Neurons and the nervous systems October 2010
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