BioPsychology - Fall 2024.pdf

8/27/24 What is it? Study of biological basis of behavior Concerned with relationship between psychological processes and underlying physiological events Focuses on function of the brain and rest of nervous system in behavior Six divisions Physiological psychology...

8/27/24 What is it? Study of biological basis of behavior Concerned with relationship between psychological processes and underlying physiological events Focuses on function of the brain and rest of nervous system in behavior Six divisions Physiological psychology ○ Focuses on direct manipulation of nervous system in controlled laboratory settings (i.e. lesions, electrical stimulation, invasive recording) ○ Subject are usually lab animals ○ Strong focus on basic/pure research - to satisfy the curiosity of the researchers and prove their hypothesis true or false (information gatherers) ○ Invasive Psychopharmacology ○ Nervous system is manipulated pharmacologically ○ Focuses on how drugs affect behavior ○ How drug effects change in neural activity ○ Some psychopharmacologists favor basic research and use drugs to reveal the nature of brain-behavior interactions ○ Others study applied questions (i.e. drug abuse) Neuropsychology ○ Focuses on behavioral deficits produced in humans by brain damage (normally cortical damage ○ Deals almost only with case studies and quasi experimental studies ○ Applied research - neuropsychological tests if brain damaged patients facilitate diagnosis, treatment, and lifestyle counseling Psychophysiology ○ Focuses on the relation between physiology and psychological processes ○ Uses noninvasive techniques and recordings from humans ○ Usual measure of brain activity is the scalp electroencephalogram (EEG) ○ Cognitive neuroscience ○ Newest division of biopsychology ○ Focuses on neural bases of cognitive processes like learning and memory, attention, and complex perceptual processes ○ Noninvasive, functional brain imaging techniques ○ Often involves collabs between researchers with widely different backgrounds (i.e. psychology, linguistics, computer science) Comparative psychology ○ Study of evolutionary and genetic factors in behavior ○ Features comparative and functional approaches ○ Features lab research as well as animals in their natural environments (ethology) 8/29/24 The Nervous System Neuraxis: imaginary line that splits the body and brain in half along the spinal cord Anterior: towards the face/nose (in the brain) and towards the head (in the body) Rostral: where a particular area is located in relation to itself (towards the beak) Frontal lobe is more rostral as compared to the occipital lobe Rostral and anterior is interchangeable Posterior: toward the back of the head (in the brain) and towards the butt (in the body) Caudal is where a particular area is located in relation to itself (interchangeable with posterior) Dorsal: toward the top of the head (in the brain) and toward the back (in the body) Ventral: toward the chin (in the brain) and toward chest (in the body) Pointing your nose to the sky aligns the neuraxis in the brain with the body Standing normally turns the axis Medial: towards the middle/neuraxis Lateral: away from the midline/neuraxis (doesn’t change) Ipsilateral: the signaling pathway is occurring on the same side of the neuraxis (i.e. nose/smelling system (olfactory)) Contralateral: the signaling pathway crosses the neuraxis (i.e. motor cortex - sends signals to the right side of the body) ○ Movement on the right side of the body is controlled by the left hemisphere of the brain ○ Movement of the left side of the body is controlled by the right hemisphere of the brain  3 planes that is used to cut up the brain/central nervous system ○ Horizontal plane Horizontal section: the surface that is parallel to the b and splits the brain in half ○ Transverse plane Frontal section: separates the forehead from the back of the head Cross section: cutting down the spinal cord ○ Sagittal plane Sagittal section: separates the left hemisphere from the right of the brain Mid sagittal: separates the the brain straight down the middle The nervous system contains the central nervous system and the peripheral nervous system ○ Central nervous system contains the brain, meninges, ventricles, and the spinal cord Brain → -encephalon Forebrain ○ Telencephalon - is the cerebral hemisphere Cerebral cortex Basal ganglia Limbic system ○ Diencephalon Thalamus Large, oval structures Serve as the brain’s relay stations Processes and transmits sensory information to appropriate areas of the cerebral cortex for interpretation Regulates consciousness, sleep, and alertness Hypothalamus Small structure located below the thalamus Regulates many essential body functions ○ Temperature