Ian Waterman

suffered a rare autoimmune reaction to a flu-like virus that attacked the sensory neurons from his neck down. He lost his ability to understand where his body was in space. He could not physically do anything because he was not receiving signals from the neurons in his muscles and joints

lesion method

the technique of destroying tissues to determine their functions

Herophilus

"Father of anatomy"-- believed that the ventricles (sacs of fluid in the middle of our brains) were the seat of intelligence

How many types of Glial cells are there?

Three

Glial Cells

Cells that provide support to the nervous system, helping neurons to communicate with one another

Microglia

provide immune system support to the nervous system

Oligodendrocytes

wraps around the axons of some neurons in the brain and spinal cord- helping to insulate

Astrocytes

play a crucial role in moderating how different cells talk to one another

Neuron

designed for electrochemical communication--they respond to chemical signals and information from the outside world.

Neural Networks

specific patterns which neurons can learn and form connections with one another that persist throughout our lives

Dendrites

structures that neurons have that reach out into a fluid filled space called the synapse

neurotransmitters

chemical messengers that play a crucial role in transmitting signals between nerve cells (neurons) and other cells in the body

excitatory messages or inhibitory messages

neurotransmitters often tell a cell to do what two types of messages?

excitatory message

tells the neuron to send its own message to another cell, like a game of "telephone" in which one player tells a message to the next, and so on and so forth

inhibitory message

tells the neuron to stop talking to others

soma

the body of the neuron-- houses important functions necessary for the cell to sustain itself-- also where neurotransmitters are made

axon

on the side of the soma that pinches off from the cell body and elongates into a structure that looks like a long tail and can travel long distances

the sciatic nerve

travels from the base of the spinal cord to the big toe

nerves

bundles of axons that all travel together to the same place

axon hillock

the place where the soma and axon meet, and action potential begins

The soma initiates an electrical response called a hillock. This electrical signal, called an action potential, travels down the length of the axon to structures called the axon terminals

What happens when a neuron's dendrites receive enough excitatory messages?

terminal buttons

at the tip of the axon-- location where neurotransmitters are released into the synapse

postsynaptic receptors

neurotransmitters will bind with these on the membrane of another cell

oligodendrocytes

wraps around axons of some neurons in the brain and spinal cord-- have an important function in speeding up the transmission of these action potentials in the central nervous system-- create a substance called myelin which acts like an insulation wrapped around nerves

nodes of ranvier

breaks in the myelin-- play an important role in helping the signal to travel down the axon

saltatory conduction

when a signal travels down the axon faster

Schwann cells

cells which perform a similar function in the peripheral nervous system-- a progression in the speed of a process

neural signals (along the axon) are electrical, while neural signals between the cells (across the razor-thin synapse) are chemical

chemical versus electrical signals

Sensory neurons

detect information from the environment and translate those signals into the electrochemical language of the nervous system-- 1. where our body is in space, or other senses, 2. they always move information inward or afferently, from the outside world toward the CNS, 3. they don't have dendrites most of the time

Motor Neurons

direct muscles to relax and contract, producing movement-- always move information outward or efferently from the CNS toward the muscles so that we can affect the outside world

interneurons

acts as messengers between neurons, forwarding the signals generated by sensory neurons to the brain-- 1. found exclusively in the brain and spine, 2. help to relay motor signals from the CNS to motor neurons, or otherwise enable two neurons within the CNS to talk to each other (Such as within the brain), 3. move information both inwardly (afferently) and outwardly (efferently)

steps for an excitatory message being received by a cell

1. neurotransmitter binds to a receptor site on the dendrite, 2. the electrical signal starts at the axon hillock, 3. the message travels down the axon, 4. neurotransmitters are released into the synapse by the terminal buttons

the language of the brain is ____

electrochemical

resting potential

the electrical charge that exists between the inside and the outside of the neuron

electrostatic pressure

when cells use positively and negatively charged molecules to help send electrical signals in neurons

ions

molecules in our bodies that have small electrical charges

ions with the same charge do what to each other?

push each other away

what charge do neurons have at rest?

