Psych Brain&Behavior INCOMPLETE

Neurotransmission

the process that occurs when
a neurotransmitter is released from a presynaptic
neuron and binds to a receptor on the postsynaptic
neuron

Neurotransmitter Receptors

Neurotransmitters evoke postsynaptic potentials by binding to members of a
diverse group of transmembrane proteins called…

Ionotropic

Ligand-gated ion channels that rapidly open when a chemical messenger, such as a neurotransmitter, binds to them, allowing specific ions (like Na⁺, K⁺, Ca²⁺, or Cl⁻) to pass through the cell membrane

Metabotropic

A class of cell surface receptors, most commonly G protein-coupled receptors (GPCRs), that do not directly open ion channels

Neurochemicals (Neurotransmitters) include

Small Molecules, Neuropeptides and Gasotransmitters

Small Molecule include

Acetylcholine, Monoamines, Amino Acids, ATP and its byproducts

Monoamides include

Catecholamines - dopamine, norepinephrine, epinephrine

Indoleamines - Serotonin and Melatonin

Histamine

Amino Acids include

Glutamate, GABA, Glycine and five others

Neuropeptides include

Endorphins, Substance P, and Insulin and 43 others

Gasotransmitters

Nitric Oxide, Carbon Monoxide

Small Molecule: Acetycholine

Plays a role in memory, learning, attention, arousal and involuntary muscle movement mostly contained in the brainstem and basal forebrain and can be broken up into Acetate and Choline.

Acetate

A compound found in acidic foods (e.g. vinegar and lemon juice)

Choline

A breakdown products of fats present in foods (e.g. egg yolk, avocado salmon, olive oil)

Acetylcholinesterase (AChE, enzyme)

Breakdown acetylcholine into acetate and choline for reuptake back into presynaptic cell.

Nicotinic-ACh Receptor

Ionotropic receptor for Na+, K+ , Ca 2+ ion channel (typically net +
change). fast acting and named after it’s ability to stimulate nicotine.

Used at the neuromuscular junction (connection
between nerves and muscles) and CNS

Muscarinic ACh Receptor

Metabotropic receptor thus slower acting. Implicated in higher brain functions such as learning and memory. Related to Alzheimer’s disease

Catecholamines

Named on the basis of the hydroxylated
phenol ring termed a catechol nucleus. Dopamine, Norepinephrine, and Epinephrine. All share similar chemical structure.

Indolamines

Serotonin (5-Hydroxytryptamine; 5-HT) and Melatonin 

Histamine

Control of arousal and waking and Regulation of immune response

Tyrosine

The catecholamines synthesis precursor chemical. Foods high in this chemical
include cheese, soybeans, beef, lamb etc.

Tyrosine hydroxylase

This enzyme changes tyrosine into L-dopa, which other enzymes convert
first into dopamine, then into norepinephrine, and finally into epinephrine

The Dopamine pathways are…

substantia nigra → striatum (caudate and putamen),

Mesolimbic DA pathway,

the ventral tegmental area (VTA) → the limbic system,

Mesocortical DA pathway

Nigrostriatal dopamine pathway

substantia nigra → striatum

Movement-related activities and Parkinson’s disease

The ventral tegmental area (VTA)  the limbic
system

Reward and pleasure, Addiction & Schizophrenia

Mesocortical DA pathway

important for cognition and the regulation of
executive functions (e.g., attention, working
memory, inhibitory control, planning, etc.)

Dopamine (DA) Receptors & DA removal

5 different types of DA receptors (D1-D5),
and all are metabotropic

DA is actively re-uptaken by dopamine
transporters (DAT) in the presynaptic
terminal → destroyed by an enzyme called
monoamine oxidase (MAO)

Adrenalin (epinephrine)

synthesized in the adrenal gland (adrenal medulla) → involved in fight or flight response. activating adrenergic receptors throughout the body

also synthesized in the brain (medulla oblongata)

Noradrenalin (= norepinephrine, NE)

Mediate fight or flight response
• Increases arousal and vigilance
• Enhances sensory processing
• Strengthens memory encoding in the
amygdala and hippocampus
• Prepares motor systems for fast reaction

• most NE neurons are clustered in
  the brainstem in a region called the locus
  coeruleus (LC)

Metropic receptors 

Serotonin(5-HT, for 5-hydroxytryptamine)

Plays an important role in many psychological
processes - regulation of mood, control of eating, sleep,
and arousal

Major source of 5-HT in the brain is the raphe
nuclei in the brainstem

Synthesized from the amino acid, L-tryptophan

Amino Acid

The transmitters of this small molecule are the workhorses of the brain because so many synapses use them. 

Glutamate, Gamma-aminobutyric acid (GABA)

Glutamate (glutamic acid, Glu)

typically opens Na + and Ca 2+ channels →
excites neurons!

the major excitatory neurotransmitter in the brain &
spinal cord

Gamma-aminobutyric acid (GABA)

typically opens Cl – channels → inhibits neurons!

the major inhibitory neurotransmitter in the brain

Glutamate Receptors

Both ionotropic. AMPA Receptor and NMDA Receptor

AMPA Receptor

This is the most common glutamate receptor. Used in most types of excitatory synaptic transmission. Passes Na+ ions

NMDA Receptor

Permits Na+ and Ca2+ to enter the cell. Important for learning and memory. Mg2+ ion must be removed for the channel to pass
ions.

