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Brain & Behavior

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Goals for Lecture & Readings

• Understand the mechanisms of neural communication

• Understand the form and function of the nervous system

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Phineas Gage

• 1848• Railway worker• Tamping iron blew

through his head• Memory and movement

intact, could learn new things

• But, personality changed

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Phineas Gage

• 1980s• Computer modelling

shows path of rod• Damaged ventromedial

frontal lobe• Brain region linked to

personality

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“Biopsychology”

• Biological approach to the study of psychology

• Various approaches to understand links between nervous system and behavior

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Characteristics of Biopsychology

• Humans & nonhumans subjects

• Experiments and case studies

• Basic and applied research

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Divisions of Biopsychology

1. Physiological Psychology• Manipulate nervous system (surgery,

chemicals); theories of neural control of behavior

2. Psychopharmacology• Effects of drugs on neural activity and

behavior

3. Neuropsychology• Study behavioral deficits produced by brain

damage; often applied

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Divisions of Biopsychology

4. Psychophysiology

• Record physiological responses to understand relation between physiology and psychology

5. Comparative Psychology

• Behavior of different species; focus on genetics, evolution, function

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Building Blocks of Nervous System

• Neurons• Specialized nerve cells• Send/receive nerve impulses• Sensory, motor, interneurons

• Neurons have a right-hand man, called glial cells• hold neurons in place and provide

nutrients• Outnumber neurons 10:1

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Neurons

• Three basic parts:• Cell body (soma)

• Metabolic centre, genetic material, etc…

• Dendrites• Specialized fibres for receiving info

• Axon • Conducts messages away from cell

body

11Also, Node of Ranvier Terminal buttons

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Neurons

• Neuron fires when stimulated– Heat– Light– Pressure– Other neurons

• The impulse is called an action potential

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Electrical Activity of a Resting Neuron

• Membrane Potential:• Difference in electrical charge between

inside and outside of cell• Resting Potential:

• -70 mV• Lots of Na(+) ions outside cell• Lots of protein(-) molecules inside cell

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When a Neuron is Stimulated…

• Stimulation causes distribution of particles to change

• Na(+) flows in• Attracted to

protein(-)• Inside now (+)

relative to outside

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Neural Conduction• Action Potential:

• Massive, brief reversal of membrane potential from –70 to +50 mV

• After an action potential, neuron has to recharge, so to speak• K(+) pumped out of cell, (-) charge

restored• Refractory period – neuron cannot fire

again during this process

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Myelinated Axons

• Myelin is fatty tissue• Faster conduction• Action potential

“jump” from one Node of Ranvier to the next

• Multiple Sclerosis – myelin sheath destroyed

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From One Neuron to the Next

• Synapse:• The site of adjacent neurons• “Synapse” - Greek word for “gap”

• (Every mall in Athens has a store called “The Synapse”)

• Action potentials at terminal buttons cause release of chemical neurotransmitters

• Neurotransmitters bind to sites on adjacent neurons and thereby induce electrochemical changes in them

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Neurotransmitters

• When they bind to an adjacent neuron, they cause chemical reactions

• Excitatory neurotransmitters

• Cause Na(+) to enter cell

• Makes action potential more likely

• Makes it more likely the cell will send signals to other neurons

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Neurotransmitters

• Inhibitory neurotransmitters

• May cause K(+) to leave the cell, or Chloride(-) to enter

• This makes an action potential less likely

• makes it less likely the cell will send signals to other neurons

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Some Neurotransmitters

• Acetylcholine

• Excitatory at synapses involved in memory and movements

• Dopamine

• Excitatory; movement, emotional arousal

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Effects of Drugs

• Drugs affect behavior and thought by influencing the activity of neurons

• Agonists• Mimic a particular neurotransmitter• Increase activity of neurotransmitter

• Antagonists• Inhibits activity of a neurotransmitter

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Effects of Drugs

• Nicotine is an agonist for Dopamine• Reward and pleasure

• Amphetamines and Cocaine: agonists for Dopamine and Norepinephrine• Reward, pleasure, arousal

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Major Divisions of Nervous System

• Central Nervous System (CNS):• Brain• Spinal cord

• Peripheral Nervous System (PNS):• Somatic Nervous System• Autonomic Nervous

System

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Peripheral Nervous System

• Somatic Nervous System:

• Interacts with external environment

• Sensory info from receptors (in skin, joints, eyes, ears, etc.) to CNS

• Signals sent back from CNS to skeletal muscles

• Deals largely with voluntary actions

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Peripheral Nervous System

• Autonomic Nervous System:• Involved in regulation of internal

environment• Deals largely with involuntary functions• Signals from organs to CNS• Signals from CNS to organs

• Sympathetic nerves• Prepare for action

• Parasympathetic nerves• Conserve energy

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Central Nervous System

• Spinal Cord• Highway for most nerves• H-shaped core of gray matter

• Cell bodies, unmyelinated interneurons

• Surrounding white matter• Ascending & descending myelinated

axons

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The Brain

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The Brain

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One More Brain Diagram

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EEG

Measures electrical activity

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CAT Scan

Computerized Axial Tomography

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PET Scan

Positron Emission Tomography

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MRI

Magnetic ResonanceImaging

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The Brain, Function & Form

• Brainstem

• Medulla:• Tracts that carry signals between

brain and rest of body

• Reticular formation:• Involved in sleep, attention,

movement, and various autonomic functions

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The Brain, Function & Form

• Cerebellum

• “Little brain”

• Walking

• Balance

• Timing and coordination of movements

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The Brain, Function & Form

• Thalamus• Sensory relay station• Info from sensory receptors processed

and sent to sensory cortex

• Basal Ganglia• Surrounds thalamus• Deliberate movements• Parkinson’s disease

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The Brain, Function & Form

• Limbic System

• Hippocampus

• memory

• Amygdala

• emotion

• Hypothalamus

• Motivation; biological drives

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The Brain

• Cerebral Cortex:• Outermost layer of brain• Wrinkled• Many connections to other areas• Frontal cortex complex cognition• Temporal auditory, language• Occipital visual• Parietal sensory stuff

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