Chapter 2Chapter 2

Neuroscience and BehaviorNeuroscience and Behavior

The NeuronThe Neuron

Communication in the Communication in the Nervous System takes Nervous System takes place in the neuronsplace in the neurons

Cells that are specialized to Cells that are specialized to receive and transmit info receive and transmit info (nerve cell)(nerve cell)

Neuroscience: the study of Neuroscience: the study of the Nervous Systemthe Nervous System

Glial Cells: support cells Glial Cells: support cells that provide structural that provide structural support, nutrition, and support, nutrition, and discard waste for neurons. discard waste for neurons. Also produce myelin.Also produce myelin.

Types of neuronsTypes of neurons

Sensory Neurons: transmit info from Sensory Neurons: transmit info from receptor cells in sensory organs (i.e. nose, receptor cells in sensory organs (i.e. nose, ears, tongue, eyes, and skin) and internal ears, tongue, eyes, and skin) and internal organs to brain.organs to brain.

Motor Neurons: Transmit info from the Motor Neurons: Transmit info from the brain to muscles.brain to muscles.

Interneurons: Communicate between Interneurons: Communicate between sensory and motor neurons.sensory and motor neurons.

Structures of the NeuronStructures of the Neuron

Cell Body: contains Cell Body: contains structures that structures that provide energy for the provide energy for the cell to function. Also cell to function. Also contains the nucleus.contains the nucleus.

Dendrites: Receive Dendrites: Receive messages from other messages from other neuronsneurons

Structures of the Neuron con’tStructures of the Neuron con’t

Axon: Carries info to Axon: Carries info to other neurons.other neurons.

Myelin Sheath: Myelin Sheath: Protects axon from Protects axon from axons of other axons of other neurons. Formed by neurons. Formed by glial cellsglial cells

Structures of the Neuron con’tStructures of the Neuron con’t

Axons vary in size. Axons vary in size. Axons may have branches that allow it to Axons may have branches that allow it to communicate with more than one neuron.communicate with more than one neuron.Gaps in the Myelin Sheath called Gaps in the Myelin Sheath called Nodes of Nodes of RanvierRanvier or just nodes or just nodesNeurons with Myelin Sheath communicate Neurons with Myelin Sheath communicate fasterfasterMultiple Sclerosis is the degeneration of Multiple Sclerosis is the degeneration of the Myelin Sheath.the Myelin Sheath.

Communication Within the NeuronCommunication Within the Neuron

Messages are gathered by the Dendrites and Messages are gathered by the Dendrites and passed along the Axon by a small electrical passed along the Axon by a small electrical impulse called Action Potential.impulse called Action Potential.Stimulus Threshold: The minimum level of Stimulus Threshold: The minimum level of Stimulation required for a neuron to activate.Stimulation required for a neuron to activate.While waiting, a neuron is While waiting, a neuron is polarizedpolarized. Interior is . Interior is more negatively charged than exterior.more negatively charged than exterior.Resting charge is -70 millivolts, referred to as Resting charge is -70 millivolts, referred to as resting potential.resting potential.Action Potential is All-or-NoneAction Potential is All-or-None

Communication Within the Neuron Communication Within the Neuron con’tcon’t

While resting, a neuron has sodium ions on the While resting, a neuron has sodium ions on the exterior of the membrane. In the interior, the exterior of the membrane. In the interior, the neuron contains potassium ions.neuron contains potassium ions.

When the action potential is sent down the axon, When the action potential is sent down the axon, channels open and the two ions briefly switch, channels open and the two ions briefly switch, creating a charge of +30 millivolts. This is creating a charge of +30 millivolts. This is depolarization.depolarization.

Refractory Period: Period the neuron is unable Refractory Period: Period the neuron is unable to fire. During this period the neuron to fire. During this period the neuron repolarizesrepolarizes..

Communication Between NeuronsCommunication Between Neurons

Primary function of a neuron is to communicate Primary function of a neuron is to communicate information to other cells.information to other cells.2 Types of Communication: Electrical and 2 Types of Communication: Electrical and ChemicalChemicalSynapse: Point of communication between two Synapse: Point of communication between two neurons.neurons. Presynaptic neuron: Neuron sending the messagePresynaptic neuron: Neuron sending the message Postsynaptic neuron: Neuron receiving the messagePostsynaptic neuron: Neuron receiving the message Synaptic Gap: Fluid filled space separating neurons.Synaptic Gap: Fluid filled space separating neurons. Axon Terminal: Located at the end of the axon. Axon Terminal: Located at the end of the axon.

Where the message is sent from one neuron to the Where the message is sent from one neuron to the next.next.

