Behavioral Neuroscience

Vertebrateneurons depend almost entirely on

glucose

In his studies of infant brains, Santiago Ramón y Cajal demonstrated that

nerve cells remain separate not together

Which cell structure performs the activities that provide cells with energy?

performs metabolic activities and provides energy that the cells require

mitochondrion

Which cell structure synthesizes the substances used for building materials by the cell?

ribosomes

protein mediated process that pumps chemicals into the brain

Active Transport

A motor neuron receives excitation through its

dendrites

Which structure conveys an impulse toward other neurons, an organ, or a muscle?

an axon

what are the tiny cells that act as part of the immune system, removing viruses, and fungi from the brain?

They proliferate after brain damage, removing dead or damaged

neurons (Brown & Neher, 2014)

• They also contribute to learning by removing the weakest synapses

microglial cells

Which type of glial cells both take up and re-release the ions and transmitters released by axons?

Wraps around the synaptic terminal to help synchronize closely related neurons

• Responsible for dilating blood vessels to bring more nutrients

into brain areas with heightened activity

astrocytes

Which type of glial cell builds myelin sheaths in the periphery of the body?

Guide the migration of neurons and their axons and

dendrites during embryonic development

• When embryological development finishes, most radial glia

differentiate into neurons

• Smaller number differentiate into astrocytes and

oligodendrocytes

radial glia

What substance is passed along the blood-brain barrier through active transport?

glucose

The slightly negative electrical potential of the inside of a resting neuron relative to the outside is called the

resting potential

The concentration gradient

When there is more salt on the outside than the inside of a neuron, and there is more potassium on the inside than the outside of the neuron.

What prevents the salt from getting back into the membrane once it is pushed out by the sodium-potassium pump?

Sodium (+), potassium (+),

calcium (+2), & chloride (-) pass

through ion channels in the

membrane

selective permeability

What happens at the peak of the action potential?

the sodium channels close

The permeability of the proteins that allow sodium and potassium to cross a neuron's membrane depends on the

voltage difference across the membrane

Transmission of the action potential down an axon is called ____.

propagation

what is the jumping of action potential from node to node called?

saltatory conduction

what type of neurons lack axons?

local neurons

Mr. Garcia has been diagnosed with Alzheimer's disease. What type of cells, that form the lining of blood vessels, will shrink, thereby allowing harmful chemicals to enter his brain?

endothelial cells

The human nervous system includes two kinds of

cells

neurons and glia

neurons: send and transmit information to other cells

glia: support neurons and serve many different functions

what separates the inside of the cell from the outside environment

the membrane

This cell structure contains the chromosomes

nucleus

Network of thin tubes that transports newly synthesized proteins to their location

Endoplasmic reticulum

Has its soma in the spinal cord

• Receives excitation from other neurons

• Conducts impulses along its axon to a muscle

Motor Neuron

Specialized at one end to be highly sensitive

to a particular type of stimulation (touch,

light, sound, etc.)

• Sensory neurons towards the brain and the

spinal cord

Sensory neuron

The greater the surface area of the dendrite, the more _________

information it can receive

CONTAINS THE NUCLEUS, MITOCHONDRIA, AND RIBOSOMES

RESPONSIBLE FOR THE METABOLIC WORK OF THE NEURON

IN MANY NEURONS, IT IS COVERED WITH SYNAPSES

ON ITS SURFACE

soma/cell body

_______________ are fatty
insulation that helps increase
speed of the nerve impulse
across the axon

Myelin sheaths

Myelin sheaths are interrupted

by nodes of that

help the impulse skip parts of

the axon

nodes of Ranvier

end points of an axon release chemicals to communicate with other neurons

presynaptic terminals

Difference between afferent and efferent neurons

Afferent brings information into a structure

Efferent carries information away from a structure

Afferent = in

Efferent = out

Interneurons or intrinsic neurons

those

whose dendrites and axons are completely

contained within a single structure

Ex: an intrinsic neuron in thalamus might

have all it’s components within thalamus

S.A.M.E between motor and sensory neurons and efferent and afferent

Sensory = afferent (sensing inwards)

Motor = Efferent (movement outwards and action)

oligodendrocytes and schwaan cells

Build the myelin sheaths that surround and

insulate certain vertebrate axons.

• They also supply an axon with nutrients

• Oligodendrocytes act in the spinal cord

and brain (central nervous system)

• Schwann Cells act in the peripheral

nervous system

electrical message that is

transmitted down the axon of a neuron

It does not travel directly down the axon, but is regenerated at

points along the axon so that it is not weakened

nerve impulse

The speed of nerve impulses ranges from less
than ________ to ____________.

