PSYCH 210 (Dr. Wickesberg) Exam 1 Study Guide

what is the outer shell of the brain?

Color/Underline = terms Underline = important Italics = extra information Neuroanatomy

• Central Nervous System

o Brain

o Spinal Cord

o Generally, does NOT regenerate

• Peripheral Nervous System

o 12 Cranial Nerves

o Spinal Nerves

o DOES regenerate after damage

o Divided into two parts

▪ Somatic – voluntary muscles

▪ Autonomic – involuntary

• Sympathetic – prepares for action

• Parasympathetic – prepares body for restoration and relaxation

• Cerebral Ventricles

o Cerebral spinal fluid inside

o Helps cushion the brain

• Brain

o Gyrus – hills on brain

o Fissure/Sulcus – valleys on brain

• Neocortex – the outer shell of the brain

o Divided into two hemispheres by the Longitudinal Fissure

▪ Right half processes information

what chemical compounds that mimic the action of neurotransmitters?

▪ Left half relays sensory information

• Regions of the Brain

o Frontal Lobe – output of information

o Parietal Lobe – integrates sensory information

o Occipital Lobe - vision

o Temporal Lobe – hearing

How Neurons Work

• Neurons -

o A single neuron can contact one to an infinite number of other neurons o Does NOT regenerate after killed

• Glia – forms a barrier between the blood and the brain (blood/brain barrier) o Supporting cells to neurons; provides nutrients

o Ex: dopamine cannot make it into your brain through your bloodstream due to  the blood/brain barrier

• Information Processing

o Electrical Signaling

▪ Controls neuron response

• Excitation

• Inhibition

▪ Graded Potentials

▪ Actions Potentials – a spike in electrical activity

what is Somatosensory system?

We also discuss several other topics like What is Merit system?

▪ How it Works

• Cell membrane is a lipid bilayer

o Forms barrier between inside/outside of the cell

o Semi-permeable membrane – only allows one type of ion  

to pass through

• Signaling “Electrical Potentials”

o Resting Potential

▪ Average resting potential of a neuron is about -

70mV

o Excitatory Postsynaptic Potential (EPSP)

o Inhibitory Postsynaptic Potential (IPSP)

o Action Potential

▪ “the heart of neuroscience”

o Sodium/Potassium Pumps

• Generation of an Action Potential

o Every cell (neuron) has a cell membrane which is semi If you want to learn more check out what is an atom?

permeable

▪ The cell membrane is a lipid bilayer

• Forms barrier between inside/outside of  Don't forget about the age old question of Why was the PR campaign that followed the Exxon Valdez oil spill considered a failure?

the cell

▪ Only allows one type of ion to pass through

o Each cell (neuron) tries to reach equilibrium based off  

which ions are inside and outside of the cell

o In the process of trying to reach equilibrium, an action  

potential can be generated if enough stimulation occurs to  

reach the threshold

• Conduction of the Action Potential

o As the action potential is conducted along the axon, the  

potential does not change size or shape

o This happens because the potential is regenerated at each  

point along the axon

o “No regeneration, potential decreases = graded  Don't forget about the age old question of Who is Henri Toulouse?

conduction”

• Regeneration of the Action Potential

o After reaching threshold, positive ions enter through the  voltage-gated channels

o The entry of positive ions cause the membrane potential  to increase

o The positive charge opposes more positive ion entry o Positive charge spreads along the membrane, depolarizes  adjacent parts and the process repeats

o Backwards spread of charge does not open voltage-gated  channels because these channels not only close but they  inactivate

• Refractory Periods

o Absolute Refractory Period

▪ Lasts about 1 msec

▪ Channels closed and inactivated, so the neuron will  not generate another action potential