Receptor only opens when glutamate is bound OR when the cell is depolarized (less negative on the inside compared to its resting state)

ligand and voltage-dependent

GABA (γ-aminobutyric acid)

Produced from glutamate is a major inhibitory neurotransmitter in the brain. Enzymatic reaction: Glutamic acid decarboxylase (GAD).

2 types of GABA receptors both create IPSPs

GABA-A receptor: ionotropic; passes Cl-
GABA-B receptor: metabotropic; controls a K+ channel

Peptide Transmitters: Neuropeptides (Chain of amino acids)

Synthesized through translation &transcription - instructions in DNA

Over 100 distinct neuropeptides

Opioid peptides: endorphin, dynorphin, enkephalins - pain modulation, reward, stress relief

Hypothalamic releasing hormones: control pituitary
hormone release

Social/affective peptides: oxytocin, vasopressin

Endocannabinoids

a class of neuromodulators derived from lipid molecules, rather than amino
acids or peptides

Acts on cannabinoid receptors
• CB1 receptors
• CB2 receptors
• Metabotropic

Affect appetite, pain, sleep, mood, memory, anxiety, and the stress
response

Cannabis and the Endocannabinoid System

Cannabis refers to all products derived from the plant Cannabis sativa

main cannabinoids are tetrahydrocannabinol (THC) and cannabidiol (CBD)

Tetrahydrocannabinol (THC)

Act on cannabinoid receptor CB1 receptors and CB2 and the principal psychoactive effect

Cannabidiol (CBD)

Reduce the number of seizures
• Reduce anxiety
• Effect on insomnia
• helps control pain

Drugs

Chemical compounds administered to produce a desired change. Three different names. chemical, generic, and branded names

Psychopharmacology

Study of the ways drugs affect the nervous system and behavior

Chemical name

Describes the drug's complex molecular structure

Generic name

Name of the drug's active ingredient

Brand name

Unique, trademarked name given by the
manufacturer (Tylenol, Advil, Midol etc.)

Intracerebral

Administered between the two cerebral hemispheres of the brain

Oral Administration

Most common and safest route for taking a substance by mouth for systemic absorption. Weak acids pass from stomach into bloodstream. Weak bases pass from intestines into bloodstream.

Intramuscular

Drugs injected into muscles encounter more barriers

Inhalation

Drugs inhaled into lungs encounter fewer barriers 

Intravenous (IV)

Drugs injected into bloodstream encounter fewest barriers to the brain but must be liquid

Blood Plasma

The liquid component of your blood. 55% of bloods total volume

Absorption rate

The time to reach maximum plasma concentration. Faster rate of absorption  higher
and earlier peak concentration. 

Circumventricular organs (CVOs)

Specialized brain regions where the BBB is weak or absent. “windows” for the brain to communicate with the blood. 7 areas are considered as CVOs such as...
• Pineal gland: Entry of chemicals that affect day-night cycles
• Pituitary gland: Entry of chemicals that influence pituitary hormones
• Choroid plexus
• Area postrema: entry of toxic substances that induce vomiting

The body eliminates drugs mainly through

Metabolism (Biotransformation) and Excretion

Metabolism (Biotransformation)

Occurs mostly in the liver, Drugs are broken down into more water-
soluble compounds for easier excretion, cytochrome P450 enzyme family is involved

Excretion

Metabolized drugs are excreted through urine,
feces, sweat, breast milk, and exhaled air

Most psychoactive drugs primarily affect

neurotransmitter release, receptor activation,
and removal from the synaps

Agonist

Mimics or enhances

A substance that binds to a receptor and
activates it, producing a biological response
similar to the natural neurotransmitter

Antagonist

Prevents or weaken receptor

A substance that binds to a receptor but
does NOT activate it, instead blocking or
reducing the effect of the natural
neurotransmitter

2 kinds of drug-receptor interaction

Competitive binding
and Non-competitive binding

Competitive binding

occurs at a neurotransmitter binding site = drug compete with the
neurotransmitter to bind to the receptor

• Direct agonist
• Direct Antagonist

Non-competitive binding

occurs at an alternate binding site on the same receptor
• Indirect agonist
• Indirect
antagonist

Psychoactive Drugs

Chemical substance that
changes the function of the nervous system and
results in alterations of perception, mood,
cognition, and behavior

Barbiturates

Indirect agonist of GABA-A
receptors

• Sedative-hypnotics properties
• Sleeping medication or anesthesia
induction

Benzodiazepines

Indirect agonist of
GABA-A receptors

• Anti-anxiety properties

Ketamine

Used medically for induction and maintenance of
anesthesia or pain management

• NMDA receptor indirect antagonist
• Binds to PCP binding site
• Prevent Ca2+ influx NMDA receptor

Esketamine

approved in conjunction with oral
antidepressant in March of this year

Sedative : Xylazine

is a non-opioid sedative or tranquilizer. Used for sedation, anesthesia, muscle relaxation, and analgesia in animals such as horses, cattle,
and other non-human mammals

First-generation antipsychotics

Mainly D2 receptor antagonist, Also block noradrenergic, cholinergic, and histamine
receptors  unwanted side effects

Second-generation antipsychotics:

D2 and 5-HT2 receptor antagonist, Increase selectivity

Major Depressive Disorder (MDD, depression)

• Prolonged feelings of worthlessness and guilt
• General slowing of behavior
• Frequent thoughts of suicide