Neurons and Neuroglia

Franz Joseph Gall - Phrenology

• The study of the cranium's shape and size as an indication of character and mental abilities
• Key assumptions:
  • The mind's functions have a biological basis
  • The brain is not a unitary organ, displaying functional specificity
  • Changes in the brain correlate with changes in personality/behavior

Cab Drivers vs. Non-Cab Drivers

• The hippocampus was larger in cab drivers

Jean Martin Charcot - Psychology

• Sigmund Freud's teacher and the grandfather of clinical neurology
• Transitioned to modern disease analysis: the symptom is a clinical sign tied to underlying pathology, rather than being the disease itself
• He was one of the first to conduct post-mortem neural examinations

Phineas Gage

• A railroad worker who survived a severe brain injury dramatically changed his personality and behavior
• The case played a role in understanding the localization of brain function

Donald Hebb - Genesis of Modern Neuroscience

• Aims to understand the relationship between brain and behavior at a molecular level
• Involved reverberating neural circuits, cell assemblies, and Hebbian synapses

Reverberating Neural Circuit

• Occurs when one neuron causes another to fire, leading to long-lasting structural synaptic changes
• As learning occurs, less sensory input is needed to activate memory by turning the circuit on
• Rehearsal of knowledge causes structural changes and lowers the threshold

Cell Assembly

• A large group of cells that tends to be active simultaneously or in close succession
• Learning is the creation of these

Hebbian Synapse

• "Neurons that wire together, fire together”
• Memories are stored as a change in activity of single nerve cells

Goals of Neuroscience

• Tracing neural circuits (S-R model, galvanism, neuron doctrine)
• Localization of function (phrenology, motor cortex, Broca's aphasia, Wernicke's aphasia)
• Correlating brain activity and behavior

Karl Lashley

• Known for frog leg stimulation experiments
• The goal: explain behavior, knowing the connections

Problems with Tracing Neural Circuits

• Tracing circuits doesn't explain kinds of activity
• Effectiveness considerations: plasticity (change) and temporal dynamics
• Spontaneous/endogenous activity factors
• Overall complexity

S-R Model

• Reflex-based conceptual framework for understanding how the nervous system's structure produces behavior
• The nervous system is comprised of neural S-R reflexes
  • S = sensory nerve coming in
  • R = motor response nerve going out

Evidence for the S-R Model

• Law of roots, neuron doctrine

Law of Roots

• Sir Charles Bell's mechanical stimulation experiments:
  • Dorsal stimulation resulted in no contraction
  • Ventral stimulation resulted in contraction
• Francois Magendie's electrical stimulation studies:
  • Dorsal stimulation sometimes resulted in contraction
  • Ventral stimulation resulted in stronger contraction
• Lesion studies
  • Dorsal lesion: No paralysis
  • Ventral lesion: Flaccid paralysis
• Convulsion-producing drugs:
  • Dorsal lesion: Yes convulsion
    • Ventral lesion: paralysis (no convulsion)
• Implications:
  • Connections can be traced
  • Ventral side = motor/response
  • Dorsal side = sensory/stimulus

Galvanism

• Electricity produced by chemical action capable of making muscle contract
• Associated with "animal electricity" which was considered the life force

Neuron Doctrine

• Cajal was the first to see individual neurons and their connections
• Used Golgi method of staining tissue
• The importance:
  • Seeing cells and connections allows tracing of specific S-R connections
  • Allows tracing of neural circuits
• Showed neurons are separate entities

Broca's Aphasia

• A condition resulting from damage to Broca's area of the left frontal lobe
• Causes inability to speak fluently, mispronounce words and speak haltingly
• Deficit in language production

Wernicke's Aphasia

• A condition resulting from damage to Wernicke's area in the left temporal lobe
• Causes inability to understand meaningful language

Fritsch & Hitzig

• Discovered the motor cortex

Modern Subsystems Approach to Neuroscience

• Emphasis on tracing circuits with logic of information flow (excitatory vs. inhibitory connections and connection effectiveness)
• Functional specificity but with function conceptualized as "states of activation"
• Correlates brain and behavior, emphasizing how signals flow in real time across different areas