a negative charge (-70 mv or -64 mv)

polarized

a neuron's resting state

where are positively charged ions found

in the extracellular fluid (mostly Na+)-- it actively keeps the negative charge inside of the cell

firing rate

how much cells talk

depolarized

when a cell becomes more positive

the more depolarized a cell becomes, the ____ the probability that the cell will fire an action potential

higher

propagation

when the threshold potential is met and additional ion channels along the axon, at the nodes of Ranvier, open as the action potential travels from the hillock to the axon terminals

hyperpolarization

a brief period when a neuron cannot create a new action potential because it has pushed too many positive ions out

steps of an action potential:

the threshold of excitation is met, the cell depolarizes as positive ions rush in, the cell sends an action potential down the axon, the cell kicks out positively charged ions and repolarizes, the cell kicks out too many positively charged ions and hyperpolarizes, the cell retrieves just a few positively charged ions and returns to resting

excitatory neurotransmitters

increases the probability of a neuron having an action potential

inhibitory neurotransmitters

decreases the probability that the neuron is activated

vesicles

little packages of neurotransmitters inside the terminal button

vesicles of neurotransmitters

housed in the presynaptic terminal button

presynaptic cell

has an action potential and releases neurotransmitters into the synapse

presynaptic

the terminal button of a cell where neurotransmitters are released

postsynaptic

the site on a dendrite where neurotransmitters bind to the receptor

reuptake

when the presynaptic neuron will reabsorb the neurotransmitter

agonists

mimic the action of an endogenous

enzymatic deactivation

when the complex molecules that make up neurotransmitters are broken down so their pieces can be reused

glutamate

excitatory, learning and movement

GABA

inhibitory, learning, anxiety regulation through inhibition of neurons

acetylcholine

excitatory, learning, muscle action

dopamine

excitatory/inhibitory, learning, reward/pleasure

serotonin

excitatory/inhibitory, elevation/depression of mood

norepinephrine

excitatory/inhibitory, elevation/depression of mood

enkaphalins/endorphins

excitatory/inhibitory, regulation of pain responses

threshold of excitation

when the cell receives a signal that enough positive ions are present to create an action potential

central nervous system

neuronal network that make up the brain and spine

peripheral nervous system

consists of the nerves that connect to the CNS, sending and receiving signals from the rest of the body,

enteric nervous system

complex network of neurons that helps the brain communicate with the gastrointestinal tract, often called the "second brain"

efferent cells

send motor signals from the central nervous system to the body

afferent cells

receive sensory signals from the environment and send them to the spine and brain

somatic nervous system

portion of the nervous system that controls the head, torso, and limbs. ex) taking certain paths, speeding up, slowing down, jumping, rolling

autonomic nervous system

automatic and involuntary movements. ex) blinking, heart beating, standing up and walking

sympathetic nervous system

in charge of preparing for action and expanding energy. ex) pupils dilate, the heart begins to pump blood faster, lungs expand to absorb more energy

parasympathetic nervous system

resting and recovering. ex) heart rate and respiration slowing down, storing energy for later

the enteric system is the location of a significant portion of the body's _____

neurotransmitters

the gut-brain axis is _____ because the system can send and receive signals from the CNS to the ENS and back again

bidirectional

gut-brain axis

pathways that the ENS uses to communicate with the CNS

signals generated in the gastrointestinal tract reach the brain via the ____

axon of the vagus nerve

the most protected organs in the body are a part of what system?

the central nervous system

cerebrospinal fluid (CSF)

fluid which helps to insulate, protect and maintain buoyancy in the CNS... also responsible for delivering nutrients and removing waste

meninges

three layers of connective tissue surrounding the CNS

pia mater

layer closest to the brain

subarachnoid space

between the pia mater and the next layer, which contains the CSF

arachnoid

middle layer of the CNS composed of spindly connective tissue and resembles a spiderweb

dura mater

outermost layer of CNS, consisting of tough layers of tissue between the brain and the skull

choroid plexus

a kind of tissue found in the ventricles in the center of the brain which produces cerebrospinal fluid constantly

