Psy 100 ECC Chapter 2 Neuroscience and Behavior.ppt

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Overview

• _{The Neuron}

• _{Communication Throughout the Body} • _{The Brain}

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Learning Objectives

• _{1. Identify the role of the neuron.}

• _{2. Identify the distinct parts of a neuron and} their function.

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The Neuron

• _{Neurons allows communication to occur in} our nervous system.

• _{They are highly specialized to receive and} transmit information from one area of the body/brain to another.

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The Neuron

• _{Three Types of Neurons:}

– _{1. Sensory Neuron – Provide sensory information}

(light, sound, etc…) from your sense organs to your brain.

– _{2. Motor Neurons – Muscles and glands (i.e.}

blinking your eyes uses thousands).

– _{3. Interneurons – Communicate information} between neurons

• _{These consist of the majority of neurons in our nervous}

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Anatomy of the Neuron

• _Three_Basic_Components:

– _{Cell Body/Soma – Makes energy for the neuron to function.} – _{Axon – Carry information}_from_{the cell body}_to_{the other}

cells/neurons via the Terminal Buttons.

– _{Dendrites – Receive messages from other neurons.}

• _{Other Important Structures:}

– _{Myelin Sheath – Speed up transmission down the axon}

(degradation of myelin can lead to disorders such as Multiple Sclerosis).

– _{Terminal Buttons – Release information to other neurons from}

the axon.

– _{Glial Cells – Provide various forms of support for the neuron (}_i.e.

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Communication Within the Neuron

• _{Information is sent down the axon via an} Action Potential.

– _{A brief electrical impulse that forms the basis for}

communication in a neuron.

– _{Produced by the movement of}_ions_{(electrically}

charged particles) across the axon.

– _{The axon membrane uses}_{ion channels}_{to allow}

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Communication Within the Neuron

• _{In order for an action potential to occur, each}

neuron requires a minimum degree of stimulation from other neurons.

– This is the Stimulus Threshold

• _{The axon’s interior is more negatively charged}

than the exterior fluid at around -70 Millivolts (this keeps us alive).

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Communication Within the Neuron

• _{Primarily dealing with two types of ions:}

– _Sodium_{(+NA, Greater concentration outside of the axon).} – _Potassium_{(+K, Greater concentration inside of the axon).}

• _{When a neuron wishes to communicate, the ion} channels open.

– _{1. Sodium rushes in at a ratio of 3/2.} – _{2. Potassium flows out.}

– _{This is known and Polarization and Depolarization or an}

increase or decrease in electrical charge.

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Communication With the Neuron

• _{All or None Law – Neurons are either sufficiently}

stimulated to fire or they aren’t.

– _{They also fire with the same intensity every time.}

• Similarly to squeezing the trigger of a gun.

– The absolute threshold of the neuron is +55mv.

• _{Refractory Period – After an action potential}

occurs the neuron repolarizes, during which time another action potential cannot occur until

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Synaptic Gap

Presynaptic Neuron

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Communication Between Neurons

• _{Communication across the synapse generally} occurs via chemicals/neurotransmitters.

• _The_{Terminal Buttons}_{contain synaptic vesicles} that release neurotransmitters into the

synapse.

• _{Transmission always occurs in this order:}

– _{Presynaptic neuron -> Synapse -> Postsynaptic}

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Communication Between Neurons

• _Question?

– _{After being released into the synapse, where do}

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Communication Between Neurons

• _{After release, neurotransmitters can either be:}

– _{Picked up by the postsynaptic neuron.} – _{Float freely in the synapse}

– _{Experience Reuptake – Neurotransmitters still floating}

in the synapse are pulled back into the synaptic vesicles by the original presynaptic neuron.

• _{Neurons and chemicals work like a lock and key:}

– _{Each neurotransmitter has a chemical shape that}

must match the receptors of the postsynaptic neuron to be accepted and effect the neuron.

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Communication Between Neurons

• _{Neurotransmitters can communicate one of two types} of messages to neurons:

– _{Excitatory Messages – Increase the likelihood that the}

postsynaptic neuron will experience an action potential.

– _{Inhibitory Messages – Decrease the likelihood that the}

postsynaptic neuron will experience an action potential.

• _{The effect of a neurotransmitter depends on both the}

chemical structure and the receptor of the neuron to which it binds.

– _{The effects of the same neurotransmitter may be different}

depending on the receptor it binds to (i.e. depending on the receptor, some neurotransmitters can be either

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Neurotransmitters

• _{Our ability to perceive, feel, think, move, etc..} relies on the balance of neurotransmitters in the nervous system.