Hebb

• Studied with Karl Lashley at the University of Chicago and Harvard
• Proposed the Hebb synapse which is a theory of synaptic plasticity where neurons that fire together strengthen those connections
• Developed the cell assembly concept, explaining how groups of neurons represent thoughts and memories
• His 1949 book, The Organization of Behavior, introduced Hebbian learning, influencing modern neuroscience and artificial neural networks
• His theories influenced cognitive psychology, artificial intelligence, and neuroscience
• The concept of Hebbian learning remains foundational in understanding learning and memory in both biological and artificial systems

Biological Psychology

• The study of the physiological, evolutionary, and developmental mechanisms of behavior and experience

Dualism

• Belief that mind and body are different kinds of substance that exist independently

Evolutionary Explanation

• Understanding in terms of the evolutionary history of a structure or behavior
• Bat wings are modified arms

Functional Explanation

• Understanding why a structure or behavior evolved as it did
• Camouflage hides from predators, thus increasing ‘survival odds’

Mind-Body/Body-Mind Problem

• Addresses the question of the relationship between mental experience and brain activity

Monism

• Belief that the universe consists of only one kind of substance

Ontogenetic Explanation

• Understanding in terms of how a structure or behavior develops
• Examining behavior at different ages and relating it to changes in the nervous system

Physiological Explanation

• Understanding in terms of the activity of the brain and other organs
• Chemical reactions example

Active Transport

• A protein-mediated process that expends energy to enable a molecule to cross a membrane

Afferent Axon

• Carries information into a structure, directed TOWARDS it
• Sensory neurons

Astrocytes

• Star-shaped glia that synchronize the activity of axons
• Remove waste chemicals and dead neurons

Axon

• Thin fiber of constant diameter that is the neuron's information sender, with 0 or 1 per neuron

Blood-Brain Barrier

• A mechanism that excludes most chemicals from the brain
• Protects the brain from harmful substances
• A layer of blood vessels that make contact with brain tissue, forming a wall made of endothelial cells
• Acts as the rate-limiting factor for drugs
• Mechanisms of transport include passive diffusion and active transport
• Viral intruders that penetrate remain in the nervous system for life

Capillaries

• Smallest blood vessels

Passive Diffusion

• The movement of substances across a semipermeable membrane with the concentration gradient
• Does not require energy
• Returns membrane potential to baseline

Cell Body (Soma)

• Contains the nucleus, ribosomes, and mitochondria

Dendrites

• Branching fibers from a neuron that receive information from other neurons
• Typically many per neuron

Dendritic Spines

• Short outgrowths that increase the surface area available for synapses
• They grow or retract during learning
• Represent the point of contact between two neurons

Efferent Axon

• A neuron that carries information AWAY from a structure
• Motor neurons

Endoplasmic Reticulum

• A network of thin tubes that transport newly synthesized proteins to other locations

Glia

• Cells in the nervous system that do not conduct impulses over long distances
• Can provide evidence of brain trauma
• Plays a role in brain development (radial glia)
• Plays a role in neural conduction (Schwann cells and oligodendrocytes)
• Astrocytes and microglia are two types of glial cells

Glucose

• A simple sugar

Interneuron

• A neuron whose axons and dendrites are all confined within a given structure;
• All other types
• They transmit locally and modulate local networks; they can be excitatory or inhibitory
• Example: Withdrawal reflex and protecting muscle from excessive contraction

Intrinsic Neuron

• A neuron whose axons and dendrites are all confined within a given structure

Membrane

• Separates the inside of the cell from the outside environment

Microglia

• Cells that remove waste material and other microorganisms from the nervous system
• Kills damaged neurons

Mitochondrion

• Structure performing metabolic activities

Motor Neuron

• A neuron that receives excitation from other neurons and conducts impulses to a muscle with one axon and many dendritic spines
• Specific projection leads to high specificity of control

Axon Hillock

• The cone-shaped area on the cell body from which the axon originates

Axon Collateral

• Branch of an axon that inhibits antagonistic systems
• Restores function after damage

Myelin Sheath

• An insulating material that covers vertebrate axons

Neurons

• Cells that receive information and transmit it to other cells

Nodes of Ranvier

• Interruptions in the myelin sheath of vertebrate axons
• Important to action potential regeneration as it travels

Nucleus

• Contains the chromosomes

Oligodendrocytes

• Glia cells that build myelin sheaths in several portions, on different axons, within the central nervous system
• They wrap around the axon

Presynaptic Terminal

• The end bulb (terminal bouton) where an axon releases chemicals

Radial Glia

• Cells that guide the migration of newborn neurons and the growth of axons and dendrites during embryological development

