Chapter 3: The Biological Bases of Behavior

Communication in the Nervous System Two basic forms of communication –Chemical –Electrical

Communication in the Nervous System Glia – structural support and insulation Neurons – communication –Soma –Dendrites –Axon –Myelin sheath –Terminal Branches / Button

Figure 3.1 Structure of the neuron

Neural Impulse The “information” traveling through the neuron. Hodgkin & Huxley (1952) - Studied a giant squid to understand mechanics of neural transmission

Resting Potential Resting potential –Cell is inactive, Stable negative charge Membrane is Polarized

The Action Potential Brief change in the electrical charge Stimulation causes cell membrane to open Membrane is Depolarized Electrical charge travels along neuron All – or – none law

The Synapse Presynaptic Neuron –Terminal Button Synaptic Cleft Postsynaptic Neuron –Cell Membrane –Dendrite or Soma

The Synapse Presynaptic Neuron –Synaptic Vesicles –Neurotransmitters Synaptic Cleft Postsynaptic Neuron –Receptor Sites –Lock and Key

When a Neurotransmitter Binds: The Postsynaptic Potential Voltage change at receptor site – Postsynaptic Potential (PSP) –Changes the probability of the postsynaptic neuron firing Positive voltage shift – Excitatory PSP Negative voltage shift – Inhibitory PSP

Figure 3.4 Overview of synaptic transmission

Neurotransmitters and Behavior Specific neurotransmitters work at specific synapses More than 40 neurotransmitters known at present – 9 are commonly researched. Terms Agonist – mimics neurotransmitter action Antagonist – opposes action of a neurotransmitter

Acetylcholine (Ach) Only neurotransmitter found between motor neurons and voluntary muscles. Contributes to the regulation of attention, arousal and memory--Alzheimer's patients have decreased levels of ACh. –Nicotine is an Agonist –Alzheimer’s medication is an Agonist –Curare is an Antagonist –Botox is an Antagonist

Monoamines Three neurotransmitters that regulate everyday behaviors. –Dopamine (DA) –Serotonin –Norepinephrine (NE)

ADHD Inattention and distractibility appear to be related to low levels of Norepinephrine. ADHD Children/Adults can't judge which things in their environment are important and which should be ignored. Low levels of Norepinephrine also make it very difficult for ADHD Children/Adults to sustain their focus on a task, plan ahead, and understand such concepts as sequence and time. The impulse and behavior problems found in Attention-Deficit Hyperactivity Disorder (ADHD) appear related to low levels of Dopamine in the brain. Low levels of dopamine in the brain makes control of impulsive behavior almost impossible in the ADHD Child/Adult.

GABA Gamma-aminobutric acid Inhibitory Anxiety

Endorphins Internally produced chemicals that resemble opiates in structure and effects.

Table 3.1 Common Neurotransmitters and Some of their Functions

Organization of the Nervous System Central nervous system (CNS) –Brain –Spinal Cord –CerebroSpinal Fluid Peripheral nervous system –Somatic nervous system –Autonomic nervous system (ANS) Sympathetic Parasympathetic

Figure 3.5 Organization of the human nervous system

Figure 3.6 The central and peripheral nervous systems

Figure 3.7 The autonomic nervous system (ANS)

Studying the Brain: Research Methods Spinal Tap EEG Electrical stimulation (ESB) Damage studies/lesioning Brain imaging – –Computerized Tomography (CAT/CT) –Magnetic Resonance Imaging (MRI) –Positron Emission Tomography (PET) Transcranial magnetic stimulation (TMS)

CT Scan X-ray Source X-ray Detectors Fan Shaped Beam

Magnetic Resonance Imaging (MRI)

Positron Emission Tomography (PET)

Transcranial Magnetic Stimulation (TMS) Pulsed Magnetic Field Positioning Frame Resting Neurons Activated Neurons Stimulated Brain Region Maximum Filed Depth Magnetic Field (a)(b) (c)

Figure 3.12 Structures and areas in the human brain

Brain Regions and Functions Hindbrain Vital Functions –Medulla –Pons –Cerebellum

Figure 3.12 Structures and areas in the human brain

Brain Regions and Functions Midbrain Sensory functions Reticular Activating System

Figure 3.12 Structures and areas in the human brain

Brain Regions and Functions Forebrain Emotion, complex thought –Thalamus –Hypothalamus –Limbic System –Cerebrum Cerebral Cortex

Right Brain/Left Brain: Cerebral Specialization Cerebral Hemispheres – two specialized halves connected by the corpus collosum –Left hemisphere – verbal processing: language, speech, reading, writing –Right hemisphere – nonverbal processing: spatial, musical, visual recognition

Figure 3.14 The cerebral hemispheres and the corpus callosum

Animation 3.7 Right Brain/Left Brain Windows Mac OS X

The Cerebrum: The Seat of Complex Thought Four Lobes: –Occipital – vision –Parietal - somatosensory –Temporal - auditory –Frontal – movement, executive control systems

Figure 3.15 The cerebral cortex in humans

Figure 3.16 Language processing in the brain

The Endocrine System: Another Way to Communicate Hormones – chemical messengers in the bloodstream Endocrine glands –Pituitary – “master gland,” growth hormone –Thyroid – metabolic rate –Adrenal – salt and carbohydrate metabolism –Pancreas – sugar metabolism –Gonads – sex hormones

Basic Principles of Genetics Chromosomes – strands of DNA carrying genetic information –Human cells contain 46 chromosomes in pairs (sex-cells – 23 single) –Each chromosome – thousands of genes, also in pairs Polygenic traits Dominant Recessive Traits

Research Methods in Behavioral Genetics Family studies – does it run in the family? Twin studies – compare resemblance of identical (monozygotic) and fraternal (dizygotic) twins on a trait Adoption studies – examine resemblance between adopted children and their biological and adoptive parents

Figure 3.19 Genetic relatedness

Figure 3.20 Twin studies of intelligence and personality

The Evolutionary Bases of Behavior 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