ventricles

sacs filled with CSF, which is why the brain is buoyancy neutral

anterior or rostral

describes structures in the front of the head

posterior or caudal

refers to the structure in the back of the head, but can sometimes also refer to things lower in the nervous system

dorsal and superior

structures toward the top of the head

ventral and inferior

refer to things lower in the brain

medial

moving more toward the middle of the body

lateral

moving toward the side, away from the midline of the body

hindbrain

most inferior and posterior portion of the brain which regulates signals associated with simple-but essential-life functions like sweating, vomiting, blood pressure regulation, and respiration

midbrain

smallest and most central portion of the brainstem-it is superior to the hindbrain and involved in many reflexive behaviors

forebrain

most superior and largest portion of the mammalian brain. it includes many structures related to complex behavior, like those related to organizing sensory information (the thalamus), explicit emotional memory (the hippocampus) and the neocortex--a structure that wraps around the top of the mammalian brain and is involved in awareness of thoughts and experiences

right brain vs. left brain

we all use both sides of our brain. aspects of human function may require one side more than the other but language is not completely localized to the left size of the brain.

corpus callosum

a thick bundle of fibers whose purpose is to connect the two hemispheres and allows them to share information, helps to make sense of crossing messages of sensory information, with the exception of olfaction (smell)

gray matter

portion of the CNS made up of dendrites, cell bodies, and unmyelinated axons

white matter

the portion of the CNS made up of axons and oligodendrocytes that myelinate the axons

hindbrain vs. forebrain behavior

simpler functions closer to the hindbrain and as we move toward the top of the head to the forebrain, functions become more complex

medulla

lowest anatomical portion of the brain and the transition point between the brain and the spinal cord. without it we could not breathe, our heart would not beat, and we would not be capable of swallowing

pons

regulates arousal (level of excitement/energy) and serves as a bridge for tracts from the upper brain to the lower brain/spinal cord-- also houses clusters of neurons that control facial expressions and eye movements

reticular activating system

network of neurons spanning the center of the medulla and pons. it helps to regulate your level of arousal and the focus of your attention

glia (nuclei, ganglia)

network of neurons in the limbic system, basal ganglia, and cerebellum designed to modify thoughts and behaviors

limbic system

large network of structures that helps to regulate hormones, emotions, and some kinds of memory

amygdala

increases electrical activity in its neurons when we are emotionally aroused. involved in aggression, fear, appetite, and responsible for the increased secretion of norepinephrine (adrenaline) in the body during our flight or fight response. plays a key role in the forming of memories of strong emotional event and acquisition of trauma responses

Hippocampus

shaped like a seahorse in the middle of the brain and contains neurons that are activated when we are forming personal memories and even the imagining new possibilities ○ Not our entire memory system, but repeatedly activating its neurons is necessary for the cataloging of new experiences ○ Relationship of the hippocampus and the amygdala to the memory of new and emotionally important events and objects is crucial to our survival

Basal ganglia

interconnected groups of neurons that modulate movement commands in the brain before they reach the spinal cord ○ They wrap closely around the side of the thalamus ○ Involved in helping us learn to make complex movements (and skills more generally) more automatic

substantia nigra

part of the basil ganglia that is a neuronal circuit where a large number of terminal buttons of these neurons secrete dopamine

Cerebellum

rhythm and timing machine. The neuronal circuits in the layers of the cerebellum are strategically connected with other parts of the brain to modify what they do, especially for movement, but also in cognitive tasks ○ Circuits in the cerebellum are set up to simultaneously receive and organize input from multiple central nervous system networks ○ Also coordinates thought and problem-solving as well as control of emotional responses by connecting with association areas of the neocortex and the hypothalamus

Thalamus

some kinds of memory, auditory information, and language processing

neocortex

the location of what we typically consider high-level processing

Humans differ greatly from other animals in two ways

1. The number of connections in the neocortex 2. the area dedicated to the frontal lobes, which govern personality, context, and decision-making

Parietal Lobe

Process information about the self and the relationship between the self and the space around "you."