Ribosomes

• Sites for cell synthesis of new protein molecules

Schwann Cells

• Glia cells that build myelin sheaths where one portion wraps around a single axon in the peripheral nervous system

Sensory Neuron

• Highly sensitive to a specific type of stimulation
• Brings sensory information to the brain with the soma located off to the side

Thiamine

• A B1 vitamin that is necessary to use glucose

Absolute Refractory Period

• A time when the membrane is unable to produce an action potential, making it impossible

Action Potential

• An all-or-none message sent by the axon
• traveling depolarization that is non-decremental (regenerates) maintaining the same shape and size every time

Action Potential Steps

• Sodium is outside, and potassium is inside with a resting membrane potential of -70mV
• The membrane depolarizes and reaches the threshold
• Sodium channels open and there is an influx of sodium, making inside the cell positive (+50 mV)
• At the peak, sodium channels close, marking the action potential
• Potassium channels open, leading to an efflux of potassium, causing repolarization
• K+ channels close slower while K+ continues to leak out, resulting in hyperpolarization and the inside of the cell becomes more negative
• Refractory period

All-Or-None Law

• The amplitude and velocity of an action potential are independent of the stimulus that initiated it

Chemical Gradient

• The difference in the distribution of ions (concentration) across the neuron's membrane
• During resting potential:
  • Sodium is pushed from outside to inside
  • Potassium is pushed from inside to outside

Depolarize

• To reduce polarization toward zero across a membrane
• Anything that reaches or passes the threshold produces an action potential, resulting in positive membrane potential

Electrical Gradient

• Difference in electrical charges between the inside and outside of the cell
• During resting potential:
  • Sodium is pushed from outside to inside
  • Potassium is pushed from outside to inside

Hyperpolarization

• Increased polarization across a membrane
• Decreased action potential
• Negative membrane potential

Local Anesthetic

• Drugs that attach to the sodium channels of the membrane to stop action potentials
• Prevents sensory neurons from conveying pain signals

Local Neurons

• Neurons without an axon

Myelin

• An insulating material composed of fats and proteins
• A poor conductor with no sodium channels under it

Why Myelin speeds action potential:

• Passive sodium movement (under myelin) is faster (vs active Na+ movement)
• No voltage-gated channels under myelin means fewer ions and less impeded movement of sodium
• Spaces under myelin are more negatively charged than at the node, so positive sodium inside the axon move more quickly

Myelinated Axons

• Axons covered with myelin sheaths

Polarization

• Difference in electrical charges between the inside and outside of the cell

Propagation of the Action Potential

• Transmission of an action potential down an axon
• Begins at the axon hillock and ends at the axon terminal
• Sodium ions enter at one node
• Positive current spreads down the axon
• When the next node is reached, the threshold of excitation is met

Orthodromic

• Normal propagation of action potential from the hillock to the terminal

Antidromic

• Propagation of action potential cannot happen normally from the terminal to the hillock

Refractory Period

• Time when the cell resists production of further action potentials
• Occurs during the period of after-hyperpolarization

Relative Refractory Period

• The time after the absolute refractory period that requires a stronger stimulus to initiate an action potential; is possible

Resting Potential

• The condition of a neuron's membrane when it has not been stimulated or inhibited before eliciting any change
• Voltage-gated channels are closed at -70mV
• Extracellular (outside): ++ (sodium out)
• Intracellular (inside): -- (potassium in)

Nernst Potential

• Equilibrium potential; overall (net) movement from chemical gradient is in balance (matched) with that from the electrical gradient
• K = -75mV
• Na = +55 mV

What Slows the Action Potential?

• Rising phase: current membrane potential approaches E™
• Falling phase: current membrane potential approaches E-

How Ion Channels Close

• For Potassium and Sodium: transient inactivation & full deactivation

Transient Inactivation

• Ball-and-chain mechanism blocks ion channel flow
• Temporary blocked state that prevents immediate reactivation

Full Deactivation

• A channel returns to its fully closed, resting state after an excitation has ended

Electrochemical Gradient

• The diffusion gradient of an ion affected by both the concentration difference of an ion across a membrane (a chemical force) and the ion's tendency to move relative to the membrane potential (an electrical force)

Membrane Potential

• The voltage difference across a membrane

Saltatory Conduction

• The jumping of action potentials from node to node
• Speeds action potential in myelinated neurons
• The action potential "regenerates" at each node