control, hunger, thirst, sleep, mood, and the release of hormones from the pituitary gland Key player in maintaining homeostasis Bands of myelinated axons Connects different regions of the brain, facilitating rapid transmission of electrical signals between neurons Crucial for efficient communication between the brain and the rest of the body Midbrain ○ Mesencephalon  Tectum Superior colliculi (visual relay) Inferior colliculi (auditory relay) Tegmentum Rostral end of reticular formation (arousal system) Periaqueductal gray area (mediates analgesia) Substantia nigra (sensorimotor system) Ventral tegmental area (reward system) Red nucleus (sensorimotor system) Hindbrain ○ Metencephalon Cerebellum Means little brain Posterior surface Has a lot to do with coordination & posture Contributes to motor learning and cognitive functions Receives sensory input and motor impulses Pons Ventral surface Bridge between myelencephalon and the mesencephalon Very important for sleep and waking ○ Myelencephalon Medulla oblongata Just above the spinal cord & just below the pons Oldest part of the brain & lowest part of the brainstem Connects the brain to the spinal cord Controls respiratory system Regulates circulatory system Has nerves that trigger swallow reflex Has connections with the parasympathetic Spinal cord Dorsal root ○ Dorsal ganglion - where cell bodies are located Type of cells - (pseudo)unipolar neuron ○ Carries afferent/sensory info ○ Neurons coming from left invades the left dorsal horn and vice versa Ventral root  ○ No ganglion ○ Carries efferent/motor impulses from the brain through the synapses and into the spinal cord Cervical Thoracic Lumbar Sacral Cauda equina Meninges Membranes made of 3 layers Protective layer of the brain and spinal cord and only found in the central nervous system Anchor the brain and spinal cord and provide cushioning and stability Dura mater: 1st layer under the scalp and the skull ○ Hardest of all 3 layers - thick, rigid, and inflexible ○ Provides the layer of protection Arachnoid membrane: 2nd layer ○ Contains the arachnoid space Fibrous filaments stems into the arachnoid space In the space flows cerebrospinal fluid around and in the central nervous system ○ Helps to absorb some of the impacts that may occur Pia mater: 3rd layer ○ Very thin ○ Wraps around the brain and spinal cord ○ Attaches the meninges to the brain and spinal cord ○ Holds the rest of the meninges in place ○ Capillaries and veins pass through ○ Helps hold blood vessels in place Ventricles Filled with cerebrospinal spinal fluid ○ Many nutrients flow into the fluid ○ Provides cushioning support Prevents the brain from collapsing from its own weight Lateral ventricle - two ○ White matter: myelinated and unmyelinated axons ○ Gray matter: cell bodies and synapses Where neurons communicate with one another Third ventricle Cerebral aqueduct Fourth ventricle - in between the cerebellum and the medulla Covered in bone - the tissue that is within the bone is apart of the system ○ Peripheral nervous system consists of the somatic nervous system and the autonomic nervous system Outside of the bone Somatic (voluntary) nervous system contains afferent and efferent nerves Soma - means body Regulate and control our movement and muscles Makes up a lot of our skeletal system Afferent (sensory) nerves and neurons carries sensory info from the body to the brain (tip: ascending) Efferent (motor) nerves and neurons sends motor signals from the nervous system to the body (tip: exiting the motor) Autonomic (involuntary) nervous system contains afferent and efferent nerves Autonomic: self governing In charge of all of our internal organs - controls all the systems in our body The efferent nerves in this nervous system contain the parasympathetic and sympathetic nervous systems ○ Controls much of our functioning (ex. vision, breathing, heart rate) ○ Sympathetic nervous system Next to the thoracic lumbar Nerves originate from the thoracic and lumbar regions of the spinal cord Ganglion contains neuronal cell bodies, synapses Sympathetic ganglion is right outside of the spinal cord Digestive and bladder system are further away Causes arousal, anxiety, heart rate, fight or flight, excitement, pupil dilation, tear production, relaxes airways, stimulates sweating, stimulates glucose release from the liver (gives energy), digestion, relaxes bladder Activates when response is needed Pupils dilate to let more light in Sympathetic activation - mouth dries, heart rate speeds, digestion slows, blood vessels constrict, blood pressure rises Redirects blood flow to limbs or whichever part of body is necessary to react ○ Parasympathetic Nerves originate from the brainstem and sacral region of the spinal cord  Rest and digest, constricts pupils & airways, contracts bladder, stimulates