Neuroscience
Ch. 1) Structure and Function
1.1) The nervous system is made of specialized cells
Neurons
Nerve cells
the basic unit of the nervous system, each composed of receptive extensions called dendrites, an integrating cell body, a conducting axon, and a transmitting axon terminal
arranged into circuits that underlie all forms of behavior
80-90 billion in the brain
Glial cells
glia
nonneural brain cells that provide structural, nutritional, and other types of support to the brain
more in the brain than neurons
Neuron doctrine
neurons and other cells of the brain are structurally, metabolically, and functionally independent
information is transmitted from neuron to neuron across tiny gaps (later called synapses)
Synapses
the cellular location at which information is transmitted from a neuron to another cell
1.1.1) The neuron has four principal divisions
Input zone
the part of a neuron that receives information from other neurons or from specialized sensory structures
dendrites
an extension of the cell body that receives information from other neurons
Integration zone
the part of a neuron that initiates neuron electrical activity
cell body
some
region of a neuron that is defined by the presence of the cell nucleus
Conduction zone
the part of a neuron (typically the axon) over which the action potential is actively propagated
axon
nerve fiber
a single extension from the nerve cell that carries action potentials from the cell body toward the axon terminals
axon collaterals
a branch of an axon
Output zone
the part of a neuron at which the cell sends information to another cell
axon terminal
synaptic bouton
the end of an axon/axon collateral, which forms a synapse onto a neuron/other target cell and thus serves as the output zone
Motor neurons
motoneurons
a neuron that transmits neural messages to muscles/glands
large with long axons reaching out to synapse on muscles
Sensory neurons
a nerve cell that is directly affected by changes in the environment, such as light, odor, or touch
specialized to gather sensory information
Interneurons
a nerve cell that is neither a sensory neuron nor a motor neuron; receives input from and sends output to other neurons
most of the neurons in the brain
multipolar
a nerve cell that has many dendrites and a single axon
most common type of neuron
bipolar
a nerve cell that has a single dendrite at one end and a single axon at the other end
especially common in sensory systems
vision
unipolar
monopolar
a nerve cell with a single branch that leaves the cell body and then extends in 2 directions
input zone
output zone
transmit touch information from the body to the spinal cord
1.1.2) Information is transmitted through synapses
a neuron’s dendrites reflect the complexity of the inputs that are received
the configuration of synapses on a neuron’s dendrites and cell body is constantly changing
synapses come & go
dendrites change shape
dendritic spines wax & wane
neuroplasticity
neural plasticity
the ability of the nervous system to change in response to experience/environment
presynaptic
referring to the “transmitting” side of a synapse
postsynaptic
referring to a region of a synapse that receives and responds to neurotransmitters
Synapse parts
presynaptic membrane
the specialized membrane on the axon terminal of a nerve cell that transmits information by releasing neurotransmitters
synaptic vesicles
a small, spherical structure that contains molecules of neurotransmitters
Neurotransmitters
synaptic transmitter
chemical transmitter
transmitter
the chemical released from the presynaptic axon terminal that serves as the basis of communication between neurons
synaptic cleft
the space between the presynaptic and postsynaptic neurons at a synapse
20-40 nanometers
postsynaptic membrane
the specialized membrane on the surface of a neuron that receives information by responding to neurotransmitters from a presynaptic neuron
neurotransmitter receptor
receptor
a specialized protein that selectively senses and reacts to molecules of corresponding neurotransmitter/hormones
1.1.3) The axon integrates & then transmits information
axon hillock
the cone-shaped area on the cell body from which the axon originates
unique properties that allow it to gather & integrate the information arriving from the synapses on the dendrites and cell body
the axon is a hollow tube, and various important substances are conveyed through the interior of the axon from the cell body
axonal transport