Selectively Permeable

• Providing a barrier that permits some chemicals to pass more readily than others

Sodium-Potassium Pump

• Mechanism that actively transports THREE sodium ions out of the cell while drawing in TWO potassium ions
• Maintains baseline (-70mV, aka resting potential)

Threshold

• Minimum amount of membrane depolarization necessary to trigger an action potential
• -55mV

Voltage-Gated Channels

• A membrane channel whose permeability to sodium (or some other ion) depends on the volt difference across the membrane

Neuroethics

• A branch of ethics that addresses the dangers and benefits of research investigating the brain
• Considers animal testing

Unipolar Neuron

• A neuron with one process extending from its cell body
• Sensory neuron

Bipolar Neuron

• A neuron with one axon and one dendrite attached to its soma
• Interneuron

Multipolar Neuron

• A nerve cell that has many dendrites and a single axon
• Motor neuron

Toxins That Block Sodium Channels

• Tetrodotoxin, brevetoxin, saxitoxin, local anesthetics (blocked in a localized area)
• Leads to impairment of neural communication

Toxin That Opens Sodium Channels

• Scorpion venom
• This causes muscle spasms

Toxin That Opens Potassium Channels

• General anesthetics
• Leads to long-term hyperpolarization

Voltage Clamp Procedure

• An experimental method used to measure ion currents across a membrane while keeping the voltage constant
• Separates sodium and potassium currents so separate roles in action potential generation can be observed
• Electrodes are inserted into a neuron
• A command voltage is set, fixing the membrane potential at a desired level
• The clamp circuit injects current to maintain this voltage
• The injected current equals the ionic currents, allowing precise measurement of ion channel activity

Logic of Blocking Potassium Channels

• To study one ion current in isolation, the other must be blocked
• Since potassium channels open more slowly than sodium channels, they interfere with late-phase measurements of sodium currents; can determine the exact timing of Na+ currents in action potential generation

Logic of Blocking Sodium Channels

• With sodium channels blocked, depolarization only activates potassium channels, allowing measurement of potassium currents without sodium interference

Plasma Membrane

• A selectively-permeable phospholipid bilayer forming the boundary of the cells
  • Phosphoriacid head is hydrophilic
  • Glyceride tail is hydrophobic

Neuron Theory

• A major breakthrough occurred in the late 1800s when Santiago Ramón y Cajal, using Camillo Golgi's staining technique, discovered that the brain is composed of separate cells called neurons with branch-like extensions
• He observed that neurons touch at certain points, later identified as synapses, where communication occurs
• Modern research has shown that the adult brain contains about 180 billion cells and remains functional despite daily cell loss
• Axons and dendrites allow neurons to communicate with each neuron having up to 15,000 synapses, forming an extensive network
• Neurons transmit signals via neurotransmitters and are organized into functional units
• The different brain regions process specific types of information
• The outdated idea claimed the brain as a single continuous network but helped inspire the modern neural network theory, which explains brain function as an interconnected system

Glia & Immune

• Explores the role of microglia as the immune cells of the central nervous system
• Challenges the earlier belief that the brain lacks immune protection due to the absence of traditional white blood cells, highlighting how microglia act as both protectors and potential contributors to neurodegenerative diseases
• Microglia Function: Microglia monitor the brain environment, respond to injury by changing shape, and can become phagocytic to clear debris, resembling macrophages
• Microglia Activation & Disease: When overactive, microglia may contribute to neurological disorders like Alzheimer's, multiple sclerosis, stroke, and the dementia associated with AIDS by releasing inflammatory cytokines and reactive oxygen species that can damage neurons
• Neurodevelopmental Role: Microglia play a role in shaping the developing brain by removing excess neurons
• Therapeutic Implications: Understanding microglia could lead to treatments that either suppress harmful inflammation or enhance their protective functions

Excitatory Postsynaptic Potential (EPSP)

• Graded depolarization from sodium ions entering the neuron
• increases frequency of action potentials

Neuron

• Receive EPSPs and IPSPs, integrate using summation EPSP + IPSP at axon hillock
• Transmit action potential and release of chemicals (communication occurs at synapse)

Inhibitory Postsynaptic Potential (IPSP)

• Graded hyperpolarization
• Produced by flow of negatively charged chlorine ions into the cell or by a flow of potassium ions out of the cell
• Decreases the frequency of action potentials