salivation & digestion Low heart rate Cranial nerves extend out from the brain into organs Comprises of most of the cranial nerves - prominent → vagus nerve 12 pairs of cranial nerves - originate on the ventral surface of the brain Efferent - motor function ○ Oculomotor (3) - controls most of the eye’s movements ○ Trochlear (4) - controls the movement of the superior oblique muscle ○ Trigeminal (5) - motor & sensory - facilitates facial sensations (touch, pain) and controls muscles involved in chewing - sends sensory nerves that is felt in the face - returns motor signals ○ Abducens (6) - controls lateral eye movement ○ Facial (7) - motor & sensory - controls the muscles of facial expressions and contributes to taste sensation from the anterior two-thirds of the tongue ○ Glossopharyngeal (9) - motor & sensory - involved in taste and other functions related to the throat and larynx ○ Spinal Accessory (11) - controls muscles in the neck that allow for movement of the head and shoulders ○ Hypoglossal (12) - controls tongue movements Afferent - sensory function ○ Olfactory (1) - smell ○ Optic (2) - vision - transmits visual information from the eyes to the brain ○ Auditory/Vestibulocochlear (8) - hearing & balance Vegus (10) - motor & sensory - part of the autonomic nervous system and goes through our internal organs ○ Affects the heart, lungs, digestive tract, and is involved in sensation from the internal organs ○ Controls/regulates the parasympathetic nervous system in organs Vegus is the only pair of nerves that goes away from the brain - the rest of the pairs stays above the shoulders Spinal nerves are considered peripheral and majority are somatic The neurons in spinal dorsal roots are afferent Cervical nerves (8 pairs) that come from the upper portion of the spinal cord - controls the movement and sensation in the arms and neck  Thoracic nerves (12 pairs): control the movement and sensation of the back, trunk, and chest Lumbar (5 pairs): Control movement in the hips, lower back, and legs Sacral (5 pairs): control movement in the legs Coccygeal (1 pair): emerges from the trunk, near the tailbone ○ Central part of the brain is not completely covered by bone Neuron: single cell in the nervous system Nerve: bundle of neurons Nuclei: specific groups of neurons that have specific functions Telencephalon (limbic system) - 4 lobe structure (cerebral cortex) ○ Frontal, parietal, occipital, temporal Frontal lobe - located in the anterior part of the brain Primary motor cortex ○ Controls voluntary movements ○ Integration of motor commands with the ongoing somatic sensory state of the body Association cortex ○ Higher order (executive) function ○ Planning ○ Thinking and worrying ○ Language production ○ Working memory Orbitofrontal cortex - ventral surface of the frontal lobe Association cortex ○ Impulsivity control ○ Personality ○ Understanding of social norms ○ Processing reward information Parietal lobe - posterior to the frontal lobe Primary somatosensory cortex ○ Process somatic sensations ○ Detect touch ○ Proprioception (body position) ○ Nociception (pain) ○ Temperature Association cortex ○ Body awareness ○ Kinesthesis ○ Mathematical calculations ○ Aspects of reading & writing (combining sound, appearance, and function of words)  Temporal lobe - lateral ventral surface of both hemispheres, anterior to the occipital lobe and posterior to the frontal lobe Primary auditory cortex ○ First relay station for auditory information ○ Awareness of sound Association cortex ○ Auditory processing ○ Language processing ○ Interprets speech Occipital lobe - located in the posterior part of the brain, dorsal region of the brain’s back Primary visual cortex ○ Detection of static object ○ Detection of moving object ○ Pattern recognition Association cortex ○ Complex processing ○ Visual interpretation ○ Spatial relation between objects ○ Each lobe has a primary motor cortex ○ Major structures Amygdala Emotional processing Forming and retrieving emotional memories Hippocampus Critical for memory formation and spatial navigation Consolidates short-term memory into long-term memory Plays a role in spatial memory that enables navigation Cingulate cortex Divided into right and left hemispheres Plays a crucial role in emotion formation and processing, learning, and memory Influences autonomic functions i.e. heart rate and blood pressure Fornix Bundle of nerve fibers Acts as a major output tract of the hippocampus, connecting it to other parts of the brain, including the mamillary bodies and septal nuclei Important for transmitting information within the limbic Septum Involved in reward and reinforcement Plays a role in processing feelings of pleasure Connections to the hippocampus and hypothalamus Hypothalamus  Mammillary body Play a