradrenergic neurons 

What neuron is found in dorsal and median raphe nuclei

Serotonergic and dopaminergic neuron

What neuron is found in pedunculopontine and laterodorsal tegmental nuclei

Cholinergic neurons

What neuron is found in tuberomammillary nucleus

Histaminergic neurons

NorE function

Projects to entire cortex to control Attention, sleep-wake, mood, pain

Serotonic projecting system (Rostral raphe)

Rostral raphe nuclei in forebrain → Project to forebrain, thalamus and basal ganglia

Serotonic projecting system (caudal raphe)

Caudal raphe of pons and medulla → Project to cerebellum, medulla and spinal cord

Serotonic projecting system function

Caudal controls breathing, temperature and motor, pain

Which neurotransmitters modulate pain

NorE and serotonic projecting system

Dopaminergic mesocortical pathway

Ventral tegmentum → Prefrontal cortex; controls working memory

Dopaminergic mesolimbic pathway

Ventral tegmentum → Limbic system and nucleus accumbens; controls addiction and reward

Dopaminergic mesostriatal/nigrostriatal pathway

Substantia nigra pars compacta → Putamen and caudate; controls motor movement

Cholinergic projecting system (peduculopontine and laterodorsal tegmental nuclei)

Cholinergic fiber project to thalamus

Cholinergic projecting system of basal forebrain

Nucleus basalis of Maynert → Entire cortex; medial septal and nucleus of diagonal band → Hippocampus; forms memory

Function of cholinergic projecting system

Facilitate memory, memory and learning

Histaminergic neuron function

Control alertness in brain and immune response outside of it; found in tuberomammillary nucleus

What are monoamines

Made from aromatic amino acid that fire spontaneous regular AP; cholinergic and linked to sleep wake cycle by modulating thalamus and cortex

Orexin projection system

Found in posterior lateral hypothalamus and targets entire brain → Controls alertness and food intake

What are the modes of firing and how does it relate to attention

Drowsy (low firing) → No attention, Phasic mode → Best concentration, tonic mode (too high firing) → No concentration but changes performance

What is the connection between dopamine and adrenergic agonists in learning

Dopamine linked to reward based learning, adrenergic agonist improves performance

Adrenergic neuron autonomic function

Maintain vascular tone; upright posture increases vascular tone and BP

What is gate theory in pain

Non painful stimuli is carried by large nerve fibers that close the gate to block pain carried by small nerve fiber; pain passes when gate is open

What is periaqueductal gray

Receive input from hypothalamus, amygdala and cortex → Inhibit pain transmission to dorsal horn by relay sent to rostral ventral medulla → Signal to locus ceruleus 

Where are opioid receptors found

Periaqueductal gray, RVM and spinal cord dorsal horn

Dopamine and basal ganglia motor movement

Low dopamine → Parkinsonism; high dopamine → Tics, chorea, compulsive behavior

Serotonin relation to motor

Serotonin activator cause serotonin syndrome, lack of firing to raphe causes atonia

Noradrenaline motor function

Can cause stereotypic and repetitive behavior

Effect of antidopaminergic drug

Daytime sleepiness

Effect of serotonin reuptake inhibitor

Decrease sleep

Effect of antihistamine

Drowsiness

Effect of adenosine

Sleepy