Transcript Communication in the Nervous System

Chapter 3: The
Biological Bases of
Behavior
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Communication in the Nervous
System
• Hardware:
1) Glia: structural support and insulation (Glue)
2) Neurons: communication (receives, integrate & transmits)
Dendrites – receive message
Soma – cell body
Axon – transmit message
Myelin sheath- speeds up transmission
Terminal Button- end of axon, release
message
Synapse- gap between Button & Dendrite
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Figure 3.1 Structure of the
neuron
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The Neural Impulse
1) Resting Potential- Neuron is Ready
› -70 millivolts
2) Action Potential- Neuron Fires (down axon)
› Sodium + ions flow in, Potassium - ions flow out
3) Refractory Period- Neuron is Recharging
› The minimum time after firing, cannot fire until charged
All or None Principle- Neuron fires at the
same speed whether it was strong or
weak. Either fires or doesn't.
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Figure 3.2 The neural impulse
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The Synapse: Chemicals as
Signal Couriers
• Neurotransmitters: is the chemical message
that transmit info from one neuron to another.
– Presynaptic neuron (Terminal Button)
• Synaptic vesicles: Contain Neurotransmitters
– Postsynaptic neuron (Dendrites)
• Receptor sites: Located on dendrites, each receptor
site receive specific neurotransmitters
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When a Neurotransmitter Binds:
The Postsynaptic Potential
Postsynaptic Potential (PSP)
Changes the probability of the postsynaptic neuron firing
– Excitatory PSP: Positive voltage shift, increase firing
– Inhibitory PSP: Negative voltage shift, decrease firing
• Reuptake: All the excess neurotransmitters that
don’t bind to a receptor site get sucked up into the
terminal button
• Synaptic connections
– Elimination and creation
– Synaptic pruning
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Figure 3.4 Overview of synaptic
transmission
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Figure 3.5 Synaptic pruning
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Types of Neurons
• Sensory Neurons
– Nerves that carry information to the central
nervous system Connect the sense organs to
the brain and spinal cord
• Motor Neurons
– Nerves that carry information from the central nervous
system Carries messages from the brain and spinal
cord to other parts of your body
• Inter Neurons
– Nerve cells in the brain and spinal cord responsible
for processing information related to sensory input
and motor output
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The Neural Chain
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Neurotransmitters
Specific neurotransmitters work at specific
synapses
– Lock and key mechanism
– (15 – 20) neurotransmitters known at present
• Agonist – mimics neurotransmitter action
• Antagonist – opposes action of a
neurotransmitter
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Table 3.1 Common Neurotransmitters
and Some of their Functions
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Neurotransmitter Helpful Hints
• ACh• DA-
•
•
•
•
AAM
Sell Dope at the Park (Parkinson)
Movement and Pleasure
NENorma PMS (Mood & Arousal)
Serotonin- Sleep/Wakefulness,
Eating/Aggression (Ninja
Turtles, SEWA)
GABA- Inhibitor
Endorphins- Natural pain reliever
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Organization of the Nervous System
• Central nervous system (CNS)
 Brain & Spine (It is the center)
– Hindbrain. Back bottom
– Midbrain. Core
– Forebrain. Outer
• Peripheral nervous system (PNS)
 Bones. Organs. Muscles. (Is everything else)
– Somatic nervous system (SNS) voluntary
• Afferent = (In) toward the CNS
• Efferent = (Out) away from the CNS
– Autonomic nervous system (ANS) automatic
• Sympathetic (Fight or Flight)
• Parasympathetic (Calming)
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Figure 3.6 Organization of the
human nervous system
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Figure 3.7 The central and
peripheral nervous systems
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Figure 3.8 The autonomic nervous
system (ANS)
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Studying the Brain: Research Methods
•
•
•
•
Electroencephalography (EEG). Brain Waves
Damage studies/lesioning
Electrical stimulation (ESB). Mapping out the Brain
Brain Imaging –
– CT Scan (computerized tomography). X-Ray of brain structure
– PET Scan (positron emission tomography). Brain function,
shows activity in the brain with chemicals
– MRI Scan (magnetic resonance imaging). 3D pictures
– fMRI Scan (functional magnetic resonance imaging).