the transportation of materials from the neuronal cell body toward the axon terminals, and from the axon terminals back toward the cell body
anterograde transport
moves materials toward the axon terminals
rapid transmission of electrical signals along the outer membrane (like a wire)
retrograde transport
moves used materials back to the cell body for recycling
slower transportation of substances within the axon, to and from the axon terminals (like a pipe)
1.1.4) Glial cells protect and assist neurons
Directly affect neuronal processes by providing neurons with raw materials, chemical signals, and specialized structural components
More glial cells than neurons in the brain
Myelin
the fatty insulation around an axon, formed by glial cells; this sheath boosts the speed at which nerve impulses are conducted
Nodes of Ranvier
a gap between successive segments of the myelin sheath where the axon membrane is exposed
Oligodendrocyte
a type of glial cell that forms myelin in the central nervous system
Schwann cell
a type of glial that forms myelin in the peripheral nervous system
Astrocyte
a star-shaped glial cell with numerous processes (extensions) that run in all directions
some stretch between neurons and fine blood vessels
controlling local blood flow to increase the amount of blood reaching more active brain regions
help to form the tough outer membranes that swaddle the brain
secrete chemical signals that affect synaptic transmission and synaptic formations
Microglial cells
microglia
extremely small motile glial cells that remove cellular debris from injured/dead cells
1.2) The nervous system extends throughout the body
Gross neuroanatomy
anatomical features of the nervous system that are apparent to the naked eye
neuron cell bodies, dendrites, axons, glial cells
Central nervous system (CNS)
the portion of the nervous system that includes the brain and spinal cord
Peripheral nervous system (PNS)
the portion of the nervous system that includes all the nerves and neurons outside the brain and spinal cord
1.2.1) The peripheral nervous system has two divisions
nerves
a collection of axons bundled together outside the central nervous system
motor nerves
a nerve that transmits information from the central nervous system to the muscles and glands
sensory nerves
a nerve that conveys information from the body to the ventral nervous system
1.2.1.1) The somatic nervous system
somatic nervous system
a part of the peripheral nervous system that supplies neural connections mostly to the skeletal muscles and sensory systems of the body
consists of cranial nerves and spinal nerves
cranial nerves
a nerve that is connected directly to the brain
12 pairs
olfactory (smell)
optic (vision)
oculomotor (muscles that move the eyes)
trochlear (muscles that move the eyes)
trigeminal (face, sinuses, teeth, jaw)
abducens (muscles that move the eyes)
facial (tongue, soft palate, facial muscles, salivary glands, tear glands)
vestibulocochlear (inner ear: hearing, balance)
glossopharyngeal (taste, other mouth sensations, throat muscles)
vagus (internal organs)
spinal accessory (neck muscles)
hypoglossal (tongue muscles)
spinal nerves
a nerve that emerges from the spinal cord
8 cervical
referring to the topmost 8 segments of the spinal cord, in the neck region
12 thoracic
referring to the 12 spinal segments below the cervical portion of the spinal cord, in the torso
5 lumbar
referring to the 5 spinal segments in the upper part of the lower back
5 sacral
referring to the 5 spinal segments in the lower part of the lower back
1 coccygeal
referring to the lowest spinal vertebra
tailbone
1.2.1.2) The automatic nervous system
autonomic nervous system
a part of the peripheral nervous system that provides the main neural connections to the internal organs
“autonomous” in the sense that we have little conscious voluntary control over its actions
Sym
1.2.2) The central nervous system consists of the brain and spinal cord
1.2.2.1) Anatomical conventions for describing the anatomy of the brain
1.2.2.2) The outer surface of the brain
1.2.2.3) Development of subdivisions within the brain
1.3) The brain shows regional specialization of functions
1.3.1) The cerebral cortex performs complex cognitive processing
1.3.2) Important nuclei are hidden beneath the cerebral cortex
1.3.3.) The midbrain has sensory & motor components
1.3.4) The brainstem controls vital body functions
1.3.5) Behaviors & cognitive processes depend on networks of brain regions
