Lecture 6 Flashcards
Emotions in brain circuits
- Detection of environmental signals: Senses and Thalamus
- Interpretation of environmental signals: Hippocampus and Amygdala
- Evaluation of these signals: PFC, NAc, Dopamine
- Action preparation: Motor cortext, Hypothalamus, Brain stem
- Visible behaviour
Psychological disorders regarding detection of environmental signals
- Autism
- ADHD
- Stress
Treatment: reduction impulses
Psychological disorders regarding interpretation of environmental signals
- PTSD
- Anxiety disorders
Treatment: reduction of overactive response
Psychological disorders regarding evaluation of environmental signals
- ADHD
- Stress
- PTSD
- Addiction
Treatment: restore cognitive control
Psychological disorders regarding action preparation
- PTSD
Treatment: restore autonomic nervous system
Treatment of ADHD
- Activating the brain, primarily PFC
- Medication:
- Ritalin: reuptake inhibitor (noradrenergic)
- Stratera Concerta (noradrenergic)
- Prozac: reuptake inhibitor (serotonergic)
- Catapres: for tics and ADHD (noradrenergic)
- Wellburtin: with depression (noradrenalin and dopamine reuptake inhibitor
- Adderal: reuptake inhibitor (dopaminergic) - Selfmedication: smoking
- Nutraceuticals: attend
Dopamine synthesis areas
- Substantia Nigra (Pars Compacta and Pars Reticulata)
- Ventral Tegmental Area
Dopamine projection areas
- Nigro-striatal projection
- Pallidum
- Caudate Nucleus and Putamen
- Frontal lobe
Functions of the different dopamine pathways
- Nigro-striatal: Modulates cortical motor control and action selection. Mediated via cortico-striatal-loop
- Meso-cortical/limbic: Reward processing, motivation, modulation of cognitive control
Dopamine receptors
All dopamine receptors are metabotropic and G-protein-coupled
Two subgroups: D1 receptors (excitatory, increase cAMP) and D2 receptors (inhibitory, decrease cAMP).
Reuptake via DAT
Basal Ganglia Motor loops dopamine brain area
- Body movement loop: Putamen
- Oculomotor loop: Caudate (body)
- Prefrontal loop: Anterior caudate
- Limbic loop: Ventral striatum
Parkinson’s Disease
Degeneration of the dopaminergic neurons in SN
Bradykinesia: slowing/loss of movements mechanism: increase of motor threshold
Nigro-striatal system
SN: dopamine
BG: GABA
Thalamus and Cortex: Glutamate
SN and motor cortex excite Dorsal Striatum
Dosral striatum inhibits Globus Pallidus which inhibits Thalamus
Thalamus excites motor cortex
Deep brain stimulation
- Mainly successfull in Parkinsons, Tourettes
- Mainly stimulation of the subthalamic nucleus
- Experimental reseach in OCD, epilepsy, addication
Dopamine stimulation Reverse U shaped curve
Working memory performance depends on D1R stimulation. It shows a reverse U shaped curve meaning that both very high and low D1R stimulation results in low working memory performance and medium stimulation results in high performance,
Noradrenaline synthesis and projections
Synthesis: Locus Coeruleus (LC)
Projection: All over the brain
Reuptake via Norepinephrine Transporter (NET)
Norepinephrine functions
Regulates arousal state (Sympathetic Nervous System)
Fight or flight response and stress
Released by adrenal medulla as a hormone.
Memory consolidation
Sleep wake cycle
Norepinephrine receptors
- All are metabotropic and G-Protein-coupled
- Subtypes: alpha 1A, alpha 2A, beta 1-3
Norepinephrine pharmacology
NE increased by:
- Antidepressants: MAO blockers, Tricyclic antidepressants
- ADHD meds: Ritalin (reuptake blocker), Strattera (reuptake blocker), Modafinil
- Stimulants: Amphetamine, Cocaine
Effects of Methylphenidate (Ritalin)
Inverted U shape for dosage and spatial working memory. Meaning a medium dosage has the best cognitive performance.
Increases Dopamine and Norepinephrine release in the PFC. Blocks reuptake.
Serotonin synthesis/projections and functions
Synthesis: Raphe nucleus
Projections: all over the brain
Functions: gut motility and vasculature
Mood, anxiety, arousal, circadian rhythm, eating disorders, migraine, pain, drug abuse
Serotonin receptors
Ionotropic receptor: 5-HT3
Metabotropic receptors:
5-HT1
5-HT2
5-HT4, 6, 7
5-HT5
Funcion of Serotonin
- Modulation of basic psychological function: mood, appetite, sleep, sexuality
- Implicated in depression (most antidepressants block 5-HT reuptake)
- Implicated in aggression (high serotonin levels)
- Stimulates vomiting
Antidepressants
- MAO inhibitors: inhibit breakdown of all monoamines
- Tricyclic antidepressants: inhibit reuptake of serotonin and norepinephrine
- SSRI’s: inhibit reuptake only of serotonin
Modulation
Neurotransmitters that modulate do not directly evoke EPSP’s or IPSP’s. They modify the effectiveness of EPSP’s generated by other synapses with transmitter-gated channels
