Chapter 2Neuroscience

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A Little Exercise

See in class!

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Brain and Mind

P h ys ica l

Th e B ra in

P sych o log ica l

Th e M in d

Th e P erson

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Topics to Explore

1. The Neuron

2. The Peripheral Nervous System

3. The Central Nervous System

Part 1The Neuron

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Neuron: Individual nerve cell; 100 billion in brain- Dendrites: Receive messages from other neurons;

have thousands of branches- Soma: Cell body; metabolic center of neuron; contains

genetic material- Axon: Carries information away from the cell body;

longest part of neuron- Axon Terminals: Branches that link the dendrites and

soma of other neurons- Synaptic Gap: Space between the end of the axon of

one neuron and the dendrites of an adjacent neuron

Neuron and Its Parts

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Picture of a Neuron

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• Resting Potential: Electrical charge of an inactive neuron

• Threshold: Trigger point for a neuron’s firing

• Action Potential: Nerve impulse

The Nerve Impulse

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Resting Potential

Resting Potential: Tiny charge between inside & outside of

neuron

• Created by electrically charged particles (ions)

- Some concentrated outside the cell (sodium and

chloride ions)

- Some concentrated inside the cell (Potassium ions)

• How is the charge maintained?

- Sodium-potassium pump

- Selectively permeable cell membrane

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Action Potential

Action potential: Change in potential, primarily because

of messages from other neurons

• Excitatory messages: Cell loses the negative charge;

Depolarization

• Inhibitory messages: Cell becomes more negatively

charged; Hyperpolarization

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Resting vs. Action Potential

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Graphic: Action Potential

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Graphic: Action Potential

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Graphic: Synaptic Gap

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Neurotransmitters: Chemicals that alter activity in

neurons; brain chemicals. Messages from one neuron to

another pass over the synapse, the microscopic gap

between neurons

Receptor Site: Areas on the surface of neurons and other

cells that are sensitive to neurotransmitters

Antagonist: drug that decreases activity of a neurotrans-

mitter

Neurotransmitters

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Some Neurotransmitters

• Acetylcholine: involved in learning, memory, and muscle contractions. Botulism toxin prevents release of acetylcholine, resulting in paralysis

• Dopamine: involved in arousal, mood, and movement. In Parkinson’s, receptors in brain fail to react to dopamine, leading to tremors, rigidity and problems initiating movement

• Serotonin and Norepinephrine: involved in arousal and mood. Cocaine blocks re-uptake of both neurotransmitters, resulting in “high”

• GABA (gamma-aminobutyric acid): main inhibitory neurotrans-mitter; lowers arousal and anxiety

• Endorphins: lower pain perception. Morphine and heroin bind to endorphin receptors, increasing endorphin activity.

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• Nerves: Large bundles of neurons

• Myelin: Fatty layer of tissue that coats axons

• Multiple Sclerosis (MS) occurs when myelin layer is destroyed; numbness, weakness, and paralysis occur

Nerves and Neurons

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A Little Exercise

Demonstration of the speed of a neural impulse.

An Organizational Pause:

Organization of the Nervous System

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• Central Nervous System (CNS): Brain and spinal cord

• Peripheral Nervous System: All parts of the nervous system outside of the brain and spinal cord

- Autonomic System: Serves internal organs and glands; controls automatic functions such as heart rate and blood pressure

- Somatic System: Links spinal cord with skeletal muscles and sense organs; controls voluntary behavior

Major Sections of the Nervous System

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Organization of Nervous System

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Graphic: Nervous System

Part 2The Peripheral Nervous System

• The Autonomic Nervous System

• The Somatic Nervous System

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• Sympathetic: Arouses body; emergency system

• Parasympathetic: Quiets body; most active after an

emotional event

Divisions of Autonomic System

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Functions of Autonomic Nervous System

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Three Components of Emotion

• Physical component: state of physiological arousal triggered by autonomic nervous system

• Behavioral component: outward expression of the emotion, including facial expression & behavior

• Cognitive component: appraisal of the situation to determine which emotion we are experiencing and why

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James-Lange Theory of Emotion

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Cannon-Bard Theory of Emotion

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Schachter-Singer Theory

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Comparison of Three Theories of Emotion

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Somatic Nervous System

• Motor Nervous System: transfers messages from CNS to control function of voluntary muscles

• Sensory Nervous System: transfers messages from sensory organs to CNS; brings information from outside the body to the brain to be processed

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Structures in Somatic System

• Sensory neuron: neuron that transmits information from sensory organ to CNS

• Motor neuron: neuron that transmits information from CNS to voluntary muscle

• Connector neuron: neuron in spinal cord connecting sensory and motor neurons to form reflex arc.

• Reflex: An innate, automatic motor response to a specific sensory stimulus

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Graphic: Somatic Nervous System

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Motor & Somatosensory Areas in Cerebral Cortex

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Motor Homunculus

“homunculus” = “a diminutive human being”

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Somesthetic Homunculus

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A Little Exercise

A demonstration of the somatosensory system, using toothpicks and little rulers.

Part 3The Central Nervous System

• The Spinal Cord

• The Brain

- The Central Core

- The Limbic System

- The Cerebral Cortex

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• Spinal Nerves: 31 of them; carry sensory and motor messages to and from the spinal cord

• Cranial Nerves: 12 pairs that leave the brain directly; also work to communicate messages

• Spinal cord functions to connect peripheral nervous system to the brain

The Spinal Cord

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The Central Core(aka the “old brain”)

• Medulla: Connects brain with the spinal cord and controls vital

life functions such as heart rate and breathing

• Cerebellum: Regulates posture, muscle tone, muscular

coordination, and procedural learning

• Reticular formation: Associated with levels of arousal and

consciousness, as well as some reflexes (breathing, coughing,

sneezing, vomiting)

• Thalamus: serves as a relay station for incoming sensory

Information

• Basal ganglia: involved in physical movement

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Graphic: Central Core

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The Limbic System

At the top border (limbus in Latin) of the brain stem.

•Hypothalamus: controls pituitary gland (directing activity of

endocrine system) and autonomic nervous system; involved in

basic drives (eating, drinking, sex)

• Hippocampus: involved in formation of memories

• Amygdala: involved in regulating emotional experiences,

particularly initial emotional responses

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Graphic: Limbic System

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• Cerebral Cortex: Outer layer of the cerebrum

• Cerebrum: Two large hemispheres that cover upper part of the brain

• Corticalization: Increase in size and wrinkling of the cortex

• Cerebral Hemispheres: Right and left halves of the cerebrum

• Corpus Callosum: Bundle of fibers connecting cerebral hemispheres

Neocortex

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Graphic: Relative Size

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Graphic: Corpus Callosum

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Left & Right Hemispheres

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• About 95 percent of our left brain is used for language

• Left hemisphere better at math, judging time and rhythm, and coordinating order of complex movements

- Processes information sequentially

• Right hemisphere good at perceptual skills, and at expressing and detecting other’s emotions

- Processes information simultaneously

Left Brain/Right Brain

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Graphic: Left vs. Right

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• Occipital Lobe: Back of brain; vision center

• Parietal Lobe: Just above occipital; bodily sensations such as touch, pain, and temperature (somatosensory area)

• Temporal Lobe: Each side of the brain; auditory and language centers

• Frontal Lobe: Movement, sense of smell, higher mental functions; contains motor cortex; controls motor movement

Lobes of the Neocortex

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Graphic: Lobes