Biological Bases of Behavior

AP Psych – Chapter 3Biological Foundations of Behavior

Alice F. ShortHilliard Davidson High School

Chapter Preview

• Nervous System• Neurons• Brain• Endocrine System• Damage, Plasticity, and Repair• Genetics and Behavior• Biological Foundations and Health and

Wellness

Nervous System

• Neuroscience…study of the body’s electrochemical communication circuitry

• Characteristics of the nervous system– complexity • (metaphor = multitasking)

– integration– adaptability (plasticity)– electrochemical transmission

Nervous System: Pathways

• Afferent Nerves– carry information spinal cord and brain

• Efferent Nerves– carry information muscles

Nervous System: Divisions

The Two Main Divisions of the Nervous System:

• 1. Central Nervous System (CNS)– brain and spinal cord

• 2. Peripheral Nervous System (PNS)– somatic nervous system – sensory nerves

• muscular activity

– autonomic nervous system – internal organs• sympathetic nervous system – arouses• parasympathetic nervous system – calms

1. Central Nervous System

• 1. Central Nervous System (CNS)– brain and spinal cord

2. Peripheral Nervous System

• 2. Peripheral Nervous System (PNS) – composed of all the sensory and motor nerves– somatic nervous system – sensory nerves

• muscular activity– allows you to move in cases of emergency– allows you to move when you want to move

– autonomic nervous system – internal organs• sympathetic nervous system – arouses

– kicks into overdrive in cases of emergency

• parasympathetic nervous system – calms– medication techniques elicit response

Nervous System: Cells

• Neurons– information processing– about 100 billion in brain– mirror neurons (in primates) – imitating behaviors of

someone else• mimicking the movements of a coach or dancer, etc.

• Glial Cells– provide support and nutrition– carries nutrients from blood vessels neurons

Neurons: Structure

• neuron – the type of cell that is the basic unit of the nervous system – the nervous system contains over 11 billion neurons1. cell body (soma) – contains the nucleus2. dendrites – branched appendages that carry

information to the cell body3. axon – conveys information away from the cell

body4. myelin sheath – covers the axon and aids in neural

transmission

Neurons: Structure

• dendrite cell body axon

Neurons: 3 Types

Neuron – the type of cell that is the basic unit of the nervous system – the nervous system contains over 11 billion neurons

1. sensory neurons are located in the body’s sense organs (for example, the eye, ear, or nose) and send information from these organs to the brain

2. motor neurons– convey information from the nervous system to the body’s organs, glands, and muscles

3. interneurons (association neurons) transmit information from one neuron to another within the nervous system

Neural Impulse

• Axons– ions/ion channel– negatively/positively charged – semipermeable membrane– polarization

• Resting Potential– stable charge of an inactive neuron– a negative charge on the inside of the cell membrane and a positive charge

on the outside

• Action Potential– depolarization (ion channel opens)

• sodium ions flow into the membrane

– repolarization– ion exchange sweeps along length of axon– all-or-none principle – intensity of the action potential is not effected by

depolarizing and greater levels– once initiated, cannot be stopped

Transmission of Nerve Impulse

Synapses and Neurotransmitters

• Synapse / Synaptic Gap– space between sending axon’s terminal buttons and the

receiving dendrite or cell body– the neural message being delivered in a synaptic

transmission is carried across the synaptic gap by chemical substances

• Synaptic Transmission– electrical impulse is converted into a chemical signal– axon vesicle releases neurotransmitter into gap– dendrite receptor site detects neurotransmitter

© 2011 The McGraw-Hill Companies, Inc.

Synapses and Neurotransmitters

Neurotransmitters• Neurotransmitters carry information across the synaptic gap to next neuron.

(chemical)

• Acetylcholine– muscle actions, learning, memory– black widow venom ↑ Ach levels – botox (botulin) ↓ Ach levels – Alzheimer’s disease: ↓ Ach levels

• GABA – anxiety: ↓ GABA levels

• Glutamate– excitatory – learning & memory– involved in many psychological disorders

• Norepinephrine– stress and mania: ↑ norepinephrine levels– depression: ↓ norepinephrine levels– regulates sleep states in conjunction with ACh

Neurotransmitters (cont.)• Dopamine

– voluntary movement– reward anticipation– stimulant drugs: activate dopamine receptors– Parkinson’s disease: ↓ dopamine levels– schizophrenia: ↑ dopamine levels

• Serotonin– regulation of sleep, mood, attention, learning– depression: ↓ serotonin levels– prozac: ↑ serotonin levels

• Endorphins– natural opiates– mediate feelings of pleasure and pain

• Oxytocin– both a hormone and a neurotransmitter– related to onset of lactation in new mothers– related to attachment/emotional bonds