somatosensory cortex

in the parietal lobe-- the portion of the brain that does the heaviest lifting when it comes to integrating the skin senses: touch, pain, and temperature

upper part of the parietal lobe

involved in working memory, spatial orientation, and attention, especially regarding the area near the hands

The lower part (the inferior parietal lobule)

involved in tasks as varied as language and mathematics: damage to the area appears to cause all sorts of problems with physically and mentally manipulating things, and may lead to deficits in reading, writing, and arithmetic

Wernicke's area

left temporal lobe-- important area for the processing of language

Frontal Lobe

Decision-making and movement

prefrontal cortex

receives input from all parts of the cerebral cortex--helps us decide when, why, and how we do things-- also contributes to our personality and where we integrate a number of memories and emotions

Phineas Gage

He was impaled with a metal rod through his frontal lobe and his personality changed drastically. Since then, scientific research has provided significant and convincing evidence that the prefrontal cortex is involved in decision-making, morality, and facets of what we call personality

Occipital Lobe

- Processing and interpreting visual information from the sensory neurons in the eyes

Dorsolateral prefrontal cortex

controls working memory

Primary motor cortex

sends efferent commands for voluntary movements

Somatosensory cortex

receives afferent signals about the state of the body

Ventromedial prefrontal cortex

regulates fear-based behavior

what causes the wrinkles in the brain

the gyri (small bumps), sulci (small grooves), and fissures (large spaces between lobes)-- allows us to fit more into a smaller space

association cortex

next to the primary lobes and contributes in further processing information, helping to integrate it with other sensory information

how do scientists study the nervous system

• Scientists change how they speak to each other through manipulating chemical messages, the electrical activity, or measuring changes in neural behavior

Lesions, Case Studies, Psychosurgery

- studying people who naturally experience brain damage due to accidents, strokes, illness, or tumors, and observational in nature

Magnetic Resonance Imaging (MRI)

- Uses different frequencies to understand different tissue types in the brain - You can look at different sizes of different parts of the brain and look at anything that looks off

Positron Emission Tomography (PET scans)

- Looks at brain function, radioactive tracer is injected into you and it sticks to certain things so when you are put into a PET scanner, you can see what parts of the brain are having blood or glucose delivered when in a certain cognitive state or doing a certain cognitive task - Shows what is active overall during a particular moment/task

fMRI: The Brain in Action

- Similar to PET but you often don’t need an injection - Measures blood flow, the deoxygenation of blood flow. - When there is brain activity in certain parts of the brain there is an increase of blood which can be measured in numbers - Can help understand functionality--> what parts of the brain are used correlationally

Single-Unit Recording

• Microscopic electrode is placed close to (sometimes inside of) a single neuron to measure its individual firing rate • Considered invasive because it is an electrode directly inserted into the brain Typically used experimentally with non-human animals

Electroencephalography (EEG)

- Wires that connect on top of our head, measuring the electrical activities that travel to the surface of our brains - Cleverly analyze the waves that show up on a screen to see what type of cognitive state people in/cognitive processes are being used

Transcranial Magnetic Stimulation (TMS): The "Virtual Lesion" Tool

Strong magnets that can alter neurofunction. a noninvasive, outpatient procedure that uses magnetic fields to stimulate nerve cells in the brain. TMS Current Flow: changes the flow of the brain activity/networks that are being impacted

Pharmacological Perturbations

• Administering drugs allows for a casual inference

Quasi-Brain Perturbation Approaches

Technique to measure natural manipulations or changes of brain activity in different people Lesions, development, aging, disease

Brain Perturbation Approach

Technique to manipulate or change brain activity in different people or under different mental states. Growing in popularity, but not emphasize. Can infer causality (to some extent) which is a pro

Functional Near-Infrared Spectroscopy (FNIRS)

- Method: Light - Purpose: Portably detect small to large functional changes - Pro: Can be used on people with mental implants and portable - Cons: Spatial resolution not as good as fMRI

phrenology

studying bumps on the head and relating these to abilities and personalities

modern view

complex behavior is the result of a conversation between many brain parts, not one-to-one mapping