role in recollective memory Act as a relay for impulses coming from the amygdala and hippocampus to the thalamus Nervous System Structure Astrocyte - cell body in the central nervous system ○ Star-like structures ○ Communicates with other neurons and contacts blood vessels ○ One astrocyte can support many neurons - all neurons in its proximity ○ Billions of astrocytes - about 3 times as many compared to neurons ○ Thought to be a cell that promotes the movement of nutrients out of the bloodstream and passes them onto the neurons Takes waste from neurons and puts back in the bloodstream to keep the balance ○ Thought to control various types of neurotransmitters around in the extracellular space that are released by the neurons When neurotransmitters are released from neurons, sometimes they float away Astrocytes keep that balance in the space so there is no excess buildup that can overstimulate and wreak havoc in the nervous system ○ Helps control/regulate the levels of potassium in the extracellular space Potassium is an ion that moves across the neural cell membrane ○ Has the ability to help with vascular constriction and relaxation ○ Skeletal support Ends of astrocytes comes in contact with vessels Keeps neurons from coming in contact with one another ○ Neurons do not directly metabolize glucose Astrocytes do Glucose enters the bloodstream, astrocytes absorb the glucose & converts it into lactate, neurons processes and uses the lactate Lactate is the fuel for neurons Satellite cells ○ Surround the cell body ○ Provide structural and metabolic support to the neuron ○ In the PNS, they perform a similar role to astrocytes in the CNS ○ Help regulate the environment around the neuron ensuring ion balance and nutrient supply Axon ○ Extends from the cell body ○ Responsible for transmitting electrical signals to and from the central nervous system (other neurons or target cells) ○ In unipolar neurons, the axon splits into 2 branches  One branch extends to peripheral tissues (brings sensory information from the body) Other branch heads to the spinal cord (sends signals to the central nervous system) Schwann cells - myelination in the peripheral nervous system ○ Surrounds the axon ○ Important for creating the myelin sheath in the peripheral nervous system ○ Myelin sheath increases the speed of electrical impulses by insulating the axon ○ Schwann cells wrap around the axon in a process called myelination, forming multiple layers of membrane/myelin ○ Wrap individual sections of axons Separated by gaps (nodes of Ranvier) Where action potentials are produced (saltatory conduction Allows for faster transmission of electrical impulses along the axons ○ Myelinate one axon section as a time Oligodendrocytes - myelination in the central nervous system ○ Perform the same function as Schwann cells Structured differently ○ One can extend its processes to multiple axons Types of Neurons ○ Unipolar neuron Body comes off the neuron itself Dendrites on one end and the terminal at the other The electrical pulse does not affect the cell body Typically sensory In the dorsal ganglion of the dorsal root Communication between peripheral and central In the joints, skin, muscles, internal organs, and in and out of the spinal cord ○ Bipolar neuron 2 axons coming off the cell body electrical impulses go through the cell body and out the other end Rare Typically sensory Found in the retina of the eye & ear ○ Multipolar neuron Many branch like extension that comes of its body Efferent neuron In the central and peripheral nervous system May have sensory functions Most abundant in the nervous system ○ Multipolar interneuron Just the cell body with branch like extensions  Found in the central nervous system and the efferent parts of the peripheral nervous system Functions as the in betweens to connect neurons to neurons Especially in the central nervous system in the brain Enables fast communication Regulates reflexes in the spinal cord ○ Myelinated axons are typically found in systems or areas that we need a fast response ○ Unmyelinated axons are typically found in systems or areas that we need a slower response Cell body & dendrites receive cell information ○ Soma Contains nucleus and organelles Metabolic center of the cell Where most of the neuron’s protein synthesis occurs Integrates coming signals from the dendrites and initiates an electrical impulse if the stimulus is strong enough ○ Dendrites Extend from the soma Receives electrical signals from other neurons or sensory cells Typically received as neurotransmitters at synapses Signals are passed to the soma for processing Large surface area - allows neuron to receive input from multiple sources ○ Myelin sheath Surrounds the axon Composed of glial cells Schwann cells in the PNS Oligodendrocytes