1.4) Specialized support system protects and nourishes the brain
1.4.1) The brain floats within layers of membranes
1.4.2) The brain relies on two fluids for survival
1.5) Scientist have devised clever techniques for studying the structure and function of the nervous system
1.5.1) Histological techniques let us view the cells of the nervous system in varying ways
1.5.1.1) Regional cell counts
1.5.1.2) Individual cell shapes
1.5.1.3) Expression of cellular products
1.5.1.4) Interconnections between neurons
1.5.2) Brain-imaging techniques reveal the structure & function of the living brain
1.5.2.1) Computerized axial tomography
1.5.2.2) Magnetic resonance imaging
1.5.2.3) Functional brain imaging
1.5.2.4) Magnetic stimulation & mapping
1.6) Careful research design is essential for progress in behavioral neuroscience
1.6.1) 3 types of study designs probe brain-behavior relationships
1.6.2) Aniamal research is an essential part of life science research, including behavioral neuroscience
1.6.3) Behavioral neuroscience use several levels of analysis
Ch. 8) Hormones & Sex
8.1) Hormones act in a great variety of ways throughout the body
Hormones
a chemical, usually secreted by an endocrine gland, that is conveyed by the bloodstream & regulates target organs/tissues
Endocrine glands
a gland that secretes hormones into the bloodstream & regulates target organs/tissues
release hormones within the body
Exocrine glands
ducts that secrete fluid outside the body
8.1.1) Hormones are 1 of several types of chemical communication
Endocrine
referring to glands that release chemicals to the interior of the body. These glands secrete the principal hormones used by the body
Methods of chemical signaling
synaptic communication
endocrine communication
pheromone communication
a chemical signal that is released outside the body of an animal & affects other members of the same species
allomone communication
a chemical signal that is released outside the body by one species & affects the behavior of other species
Hormones can be classified by chemical structure
3 categories
peptide hormones
aka protein hormones
a hormone that consists of a string of amino acids
amine hormones
monoamine hormones
a hormone composed of a single amino acid that has been modified into a related molecule, such as melatonin/epinephrine
steroid hormones
any of a class of hormones, each of which is composed of 4 interconnected rings of carbon atoms
Hormones act on a wide variety of cellular mechanisms
peptide/amine hormones
bind to specifc receptor proteins on the surface of the target cell
Figures to study
8.8; 8.12; 8.14; 8.20; 8.24; 8.25
Ch. 10) Biological Rhythms & Sleep
10.1) Biological rhythms organize behavior
Biological rhythms
a regular fluctuation in any living process
hormone levels
body temperature
drug sensitivity
circadian rhythms
a pattern of behavior, biochemical, or physiological fluctuation that has a 24-hour period
ultradian
referring to a rhythmic biological event with a period shorter than a day, usually from several minutes to several hours long
bouts of activity, feeding, and hormone release
infradian
referring to a rhythmic biological event with a period longer than a day
menstrual cycle
behavioral disorders
seasonal depression
10.1.1) Circadian rhythms are generated by an endogenous clock
Humans are diurnal
active during the day
nocturnal
active during dark periods
Free-running
referring to a rhythm of behavior shown by an animal deprived of external cues about time of day
Period
the interval of time between 2 similar points of successive cycles
Every animal has its own endogenous clock; periods vary from one individual to another
Normally, reset by light
phase shift
a shift in the activity of a biological rhythm, typically provided by a synchronizing environmental stimulus
like light
entrainment
the process of synchronizing a biological rhythm to an environmental stimulus
Zeitgeber
literally “time giver” in German
the stimulus that entrains circadian rhythms
usually the light-dark cycle
Jet-lag
10.1.2) The hypothalamus houses a circadian clock
large lesions of the hypothalamus interfered with circadian rhythms
Suprachiasmatic Nucleus (SCN)
located above the optic chiasm
lesions damaged rhythms of drinking, locomotor behavior, and hormone secretion
if SCN cells are taken from the brain and placed in a dish, they will still show electrical activity of circadian rhythms for days-weeks.