Additional oxygen & blood flow. Structure & function
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Brain Regions and Functions
• Hindbrain:
– Medulla. vital functions
– Pons. sleep & arousal
– Cerebellum. movement & balance
• Midbrain: (Plug into hard drive)
– Reticular Formation. sensory functions
• Forebrain:
– Thalamus. All senses except smell
– Hypothalamus. 4 “F’s”
– Limbic system
• Hippocampus. Learning & Memory (Hip to the campus)
• Amygdala. Emotion (Amy is emotional)
– Cerebrum. Outer layer of brain (largest)
– Cerebral cortex. Wrinkles in the outer layer 1.5 sqf
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The Cerebrum:
Two Hemispheres, Four Lobes
• Cerebral Hemispheres – two specialized
halves connected by the corpus collosum
– Corpus Collosum- connects the hemispheres
– Left hemisphere – verbal processing: language,
speech, reading, writing
– Right hemisphere – nonverbal processing:
spatial, musical, visual recognition
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The Cerebrum:
Two Hemispheres, Four Lobes
• Four Lobes:
– Occipital – vision
– Parietal – somatosensory/motor cortex
– Temporal - auditory
– Frontal – movement, executive control
systems
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Figure 3.16 Structures and areas in the
human brain
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Figure 3.18 The cerebral hemispheres and the
corpus callosum
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Figure 3.19 The cerebral cortex in
humans
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Figure 3.20 The primary motor cortex
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Figure 3.21 Language processing in the brain
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The Endocrine System:
Hormones
 Hormones – Chemical messengers
produced by the endocrine glands and
circulated in the blood
 Similar to neurotransmitters in that they
are also messengers
 Slower communication system, but with
longer lasting effects
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The Endocrine System:
Glands
• Endocrine glands
– Pituitary – “master gland,” growth hormone
– Thyroid – helps regulate the energy level in
the body metabolic rate
– Adrenal – help to arouse the body in times of
stress, Located above the kidneys, Release
epinephrine (adrenaline) and norepinephrine
– Pancreas – regulates the level of sugar in the
blood
– Gonads – sex hormones, Ovaries (females)
and testes (males) influence emotion and
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physical development.
Genes and Behavior:
The Field of Behavioral Genetics
• Behavioral genetics = the study of the
influence of genetic factors on behavioral traits
• Chromosomes – strands of DNA carrying
genetic information
– Human cells contain 46 chromosomes in pairs
(sex-cells – 23 single)
– Each chromosome – thousands of genes, in pairs
• Dominant, recessive/Homozygous,
heterozygous
• Genotype- Genetic makeup
• Phenotype- manifested in characteristics
• Polygenic Inheritance- characteristics
influenced by more than one gene
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Figure 3.25 Genetic material
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Research Methods in Behavioral
Genetics
• Family studies – does it run in the family?
• Twin studies – compare resemblance of
identical and fraternal twins on a trait
• Adoption studies – examine resemblance
between adopted children and their
biological and adoptive parents
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Figure 3.27 Genetic relatedness
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Figure 3.28 Family studies of risk
for schizophrenic disorders
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Figure 3.30 Twin studies of intelligence
and personality
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Modern Approaches to the
Nature vs. Nurture Debate
• Molecular Genetics = the study of the
biochemical bases of genetic inheritance
– Genetic mapping – locating specific genes The Human Genome Project
• Behavioral Genetics
– The interactionist model
– Richard Rose (1995) – “We inherit
dispositions, not destinies.”
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Evolutionary Psychology:
Behavior in Terms of Adaptive Significance
• Based on Darwin’s ideas of natural
selection
– Reproductive success key
• Adaptations – behavioral as well as
physical
– Fight-or-flight response
– Taste preferences
– Parental investment and mating
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