Psychology as a Nat Sci Chapter 4 Pt. 1

Brain

Brain

"at a microscopic level it is the most dynamic organ of the body"

86

"The human brain contains roughly __ billion nerve cells"

Neurons

Nerves cells are also called

Through Synapses

How do neurons communicate with each other?

Neurons

Their collective activity monitors internal and external environments

Neurons

"creates all of our mental experiences, and controls all of our behavior"

central nervous system

"The brain and spinal cord (which extends from the brain down through the bones of the spinal column) make up the _________, which integrates and synthesizes neural information."

nerves

Extensions from the nervous system are called

nerves

make up the peripheral nervous system

neuron

a single cell in the nervous system

nerve

is a bundle of many neurons—or, more precisely, a bundle consisting of the axons

nerves

connect the central nervous system to the body’s sensory organs, muscles, and glands

sensory neurons

bundled together to form nerves, carry information from sensory organs (including the eyes, ears, nose, tongue, and skin) into the central nervous system

motor neurons

also bundled into nerves, carry messages out from the central nervous system to operate muscles and glands.

interneurons

exist entirely within the central nervous system and carry messages from one set of neurons to another. Interneurons collect, organize, and integrate messages from various sources. They vastly outnumber the other two types.

cell body

the widest part of the neuron. It contains the cell nucleus and other basic machinery common to all bodily cells

Dendrites

are thin, tubelike extensions that branch extensively and function to receive input to the neuron

motor neurons and interneurons

In what neurons do the dendrites extend directly off the cell body and generally branch out from it, forming bushlike structures?

sensory neurons

In what neuron do dendrites branch out from one end of the axon, rather than directly from the cell body

axon

The ______ is another thin, tubelike extension from the cell body and its job is to carry messages to other neurons

axon terminal

each branch ends with a small swelling called an

Axon terminals

are designed to release chemical transmitter molecules onto other neurons or, in the case of motor neurons, onto muscle cells or glandular cells

myelin sheath

axons of some neurons are surrounded by a casing called a

glial cells

Myelin is a fatty substance produced by supportive brain cells called

action potentials

Neurons exert their influence on other neurons and muscle cells by firing off all-or-none impulses called

motor neurons and interneurons

"In which neurons are action potentials triggered at the junction between the cell body and the axon"

Sensory neurons

Which neurons are triggered at the dendritic end of the axon and travel through or past the cell body to the axon terminals

action potential

Which term when regarding chapter 4 is described as all or none because they either occur or don’t

action potential

" Each of these produced by a given neuron is the same strength as any other produced by that neuron, and each retains its full strength all the way down the axon."

a neuron

"can varying degrees of intensity in its message by varying its rate of producing action potentials."

cell membrane

is a porous “skin” that permits certain chemicals to flow into and out of the cell, while blocking others.

intracellular fluid

The tube is filled with a solution of water and dissolved chemicals called intracellular fluid

extracellular fluid

It is bathed on the outside by another solution of water and dissolved chemicals called

soluble protein molecules (A−)

have negative charges and exist only in the intracellular fluid

potassium ions (K+)

are more concentrated in the intracellular than the extracellular fluid

sodium ions (Na+) and chloride ions (Cl−)

are more concentrated in the extracellular than the intracellular fluid

−70 millivolt

This charge across the membrane of an inactive neuron is

resting potential

This charge across the membrane of an inactive neuron is called its

Action Potential

Is Elicited by a Brief Change in Membrane Permeability

action potential

is a wave of change in the electrical charge across the axon membrane

depolarization phase

The sudden shift constitutes which phase of the action potential

the repolarization phase

when enough positively charged potassium ions move out of the cell to reestablish the original resting potential. This constitutes which phase of the action potential

cell’s threshold

The axon’s membrane is constructed so that its sodium channels open in response to depolarization to some critical value; this triggers an action potential. This critical value (e.g., −65 millivolts inside, compared with a resting potential of −70 millivolts inside) is called the

axon’s diameter

The speed at which an action potential moves down an axon is affected by the

large diameter axons

present less resistance to the spread of electric currents and therefore conduct action potentials faster than thin ones

myelin sheath

A factor that speeds up the rate of conduction in many axons is the

myelin

What protects and insulates axons, speeding the rate at which nervous impulses can be sent and reducing interference from other neurons?