10.1.3) In mammals, light information from the eyes reaches the SCN directly
most vertebrates have photoreceptors outside the eye that are part of the mechanism of light entrainment
at night, the pineal gland secretes melatonin
an amine hormone that is secreted by the pineal gland at night, thereby signaling day length to the brain
in humans, the cells in the eye tell the SCN when it gets dark
retinohypothalamic pathway
the route by which specialized retinal ganglion cells send their axons to the SCN
veers out of the optic chiasm to synapse directly to the SCN
carries information about light to the hypothalamus
most of these cells don’t rely on traditional photoreceptors to learn about light
melanopsin makes them sensitive to light
a photopigment found in those retinal ganglion cells that project to the suprachiasmatic nucleus
appear to be absent/dysfunctional in most totally blind humans
taking melatonin helps sighted people to get to sleep & helps blind people to entrain to daylight
while humans rely primarily on light stimulation of the retinohypothalamic tract to the SCN, our brains have enough sensitivity to melatonin that we can use it as a cue in the absence of light information
10.1.4) Circadian rhythms have been genetically dissected in flies & mice
Neurons in the mammalian SCn make the proteins Clock & Cycle
bind together to form a dimer
a pair of proteins attached to each other
Clock/Cycle dimer binds to the cell’s DNA to promote the transcription of other genes
The proteins made from these other genes go back to inhibit the action of Clock & Cycle
proteins degrade with time, therefore allowing the inhibition to be lifted
whole cycle takes ~24-hr to complete
People who feel energetic in the mornings are likely to carry a different version of the Clock gene than night owls
night owls are at a greater risk of depression and obesity
at puberty, most people shift their circadian rhythm of sleep
they get up later in the day
10.2) Sleep is an active process
10.2.1) Human sleep exhibits different stages
Electroencephalography (EEG)
the recording of gross electrical activity of the brain via large electrodes placed on the scalp
provides a way to define, describe, and classify levels of arousal & states of sleep
2 distinct classes of sleep:
Rapid-Eye-Movement (REM) sleep
aka: paradoxical sleep
a stage of sleep characterized by small-amplitude, fast EEG waves, no postural tension, and rapid eye movements
non-REM sleep
sleep divided into stages 1-3
defined by the presence of distinctive EEG activity that differs from that seen in REM sleep
Brain activity in a fully awake, alert person
desynchronized EEG
beta activity
low-amplitude waves with many relatively fast frequencies
>15-20 Hz
Brain activity in a relax and closed-eyed person
alpha rhythm
8-12 Hz
As drowsiness sets in, the time spent in the alpha rhythm decreases
shows waves of smaller amplitude & irregular frequency
vertex spikes
a sharp-wave EEG pattern that is seen during stage 1 sleep
the initial stage of non-REM sleep, which is characterized by vertex spikes, slow heart rate, and reduced muscle tension; the closed eyes may also roll slowly
Usually lasts several minutes
Stage 2 sleep
A stage of sleep that is defined by sleep spindles and K complexes
A characteristic 12-14 Hz wave in the EEG of a person said to be in stage 2 sleep
A sharp, negative EEG potential that is seen in stage 2 sleep
If woken up, people in the first 2 stages of sleep will deny even being asleep
Stage 3 sleep
Aka: Slow Wave Sleep (SWS)
A stage of non-REM sleep that is defined by the presence of large amplitude, slow delta waves
The slowest type of EEG wave, about 1/sec, is characteristic of stage 3 sleep
Represent a widespread synchronization of cortical neuron activity that has been likened to a room of people who are all chanting at the same time
As the night progresses, delta waves become more prominent
When the pituitary releases growth hormones
More prominent early in the night & then tapers off
REM sleep
After about an hour of stage 3 sleep
Abruptly
EEG displays a pattern of small-amplitude, high-frequency activity similar to being awake
Eyes dart rapidly while all other skeletal muscles show atonia
Complete absence of muscle tone
Brainstem regions are profoundly inhibiting motor neurons
More prominent in later cycles of sleep
First REM cycle is the shortest, while the last cycle (just before waking up) can be 40 minutes long
The total sleep time of young adults usually ranges from 7-8 hours
~half is in stage 2 sleep
REM accounts for ~20%
Repeating cycles of ~90-110 minutes long, recurring 4-5x a night
10.2.2) We do our most vivid dreaming during REM sleep
Dreams occur in all stages of sleep
REM dreaming
has visual imagery
Include a story that has odd perceptions
Sense that you’re there
non-REM dreaming
like thinking
Nightmares
A long, frightening dream that awakens the sleeper from REM sleep
Medications can make them more frequent