Graded Potential

• Relatively small membrane potentials proportional to the size of the stimulus
• Show decremental decay and are non-regenerative
• Summate at the axon hillock; can be depolarizations or hyperpolarizations

Postsynaptic Neuron

• A neuron that receives transmission from another neuron
• Can be ionotropic and metabotropic

Presynaptic Neuron

• A neuron that delivers transmission to another neuron

Reflex Arc

• A circuit from sensory neuron to muscle response

Reflexes

• Automatic muscular responses to stimuli

Spatial Summation

• Simultaneous graded potentials each originating at a different place

Spontaneous Firing Rate

• A periodic production of action potentials even without synaptic input

Synapse

• Specialized gap, a point of communication between two neurons
• Anatomy of chemical events

Summation

• Initiating cause of neuron firing
• EPSPs and IPSPs add together

Temporal Summation

• Successive graded potentials each originating at the same place

Acetylcholine

• A chemical similar to an amino acid, except that it includes an N(CHf)f group instead of an NH,
• Involves motor control

Categories of Neurotransmitters

• Biogenic amines, amino acids, peptides, purines, gases

Biogenic Amines

• Acetylcholine & monoamines

Amino Acids

• Acids containing an amine group (NH,)
• Can be either excitatory or inhibitory
• Include glutamate and GABA

Amphetamine

• A drug that blocks the reuptake of dopamine and other neurotransmitters

Anterior Pituitary

• Portion of the pituitary gland, composed of glandular tissue

Autoreceptors

• Receptors on a presynaptic neuron that respond to the released transmitter by inhibiting further release of it via negative feedback when there is too much
• Leads to hyperpolarized terminal

Cannabinoids

• Chemicals related to "-9THC"

Catecholamines

• Compounds that contain a catechol and an amine group
• Includes dopamine (addiction), norepinephrine (emergency), and epinephrine

Cocaine

• A drug that blocks reuptake of dopamine

Endocrine Glands

• Hormone-producing glands

Exocytosis

• Release of neurotransmitter from the presynaptic neuron into the synaptic cleft
• Caused by the entry of calcium

G Protein

• A protein coupled to guanosine triphosphate (GTP); an energy storing molecule

Gap Junction

• A direct contact of one neuron with another, enabling electrical transmission for two neurons acting as one

Gases

• One of the neurotransmitter categories, includes nitric oxide and possibly others

Hallucinogenic Drugs

• Drugs that distort perception

Hormone

• A chemical that is secreted by cells in one part of the body and conveyed by the blood to influence other cells
• Can be direct or indirect, and are less localized

Ionotropic Effects

• Synaptic effects that depend on the rapid opening of some kind of gate in the membrane
• They are localized and have direct and immediate change of ion channel
• They are fast, short duration

Ligand-Gated Channels

• Channels that open when a neurotransmitter attaches

Metabotropic Effects

• A sequence of metabolic reactions that produce slow and long-lasting effects at a synapse
• Requires neurotransmitter (NT) binding activating a second messenger system

Methylphenidate

• Stimulant drug prescribed for ADHD that increases the stimulation of dopamine synapses by blocking the reuptake of dopamine by the presynaptic neuron

Monoamines

• Chemicals formed by a change in certain amino acids
• Includes serotonin and catecholamines
• Treats depression

Neuromodulators

• Chains of amino acids that have indirect and localized results

Neuropeptides

• Chains of amino acids

Neurotransmitters

• Chemicals that have direct and localized effects released by neurons that affect other neurons, agonists, and antagonists

Nitric Oxide

• A gas released by many small local neurons

Opiate Drugs

• A gas released by many small local neurons

Oxytocin

• A hormone released by the posterior pituitary
• Important for sexual and parental behaviors

Pituitary Gland

• An endocrine gland attached to the base of the hypothalamus
• Has two parts: anterior and posterior

Posterior Pituitary

• Portion of the pituitary gland that releases hormones synthesized by the hypothalamus

Purines

• A category of chemicals including adenosine and several of its derivatives

Releasing Hormone

• A hormone released by the hypothalamus that flows through the blood to the anterior pituitary

Reuptake

• Reabsorption of a neurotransmitter by the presynaptic terminal
• Recycles and halts its effect on the postsynaptic cell
• Enables chemicals to build up enough concentration to have significant effects on their receptors

Endocytosis

• Repacked into vesicles and used in reuptake

Second Messenger

• A chemical that, when activated by a neurotransmitter initiates communication to many areas within the neuron