▪ Limits a neuron to a maximum of 1000 action  

potentials per second

o Relative Refractory Period

▪ Lasts 3-4 seconds

▪ Hard to regenerate action potential, but possible

• Conduction Velocity

▪ Speed of conduction in unmyelinated (uninsulated)  axons varies from 0.1 m/sec to 35 m/secs, but it  

depends on the axonal thickness

• Thick Axon = fast conduction, more charge  

carriers (ions)

• Thin Axon = slow conduction, fewer charge  

carriers

• Saltatory Conduction in Myelinated Axons

o Many axons are insulated by myelin, which is made by  Schwann cells (Peripheral Nervous System) and  

Oligodendrocytes (Central Nervous System)

o Current flows to the next Node of Ranvier so the action  potential “jumps” from node to node (saltatory  We also discuss several other topics like What is Hormones?

conduction)

o Action potential can fail at two nodes and still be  regenerated

o Speed of saltatory conduction is up to 120 m/secs (4 times  faster than unmyelinated axons)

o Chemical Signaling

▪ Neurotransmitters – can either excite/inhibit the next neuron

▪ Agonists – chemical compounds that mimic the action of  

neurotransmitters (can be natural or synthetic)

▪ Antagonists – chemical compounds that bind at a receptor and may or  may not be a neurotransmitter (can be natural or synthetic)

• Competitive – blocks binding site

• Non-competitive – does not prevent binding but neurotransmitter  has no effect

• Two Types of Synapses  

o Chemical Synapses

▪ Most common  

▪ Terminal filled with vesicles that release neurotransmitter

▪ Synaptic delay (~1ms)

▪ Can be modulated by chemicals (good or bad chemicals)

o Electrical Synapses

▪ Rarer

▪ Tight junction

▪ Fast/No cleft

▪ Electrical potential travels directly to next neuron

• Events at a Chemical Synapse

o Action potential invades synaptic terminal

o Open voltage-gated calcium channels, calcium enters the terminal ▪ There are many voltage-gated channels all dependent on the type of ion o Calcium causes synaptic vesicles to bind presynaptic membrane If you want to learn more check out What is the homeostasis?

o Vesicles burst open and release contents

o Neurotransmitter diffuses across cleft and binds to receptors

o Neurotransmitter becomes unbound

• Reuptake into vesicles (most efficient process)

• Removal from cleft

▪ Diffusion

• The neurotransmitter can be removed from the cleft by simple  

diffusion and often there is uptake by glial processes close to the  

synapse (common at glutamate synapses)

▪ Deactivating Enzymes

• An enzyme can be used to deactivate the neurotransmitter

▪ Reuptake

• The neurotransmitter (along with parts of the synaptic vesicles) is  reabsorbed (reuptake) at the nerve terminal by transporter  

proteins and then this material is used to makes new synaptic  

vesicles

• Types of Receptors

o Ionotropic

▪ Neurotransmitter binds directly to the channel proteins  

(neurotransmitters can open up multiple ion channels)

▪ Channel opens immediately

▪ Ions flow across membrane for a brief time (change potential across  membrane directly)

▪ Produces a fast response: EPSP or IPSP

o Metabotropic (doesn’t allow ions in directly)

▪ Neurotransmitter binds G-protein coupled receptor

▪ G-protein is activated

▪ Activated G-protein subunit moves to adjacent ion channel which causes  a brief delay

▪ Channel opens, ions flow across membrane for a longer period

Touch and Pain

• Somatosensory System – relays information about the body

o Touch, temperature, body position (proprioception), organic senses (heart burn),  and pain (nociception)

• Labeled Line System  

o In the skin, each receptor has a specialized ending that responds to a specific  attribute of the stimulus

o Receptors – neurons that transduce or change a physical stimulus into neural  events

o Labeled Line – different receptors for different qualities and have different lines  to the brain

• Receptor Potential

o Bi-polar cells (neurons) commonly found in sensory system

▪ The axons in this cell can be very long

▪ The cell body is closer to spinal cord

• They don’t really have dendrites

o A Pacinian corpuscle responds to pressure

▪ When deformed (skin pressed), sodium channels are opened, which  

depolarizes the ending

▪ Receptor or generator potential is the potential measured in the  

specialized ending. If the ending is depolarized enough, it will produce an  action potential.

• Adaptation – loss of sensitivity to continuous presence of stimulus

• Receptive Fields – the region of the receptor surface that excites or inhibits a sensory  neuron

o Size of Receptive Fields

▪ Receptive fields are smallest in the fingertips, larger in the hand, and  even larger in the arm

• Fingertips have the finest discrimination between sensory inputs

▪ Receptive field size varies with use

• Somatosensory Pathways

o Necessary for information to travel up the spinal cord to the brain

▪ Information ascends in the dorsal columns to the medulla, then to the  thalamus and then to somatosensory cortex

o The cell body is found in the dorsal root ganglion

▪ Ganglion – many cell bodies stuck together

o If there is damage to the dorsal root ganglia, the individual would end up not  being able to feel anything

o Somatosensory Cortex (posterior to central sulcus)

• Pain Receptors (also found in somatosensory system)

o Thermal or Mechanical Receptors 

▪ A type of pain that needs immediate attention

▪ Sharp, prickling pain

▪ Axons (A – fibers) are myelinated  

• Myelinated axons allow for information to travel faster

o Polymodal Receptors 

▪ Searing, diffuse pain

• Heartburn or a burning sensation

▪ Axons (C – fibers) are unmyelinated  

• Unmyelinated axons take longer to pass on information

• Ascending Pain Pathways

o Pain fibers synapse in the dorsal horn

o Spinothalamic tract (anterolateral tract) carries the pain fibers to the thalamus o Left 

▪ Spinothalamic tract carries the pain fibers to the thalamus

▪ Spinoparabrachial pathway innervates areas of the brain concerned with  affect

o Right 

▪ Descending pain pathway begins in periaqueductal gray (PAG)

• Midbrain (periaqueductal gray) (EPSP)???? Medulla (Raphe nucleus)  (IPSP)???? Doral Horn Neuron ???? Spinothalamic tract

• The brain can modulate pain to be taken cared of later

o Can modulate by activating or shutting down a synapse at  

the dorsal horn

• Referred Pain

o Pain fiber from skin or muscle and pain fiber from an internal organ (i.e. heart)  synapse on the same dorsal horn neuron

▪ Pain in an internal organ will feel like pain in a muscle or on the skin

• Modulation of Pain

o Analgesic – blocks the sensation of pain but does not produce unconsciousness o Anesthetic – analgesia plus unconsciousness

o Placebo – fake drug that appears to alleviate pain (~30% of the time) o Endorphins – endogenous drugs that produce pain relief by activating the  descending pathways  

Movement

• Structures within a Hemisphere

o The basal ganglia are involved in movement and response learning

o The hippocampus, part of the limbic system, is involved in spatial (place) learning • Major Components of Movement

o Motor Cortex (planning, initiating, and directing voluntary movement) Spinal Cord Brainstem Basal Ganglia Cerebellum

Thalamus

Muscles of the  

Muscles of  the head and  

body

neck

o Cortical (pyramidal)

▪ Primary motor cortex o Extracortical  

▪ Cerebellum and pons o Spinal reflexes

• Antagonistic Pairs – muscles arranged in opposite pairs with extensors and flexors o Muscles can only contract

• Muscles and Motor Neurons

o Muscles receive neural input from motor neurons in the spinal cord ▪ Motor neurons release acetylcholine (ACh)

o Muscles receptors connected to sodium channel

▪ Receptors blocked by curare

• Contracting a Muscle

▪ It receives a signal from motor neurons in the ventral horn of the spinal  cord

▪ The signal depolarizes the muscle, which releases calcium from  

intracellular stores and then the actin and myosin molecules change  configuration

▪ The muscles must remain depolarized to maintain actin/myosin  

configuration, which will require continuous neural input

• Feedback from Muscles and Tendons

▪ The command signal is delivered to intrafusal muscle fibers to set,  stretch, and gain

▪ The error is the difference between the position of the muscle and the  intrafusal muscle fibers

▪ The feedback comes from stretch receptors and Golgi tendon organs ▪ The error signal is used to set the position of the extrafusal muscle fibers o The brain does not have to calculate/adjust for weight because the feedback  loop does so

Motor Cortex  (Command)

Alpha Motor  Neurons

Gamma Motor  Neurons

Feedback

Extrafusal Muscle  Fibers

(Current Position)

Intrafusal Muscle  Fibers (Set Point)

Stretch  

Receptors  (Compare)

• Alpha motor does most of the work

• Stretch Reflex

o The position of the muscle is set by the brain

o The tap on the patella tendon creates an error and the error signal to try to  return the limb to its original position

o The error signal must also change the opposite muscle

• Central Pattern Generators

o Fixed Action Patterns (FAP)

• Primary Motor Cortex

o It is anterior to the central sulcus is primary motor cortex

o Pyramidal neurons project to motor neurons in the spinal cord o Human Motor Cortical Areas

▪ Premotor Cortex – plans the movement that is to be made

▪ Supplementary Motor Area

▪ Primary Motor Cortex

• Cerebellum

o Complex coordination

o Is easily affected by alcohol

o The cerebellum and pons compute a smoot movement

• Basal Ganglia

o Parts of Basal Ganglia

▪ Caudate, Putamen, Globus Pallidus

o Amplitude and direction and initiation of movement

o Response learning

o Parkinson’s disease is the loss of dopamine from the substantia nigra (midbrain)  to the basal ganglia

• Voluntary Movement

o The visual cortex sees an object and determines what and where it is o Prefrontal cortex decides to make a movement

o Premotor plans the movement

o Extracortical systems calculate a smooth movement

o Motor cortex makes the movement

Hearing

• Sound – is the vibration of air molecules

o A tuning fork produces a sinusoidal vibration

▪ The number of cycles each second is the frequency (Hertz)

• We hear frequencies between 20 Hz and 20,000 Hz

• Animals hear at different frequencies

• Spectrograms – displays how the frequency contents of a sound change over time • Ear separates sound into its different frequency components

• Intensity of Sound is known as Decibels of sound pressure

• Peripheral Auditory System

o Pinna (external ear) – amplifies sound

o Cochlea – the place where neurons transduce sound into neural signals; it is  filled with fluid; it is two tubes coiled together and filled with fluid

▪ The top tube is divided into two parts by Reissner’s Membrane

▪ The two tubes are separated by the Basilar Membrane

• Basilar Membrane – analyzes frequencies

o Runs the length of the Cochlea

o Vibrates up and down

o It is short and stiff at the base of the Cochlea 

▪ High frequencies 

o It is wide and floppy at the apex of the Cochlea 

▪ Low Frequencies  

o Place Theory of pitch perception – pitch is the location of  

the largest vibrations

• The Organ of Corti sits on Basilar Membrane and is the structure  

that changes sound vibrations into neural signal

▪ On top of each hair cell is a band of stereocilla

▪ There are also descending inputs onto the hair cells

▪ Innervation of the Cochlea

• There are about 30,000 – 50,000 auditory nerve fibers

• 95% of the auditory nerve fibers innervate inner hair cells and  

only 5% go to the outer hair cells

o Middle Ear – compensates for the loss of intensity as vibrations in the air are  changed to vibrations in fluid by gathering energy over a large area and focusing  it on a small area (i.e. like pushing in a thumb tack)

▪ Sound tends to reflect off water, which is why it’s necessary for the Pinna  and Middle Ear to amplify sounds

▪ Muscles in the Middle Ear can dampen sound, but it acts slowly

o Auditory nerve – carries the signal to the brain stem (medulla)

• Transduction of Sound into Neural Signals

o Vibrations of the Basilar Membrane wiggle the stereocilla

▪ The back and forth movement of the stereocilla opens and closes  channels at their tips

o When the channels open, positive ions enter and depolarize the hair cell, which  releases neurotransmitters onto auditory nerve fibers

o Scala Media contains a very high concentration of K+ (Potassium)

▪ K+ enters the hair cell when the channels at the tips of the stereocilla  opens and the hair cell becomes depolarized

▪ K diffuses into perilymph at the base of cells when tip channels are  closed. No need for Na/K (Sodium/Potassium) pumps in hair cells

• Volley Theory – proposes that the number of action potentials equals the frequency of  the sound, and the interval between them equals the period of the stimulus frequency o Example: Basilar Membrane vibrates in response to a 500 H tone

▪ Motion of stereocilla on hair cells

▪ Excitatory neurotransmitter release

▪ Action potentials in auditory nerve fiber

▪ In response to a 500 Hz tone, there are 500 action potentials spaced 2  msec apart

• Ascending Auditory Pathways

o Auditory nerves project to the cochlear nucleus on the side of the brain stem o From the cochlear nucleus, parallel pathways convey information to the inferior  colliculus in the midbrain

• Sound Localization in Superior Olive

o Location of a sound must be computed by the auditory system

o Two cues

▪ Difference in the arrival time of the sound at each ear

▪ Intensity difference between the two ears caused by the head

o Medial Superior Olive – computes time difference

o Lateral Superior Olive – computes intensity difference

• Descending Pathway (Efferents)

o Two pathways project from the SOC to the Cochlea 

▪ Medial System (around MSO) – large, myelinated fibers

▪ Lateral System (around LSO) – thin, unmyelinated fibers

• Exciting the Cochlea without Sound

o Auditory nerve fibers send a message to the brain following depolarization  produced by neurotransmitter

o For deaf people, the nerve can be depolarized by stimulating with electrical  currents from a cochlear implant

▪ There is not a precise enough stimulation for music, but good enough for  speech

Language, Methods, and Memory

• Tonotopic Map

o Information from several brainstem auditory structures is combined in the  inferior colliculus

• Auditory Areas in Neocortex

o Primary auditory cortex is in the temporal lobe on the bank of the Sylvian fissure o Wernicke’s Area is involved in speech analysis

o Broca’s Area is for speech production

o All components of speech identified and combined before the information  reaches this level

• Lesions Studies

o The most famous lesion study was done by Paul Broca

▪ Studied a man named “Tan” because he didn’t say anything other than  “tan”

▪ Broca found a large lesion in a region of frontal cortex (Broca’s Area) that  is responsible for language production

o Carl Wernicke, a German neurologist, studied stroke victims

▪ Found that people who had strokes damaged part of their temporal  

cortex (killed it off) and could produce speech, but not understand it

• Fluent speech but it was nonsense and could not comprehend  

language 

▪ Paraphasia – putting the wrong word in a sentence

• Speech vs. Language

o Speech – is just a sequence of acoustic symbols

o Language requires structure (grammar) and meaning

• Electrical Potentials of the Human Nervous System (EEG)

o Event related potentials sync signals to a specific event

o Initial potentials (N1 and P2) are influenced by selective attention. The mismatch  negativity (MMN) is caused by a n auditory stimulus that is physically deviant  from the previous. The other two components are determined by cognitive  rather than physical attributes

o N400; takes 400 msec to realize mistake

▪ Semantically incorrect words

• “Coffee with cream and cat”

▪ False statements of category relationships

• “A good grade is an F”

▪ Information that is inconsistent with prior knowledge  

• “The professor knew what he was talking about”

o P600/SPS; takes 600 msec to realize mistake

▪ The syntactic positive shift (SPS) is elicited by

• Phrase structure anomalies

o “He gave the ball the to man”

• Verb tense anomalies  

o “The cats wont eating the food”

• Subject-verb disagreement

o “The lecture were interesting”