Prevalent
At least 25% of college students report having 1+ a month
Night terrors
Sudden arousal from stage 3 sleep that is marked by intense fear and autonomic activation
Sleeper doesn’t recall a vivid dream but may remember a crushing feeling in the chest
Common in children during the early part of an evening’s sleep
Don’t know the function of dreams
If they have a function at all
Activation-synthesis theory
Suggests our experiences in REM sleep are the more/less random result of neurons happening to be activated
10.3) Our sleep patterns change across the lifespan
The functions of sleep are more important during some stages of life than others
Human infants sleep a lot
But a clear cycle can take several weeks
Evident in 16 weeks
Characterized by shorter sleep cycles
Half of sleep in the first 2 weeks is in REM sleep
Can move directly from awake to REM
Active REM
Muscle twitching
Smiles
Grimaces
Vocalizations
REM may provide stimulation that is necessary for the maturation of the nervous system
10.3.1) Most people sleep appreciably less as they age
The character of sleep changes in old age
Total amount declines
The number of awake hours increases
Lack of sleep/insomnia is common in the elderly
60 y/os spend about half as much time in stage 3 sleep as they did at 20 y/o; by 90 y/o it disappeared
This may be related to diminished cognitive functions
Elderly are able to fall asleep easily, but they have a hard time staying asleep
10.3.2) Manipulating sleep reveals an underlying structure
Mental function is impaired
After sleep deprivation, we tend to need more than we would have
The particle or total prevention of sleep
Makes us sleepy
Behavioral effects of prolonged, total sleep deprivation vary appreciably & may depend on general personality factors & age
Occasional episodes of hallucinations
Increased irritability
Difficulty concentrating
Episodes of disorientation
Moderate effects of sleep debt can accumulate with successive nights of little sleep
Ever-mounting deficits in attention tasks and reaction speeds
Sleep-deprived patients reported not feeling sleepy, yet still displayed behavioral decifits
10.3.3) Sleep recovery may take time
Sleep recovery
The processes of sleeping more than normally after a period of sleep deprivation, as though in compensation
Stage 3 sleep shows the greatest difference from normal
Increase at the expense of stage 2
Makes up for accumulated deficits
REM sleep is more intense
More rapid eye movements
Prolonged sleep deprivation compromises the immune system & can lead to death
10.3.4) What are the biological functions of sleep?
10.3.4.1) conservation of energy
Use less energy when asleep than awake
SWS is marked by:
reduced muscular tensions
Lowered heart rate
Reduced blood pressure
Reduced body temperature
Slower respiration
10.3.4.2) niche addaptation
Ecological niche
The unique assortment of environmental opportunities & challenges to which each organism is adapted
10.3.4.3) physical restoration
Could be why most growth hormones are released during stage 3
Prolonged sleep deprivation leads to immune system compromization and in extreme cases, death
Mild sleep deprivation leads to more sensitive pain receptors
Those who work night shifts and sleep during the day were more likely to develop cancer
Evidence that sleep helps “clean” the brain
Flow of CSF is much faster during sleep, cleaning the brain’s waste
10.3.4.4) memory consolidation
We forget dreams soon after waking, unless we tell them to someone else or write them down
We cannot learn new materials while sleeping
May help us retain the things we learned before falling asleep
Most research suggests that SWS helps with memory consolidation
Synapses are rearranged during REM sleep, and some memory consolidation is dependent on REM sleep
10.3.5) At least 4 interacting neural systems underlie sleep
Sleep is an active state mediated by at least 4 interacting neural systems:
Forebrain
Generates SWS
Brainstem
Activates the sleeping forebrain into wakefulness
Pontine
Triggers REM sleep
Hypothalamic
Coordinates the other 3 brain regions to determine which state we’re in
10.3.6) The reticular formation wakes up the forebrain
Reticular formation
Aka: reticular activating system
An extensive region of the brainstem (extending from the deulla through the thalamus) that is involved in arousal
A diffuse group of cells whose axons & dendrites course in many directions
Lesions cause persistent sleep in animals
Basal forebrain region actively imposes SWS on the brain
Brainstem reticular formation seems to puch the brain from SWS to wakefulness
10.3.7) The pons triggers REM sleep
Locus coeruleus
A small nucleus in the brainstem whose neurons produce norepinephrine & modulate large areas of the forebrain
Important for REM sleep
Lesions to this area completely get rid of REM sleep
Electrical stimulation can induce/prolong REM sleep
Some neurons seem to be active only during REM sleep