Synaptic Cleft

• The space between the presynaptic and postsynaptic neurons

Transmitter-Gated Channels

• Ion channels that open temporarily when a neurotransmitter binds to it

Transporters

• Special membrane protein where reuptake occurs in the neurotransmitter binds to it

Vasopressin

• An antidiuretic hormone released by the posterior pituitary that raises blood pressure and enables kidneys to use water

Vesicles

• Tiny nearly spherical packets filled with neurotransmitter molecules

Loewi Frog Heart Experiment

• Provided the first direct evidence that nerve impulses are transmitted by chemical messengers rather than solely by electrical signals
• The first heart that was slowing down released a chemical substance into the surrounding fluid, which slowed the second heart -- later identified as acetylcholine

Chemical Transmission

• Communication between neurons via release of chemical substances (neurotransmitters) that are contained in synaptic vesicles in the presynaptic terminals

Events in Chemical Transmission

• Synthesis
• Transport to axon terminal
• Release
• Receptor binding
• Inactivation

Events in Chemical Transmission: Synthesis

• Multiple neurotransmitters can be affected by a single precursor or catalytic agent
• Dysregulation example: phenylketonuria

Phenylketonuria (PKU)

• Caused by PAH gene mutation, specifically a deficient phenylalanine hydroxylase (enzyme)
• Phenylalanine accumulates 20x normal, a genetic inability to metabolize the amino acid phenylalanine
• Normal first few months but then leads to brain damage & permanent cognitive impairment, physical retardation, epilepsy, cardiac problems, and/or early death
• Treatment: early diagnosis and restricting dietary phenylalanine

Events in Chemical Transmission: Transport

• Neurotransmitters packaged into vesicles produced by the Golgi apparatus and then transported via microtubules

Events in Chemical Transmission: Release

• When an action potential arrives at an axon terminal, voltage-gated Ca²z channels open
• Vesicles fuse with the cell membrane, which is called exocytosis.

Presynaptic Receptors

• Autoreceptors and heteroreceptors
• Neurotransmitter is released from vesicles

Heteroreceptors

• facilitate or inhibit and respond to a neurotransmitter other than the one the cell releases

Events in Chemical Transmission: Receptor Binding

• Regulated by ionophore and activated by a voltage-gated channel or ligand-gated channel

Ionophore

• A chemical that binds to and transports ions across cell membranes
• How neurotransmitters mediate their effects
• Regulates channels

Voltage-Gated Channels vs. Ligand-Gated Channels

• Voltage-gated: Propagates action potentials
• Ligand-gated: Mediates synaptic transmission
• Voltage-gated Ca²z channels at the synaptic terminal open in response to an action potential, triggering neurotransmitter release, which then binds to ligand-gated ion channels on the postsynaptic neuron, leading to excitatory or inhibitory effects

Receptor Subtypes

The different types of receptors to which a particular neurotransmitter can bind

• Acetylcholine = nicotinic (motor) and muscarinic (heart)
• Dopamine: D1, D2 (addiction and novelty seeking), D3, D4, D5
• Serotonin: 5-HT1, 5-HT2 (depression), 5HT1a & 5HT1b, (aggression) 5-HT1d

Events in Chemical Transmission: Inactivation of Neurotransmitters

• Enzymatic breakdown and reuptake

Enzymatic Breakdown

• Enzymes located in the synaptic cleft or near the receptor, where different enzymes break down different neurotransmitters
  • AChE: acetylcholinesterase breaks down ACh into choline and acetate
    • MAO: monoamine oxidase breaks down monoamines
    • If AChE is inhibited after ACh release, it would last longer in the synapse

Different Ways Drugs Affect Transmission

• By altering synthesis of neurotransmitters
• Prevent packaging in Synapses
• Affecting inactivation
• Affecting reuptake

Types of Drug Effects

• Agonist and Antagonist

Agonist

• Same effect as neurotransmitter, may bind to the same receptor, has postsynaptic effect
• High affinity, high efficacy

Antagonist

• Prevents effects of neurotransmitter, blocks neurotransmitter from binding, and has no direct effect
• High affinity, low efficacy

Types of Drug Binding Sites

• Orthosteric and allosteric

Orthosteric

• Drug attaches to the same recepter a neurotransmitter would

Allosteric

• Drug attaches to a different receptor from the neurotransmitter resulting in indirect effects