Neurotransmitters

• Note: Drugs can interfere with neurotransmitters– mimics or enhances NT effects– blocks effects of NT

Neural Networks

• interconnected pathways of nerve cells • integrate sensory input and motor output• take years to develop• a given piece of information embedded in

multiple connections between neurons

Studying the Brain

• Brain Lesioning– naturally occurring or induced

• Electrical Recording– electroencephalograph (EEG)– single-unit recording

Brain Imaging

• X-Ray• CT Scan• PET• MRI• fMRI• TMS

Areas of the Brain

1. Hindbrain2. Midbrain3. forebrain

Reminder: any part of the brain is a part of the central nervous system (CNS), which is a part of the nervous system in general

Areas of the Brain: 1. Hindbrain

• Brainstem– medulla – control breathing, regulate reflexes– pons – sleep & arousal

• Cerebellum– motor coordination

Areas of the Brain: 2. Midbrain

• Substantia Nigra – Parkinson disease

• Reticular Formation– stereotyped behavior patterns like walking– manipulates neurotransmitters

Brain: Structure and Function

Areas of the Brain: 3. Forebrain• Limbic System

– memory and emotion– amygdala

• discrimination of objects needed for survival• emotional awareness and expression

– hippocampus• formation and recall of memories

• Thalamus– relay station for much sensory information

• Basal Ganglia– coordination of voluntary movements

• Hypothalamus– eating, drinking, sexual behaviors– regulate body’s internal state – emotion, stress, reward

Cerebral Cortex

• Neocortex: outermost layer

• Four Lobes:– occipital (vision)– temporal (hearing, language processing, memory)– frontal (intelligence, personality, voluntary

muscles)– parietal (spatial location, attention, motor control)

Cerebral Cortex

Are Brains Wired to Recognize Faces?

• prosopagnosia• fusiform face area (FFA)– FFA – specifically for processing faces?

Somatosensory, Moor, and Association Cortex

• Somatosensoy Cortex (in parietal lobe)– body sensations

• Motor Cortex (in frontal lobe)– voluntary movements

• Point-to-Point Mapping

• Association Cortex (75% of cortex)– not sensory or motor, but associations between

Split-Brain Research

• Corpus Callosum– Large bundle of axons that connects the two

hemispheres of the brain

• W.J., the Split Brain Patient

Hemispheres of the Cortex

• Hemispheric Specialization of Function– left hemisphere– verbal processing, speech, grammar• Broca’s Area• Wernicke’s Area

– right hemisphere• spatial perception, visual recognition, emotion

Happy Brains

• Happiness: Prefrontal Lobe Asymmetry– positive emotional responses• more left prefrontal lobe activity

– negative emotional responses• more right prefrontal lobe activity

• Biofeedback• Mindfulness (Awareness) Meditation

Endocrine System

• set of glands that regulate the body by secreting hormones into the bloodstream

• hormones = chemical messages• relatively slow communication system• interconnected with the nervous system• pituitary, thyroid, parathyroid, adrenal glands,

pancreas, ovaries, testes

Brain Damage and Plasticity

• Recovery from brain damage depends on– age of the individual– extent of the damage

• Repairing the damaged brain– collateral sprouting– substitution of function– neurogenesis– brain tissue grafts

Genetics and Behavior

• chromosomes, genes, and DNA• Human Genome Project• dominant-recessive genes principle• molecular genetics• selective breeding• behavior genetics and adoption studies

Genes and the Environment

• Genotype – genetic heritage + the effects of experience =

• Phenotype – observable characteristics– environment alters how genetic traits develop– both physical & psychological characteristics – genetic expression

Biological Foundations and Health and Wellness

• stressors – …circumstances and events that threaten

individuals and/or tax their coping abilities• stress– …our response to those stressors

• causes/effects of acute and chronic stress

Chapter Summary

Chapter Summary

• Discuss the nature and basic function of the nervous system.

• Explain what neurons are and how they process information.

• Identify the brain’s levels and structures and summarize the function of those structures.

• Identify the endocrine system and describe how it affects behavior.

Chapter Summary

• Describe the brain’s capacity for recovery and repair.

• Explain how genetics increases understanding of behavior.

• Describe the role of the biological foundations of human psychology in the body’s stress response.

Chapter Summary

• The Nervous System– structure and function of the nervous systems– structure of a neruon– electrochemical communication– neurotransmitters and their effects

• Brain: Structure and Function– brain imaging techniques– hindbrain, midbrain, forebrain– cerebral lobes and functions

Chapter Summary

• Brain Damage and Plasticity– collateral sprouting, substitution of function,

neurogenesis, brain tissue grafts

• Genetics and Behavior– “genes v. environment” and adoption studies

• Biological Foundations & Health and Wellness– acute and chronic stress