• Reflexive antecedent gender disagreement

o “The man gave herself a raise”

• Hypothesized Memory Process

o Encoding

o Consolidation

o Retrieval  

• Model of Working Memory in Humans

o Visuospatial ???? Central Executive ???? Phonological Loop

o Baddeley and Hitch proposed that working memory has three major parts ▪ Central Executive – is the command and control center

▪ “Phonological Loop” – acoustically codes information

▪ Visuospatial Sketchpad – represents vision and spatial storage of  

information

▪ “Episodic Buffer” – is a recent fourth part that links information to form  integrated units that are held in memory longer than with a Phonological  Loop

• Working Memory

o Lateral prefrontal cortex may provide a transient buffer for sustaining  information stored in other cortical regions

▪ Damage to LPC causes difficulty in remembering what certain things look  like

o Long-term knowledge is reactivated and maintained by connections between  prefrontal cortex and other more posterior regions of cortex

• Prefrontal Cortex

o Frontal cortex consists of the motor and premotor areas (including Broca’s area  and the frontal eye fields) and the prefrontal cortex which is divided in to lateral  and ventromedial subdivisions

• The Multiple-Trace Hypothesis of Memory

o Different cognitive and biological processes

o Different temporal stages of memory

o Two Important Structures for Memory

▪ Basal Ganglia

▪ Hippocampus

Memory

• Limbic System

o Temporal Lobe

▪ Amygdala

▪ Hippocampus

• Only structure in the brain that can generate new neurons

• Regenerates, but not at a rapid rate

• Hippocampus and Basil Ganglia are necessary for creating  

memories but memory is stored in the frontal cortex 

o Patients with Huntington’s Chorea, which causes a  

degeneration of cells in the Basal Ganglia are impaired on  

the mirror drawing task (not good with skill learning)

▪ Fornix

▪ Mammillary Bodies

• Output

• Does NOT regenerate

• Korsakoff’s Syndrome

o Alcoholics do not get enough Thiamine in their diet

o Temporal lobe structures are normal, but the Mammillary  

Bodies are severely damaged (degenerated) as well as  

parts of the Thalamus

• When damaged, cannot form new declarative memories 

▪ Thalamus

• Henry Gustav Molaison (HM)

o He suffered from severe epilepsy that started in his hippocampus, so he ended  up having his hippocampus and entorhinal cortex surgically removed

o Due to this he suffered two forms of amnesia

▪ Amnesia – memory loss

▪ Retrograde Amnesia – loss of memories formed before a traumatic event • Problem of consolidation (short and intermediate term memories) • Problem of retrieval (intermediate and long term memories)

▪ Anterograde Amnesia – inability to form new memories

• Problem of consolidation

o His short-term memory was normal, however, he could not form new long-term  memories

o Although, he could learn a mirror-tracing task without even remembering it,  which then implies that there are two forms of memory

• Long-term Memory

o Declarative – things you know that you can tell others

▪ Episodic (right ventral frontal cortex) – remembering your first day of  school

• Sense of subjective time

• Ability to be aware of subjective time

• A self that can travel in subjective time (autobiographical)

▪ Semantic (left temporal lobe) – knowing the capital of France

• Knowledge about the world (school)

• Not autobiographical

• Recognize people, family, friends, and words

o Procedural – things you know that you can show by doing

▪ Skill Learning (basal ganglia, motor cortex, cerebellum) – knowing how to  ride a bicycle

▪ Priming – being more likely to use a word you heard recently

• Perceptual – reduces activity in the bilateral occipitotemporal  

cortex

• Conceptual – reduces activity in left frontal cortex

▪ Conditioning – salivating when you see a favorite food

• Simple Delay Conditioning – cerebellar circuit

• Trace Conditioning – hippocampus and cortex

• Memory and Aging

o Glucose improves the performance of older rats on a memory task with mazes o Glucose also improves the performance of elderly humans on some memory  tasks