neural communication biological psychology branch of psychology concerned with the links between...
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Neural Communication
Biological Psychology branch of psychology concerned with
the links between biology and behavior some biological psychologists call themselves behavioral
neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or biopsychologists
Phrenology (Franz Gall) Study of the bumps on your head Bumps reveal a person’s abilities and
traits
Phrenology
Neural Communication
Resting Potential
• At rest, the inside of the cell is at -70 microvolts• With inputs to dendrites inside becomes more positive • If resting potential rises above threshold, an action
potential starts to travel from cell body down the axon• Figure shows resting axon being approached by an AP
Depolarization Ahead of AP
• AP opens cell membrane to allow sodium (Na+) in
• Inside of cell rapidly becomes more positive than outside
• This depolarization travels down the axon as leading edge of the AP
Repolarization follows
• After depolarization potassium (K+) moves out restoring the inside to a negative voltage
• This is called repolarization• The rapid depolarization and repolarization produce a
pattern called a spike discharge
Finally, Hyperpolarization
• Repolarization leads to a voltage below the resting potential, called hyperpolarization
• Now neuron cannot produce a new action potential• This is the refractory period
Neural Communication
Locks and Keys
• Neurotransmitter molecules have specific shapes
When NT binds to When NT binds to receptor, ions enterreceptor, ions enter
Receptor molecules Receptor molecules have binding siteshave binding sites
Some Drugs Work on Receptors
• Some drugs are shaped like neurotransmitters
• AntagonistsAntagonists: fit the receptor but poorly and block the NT– e.g., beta blockers
AgonistsAgonists: fit : fit receptor well and receptor well and act like the NTact like the NTe.g., nicotinee.g., nicotine
Neural Communication
Neurotransmitter molecule
Receiving cellmembrane
Receptor site onreceiving neuron
Agonist mimicsneurotransmitter
Antagonistblocksneurotransmitter
12
Excitatory and Inhibitory Messages
• Excitatory message— increases the likelihood that the postsynaptic neuron will activate
• Inhibitory message— decreases the likelihood that the postsynaptic neuron will activate.
Neural Communication
Serotonin Pathways Dopamine Pathways
Neurons and Synapses
Types of Neurons
Sensory Motor Interneurons
SpinalCord
BrainSensoryNeuron
Sensory Neurons
• INPUT From sensory organs to the brain and spinal cord
Drawing shows a somatic neuron
Also called AFFERENT NEURONS
SpinalCord
BrainSensoryNeuron
MotorNeuron
Motor Neurons
• OUTPUT From the brain and spinal cord, to the muscles and glands
Also called EFFERENT NEURONS
SpinalCord
BrainSensoryNeuron
MotorNeuron
Interneurons
• Interneurons carry information between other neurons only found in the brain and spinal cord
The Nervous System
Nervous System the body’s speedy, electrochemical
communication system consists of all the nerve cells of the peripheral
and central nervous systems
Peripheral Nervous System (PNS) the sensory and motor neurons that connect
the central nervous system (CNS) to the rest of the body
The Nervous System
Central(brain and
spinal cord)
Nervoussystem
Autonomic (controlsself-regulated action of
internal organs and glands)
Somatic (controlsvoluntary movements of
skeletal muscles)
Sympathetic (arousing)
Parasympathetic (calming)
Peripheral
The Nervous System
Somatic Nervous System the division of the peripheral nervous system
that controls the body’s skeletal muscles
Autonomic Nervous System the part of the peripheral nervous system that
controls the glands and the muscles of the internal organs (such as the heart)
The Nervous System
Sympathetic Nervous System division of the autonomic nervous system that
arouses the body, mobilizing its energy in stressful situations
Parasympathetic Nervous System division of the autonomic nervous system that
calms the body, conserving its energy
Brain and Spinal Cord
Central Nervous System (CNS) the brain and spinal cord
Brain part of the CNS that plays important roles in
sensation, movement, and information processing.
Spinal Cord plays a role in body reflexes and in communication
between the brain and the peripheral nervous system.