100 meters per second

The thickest and most thoroughly myelinated axons in the nervous system can conduct action potentials at a velocity of about

1 or 2 meters per second

Very thin axons without myelin sheaths, in contrast, may conduct at rates as slow as

myelination

"The process of developing myelin, called _________, begins before a child is born but is not complete until some time in adulthood, during the third decade of life or beyond."

sensory system

"Neurons in which system are the first to be myelinated"

associative areas

"The last areas to become fully myelinated are the __________ in the frontal cortex—the “thinking” area of the brain"

synapse

The junction between each axon terminal and the cell body or dendrite of the receiving neuron is called a

neurotransmitter

When an action potential reaches an axon terminal, it causes the terminal to release packets of a chemical substance, called a

Neurotransmitters

are chemicals released by one neuron at the axon terminal to influence the action of an adjacent neuron

dopamine

"Influences movement and reward-motivated behavior"

acetylcholine

Is released at neuromuscular junction and associated with the activation of muscles.

acetylcholine

Within the brain, _______ functions to alter the way other brain structures process information "

serotonin

Influences many behaviors

serotonin

includes sleep, mood, and is implicated in depression

gamma-aminobutyric acid

As referred to as GABA

gamma-aminobutyric acid

"An inhibitory neurotransmitter, which weakens or slows down signals"

gamma-aminobutyric acid

plays an important role in anxiety

too much or too little

"Individuals who have___________ of some of these neurotransmitters may experience physical and psychological disorders."

Dopamine

Low levels of this neurotransmitter are associated with parkinson’s disease

Schizophrenia

High levels of this neurotransmitter are associated with

synaptic cleft

"A very narrow gap, called the , separates the axon terminal from the membrane of the cell that it influences. "

presynaptic membrane

membrane of the axon terminal that abuts the cleft is the

postsynaptic membrane

that of the cell on the other side of the cleft is the

excitatory synapse

"At an ________ , the transmitter opens sodium (Na+) channels in the postsynaptic membrane."

inhibitory synapse

"At an ___________, the transmitter opens either chloride (Cl–) channels or potassium (K+) channels."

hyperpolarization

tends to decrease the rate of action potentials triggered in that neuron

depolarization, hyperpolarization

"At each excitatory synapse the transmitter causes a slight ______, and at each inhibitory synapse the transmitter causes a slight ______."

neurogenesis

"The process of creating new neurons is referred to as _________(literally, birth of neurons), and it occurs during the first 20 weeks after conception"

differentiation

"Beginning about 20 weeks after conception, neurons enter the last stage of their development, termed

differentiation

This doesn’t stop at birth

losses of them

Beginning late in the prenatal period and continuing after birth, the primary changes in brain development are not in growth of neurons and synapses, but rather in

synapses

40 to 50% of these _______ will be lost, or pruned

apoptosis

neurons themselves also die in a process, known as selective cell death, or

mirror neurons

"Neuroscientists have discovered that the brains of human beings and of at least some nonhuman primates contain organized systems of neurons that seem to be well designed to foster social learning. These are referred to as ________ because they are believed to help us behave in ways that mirror (mimic) what we observe or experience."

Mirror Neurons

"are active both when a subject engages in a behavior, such as grasping a piece of food, and when the subject observes someone else perform a similar action."

mirror neurons

Are found in different parts of the monkey and human cerebral cortex

resting potential

is an electrical imbalance

analyzing electrical brain activity

EEGs, ERPs, MEG, TMS, tDCS are all used for

Electroencephalography (EEGs)

"Recording of the electrical activity of the cortex using multiple scalp electrodes."

Event Related Potentials (ERPs)

An encephalographic measure of local changes in the brain electrical activity in response to specific stimuli.

Magnetoencephalography

"Detects the magnetic field changes produced by the cortical electrical activity."

Transcranial Magnetic Stimulation (TMS)

The localization of a brain function by temporarily blocking the electrical activity of an area by exposure to a magnetic field

Transcranial Direct Current Stimulation (tDCS)

The localization of brain function by temporarily stimulating electrical activity directing weak electrical currents to specific areas of the brain

analyzing anatomical structure

MRIs and DTIs are used for

Magnetic Resonance Imaging (MRI)

High-resolution image of brain anatomy measuring energy changes of brain tissue after an exposure to a strong magnetic field

Diffusion Tension Imaging (DTI)

Measures the diffusion of water in the brain tissue, permitting the imaging of the white matter tracts

analyzing functional metabolic activity

PETs and fMRIs are used for

Positron Emission Tomography (PET)

Assesses the metabolic activity of glucose or oxygen in the brain by following the path of a radioactive tracer injected intravenously

Functional Magnetic Resonance Imaging (fMRI)

Assesses indirectly the metabolic activity of the brain through measuring the changes of the blood flow

TMS

"Although ___ is usually used to study the effects of temporary inactivation of a brain area, it can also be used to study the effects of temporary activation"

TMS

"___ can be used to produce a map showing the functional connections between specific areas within movement-control portions of the cerebral cortex and the muscles controlled by those areas."

transcranial direct current stimulation (tDCS)

" a technique called _________ involves directing weak electrical currents to specific areas of the brain; it has been found to alter perceptual, cognitive, and motor functioning."

EEG

" Patterns in the ___ can be used as an index of whether a person is highly aroused, or relaxed, or asleep and can be used to identify various stages of sleep."

positron emission tomography (PET)

The first of these neuroimaging methods (developed in the 1970s) was