in the CNS Acts as an insulator Increases the speed of electrical signal transmission by allowing the action potential to go between nodes (saltatory conduction) ○ Responds to neurotransmitters ○ Receptors on the cell body membrane ○ The dendritic spine is where receptors are located Large Hundreds ○ Myelin is thought to get protect accidental responses ○ Change from a chemical impulse/signal to an electrical impulse ○ Axon hillock ○ At the end of the axon, it breaks off and turns into terminal buttons No myelin Releases neurotransmitters into the synaptic cleft when an action potential reaches them  Neurotransmitters bind to receptors on the next neuron or target cell - passes the signal along Important for communication between neurons or between neurons and other types of cells ○ Electrical signals flow from the dendrites to the soma then down the axon to the terminal buttons where neurotransmitters are released One-way flow Axon hillock ○ Lipid membrane that enables the passage of different ions ○ When the cell is resting, it is not firing Resting phase - relative resting potential Distribution of charge across the cell membrane The inside of the cell is slightly more negative than the outside Sodium and potassium - positively charged ions Resting potential is about -70 milliables On the inside of the cell there is more potassium as compared to sodium More sodium outside of the cell compared to potassium More sodium on the outside More potassium on the inside Resting potential is different over different types of neurons and the nervous system Diffusion - passive/does not require cellular energy - allows potassium and sodium to move out the cell and spread out evenly Electrostatic pressure - passive/does not require cellular energy - the attraction between oppositely charged particles and the repulsion of same charge particles When channels open, opposite charges attract If the cell is resting, it works against potassium The change in membrane potential will trigger the opening of channels along the axon The threshold of excitation triggers sodium channels to start opening About 10-15 millivolts more positive than the resting potential When the channels open, sodium is attracted to the negative charges inside the cell - causes the inside to become more positively charges ○ Cause sodium channels to start opening down the line Potassium will try to escape because there is more in the inside and sodium will try to come in because there is more on the outside Sodium & potassium channel - transport mechanism It tries to reestablish the resting potential of the cell Will grab 3 sodium ions to push them out of the cell and grab 2 potassium ions to get back into the cell  There's always an extra sodium outside to maintain the slightly negative charge The voltage triggers the opening ○ When each segment hits the voltage of -55, the channels open The strength of the action potential does not change The charge near the threshold of excitation keeps the potassium channels close Diffusion and electrostatic pressure is occurring 1. Membrane potential (mV) rises 2. Diffusion begins 3. Sodium channels open, & sodium begins to enter the cell 4. Potassium channels open, potassium begins to leave the cell 5. Depolarization occurs - the cell at rest is polarized at -70 charge - means that the membrane charge is moving toward zero/the more positive numbers 6. Sodium channels become refractory - no more sodium enters the cell 7. Potential has reached its peak at +40 8. Potential begins to decrease to its resting potential level - repolarization occurs 9. Potassium continues to leave the cell causing the membrane potential to return to resting level 10. Potassium channels close and sodium channels rest 11. Hyperpolarization occurs - the cell is more negatively charged than its resting potential 12. The channels work in hyper mode to even the distribution and bring the potential back to resting potential 13. Extra potassium outside diffuses away 14. **all or nothing (once the threshold is reached, the action potential is completed fully)**  Synapse ○ Each neuron receives numerous synaptic contacts ○ There are hundreds of synapses on cell bodies and dendrites ○ Synapse is a communication point between neurons ○ 3 parts Presynaptic membrane Where neurotransmitters are released Postsynaptic membrane - cell body or dendrite membrane Receptors imbedded for neurotransmitters Synaptic gap or synaptic cleft ○ Neurons release neurotransmitters that cause electrical changes in the postsynaptic membrane ○ Synaptic vesicles that contain and protect the neurotransmitters Vesicles bind with the membrane to release the neurotransmitters into the synaptic cleft ○ Neurotransmitters can be created in the cell body or in the terminal Neurotransmitter