Electrical CommunicationElectrical Communication

Synapse extremely Synapse extremely narrownarrow

Ion Channels serve Ion Channels serve as a bridge between as a bridge between neuronsneurons

Communication is Communication is instananeousinstananeous

Chemical Communication: Synaptic Chemical Communication: Synaptic TransmissionTransmission

When message reaches the axon terminal, When message reaches the axon terminal, synaptic vesicles dock with membrane and synaptic vesicles dock with membrane and release chemical messengers called release chemical messengers called neurotransmitters.neurotransmitters. Neurotransmitters cross the synaptic gap and Neurotransmitters cross the synaptic gap and attach to receptor sites on the dendrites of attach to receptor sites on the dendrites of postsynaptic neurons.postsynaptic neurons.Neurotransmitters must fit receptor sites exactly.Neurotransmitters must fit receptor sites exactly.Reuptake: Process of neurotransmitters being Reuptake: Process of neurotransmitters being reabsorbed by presynaptic neuron. Those not reabsorbed by presynaptic neuron. Those not reabsorbed are dissolved by enzymes.reabsorbed are dissolved by enzymes.

Synaptic Transmission

Types of messagesTypes of messages

Neurotransmitter gives one of two Neurotransmitter gives one of two messages. Message depends on the messages. Message depends on the receptor it attaches to.receptor it attaches to.Excitatory message: increases the Excitatory message: increases the likelihood that the postsynaptic neuron will likelihood that the postsynaptic neuron will activate action potential.activate action potential.Inhibitory message: decreases the Inhibitory message: decreases the likelihood that the postsynaptic neuron will likelihood that the postsynaptic neuron will activate action potential.activate action potential.

Neurotransmitters and their effectsNeurotransmitters and their effects

AcetylcholineAcetylcholine

11stst neurotransmitter discovered neurotransmitter discovered

Found in all motor neurons; stimulates Found in all motor neurons; stimulates muscles to contractmuscles to contract

Also found in brain; essential to memory, Also found in brain; essential to memory, learning, and general intellectual learning, and general intellectual functioning.functioning.

Alzheimer’s DiseaseAlzheimer’s Disease linked to a depletion linked to a depletion of Acetylcholineof Acetylcholine

DopamineDopamine

Involved in movement, attention, learning, and Involved in movement, attention, learning, and pleasurable or rewarding sensations.pleasurable or rewarding sensations.Addictiveness of some drugs related to Addictiveness of some drugs related to dopamine increasing properties. (i.e. cocaine, dopamine increasing properties. (i.e. cocaine, nicotine)nicotine)Degeneration in brain linked to Degeneration in brain linked to Parkinson’s Parkinson’s Disease. Disease. Symptoms include rigidity, muscles Symptoms include rigidity, muscles tremors, poor balance.tremors, poor balance.Excessive levels linked to hallucinations and Excessive levels linked to hallucinations and SchizophreniaSchizophrenia. .

The Brain: Studying the brainThe Brain: Studying the brain

Case Studies: Monitoring behavior of people Case Studies: Monitoring behavior of people with damage or disease. Limitedwith damage or disease. Limited

Lesions: Removing or damaging a part of the Lesions: Removing or damaging a part of the brain.brain.

Bipolar electrodes: Surgically implanted wires or Bipolar electrodes: Surgically implanted wires or disks that stimulate areas of the braindisks that stimulate areas of the brain

Electroencephalogram: Records the electrical Electroencephalogram: Records the electrical activity of the brain from millisecond to activity of the brain from millisecond to millisecond. Recorded on an EEG.millisecond. Recorded on an EEG.

Brain Structures: BrainstemBrain Structures: Brainstem

Brainstem: Includes the hindbrain and mid brain. Brainstem: Includes the hindbrain and mid brain.

Hindbrain connects the Spinal Cord with the rest Hindbrain connects the Spinal Cord with the rest of the brainof the brain

Made up of 3 structures:Made up of 3 structures: Medulla: Controls breathing, heart rate, etcMedulla: Controls breathing, heart rate, etc Pons: Relays info from forebrain to cerebellumPons: Relays info from forebrain to cerebellum Cerebellum: Controls balance & coordinationCerebellum: Controls balance & coordination Reticular Formation: Group of neurons in medulla that Reticular Formation: Group of neurons in medulla that

project up the brain and down Spinal Cord.project up the brain and down Spinal Cord.

Brain Structures: Brainstem con’tBrain Structures: Brainstem con’t

Midbrain: Processes auditory and visual Midbrain: Processes auditory and visual information.information.

Substantia Nigra: Involved in motor control Substantia Nigra: Involved in motor control and contains a large concentration of and contains a large concentration of dopamine-producing neurons.dopamine-producing neurons.

Brain Stem

Brain Structures: ForebrainBrain Structures: Forebrain

Also called cerebrum; makes up 90% of Also called cerebrum; makes up 90% of brain.brain.

Outer portion called Cerebral Cortex. Outer portion called Cerebral Cortex. Divided into 2 cerebral hemispheres that Divided into 2 cerebral hemispheres that are connected by the corpus callosum.are connected by the corpus callosum.

Each Hemisphere has 4 Lobes: Temporal, Each Hemisphere has 4 Lobes: Temporal, Occipital, Parietal, and Frontal.Occipital, Parietal, and Frontal.

Brain Structures: Forebrain con’tBrain Structures: Forebrain con’t

Temporal Lobe: Primary Auditory CortexTemporal Lobe: Primary Auditory Cortex

Occipital Lobe: Primary Visual CortexOccipital Lobe: Primary Visual Cortex

Parietal Lobe: Somatosensory Cortex- Parietal Lobe: Somatosensory Cortex- processes bodily info (i.e. touch, temp. processes bodily info (i.e. touch, temp. pressure)pressure)

Frontal Lobe: Involved in planning, Frontal Lobe: Involved in planning, initiating, and executing voluntary initiating, and executing voluntary movements.movements.

Forebrain

The Brain: The Limbic SystemThe Brain: The Limbic System

Form complex neural circuits that play Form complex neural circuits that play critical roles in learning, memory and critical roles in learning, memory and emotional control.emotional control.

4 Key Structures:4 Key Structures: HippocampusHippocampus ThalamusThalamus HypothalamusHypothalamus AmygdalaAmygdala

The Brain: The Limbic System con’tThe Brain: The Limbic System con’t

Hippocampus: Involved in forming new Hippocampus: Involved in forming new memories. Neurogenesis takes place.memories. Neurogenesis takes place.

Thalamus: Processes and distributes sensory Thalamus: Processes and distributes sensory and motor info to and from cerebral cortex. and motor info to and from cerebral cortex. Regulates awareness, attention, and motivationRegulates awareness, attention, and motivation

Hypothalamus: Regulates both divisions of the Hypothalamus: Regulates both divisions of the Autonomic Nervous System.Autonomic Nervous System.

Amygdala: involved in a variety of emotional Amygdala: involved in a variety of emotional responses: fear, anger, and disgust.responses: fear, anger, and disgust.

LimbicSystem

HumanBrain

Specialization of the HemispheresSpecialization of the Hemispheres

Cerebral hemispheres work together but Cerebral hemispheres work together but have different responsibilities.have different responsibilities.

Lateralization of Function: The idea that Lateralization of Function: The idea that different hemispheres exert more control different hemispheres exert more control over the other in specific functions.over the other in specific functions. Cortical Localization: The idea that particular Cortical Localization: The idea that particular

areas of the brain are associated with areas of the brain are associated with particular functionsparticular functions

Specialization of the Hemispheres Specialization of the Hemispheres con’tcon’t

Broca’s Area: Lower left frontal lobe-Broca’s Area: Lower left frontal lobe-responsible for speech.responsible for speech.

Wernicke’s Area: Left Temporal Lobe- Wernicke’s Area: Left Temporal Lobe- responsible for language comprehensionresponsible for language comprehension

Aphasia- Partial or complete inability to Aphasia- Partial or complete inability to articulate ideas or understand spoken or articulate ideas or understand spoken or written language as a result of brain written language as a result of brain damage.damage.

Cutting the Corpus CallosumCutting the Corpus Callosum

Done to reduce severity of or eliminate epileptic Done to reduce severity of or eliminate epileptic seizures.seizures.Roger Sperry’s experiment shows that the Roger Sperry’s experiment shows that the procedure eliminates communication between to procedure eliminates communication between to hemispheres. (P.74)hemispheres. (P.74)Left Hemisphere superior in language abilities, Left Hemisphere superior in language abilities, speech, reading, and writing.speech, reading, and writing.Right Hemisphere dominate in nonverbal Right Hemisphere dominate in nonverbal emotional expression and visual-spacial tasks. emotional expression and visual-spacial tasks. Creative.Creative.

PlasticityPlasticity

Functional Plasticity: Brain’s ability to shift Functional Plasticity: Brain’s ability to shift functions from damaged areas of the brain functions from damaged areas of the brain to undamaged areas.to undamaged areas.

Structural Plasticity: Idea that the brain’s Structural Plasticity: Idea that the brain’s structure is sculpted by experience.structure is sculpted by experience.

Brain LobesBrain Lobes

ForebrainForebrain

Brain StemBrain Stem

Limbic SystemLimbic System

Human BrainHuman Brain