The Nervous System
Reflex a simple, automatic, inborn response to a sensory stimulus
Skinreceptors
Muscle
Sensory neuron(incoming information)
Motor neuron(outgoing information)
Brain
Interneuron
Spinal cord
The Brain
Lesion tissue
destruction a brain lesion
is a naturally or experimentally caused destruction of brain tissue
Electroencephalogram (EEG)
an amplified recording of the waves of electrical activity that sweep across the brain’s surface
these waves are measured by electrodes placed on the scalp
The Brain
CT (computed tomography) Scan a series of x-ray photographs taken from different
angles and combined by computer into a composite representation of a slice through the body; also called CAT scan
PET (positron emission tomography) Scan a visual display of brain activity that detects where a
radioactive form of glucose goes while the brain performs a given task
PET Scan
PET Scan
Pet Scan of a Normal Brain
The Brain MRI (magnetic resonance imaging)
a technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain
Stimulation Electrical stimulation of the brain involves sending a
weak electric current into a brain structure to stimulate it. (It is not painful because the brain has no pain receptors
MRI Scan
The Cerebral Cortex
Functional MRI scan shows the visual cortex activated as the subject looks at faces
Association Areas– Association Areasof the cerebral cortex that are not
involved in primary motor or sensory functions. They are involved in higher mental functions such as learning, remembering, thinking and speaking.
– Phineas Gage
– AreAeas of the cerebral cortex that are not involved in primary motor or sensory functions. They are involved in higher mental functions such as learning, remembering,
The Brain
Brainstem the oldest part and central core of the brain,
beginning where the spinal cord swells as it enters the skull
responsible for automatic survival functions
Developing Brain
•Neural tube—beginning of nervous system develops at 2 weeks after conception
•Neurogenesis—development of new neurons
Hindbrain Structures
• Cerebellum • Brainstem
y medullay reticular
formationy pons
Medulla
• Breathing• Heart rate• Digestion• Other vital
reflexesy swallowingy coughingy vomitingy sneezing
Pons
• Helps coordinate movements on left and right sides of the bodyy e.g., postural
reflexes which help you maintain balance while standing or moving
Reticular Formation
• Network of neurons in the brainstem (and thalamus)
• Sleep and arousal
• Attention
Cerebellum
• Coordinated, rapid voluntary movementsy e.g., playing the
piano, kicking, throwing, etc.
• Lesions to cerebellumy jerky, exaggerated
movementsy difficulty walkingy loss of balancey shaking hands
The BrainCerebellum [sehr-
uh-BELL-um] the “little brain”
attached to the rear of the brainstem
it helps coordinate voluntary movement and balance
Forebrain Structures• Thalamus• Limbic
System• Cortex
Thalamus
• Relay station in brain
• Processes most information to and from higher brain centers
The Limbic System
The Limbic System
• Hypothalamus• Amygdala• Hippocampus
The Limbic System
Electrode implanted in reward center
Amygdala and Emotion
• Identify emotion from facial expressions
Amygdala damage makes this task difficult
The Cerebral Cortex
SensoryHomunculus
Specialization and Integration
The Cerebral Cortex
Aphasia impairment of language, usually caused by left
hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding)
Broca’s Area (Disrupts speaking) an area of the left frontal lobe that directs the
muscle movements involved in speech Wernicke’s Area (Disrupts understanding)
an area of the left temporal lobe involved in language comprehension and expression
Visual and Auditory Cortex
Specialization and Integration
and InInteIntegration Brain activity when hearing, seeing, and speaking
words
Brain Reorganization
Plasticity the brain’s capacity for
modification, as evident in brain reorganization following damage (especially in children) and in experiments on the effects of experience on brain development
Brain Reorganization
• Hemispherectomy
– The surgical removal of an entire cerebral hemisphere
Our Divided Brain
Corpus Callosum large band of
neural fibers connects the
two brain hemispheres
carries messages between the hemispheres
Corpus callosum
Split Brain
a condition in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them
Our Divided Brain
The information highway from the eye to the brain
Split Brain
“Look at the dot.” Two words separatedby a dot are momentarily projected.
“What worddid you see?”
or
“Point withyour left hand to theword you saw.”
HemisphericSpecialization
The Endocrine System
Endocrine Systemthe body’s “slow”
chemical communication system
a set of glands that secrete hormones into the bloodstream
Neural and Hormonal Systems
Hormoneschemical messengers, mostly those
manufactured by the endocrine glands, that are produced in one tissue and affect another
Pituitary Glandunder the influence of the hypothalamus, the
pituitary regulates growth and controls other endocrine glands
The effects of the pituitary are clearly shown here. Entertainer David Frost stands between the
world’s tallest and smallest man.
The tallest man in history was 8 feet 11 inches tall. He died at the age of 22, partly as a result of this defect. The shortest known person was 23 inches tall when she died at the age of 19. Today’s medicines can handle most of these problems if caught earlier enough, but these cases show what happen if the pituitary gland goes awry.
Neural and Hormonal Systems
• Oxytocin– stimulates contractions of the uterus during labor and secretion of milk during nursing.
• Growth Hormone– stimulates the physical development of bones and muscles.
Neural and Hormonal Systems
Adrenal [ah-DREEN-el] Glands a pair of endocrine glands just above the kidneyssecrete the hormones epinephrine (adrenaline) and
norepinephrine (noradrenaline), which help to arouse the body in times of stress
Cortisol– regulates metabolism and response to stress.
Neural and Hormonal Systems
• Pancreas Hormones
– Insulin– decreases blood sugar
– Glucagon– Increases blood sugar
Neural and Hormonal Systems
• Thyroid Hormone
– Thyroxin– regulates metabolism and growth
Neural and Hormonal Systems
• Sex Glands (Gonads)
– Female Sex Hormone– Estrogen (Ovary)
– Male Sex Hormone– Androgen (Testis)
Association Areas• Association Areas
– Areas of the cerebral cortex that are not involved in primary motor or sensory functions. They are involved in higher mental functions such as learning, remembering, thinking and speaking.
– Phineas Gage
Association Areas
More intelligent animals have increased “uncommitted” or association areas of the cortex
The Cerebral Cortex
Aphasia impairment of language, usually caused by left
hemisphere damage either to Broca’s area (impairing speaking) or to Wernicke’s area (impairing understanding)
Broca’s Area (Disrupts speaking) an area of the left frontal lobe that directs the
muscle movements involved in speech Wernicke’s Area (Disrupts understanding)
an area of the left temporal lobe involved in language comprehension and expression
Hypothalamus (The Four F’s)
• Contains nuclei involved in a variety of behaviors– sexual behavior– hunger, thirst– sleep– water and salt balance– body temperature regulation– circadian rhythms– role in hormone secretion
Hypothalamus and Hormones
Hypothalamus releases hormones or releasing factors which in turn cause pituitary gland to release its hormones
Hippocampus
• Hippocampus– structure that contributes to the formation of memories.
• Damage to the hippocampus has been implicated in the memory loss associated with Alzheimer’s.
Specialization and Integration
Disappearing Southpaws
The percentage of left-handers decreases sharply in samples of older people (adapted from Coren, 1993).
The percentage of lefties sharplydeclines with age
10 20 30 40 50 60 70 80 90Age in years
14%
12
10
8
6
4
2
0
Percentage ofleft-handedness
Brain Structures and their Functions
The Nervous System
Neural Networks interconnected neural
cells with experience,
networks can learn, as feedback strengthens or inhibits connections that produce certain results
computer simulations of neural networks show analogous learning
Inputs Outputs
Neurons in the brain connect with one
another to form networks
The brain learns by modifyingcertain connections in response to feedback
Neural Communication
Neuron a nerve cell the basic building
block of the nervous system Soma
cell body; serves as neuron’s control center
Neural Communication Dendrite
the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body
Axon the extension of a neuron, ending in branching
terminal fibers, through which messages are sent to other neurons or to muscles or glands
Myelin [MY-uh-lin] Sheath a layer of fatty cells segmentally encasing the
fibers of many neurons enables vastly greater transmission speed of
neutral impulses
Neural Communication
Action Potential a neural impulse; a brief electrical
charge that travels down an axon generated by the movement of
positively charged atoms in and out of channels in the axon’s membrane
Threshold the level of stimulation required to
trigger a neural impulse
Neural Communication
Cell body end of axon
Direction of neural impulse: toward axon terminals
Action Potential Within a Neuron
How Neurons Communicate
Neurons communicate by means of an electrical signal called the Action Potential
Action Potentials are based on movements of ions between the outside and inside of the cell
When an Action Potential occurs, a molecular message is sent to neighboring neurons
Neural Communication Synapse [SIN-aps]
junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron
tiny gap at this junction is called the synaptic gap or cleft
Neurotransmitters chemical messengers that traverse the
synaptic gaps between neurons when released by the sending neuron, neuro-
transmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether it will generate a neural impulse
Neurotransmitter Release
Action Potential causes vesicle to open
Neurotransmitter released into synapse
Locks onto receptor molecule in postsynaptic membrane
Locks and KeysLocks and Keys
Neurotransmitter Neurotransmitter molecules have molecules have specific shapesspecific shapes
When NT binds to When NT binds to receptor, ions enterreceptor, ions enter
Receptor molecules Receptor molecules have binding siteshave binding sites
Some Drugs Work on Some Drugs Work on ReceptorsReceptors
Some drugs are Some drugs are shaped like shaped like neurotransmittersneurotransmitters
AntagonistsAntagonists: fit the : fit the receptor but poorly receptor but poorly and block the NTand block the NT e.g., beta blockerse.g., beta blockers
AgonistsAgonists: fit : fit receptor well and receptor well and act like the NTact like the NTe.g., nicotinee.g., nicotine
Dopamine
Involved in movement, attention and learning
Dopamine imbalance also involved in schizophrenia
Loss of dopamine-producing neurons is cause of Parkinson’s disease
Parkinson’s DiseaseParkinson’s Disease
Results from loss of dopamine-producing Results from loss of dopamine-producing neurons neurons
Symptoms includeSymptoms include difficulty starting and stopping voluntary difficulty starting and stopping voluntary
movementsmovements tremors at resttremors at rest stooped posturestooped posture rigidityrigidity poor balancepoor balance
Parkinson’s DiseaseParkinson’s Disease
TreatmentsTreatments L-dopaL-dopa transplants of fetal dopamine-transplants of fetal dopamine-
producing substantia nigra cellsproducing substantia nigra cells adrenal gland transplantsadrenal gland transplants electrical stimulation of the thalamus electrical stimulation of the thalamus
has has been used to stop tremorsbeen used to stop tremors
Serotonin
Involved in sleep Involved in depression
Prozac works by keeping serotonin in the synapse longer, giving it more time to exert an effect
Excitatory and Inhibitory Messages
Excitatory message— increases the likelihood that the postsynaptic neuron will activate
Inhibitory message— decreases the likelihood that the postsynaptic neuron will activate.
Neural Communication
Neurotransmitter molecule
Receiving cellmembrane
Receptor site onreceiving neuron
Agonist mimicsneurotransmitter
Antagonistblocksneurotransmitter
Acetylcholine
First neurotransmitter discovered Ach is found in all motor neurons It stimulates muscles to contract,
including the heart and stomach muscles
Primary Roles: learning, memory, muscle contractions
Disruption of Acetylcholine Functioning
Curare—blocks ACh receptorsparalysis results
Nerve gases and Black Widow spider venom; too much ACh leads to severe muscle spasms and possible death
Disruptions in ACh Functioning
Cigarettes—nicotine works on ACh receptorscan artificially stimulate skeletal
muscles, leading to slight trembling movements
Alzheimer’s Disease
Deterioration of memory, reasoning, and language skills
Symptoms may be due to loss of ACh neurons
Endorphins Control pain and pleasure Released in response to pain Morphine and codeine work on
endorphin receptors; involved in healing effects of acupuncture
Runner’s high— feeling of pleasure after a long run is due to heavy endorphin release
Norepinephrine
Arousal“Fight or flight” responsePrimary Roles: physical
arousal, learning, memoryDisorders: depression
GABA
Inhibition of brain activity Huntington’s disease involves loss
of neurons in striatum that utilize GABASymptoms:
jerky involuntary movements mental deterioration
Glutamate
Major excitatory neurotransmitterToo much glutamate (and too
little GABA) associated with epileptic seizures
Neural Communication
Summary
z Neuron structurez Action potentialsz Synapsez Receptors and ionsz Neurotransmitters z Agonists and
antagonists
The Nervous System
Nerves neural “cables” containing many axons part of the peripheral nervous system connect the central nervous system with
muscles, glands, and sense organs
The Cerebral Cortex
Cerebral Cortex the intricate fabric of
interconnected neural cells that covers the cerebral hemispheres
the body’s ultimate control and information processing center
Glial Cells cells in the nervous system that
support, nourish, and protect neurons
The Cerebral Cortex Frontal Lobes
involved in speaking and muscle movements and in making plans and judgments
Parietal Lobes include the sensory cortex & processes somatic
information Occipital Lobes
include the visual areas, which receive visual information from the opposite visual field
Temporal Lobes include the auditory areas
The Cerebral Cortex
Motor Cortex area at the rear of the frontal lobes that
controls voluntary movements Sensory Cortex
area at the front of the parietal lobes that registers and processes body sensations