release - exocytosis Excess neurotransmitters leads to neuron stimulation and even cell death Terminating neurotransmitter actions ○ Reuptake Transport mechanism where neurotransmitters are recycled - broken down and its parts are used to create more neurotransmitters Depends on the type of neurotransmitter and neuron ○ Enzymatic degradation An enzyme is released into the synaptic cleft to break down the neurotransmitters There are synapse that are gap junctions ○ Thin tube that connect cell membranes  ○ The cytoplasm moves back and forth ○ Connect the cytoplasm of two adjacent cells ○ In mammalian brains, there are many gap junctions between glial cells & neurons ○ Found in the cardiac muscles (heart), smooth muscles (intestines), skin cells, and blood vessels Generation & conduction of postsynaptic potentials ○ Postsynaptic potentials Role of neurotransmitters in the postsynaptic neuron ○ Excitatory postsynaptic potentials (EPSP) Becomes more positively charged - depolarization to rest Results from the opening of sodium channels Don't respond to voltage like action potentials Responds to neurotransmitters Increases likelihood of action potentials Multiple can bring the neuron’s membrane potential to the excitation threshold, triggering an action potential ○ Inhibitory postsynaptic potentials (IPSP) Leads to hyperpolarization to rest Results from the opening of potassium channels Don't respond to voltage like action potentials Responds to neurotransmitters Decreases likelihood of action potentials ○ If IPSP counteracts EPSP, action potential is not triggered in the axon ○ EPSP and IPSP how close a neuron is to the excitation threshold by depolarizing or hyperpolarizing ○ Graded responses → their magnitude varies based on the intensity of the stimulus - more neurotransmitters lead to a larger potential ○ Temporal and spatial summation - cumulative effect of everything occurring in the cell membrane Rapid responding of synapses - more sodium comes into the neuron = temporal summation Many points along the membrane where sodium comes in (flooding) - more synaptic active summation at different spots = spatial summation ○ 3 important properties Graded Difference in strength between EPSP and IPSP Decremental As we move away from where the channels open, there is a weaker charge change Where the ions shift - strongest polarity Rapid transmission Quick change like action potentials ○ Many neurons fire action potentials in the absence of input or do not fire APs at all  ○ Action potentials vary in terms of amplitude, duration, and frequency ○ Dendritic function is very complex Dendrites appear to be able to actively conduct action potentials ○ Only channels along the axon are voltage sensitive ○ Neurotransmitter activation for dendrites and cell bodies - triggers EPSP and IPSP - ligand gated Either potassium or sodium channels 9/17/24 Neurotransmitters Binds to receptors on cell dendrite and soma Causes changes in electrical charges Does not cross the postsynaptic membrane Amino acid neurotransmitters ○ Found in fast acting “directed” synapses in central nervous system ○ Molecular building blocks of protein ○ Creates neuropeptides with protein ○ Glutamate Most prevalent excitatory neurotransmitter Common in proteins that we eat Found throughout the central nervous system Always depolarizes the cell The main neurotransmitter in some parts of the brain Some other parts it may play a secondary role Glial cells—astrocytes—absorbs glutamate & breaks it down to glutamine Feeds the glutamine back to the neuron to make more glutamate ○ GABA (gamma-aminobutyric acid) Most prevalent inhibitory neurotransmitter Synthesized from glutamate by the enzyme glutamate decarboxylase Anxiety may be caused by imbalances of GABA Benzodiazepines give more GABA to calm a system down ○ Acetylcholine Primary neurotransmitter secreted by efferent axons in the peripheral nervous system i.e. neuromuscular junction More released in the PNS than CNS Major concentrations of ACh in the CNS Dorsolateral pons (in REM sleep) Basal forebrain (in learning) Medial septum (in memory) Excitatory - stimulates muscle contractions Plays a role in regulating some of the functions in out smooth muscles in our organs - parasympathetic division of the autonomic nervous system Causes blood vessels to dilate Stimulates secretions in the pancreas, liver  Inhibitory on heart muscles - causes the heart to slow down (relax) Synthesized through a process of transferring a choline molecule -ase = enzyme Choline acetyltransferase is the enzyme that assist in transferring the acetate to the choline - becomes the neurotransmitter Acetylcholinesterase (AChE) separates the two ions to recycle them Acetate goes out of the synapse and fuses with the extracellular space Choline