– _{Too much or too little of a neurotransmitter can}

cause problems.

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Neurotransmitters

• _{Acetylcholine – Important for memory,} learning, intellectual functioning, and all motor movement.

• _{Dopamine – Important for memory,} movement, and reward sensations.

• _{Serotonin – Important for regulation of} emotional states, sleep, and sensory

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Neurotransmitters

• _{Norepinepherine – Important for physical}

arousal, learning, memory, and regulation of sleep.

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Neurotransmitters

• _{Drugs can increase or decrease the amount of}

time a neurotransmitter stays in the synapse.

– _{This determines how much of a neurotransmitter the}

postsynaptic neuron has access to.

– _{This can either prolong or weaken the effects of the}

neurotransmitter.

• _{Drugs can prolong the effects by blocking}

reuptake. (i.e. SSRI).

• _{Weaken the effects by increasing the rate up}

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Neurotransmitters

• _{Drugs that block the effect of neurotransmitters}

are called Antagonists.

– _{Drugs can do this by either fitting into the}

postsynaptic receptors and blocking the

neurotransmitters from binding to them, by changing the physical structure of the receptors.

• _{For example: Decreasing the effects of dopamine in addicts.}

– _{Drugs that mimic specific neurotransmitters to}

increase or prolong the effects are called Agonists. • _{For example: Increased serotonin leads to decreased rates}

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Nervous System

• _{Your nervous system consists of two parts:}

– _{Central Nervous System – Brain and spinal cord.} – _{Peripheral Nervous System – All the nerves}

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Central Nervous System

- Almost all behaviors are controlled by the brain/CNS.

- However, the spinal cord can produce spinal reflexes – simple, automatic behaviors that occur without brain involvement.

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Peripheral Nervous System

• _{All the nerves outside the CNS that extend}

outward from your body towards your limbs/skin/etc…

• _{NOT THE BRAIN/SPINAL CORD} • _{Consists of two parts:}

– _{Somatic Nervous System – Sends sensory information}

to and from the CNS and motor nerves to perform voluntary muscle movements.

– _{Autonomic Nervous System – Regulates involuntary}

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Autonomic Nervous System

• _{Two parts:}

– _{Sympathetic Nervous System – The body’s}

emergency system. Rapidly activates the body in times of stress to assist you in dealing with

threats. Represents the fight or flight response when confronted with a threat.

– _{Parasympathetic Nervous System - The body’s}

relaxation system. Conserves and maintains

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Nervous System

Central Nervous

System Peripheral Nervous _System

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Plasticity

• _{Brain does not have a fixed or hard-wired} structure.

• _{Functional Plasticity – Ability to shift functions} from damaged to undamaged areas.

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Cerebral Cortex

• _{Outer Layer of the brain – generally what we} think of when we think “Brain”.

• _{Divided into two}_Hemispheres_.

• _{The two hemispheres are attached in the} middle by the Corpus Collosum.

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Cerebral Cortex

• _{What are the 4 lobes?}

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Lobes of the Brain

• _{Frontal Lobe – Planning, muscle movements,} emotional control, personality.

• _{Parietal Lobe – Bodily information}

(Somatosensory) such as touch, temp, pressure, etc…

• _{Occipital Lobe – Visual Information}

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Limbic System

• _{Structures of the brain involved in learning, memory,} and emotional control.

• _{Hippocampus – Latin for sea horse. Involved in forming} and learning new memories.

– _{Fifty First Dates, Memento, etc..}_.

• _{Thalamus – Sends and receives sensory information} to/from the brain. (Except olfactory/smell).

• _{Amygdala – Involved in emotional responses,} particularly fear.

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Cortical Localization

• _{The idea that particular brain areas are} associated with specific functions.

– _{This is why the hemispheres of the brain have}

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Broca and Wernicke’s Areas

• _{Broca’s Area – Left Frontal Lobe. Can’t speak}

language, but can comprehend written or spoken language.

– “Tan”.

• _{Wernicke’s Area – Left Temporal Lobe. Can speak}

but makes no sense. Can’t understand language but can speak it.

– _{“Don’t glow glover, Yes, Uuh, umm, bick”.}

• _{These highlight}_{Lateraliation of Functioning.}

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Cutting the Corpus Collosum

• _{To reduce seizures, a Split-Brain Operation} was used in which the Corpus Collosum is severed.

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Cutting the Corpus Collosum

• _{Many processes of the patients actually go} unchanged.

• _However: