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the multidisciplinary study of the nervous system and its role in behavior
- the branch of psychology that studies the
- relationship between behavior and the body, particularly the brain. Also known as psychobiology or physiological psychology
- a very broad term that includes internal events such as learning, thinking, and emotion, as well as the overt acts
- everyone would identify as behavior
When did psychology arise as a discipline?
- 1879 when William Wundt established the
- first psychology laboratory in Leipzig Germany
mind brain/ mind body problem
- deals with what the mind is and what its
- relationship is to the brain
- the idea that the mind and the body consist
- of the same substance
idealistic monists believe that everything is nonphysical mind
- most monists take the position that the
- body and mind and everything else are physical
- the idea that the mind and the brain are separate. The body is material and the
- mind is nonmaterial
- a proposed mechanism for how something works, sometimes a model is in the form of
- a theory. Can also be a simple organism or system that researchers study in an
- attempt to understand a more complex
- one. Ex: rat
Rene Descartes explanation of brain activity
- A hydraulic model
o Proposed that nerves were hollow tubes that carried animal spirits
o Said that the pineal gland pumped the animal spirits through the brain
- o it appeared capable of bending at different angels to direct the flow of animal
- spirits into critical areas of the brain. Descartes called it the seat of the
- soul, where the mind interacted with the body.
attached just below the two cerebral hemispheres by its flexible stalk
- gather information through observation
- rather than logic intuition, or other means
- late 1700’s made a frogs leg muscle twitch by stimulating the attached nerve with
- electricity, even after the nerve and muscle had been removed from the body
1800’s Frtich and Hitzig
- produced movement in dogs by electrically stimulating their exposed brains
o Each of these cases showed that nerves operated by electricity
- o After, Hemholtz demonstrated that nerves do not behave like wires conducting
- electricity. Measured the speed of conduction in nerves, and his calculation of
- about 90 feel/second
- the idea that specific areas of the brain carry out specific functions
o Functions are as much distributed as they are localized
- each of 35 different faculties of emotion
- and intellect- such as combativeness,
- inhabitiveness (love and home), calculation, and order – was located in a
- precise area of the brain
- the idea that the brain functions as an undifferentiated whole. The extent of
- damage, not the location, is what determines how much function is lost
- a biological unit that directs cellular processes and transmits inherited
- characteristics. Most genes are found on the chromosomes, which are located in
- the nucleus of each cell
few genes in structures outside the nucleus
- - 46 chromosomes in 23 pairs. Genes for
- specific functions are found on specific chromosomes. Referred to by number,
- except for the sex chromosomes. All pairs are similar except for the sex
- chromosomes – y is much shorter than x
How many chromosomes do sex cells have?
Deoxyribonucleic acid (DNA)
- a double stranded chain of chemical molecules that looks like a ladder that has
- been twisted around itself. Also known as the double helix
- o Composed of adenine, thymine, guanine, and cytosine – the order that these appear on the ladder forms the code that carries all our genetic information
What do proteins do?
- - Genes make proteins, some of these proteins are used in the construction of the body, and others are enzymes; enzymes act
- as caralysts, modifying chemical reactions in the body
o Because chromosomes are paired, most genes are as well
- different versions of a gene
- o ex: an
- allele for type A blood on one chromosome and the allele type B blood on the
- other will have AB blood
all the genes in our chromosomes
How many different combinations of chromosomes can a parent produce?
- – the percentage of the variation in a characteristic that can be attributed to
- genetic factors
- specialized cells that convey sensory information into the brain; carry out the operations involved in thought, feeling, and action;and transmit commands out into the
- bnody to control muscles and organs
How many neurons are in the brain?
What makes up the brains cells?
10% neurons 90% glial cells
- the most prominent part of the neuron. Filled with a watery liquid called cytoplasm
- and contains a number of organelles. The largest organelle is the nucleus,
- which contains the cells chromosomes
What are some responsibilities of organelles?
- Converting nutrients into fuel for the cell, constructing proteins, and removing waste
carries commands to the muscles and organs
- extensions that branch out from the cell body to receive information from other neurons.
- Branchlike structures allow them to collect information from many neurons
extends like a tail from the cell body and carries information to other locations
What does Myelin sheath do?
- supports the axon and provides other
- benefits that we will consider later.
- contain chemical neurotransmitters which the neuron releases to communicate with a
- muscle or an organ or the next neuron in a chain
- carry information from the body and from the outside world into the brain and spinal
- cord. Can be either unipolar or bipolar
Why is a motor neuron also known as a multipolar neuron?
- Its axon and dendrites extend in several
- directions from the cell body
connect one neuron to another in the same part of the brain or spinal cord. Because they make connections over short distances they don’t need long axons
What is the most critical factor in the neurons ability to communicate?
The membrane that encloses the cell
What are some molecules that can pass through the cell membrane?
Water, oxygen, and carbon dioxide
- there is a difference in electrical charge between the inside and the outside of the
- cell. Difference between two points is called voltage
- difference in charge between the inside and outside of the membrane of a neuron
- at rest. The voltage is negative and varies anywhere from -40 to -80 millivolts
- (mV) in different neurons but is typically around -70. Result from charges from
What makes the resting potential of a neuron negative
- The inside of the neuron has more negative
- ions than positive ions, while the ions on the outside are mostly positive
Why do ions move through the membrane to the side where they are less concentrated?
The force of diffusion
What is a result of electrostatic pressure?
- Ions are repelled from the side that is similarly charged and attracted to the side
- that is oppositely charged
Sodium potassium pump
- consists of large protein molecules that
- move sodium ions through the cell membrane to the outside and potassium ions
- back inside. Metabolic process (uses energy)
- an abrupt depolarization of the membrane that allos the neuron to communicate over
- long distances
What is the voltage across the resting neuron?
What happens at the peak of action potential?
- The sodium channels close, so there is no
- further depolarization. By that time the potassium ions inside the membrane
- combine to move potassium ions out. This outward flow of potassium ions returns
- the axon to its resting potential
How does the action potential differ from the local potential?
- The local potential is a graded potential, which means that it varies in magnitude
- with the strength of the stimulus that produced it. The action potential on the
- other hand is ungraded. It operates according to the all or none law. Meaning
- that it occurs at full strength or not at all
How is action potential nondecremental?
- It travels down the axon without any decrease in size, propagated anew and at full
- strength at each successive point along the way, which allows the neuron to
- work over long distances.
Absolute refractory period
- right after the action potential occurs the is a brief time during which it
- cannot fire again. Occurs because the
- sodium channels cannot reopen
Relative refractory period
- the neuron can be fired again, but only by a stronger than-threshold stimulus. A
- stimulus that is greater than threshold will cause the neuron to fire again
- earlier and thus most frequently
- the axon encodes stimulus intensity not
- in the size of its action potential but in its firing rate
- nonneural cells that provide a number of
- supporting functions to neurons. Glial = glue
- glial cells produce myelin, a fatty tissue that wraps around the axon to
- insulate it from the surrounding fluid and from other neurons. Only the axon is
- covered, not the cell body. Myelin is produced in the brain and spinal cord by
- a type of glial cell called oligodendrocytes and in the rest of the nervous
- system by schwann cells
Can action potentials occur in the myelin sheath?
No because there are very few sodium channels there.
What are the gaps in the myelin sheath called?
Nodes of Ranvier
form of transmission when action potentials jump from node to node
How did Santiago Ramon y Cajal find that each neuron is a separate cell
Tissue staining method
the connection between two neurons
What did loewi demonstrate about transmission?
- That transmission at the synapse is chemical and that there are at least two
- different chemicals that carry out different functions
- membrane enclosed containers that store neurotransmitters. When the action potential arrives at the terminals, it opens that channels that allow calcium ions o
- enter the terminals from the extracellular fluid.
- open the channels directly to produce the immediate reactions required for muscle
- activity and sensory processing; metabotropic receptors open channels indirectly and slowly to produce longer lasting effects
What effects can opening ion channels on the dendrites and cell body have?
- It can cause the local membrane potential
- to shift in a positive direction toward zero, partially depolarizing the membrane or it can shift the potential farther in the negative direction.
Partial depolarization, or hypopolarization
is excitatory and facilitates the occurrence of an action potential
Increased polarization or hyperpolarization
- inhibitory and makes an action potential
- less likely to occur
How many mVs does it take for depolarization to trigger and action potential?
How many synaptic connections are in the brain?
- 10000 in most parts of the brain and up to
- 100000 in the cerebellum.
- combines potentials occurring simultaneously at different locations on the dendrites and
- cell body
- combines potentials arriving a short time apart. Possible because it takes a few
- milliseconds for a potential to die out
- chains of amino acids (longer chains are called proteins). Neuropeptides are peptides
- that act as neurotransmitters.
- transmitter at muscles; in brain involved
- in learning etc. neurotransmitter
involved in mood, sleep,and arounsal and in aggression,depression, obsessive-compulsive disorder and alcoholism. Monamine
contributes to movement control and promotes reinforcing effects of abused drugfs, food, and sex; involved in schizophrenia and Parkinson’s disease. Moamine
- a hormone released during stress.
- Functions as a neurotransmitter in the brain to increase arousal and attentiveness to events in the environment; involved in depression. Monamine
a stress hormone related to norepinephrine; plays a minor role as a neurotransmitter in the brain. Monamine
- the principal excitatory neurotransmitter in the brain and spinal cord. Vitally
- involved in learning and implicated in schizophrenia. Amino acid
Gamma-aminobutyric acid (GABA)
- the predominant inhibitory neurotransmitter. Its receptors respond to alcohol and
- the class of tranqulizers called benzodiazepines. Deifiency in GABA or
- receptors is one cause of epilepsy. Amino acids
- inhibitory transmitter in the spinal cord and lower brain. The posion strychnine causes
- convulsions and death by affecting glycine activity. Amino acids
neuromodulators that reduce pain and enhance reinforcement. Peptides
transmitter in neurons sensitive to pain. Peptides
initiates eating and produces metabolic shifts. Peptides
- groups of neurons that function together to carry out a process. Where the most
- complex neural processing is carried out
Central nervous system (CNS)
includes the brain and the spinal cord
- a bundle of axons running together like a multiwire cable – this term is only
- used in the peripheral nervous system, inside the CNS bundles of axons are
- called tracts
What is a group of bodies called in the CNS and the Peripheral Nervous System?
- CNS = nucleus PNS = ganglion
What are the major structures of the forebrain?
- The two cerebral hemispheres, the thalamus,
- and the hypothalamus
Where does the highest level processing occur in the brain?
The cortex- the outer layer of the hemispheres
runs the length of the brain and separates the two cerebral hemispheres
- the ridges and grooves that give the brain
- a wrinkly appearance
each ridge in the brain
the groove or space between two gyri, if it is large it is called a fissure
How thick is the cortex?
1.5-4 millimeters thick
How many layers are in the brain?
The frontal lobe
the area anterior to (in front of) the cenral sulcus and superior to (above) the lateral fissure
The coronal plane
divides the brain vertically from side to side
The precentral gyrus
extends the length of the central sulcus, is the location of the primary motor cortex, which controls voluntary (nonreflexive) movement
controls speech production, contributing the movements involved in speech and grammatical structure
- the largest region in the human brain (29% of the brain) involved in planning and
- organization, impulse control, adjusting behavior in response to rewards and
- punishments, and some forms of decision making
- a surgical procedure that disconnects the
- prefrontal area from the rest of the brain
- the use of surgical intervention to treat cognitive and emotional disorders, is
- generally held in disfavor
- located superior to the lateral fissure
- and between the central sulcus and the occipital lobe
The primary somatosensory cortex
- located on the postcentral gyrus, processes
- the skin senses (touch, warmth, cold, and pain) and the senses that inform us
- about body position and movement. Usually serves the opposite area of the body
What happens when the posterior parietal cortex is damaged?
- May produce neglect, a disorder in which
- the person ignores objects, people, and activity on the side opposite the
- damage. Occurs more frequently when the right side is damaged
Primary projection area
in occipital lobes. Occupies the posterior tip of each lobe, anterior to the primary area are four secondary areas that detect individual components of a scene, such as color, movement, and form, which are then combined in association areas
lies just below the lateral ventricles, where it receives information from all the sensory systems except olfaction and relays it to the respective cortical projection areas
a smaller structure just inferior to the thalamus, plays a major role in controlling emotion and motivated behaviors such as eating, drinking, and sexual activity. Controls the autonomic nervous system and the pituitary gland (hormonal environment)
- known as the master gland because its
- hormones control other glands in the body
- secretes melatonin, a hormone that induces sleep. It controls seasonal cycles in
- nonhuman animals and participates with othe strctures in controlling daily
- rhythms in humans
a dense band of fibers that carry information between the hemispheres
What does each hemisphere specialize in?
left: language (language activity is mostly controlled by the left in 9 out of10 people) right: spatial tasks and face recognition
cavities in the brain andcentral canal in the spinal cord. Filled with cerebrospinal fluid, whichcarries material from the blood vessels to the CNS and transports wastematerials in the other direction
contains structures that havesecondary roles in vision, audition, and movement
help guide eyemovements and fixation of gaze and the inferior colliculi help locate thedirection of sounds
contain centers related to sleep and arousal, which are part of the reticular formation
a collection of manynuclei running through the middle of the hindbrain and the midbrain
forms the lower part of thehindbrain; its nuclei are involved with control of essential life processes,such as cardiovascular activity and respiration
How do sensory neurons enter the spinal
Through the dorsal root of each spinal nerve
an automatic movement in responseto a sensory stimulus
Peripheral nervous system (PNS)
made upof the cranial nerves, which enter and leave the underside of the brain
connect to the sides of thespinal cord at each vertebra
Somatic nervous system
includes the motorneurons that operate the skeletal muscles
Automatic nervous system (ANS)
controlssmooth muscle (stomach, blood vessels, etc) the glands, and the heart and otherorgans
Sympathetic nervous system
activates thebody in ways that help it cope with demands such as emotional stress andphysical emergencies
Parasympathetic nervous system
slows theactivity of most organs to conserve energy and activates digestion to renewenergy
What are the four stages of the development
of the nervous system?
Cell proliferation, migration, circuit formation, andcircuit pruning
cells that will becomeneurons divide and multiply at the rate of 250,000 new cells every minute
newly formed neurons migratefrom the ventricular zone outward to their final location. Do so with the aidof specialized radial glial cells
the axons of developingneurons grow toward their target cells and form functional connections
involves the eliminationof excess neurons and synapses
chemicals that enhance the development and survival of neurons
the growth of severed axons
occurs when the circulationof cerebrospinal fluid is blocked and the accumulating fluid interferes withthe brain’s growth producing severe intellectual impairment
undifferentiated cells thatcan develop into specialized cells such as neurons, muscle, or blood
How does action potential work?
The actionpotential causes nearby sodium channels to open as well. A new action potentialis triggered right next to the first one. A signal flows from one end of theneuron to the other