One important job is to prevent motor neurons from firing
Inhibitory transmitters GABA & glycine produce powerful inhibitory postsynaptic potentials in spinal motor neurons
10.4) Sleep disorders can be serious, even life-threatening
10.4.1) A hypothalamic sleep center was revealed by the study of narcolepsy
Narcolepsy
A disorder that involves frequent, intense episodes of sleep, which last from 5-30 minutes & can occur anytime during the usual waking hours
Occur several times a day
Tend to enter REM in the first few minutes of sleep
Exhibit an otherwise normal sleep pattern at night
Cataplexy
Sudden loss of muscle tone, leading to collapse of the body without loss of consciousness
Can be triggered by sudden, intense emotional stimuli
Usually manifests itself between 15-25 years old & continues throughout life
Orexin
Aka: hypocretin
A neuropeptide produced in the hypothalamus that is involved in switching between sleep states, in narcolepsy, and in the control of appetite
People with narcolepsy have lost ~90% of these neurons
Seems to cause inappropriate activation of the cataplexy pathway that normally only happens in REM sleep
Normally keeps sleep at bay & prevents the transition from being awake to being in REM sleep
Neurons that produce orexin are almost exclusively found in the hypothalamus
The release of orexin goes to the previously mentioned 3 areas involved in sleep
Basal forebrain
reticular formation
Locus coeruleus
As well as the hypothalamic tuberomammillary nucleus
The same structure that is inhibited by the basal forebrain to induce SWS
The hypothalamus contains an orexin-based “switching board” between wakefulness states
Treatments for narcolepsy
Traditionally, amphetamines in the daytime were used
GHB helps some patients with narcolepsy
Aka: sodium oxydate
A newer drug is modafinil
Effective for preventing narcoleptic attacks
Posed as an alertness drug for those with ADHD
Sleep paralysis
A state, during the transition to/from sleep, in which the ability to move/talk is temporarily lost
People may experience sudden sensory hallucinations
The belief that something is crushing their chest
Never lasts for more than a few minutes
Best to relax and avoid panicking
One hypothesis states that it could be from the pontine center continuing to impose paralysis for a short period of time after the person wakes from a REM cycle
10.4.2) Some minor dysfunctions are associated with non-REM sleep
Some sleep dysfunctions are more common in children than adults
Night terrors
Sleep enuresis
Bed-wetting
associated with SWS
Most grow out of this without intervention
Some doctors prescribe a nasal spray of the hormone vasopressin before bed
Decreases urine production
Somnambulism
Sleepwalking
Getting out of bed & walking around the room - appearing awake
Sometimes persists into adulthood
Episodes can last a few seconds - minutes
The person usually doesn’t remember the episode
Occurs during stage 3 SWS
More common in the first half of the night
10.4.3) Some people appear to be acting out their nightmares
Most sleepwalkers don’t act out any dreams they may be having
REM behavior disorder (RBD)
A sleep disorder in which a person physically acts out a dream
Sometimes the person remembers a dream that fits well with the behavior
Usually begins after 50 years old
More common in men than women
The onset of RBD is often followed by symptoms of Parkinson’s disease & dementia
Suggesting that RBD may be a marker of neuro-degeneration
Breakdown appears to begin in the brainstem region
May be controlled by anti-anxiety drugs taken at bedtime
10.4.4) Insomniacs have trouble falling/staying asleep
Depending on the definition being used, the prevalence ranges from 10-40% of the adult population
More commonly reported in older populations, females, and tobacco/caffeine/alcohol users
It seems to be the outcome of various conditions
Situational factors
Work shift changes
Time zone changes
Changes in daily routine
Sleep-onset insomnia
Difficulty in falling asleep
Situational factors
Sleep-maintenance insomnia
Difficulty in staying asleep
Neurological & psychiatric factors
Sleep state misperception
Commonly, the perception of not having been asleep when in fact the person has been
Typically occurs at the start of a sleep cycle
Sleep apnea
A sleep disorder in which respiration slows/stops periodically, waking the sleeper
Excessive daytime sleepiness results from the frequent waking
Breathing may stop for about a minute
Breathing may slow alarmingly
Blood levels of oxygen drop markedly
Arises from the progressive relaxation of muscles in the chest, diaphragm, and throat cavity
Relaxation of the throat obstructs the airway - a kind of self-choking
Common in obese people
Or it arises from changes in the pacemaker respiratory neurons of the brainstem
Often accompanied by loud, interrupted snoring
Sudden infant death syndrome (SIDS)
Aka: crib death
