Neurons and the nervous systems

October 2010

Q1 - Parts of the neuron

• Dendrites

• Cell body

• Axon

• Axon segments

• Axon terminals

• Synapse

• Myelin sheath

How neurons work

• Neurons are cells - with walls, nucleus, etc

• Q2 - Neurons receive information

• Receive both excitatory and inhibitory messages

• Q3 The neuron exceeds threshold when

What does fire mean?

• By “firing,” the neuron transmits a signal to either the receptor of another neuron or to some other body structure (eg, muscles)

• Q4 - When neurons fire, it is “all or nothing”.

• When it “fires,” it sends neurotransmitters into the synapse (or synaptic gap) where other neurons can receive them

Neurotransmitters Q5

• They are chemical compounds that are used in the brain and the body.

• Most are associated with one or more physical or brain functions.

• Excess or deficit of certain NTs is associated with different psychological and physical diseases - schizophrenia, Parkinson’s

Q6 - An action potential

• A neuron fires!

• www.sheatech.net/axon.swf

• Refractory phase

After NTs released

• See p 57 - diagram

• Receptor sites on next neuron

• Reuptake – Q7

• Note - NTs are not used up or destroyed in the synapse

NTs you should know

• Q8 - Dopamine

• Acetylcholine (Ach)

• Q9 - Serotonin

• Norepinephrine

• Q10 - GABA

• Glutamate

• Q11 - Endorphins

Nervous system hierarchy

C….P…

A.. S…

S P

B.. SC

Q12

Kinds of neurons

• Q13 - Sensory neuron - afferent

• Motor neuron - efferent

• Q14 - Interneuron (and reflexes)

• Mirror neurons

Misc facts

• Q15 - Neural networks• Q16 - Antagonist / agonist• Q17 - Nerve - a nerve is a bundle ..• Q18 – Spinal cords • Graphic on pg 62

Endocrine system

Glands, hormones and behavior

Endocrine system

• _____ messenger system Q19

• Controlled by ____________ which is controlled by ________________

• Hormones– Q20 – norepinephrine

Controlling structures

• Hypothalamus- Q21– Controls _________________ – Produces _________________ – Other brain functions …..

• Pituitary –Q22– Produces both _________________________– Controls ______________________________

• Adrenal (“next to kidneys”) Q23– Arousal– Produces ________________________ – Fight or flight

• Pancreas Q24– Produces– Produces

• Thyroid controls ___________ Q25• Pineal - melatonin - bio rhythms Q26

Sex and the endocrine system

• Ovaries Q27

• Testes

• Primary sex characteristics

• Secondary sex characteristics

The Brain

Q28 - Brain research

• MRI

• fMRI

• CAT scan

• PET scan

• Ablation / lesion

• EEG

Brainstem – Q29

• Medulla -

• Pons -

• Reticular Formation -

Thalamus – Q30

• Thalamus - the sensory switchboard

Cerebellum – Q31

• Non-verbal

• All non-conscious

Limbic system – Q32

• Hypothalamus

• Amygdala

• Hippocampus

• Pituitary gland

Cerebral cortex

• Assume many parts of the brain are involved in most mental processes

• Temporal lobes are not the only parts involved in hearing, right brain / left brain, etc

• We will identify major functions of different parts - not necessarily all their functions, nor all the parts of the brain involved in different functions

Structure

• Glial cells - Q33

• 2 hemispheres

• Lobes – Q34

• Cortexes - motor, sensor

• Association areas

Cortexes – Q35

• Sensory cortex

• Motor cortex

Lobes – Q36

• Frontal

• Parietal

• Occipital

• Temporal

Association areas

• Q37

• Is it true that we use only 10% of our brains?

Q38 - Reading aloud - see pg 81

• Text to visual cortex as graphics• Angular gyrus interprets picture as auditory

code• Wernicke’s area interprets auditory code as

language• Broca’s area controls speech using the

motor cortex• Motor cortex controls lips, tongue, etc

Brain plasticity

• Q39

• What do we mean by plasticity?

Corpus callosum

• Q40

• How is the corpus involved in seizure treatment?

Split brains

• Q41 - HE * ART experiment

• Q42 – Who was Phineas Gage?

• Q43 - right side functions

• left side functions

Nature vs nurture

Or what the heck is heritability?

Q44 - Behavioral genetics

• The study of how genes and environment interact to affect our behavior, personality

• Heritability - the extent to which differences between groups of people can be attributed to genetics

Q45 - Genes

• Genome

• Chromosomes

• Genes

• DNA

Twins and adoptees – Q46

• Q47 - MZ’s and DZ’s - monozygotes and dizygotes

• MZ’s share 100% of genetic material• DZ’s share 50%• All siblings share 50% (on average)• Adoptees share environment with adopted

family• MZ’s and DZ’s may not share environment

Q48 - Shared environment

• Assumption is that living in the same home with same parents and same general environment will cause children to be similar

• And different from kids from another family

Shared environment

• Seems reasonable

• Except it doesn’t seem to happen

Evidence

• Similarities among MZA’s, MZ’s, DZ’s, DZA’s

• Low correlations between traits of adopted child and adopted parents

• Multiple adoptees in one family don’t become similar

• Large differences among natural siblings

Why do siblings differ?

• They are different genetically

• How “shared” is the shared environment?

• Pre-natal influences

• Birth order effects?

• Age and sex of older sibs

• Unique experiences - injury, illness

Another intelligence study

• Generally it appears that the higher the genetic relatedness, the higher the correlation of IQ scores

• Appears that IQ has a high degree of heritability

• How about schizophrenia?

• Predict:– Will both identical twins be schizophrenic?– How about fraternal twins?– Child of schizophrenic parents?– Sibling of schizophrenic?

Q49

• Once again the closer the genetic relationship, the higher concordance

• That argues for a high level of heritability - that is, we can explain the differences by genetics

• Let’s look at that IQ slide again

• Can’t we argue that the more we share environment, the closer our IQ scores will be?

Q50 - Heritability

• Some traits are more heritable than others– Physical traits show high heritability– Intelligence shows moderate heritability– Personality traits tend to show low to moderate

heritability

Caution

• Do not apply to individuals

• Do not apply to average differences between groups

• Heritability statistics can vary depending on environmental variation in a group

Here’s another way to look at it

Nature vs nurture?

• The evidence is clear - the vast majority of behaviors are influenced by the interaction both our genes and our environment

• There is now evidence that the interaction can be reciprocal – as on the epigenome

Temperament

• Q51 - Temperament

• Temperament is highly stable over a lifetime, though it may moderate over time

Evolutionary psychology

• The ultimate interaction of genes and environment.

• Mate selection as interpreted by evolutionary psychology