Affinity

• How strongly a drug binds to a receptor

Efficacy

• A drug's ability to activate a receptor

Dopamine and Addicted Article

• Why some individuals become dependent on substances while others do not
• Biological Basis of Addiction: Drugs like nicotine alter brain chemisty mirroring the neurotransmitter especially affecting dopamine system, linked to pleasure and reward
• Some people are genetically more suseptiable for addiction
• Studies suggest that variations in brain receptors and neurotransmitter levels make individuals more pone to substance dependance.
• Drugs hijack the brains natrual reward pathway reinforcing the compulsive drug behavior
• Over time the brain adapts leading to taking more for the same effect and withdrawl when abstantion.
• Treats include medication with medication and bahavioral therapy

Amygdala

• Temporal lobe structure, role in aggression and fear
• Attaches emotional significance to sensory world, helps you evaluate

Autonomic Nervous System

• Peripheral System controls the heart, smalll intestine , other organs
• Somatic and parasompathetic system

Basal Ganglia

• Group of sturctures lateral to the thalamus
• movement control

Brainstem

• Midbrain, Medulla, pons and central structure of the forebrain

Spinal Cord

• Communicates with all sense organs - except head

Spinal nerve damage

• Muscle paralysis and loss of sensation

Substantia Nigra

• Path rising to pathways releasign dopamine

Superior Colliculus

• processing vision

Sympathetic nervous system

• Nerves prepairing organs for big activity

Tectum

• roof of midbrain

Tegumtum

• Floor of midbrain

Thalamus

• Two structures in forebrain
• Sensory

Central Sulcus

• Deepest groves in brain

Cerebral Cortex

• Layers of the outer surface

Corpus Collusm

• Axons connecting two hemespheres

Frontal Lobe

• Section extending to limite, highest cognitive function

Optic Lobe

• Primary visual context vision

Perietal Lobe

• perception section

Post Central Gyrus

• touch
• sensory

Pre Central Gyrus

• movement, motor cortex

Pre Frontal Cortex

• resonds to need of movemnt

Temporal Lobe

• near temples
• object recognition
• face recognition and hearing and language
• Wernickes area

Ablation

• Surgical removcal brain area

CT Scan

• inject die to blood visulaize structure

EEG

• recording through elecrical energy

FMRI

• measure engery
• area with greates blood supply using oxygen

lesion

• damaged structue
• cause loss

MRI

• Radio field to make atoms move
• good imaging

Meg

• measurement in brain

Ptogenetics\

• stimualation of light for neuron

Depolaratization

• mapping activity injected Chemicals for cent

Stereotax instrument

• Brain electrodes placement

BrainAtlas

• structures relative of brema

Tms

• Application of scalp under magnets

EBS

• implantation of elextordes

Directional Terms

• Planes
  • Carnal, saggart, lateral horizontal
• Dimensions
• Anteriour posterior dorsal

Hereditary

• Estimate variation depending on genetic variation

Evolution

• Change overtime with in frequencies
• Kin selection
• benefit of indiulals.

Lamarckian Evolution

• Acquired characterics

Apoptosis

• Mechanism leading to death

ViktOr

• Neurons initially reproduce them but die from aptopsios

Fetal Alcohol Syndrome(FAS) Symptoms

• Low IQ, Cognitive disabilities, Motor Skill issues

Daughter cells

• New cells by production

Synogensis

• Synapes forms
• axon pathfinding

spermatics

• Newts eye surgery
• eye returned world still upside down

Types is stroke resulting from artery blockage

• Hemerage and Ischemia

Imprinting

• Critically early period when animal form Attechments

`### Critical Period

• Animals exposure to stimulai, produces development

Hubbel and Weiss

• mono ocular deprivation during critical period impairing ocular sominance
• Line Deprivation impacting future detection Neurons

Sensory Deprivation

• Brains needs regular sensory stimulation

Sensory Enrichment

• Thicker cortex, more clia

Neuro Genesis

• Training new neurons
• BNDF
• MAP

BDNF

• Brain Deprive new trphic is protein promote survival and formation new sanpaes

Release From Inhiibition

• Function recovery where brain stem more active

Strokes

• Stimulation

Delve into the intricate world of neurons and neuroglia. Explore the challenges posed by the blood-brain barrier for drug delivery. Neuronal function, microglial roles, and the impact of inhibitory postsynaptic potentials are discussed.