1 meter/second to 100 meters/second

Polarization

A difference between the electrical charge inside and outside of the cell

state of the

neuron prior to the sending of a nerve

impulse

The inside of the membrane is slightly

negative with respect to the outside

(approximately -70 millivolts)

resting potential

When the membrane is at rest:

Sodium channels are closed
• Potassium channels are partially open allowing the slow passage of
potassium

a protein complex continually pumps three sodium ions out of the cells while drawing

two potassium ions into the cell

• Helps to maintain the electrical gradient

• Uses active transport (requires ATP)

sodium-potassium pump

difference in electrical charge between the inside and outside of the cell

sodium and potassium

electrical gradient

difference in distribution of ions between the inside and the outside of the membrane

concentration gradient

When the cell is at rest, are sodium ions concentrated more
inside or outside?

it is more concentrated outside

When the cell is at rest, what drives potassium ions out of the

cell?

a) Concentration gradient

b) Electrical gradient

concentration gradient

-everything else is into the cell

hyperpolarization vs depolarization

hyperpolarization: increasing the polarization (-70 mv)

depolarization: decreasing the polarization to 0 (action potential is a rapid depolarization of a neuron)

Voltage-gated channels

proteins on the membrane that allow sodium and potassium to cross in and out of cells

Na⁺ channels open → Na⁺

rushes in

• Membrane reaches about +30

mV → Na⁺ channels close

• K⁺ channels begin opening

depolarization

• K⁺ channels fully open → K⁺

rushes out

• Membrane potential becomes

negative again

• Na⁺/K⁺ pump moves 3 Na⁺ out

+ 2 K⁺ in

repolarization

• K⁺ channels remain open

briefly → membrane reaches

about –80 mV

• K⁺ channels close

• Na⁺/K⁺ pump and leak

channels restore resting

potential to –70 mV

Hyperpolarization

Specialized gap between neurons

Neurons communicate by transmitting
chemicals at this junction

was coined by Charles Scott

synapse

automatic muscular

responses to stimuli

Reflexes

circuits from sensory

neuron to muscle response

Example

Leg flexion reflex: sensory neuron

interneuron motor neuron

 muscle

Reflex arc

Sherrington’s observations

1. Reflexes are slower than conduction along an axon

2. Several weak stimuli present at slightly different times

(temporal summation) or slightly different locations (spatial

summation) produce a stronger reflex than a single

stimulus

3. As one set of muscles becomes excited, another set

relaxes

Graded Potential

- A short-lived, localized change in

a neuron's membrane potential

- The strength of the electrical

change depends directly on the

size of the stimulus

Presynaptic neuron

neuron that delivers the

synaptic transmission

Postsynaptic neuron

neuron that receives
the message

graded

potential that decays over time and space (occurs

when Na+ enters the post synaptic neurons)

•The cumulative effect of this is the basis for
temporal and spatial summation

Excitatory Postsynaptic potential (EPSP)

How does EPSP differ from an action potential?

Several small stimuli in a similar location produce a reflex even when a

single stimulus does not

Spatial summation

Inhibitory Postsynaptic Potential (IPSP)

The temporary hyperpolarization of a membrane

• Occurs when synaptic input selectively opens the gates

for positively charged potassium ions to leave the cell,

or negatively charged chloride ions to enter the cells

The cell becomes extra negatively charged, making
excitation harder

One interneuron in the spinal cord

sent an excitatory message to flex

the bicep and another interneuron

sends an inhibitory message to

relax the tricep

inhibitory synapses

Spontaneous firing rate

The periodic production of action potentials

despite synaptic input

EPSPs increase the number of action

potentials above the spontaneous firing rate

IPSPs decrease the number of action

potentials below the spontaneous firing rate

If a neuron receives an Excitatory

Postsynaptic Potential (EPSP), will an

action potential/nerve impulse occur?

It depends. An excitatory potential does not equal action potential

but EPSPs make it more likely to fire

Otto Loewi’s experiment

Transmission

through chemicals

• Stimulating one nerve inhibited

heart rate

• Stimulating a different

nerve increased heart rate

• Realized that he was collecting

and transferring chemicals, not

loose electricity

Nicola just burned her finger on a hot pan. What is the circuit from sensory neurons to muscle response called that transmitted the message that she should remove her finger from the pan?

reflex arc

Sherrington inferred the presence of a gap between neurons based on ____.

the slower-than-predicted speed of conduction along an axon

What term is used for the cumulative effect of repeated stimulation over a brief period?

temporal summation

The temporary hyperpolarization of a membrane is a(n) ____.

Inhibitory post synaptic potential

What term describes periodic production of action potentials, even without synaptic input?

spontaneous firing

two neurons (A and B) stimulate a third neuron (X). Neither neuron A nor B can stimulate neuron X on its own, but, in combination, they can excite neuron X. This demonstrates ____.

spatial summation

when multiple EPSPs and/or IPSPs combine together to determine whether a neuron reaches threshold and fires an action potential.

summation