gets recycled - reuptake ○ Non-directed synapses Slower than a directed synapse More long-lasting effect because of the excess neurotransmitters The bumps along the axon where it splits (its extension) - varicosities Contain neurotransmitters Allow neurotransmitter release at multiple sites along the axon ○ Released when an electrical signal reaches these points along the axon Once released, neurotransmitters travel across the synaptic cleft to bind with receptors on the next neuron or target cell More widespread and diffuse release of neurotransmitters - influences a larger area of target tissue ○ Monoamine - one amino acid Catecholamine Order of synthesis ○ Tyrosine Starting point of all neurons to create neurotransmitters Tyrosine hydroxylase changes into L-dopa ○ L-dopa Does not function as a neurotransmitter on its own Given as a treatment for parkinson’s DOPA decarboxylase changes into dopamine ○ Dopamine Released by dopaminergic Synthesis stops for neurons that release dopamine Doesn’t cross the blood brain barrier Dopamine B-hydroxylase Released in high concentrations in the thalamus Tied to happiness, arousal, thrill-seeking, attention, memory, movement Parkinson's disease - loss of dopamine - about 80% loss of neurotransmitters in the substantia nigra  ○ Norepinephrine Released from central nervous system neurons or adrenal glands (hormones - released by endocrine glands) In the medulla & metencephalon Stimulate and increases arousal, attention Released during fight or flight - keeps the response going Only gets to this step if the neuron is norepinephrinergic Phenylethanolamine-N-methyltransferase ○ Epinephrine Less released and synthesized in the CNS than norepinephrine Released in high concentrations in the hypothalamus, central pathway, medulla Released from adrenal glands Adrenaline Serotonin Order of synthesis ○ Tryptophan Tryptophan hydroxylase ○ 5-hydroxytryptophan (5-HTP) 5-HTP decarboxylase ○ 5-hydroxytryptamine (5-HT or Serotonin) Synthesized in high concentrations in the raphe nuclei Involved in blood clotting, mood stability, sleep arousal Regulates bowel functioning Monoamine oxidase Breaks down monoamines 2 forms ○ MAO-A Preferentially breaks down norepinephrine, serotonin, tyramine, & dopamine Tyramine ○ Excess - high blood pressure ○ MAO-B Preferentially breaks down dopamine ○ Foods that shouldn't be taken while taking MAO inhibitors Processed meats Aged cheeses Wines  Kimchi ○ Synaptic events (mechanisms) 1. Neurotransmitter molecules are synthesized from their precursors under the influence of enzymes 2. Neurotransmitter molecules are stored in vesicles 3. Neurotransmitter molecules that leak from their vesicles are destroyed by enzymes 4. Action potentials cause vesicles to fuse with the presynaptic membrane and release their neurotransmitter molecules into their synapse 5. Released neurotransmitters bind with autoreceptors and inhibit subsequent release 6. Released neurotransmitters bind to postsynaptic receptors 7. Released neurotransmitters are deactivated by either reuptake or enzymatic degradation ○ Transmitters can either be neurotransmitters or hormones depending on where they're made ○ Autoreceptors monitor how many neurotransmitters are released with every action potentials If a signal is sent that there isn’t enough the neuron makes more neurotransmitters ○ Antagonist drugs reverse or reduce the drugs intended effect Drug effects Blocks the synthesis of neurotransmitters - destroying synthesizing enzymes Causes neurotransmitters to leak from their vesicles and be destroyed by enzymes Blocks the release of neurotransmitters from terminals Activates autoreceptors and inhibits neurotransmitter release Receptor blockers - binds to postsynaptic receptors and blocks the effect of the neurotransmitter Examples Botulinum toxin ○ Inhibits release of acetylcholine ○ Acetylcholine antagonist Curare ○ Blocks postsynaptic receptors ○ Acetylcholine antagonist Caffeine ○ Blocks postsynaptic receptors ○ Adenosine antagonist ○ Agonist increases the drugs intended effect Drug effects  Increases the synthesis of neurotransmitters - increasing the amount of precursors Increases the number of neurotransmitters by destroying degrading molecules Increases the release of neurotransmitters from terminals Binds to autoreceptors and blocks their inhibitory effect on neurotransmitter release Binds to postsynaptic receptors and either activates them or increases the effect on them of neurotransmitter Blocks the deactivation of neurotransmitters by blocking degradation or reuptake Examples Cocaine ○ Blocks reuptake of dopamine ○ Dopamine agonist Nicotine ○ Stimulates postsynaptic receptors ○ Acetylcholine agonist L-dopa ○ Precursor for dopamine ○ Increases synthesis of dopamine ○ Dopamine agonist