Anatomy of a neuron A cell body (soma)

The dendrites

The axon

Dendrite the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body

The cell body

Contains the cells Nucleus

Axon

The cells output structure

One axon per cell 2 disBnct parts

tube-like structure branches at end that connect to dendrites of other cells

Myelin sheath

White faGy casing on axon Acts as an electrical insulator Increases the speed of neural signals down the axon

Myelin Sheath

Types of neurons

Sensory Neurons

Inter- Neurons

Motor Neurons

FuncBon of a Neuron

How does a neuron funcBon?

DemonstraBon

6-7 volunteers Form a conBnuous chain by holding hands Wait for my signal 1st person Bghten the grip on the second one, 2nd on the 3rd, ..9th on the 10th

And TIME?

DemonstraBon

Now grip your neighbors shoulder Repeat the same procedure Signal-1st person starts TIME with the last person?

Shoulder-squeezing consistently faster than hand-squeezing

Why?

DemonstraBon

Shoulder-squeeze < hand-squeeze

Sensory input through hand shoulder

travel a greater distance, 2-feet (longer in the average person, to reach the brain

(Rozin & Jonides, 1997)

Neuron communicaBon

Neurons in the CNS process informaBon interpret it send commands to muscles, glands, and organs

Receive and transmit informaBon electrochemically

Neuron communicaBon

AcBon potenBals axons convey informaBon by a combinaBon of electrical and chemical processes

this combinaBon is called an ac#on poten#al signal that travels along the axon at a constant strength no maGer how far it travels

the all-or-none process its either happening or not influences receiving neuron

Neuron communicaBon

Synapses communicaBon between neurons occurs at the synapses synapses are specialized juncBons between neurons

juncBon between axon Bp of the sending neuron and the dendrite or cell body of the receiving neuron

Bny gap at this juncBon is called the synapBc gap or synapBc cle`

Synapses

Chemicals released at the synapse excite or inhibit neighboring cells, making acBon potenBals more or less likely traverse between neurons

SynapBc acBvity is crucial to brain funcBon hGp://www.youtube.com/watch?v=LT3VKAr4roo&feature=related (excitatory/inhibitory)

CommunicaBon process

AcBon potenBal travels down axon Causes neurotransmiGer to release from axon terminal

NeurotransmiGer travels across synapse Then binds with the receptors on receiving neuron

http://www.youtube.com/watch?v=90cj4NX87Yk&feature=related

NeurotransmiGers (NT) Acetylcholine (ACh)

enables muscle acBon, learning, & memory Dopamine

influences movement, learning, aGenBon and emoBon excess linked with Schizophrenia

Serotonin affects mood, hunger, sleep & arousal too liGle depression

Norepinephrine controls alertness & arousal too liGle affects mood negaBvely

Nerve cell growth

Neurons constantly grow and lose branches to dendrites and axons this growth is related to new experiences and learning

Neural Development:

A Wiring-Up process

New-Born

6 M

2 Y

Neural Development Synaptic Wiring Over The Years From a Neonate To 6 months To 2 years Of age wow1

Neural Development Synaptic Wiring Over The Years From a Neonate To 6 months To 2 years Of age wow1

Brain plasBcity

Our brains are plasBc PlasBcity

brains ability to rewire itself relocaBng informaBon processing funcBons to different brain areas and/or neural networks

the study of brain plasBcity has profound implicaBons on human learning, behavior, and mental health

QuesBon

Learning and environmental challenges someBmes produce branching in axons and dendrites of an organisms neurons. How would that affect the number of synapses?

It would increase the number of synapses.

QuesBon

If a hamster and a seven-foot-tall human step on a sharp object, which will respond faster? Why?

The hamster, because the action potential has a shorter distance to travel.

Who cares about neurons?

Affect our senses Our movements Our funcBoning

How the brain relates to mind microstructure

LocalizaBon of funcBon in the brain

CNS Methods of localizaBon

how to study the brain

Lecture on brain

Phrenology (Gall, 1819)

The theory that each brain area has a specific funcBon, with different general mental facul#es located in different parts of this brain

Mental faculBes = moral and intellectual propensiBes

Franz Galls phrenology

Franz Gall (1758 1828)

Localization of function

Wrong about

Bumps Traits

Right about

LocalizaBon

Franz Galls phrenology

LocalizaBon of funcBon

Science works this way

Phrenologists did not have scienBfic methodologies to validate their theories calipers just werent good enough measurement tools

BeGer Measuring Apparatus

In a way..

Brain locaBon and funcBoning is an oversimplificaBon

E.g., paBents with damage to Brocas area experience Brocas aphasia

But many of them can re-learn to speak coherently with therapy other parts of the brain can help out, so to speak

Wrong about

Bumps Traits

Right about

LocalizaBon

Franz Galls phrenology

LocalizaBon of funcBon

Brain localizaBon

Note that its a #useful#oversimplificaBon

as is most of science, really

Most of the processing that is now thought to occur in certain areas really does occur there, in normal cases

just not all of it, and not in all cases

The Brain & Our Body

The Nervous System

The central nervous system and the peripheral nervous system CNS consists of the brain and the spinal cord communicates with the rest of the body via the peripheral nervous system

PNS set of nerves that connects the CNS to the sensory organs, muscles and glands

Embryological development

The vertebrate nervous system forms out of a simple tube with three lumps the midbrain and hindbrain become the brainstem

the forebrain becomes the cerebral cortex and other higher structure

Brain organizaBon

Necessities

Luxuries

Basic motor programs

Sensory information

Emotion, motivation, simple judgment

Voluntary action, complex judgment, symbolic thought

Basic life functions (breathing, heartbeat)

RepeBBve movement

Sensory informaBon

EmoBon, moBvaBon, simple judgment

Voluntary acBon, complex judgment, symbolic

thought

Breathing

Brainstem = Survival

Cerebellum = Movement

Lymbic System = Border

Lymbic

System

The Forebrain

Cerebral cortex the outer covering of the forebrain its composed of gray maGer

the cell bodies of the corBcal neurons interior of the forebrain is composed of white maGer or axons of corBcal neurons

it is white because of its myelin coaBng

Lymbic System = Border

Structures of the forebrain Hypothalamus

regulates emoBonal and moBvated behavior Amygdala

an almond-shaped structure crucial for emoBonal processing

deep inside the temporal lobes Hippocampus

vital for memory processing