The sudden, unexpected death of an apparently healthy human infant who simply stops breathing, usually during sleep
Speculated to be from sleep apnea
10.4.5) Although many drugs affect sleep, there is no perfect sleeping pill
Reliance on sleeping pills poses many problems
The newest classes of sleeping pills do little more for sleep than a placebo
Continued use causes a loss of effectiveness
Causing an increase in self-dosage
Cause changes in sleep patterns
Sleep drunkenness
Impairs waking activity
Memory gaps in daily activities
Trying to drive
Snaking
Internet shopping
Sex
drowsiness
10.4.6) Everyone should practice good sleep hygiene
Develop a routine
Get up at the same time every day (including weekends)
Go to bed at the same time every night
Avoid daytime naps
Avoid caffeine at night
Have a bedtime routine in a quiet & dark environment
Avoid using electronics
Figures to study
10.5; 10.8; 10.11; 10.20
Ch. 11) Emotions, Aggression, & Stress
11.1) Theories of emotion integrate physiological & behavioral processes
Our emotions are evolved programs that guide our responses to daily threats and opportunities
Emotion
A subjective mental state that is usually accompanied by distinctive cognition, behaviors, and physiological changes
Sympathetic nervous system
Part of the autonomic nervous system that acts as the fight-or-flight system, generally preparing the body for action
Parasympathetic nervous system
The part of the autonomic nervous system that generally prepares the body to relax & recuperate
11.1.1) Do emotions cause bodily changes or vice versa?
James-Lange theory
William James (1842-1910)
Carl Lange (1834-1900)
Autonomic reaction triggers feelings
Bodily responses cause the emotional experience
Therefore, different emotions feel different because they are generated by different constellations of physical responses
Cannon-Bard theory
Walter Cannon (1871-1945)
Philip Bard (1898-1977)
The brain must interpret the situation to decide which emotion is appropriate
The cerebral cortex simultaneously decides on the appropriate emotional experience & activates the autonomic nervous system to appropriately prepare the body, using either the parasympathetic system to help the body relax or the sympathetic system to ready the body for action
Simultaneous feeling & autonomic reaction
Folk psychology
Feeling triggers autonomic reaction
Informal observation suggested that emotions cause the body to react
Schachter & Singer theory
Cognitive attribution of emotion to arousal
Use context to cognitively attribute specific emotions to arousal
11.1.2) Is there a core set of emotions?
Like how the color spectrum can combine to make different hues, researchers wonder if it’s the same with emotions
Pluntchik, 2001
Proposes there are 8 basic emotions grouped in 4 pairs of opposites
joy/sadness
affection/disgust
anger/fear
expectation/surprise
All other emotions are combinations of these basic 8
11.1.3) Facial expressions have complex functions in communication
Ekman et. al.
Suggests there are distinctive expressions for anger, sadness, happiness, fear, disgust, surprise, & contempt
11.2) Do distinct brain circuits mediate different emotions?
One way to study the neuroanatomy of emotion is to electrically stimulate brain sites in conscious animals and then observe the effects on behavior
Brain self-stimulation
The process in which animals will work to provide electrical stimulation to particular brain sites, presumably because the experience is rewarding
People can also experience this
People receiving electrical stimulation in the septum feel a sense of pleasure ot warmth, or sometimes sexual excitement
Building on this, researchers started mapping brain sites that support self-stimulation responses
Almost all of these sites are subortical & are especially concentrated in the Medial Forebrain Bundle
A collection of axons traveling in the midline region of the forebrain
Nucleus accumbens
A region of the forebrain that receives dopaminergic innervation from the ventral tegmental area, often associated with reward & pleasurable sensations
One theory for this is that the electrical stimulation taps into dopaminergic circuits that are normally activated by behaviors that produce pleasurable feelings
11.2.1) Brain lesions also affect emotions
In the early 20th century, dogs that had their cortex removed were found to respond to routine handling with sudden intense decoricate rage
Decorticate rage
Aka sham rage
Sudden intense rage characterized by actions (snarling & biting in dogs) that lack clear direction
James Papez (1937)
Proposed a subcortical circuit of emotion
Noted associations between emotional changes and specific sites of brain damage
Limbic system
A loosely defined, wide-spread group of brain nuclei that innervate each other to form a network. These nuclei are implicated in emotions
Includes the mammillary bodies of the hypothalamus, the anterior thalamus, the cingulate cortex, the hippocampus, the amygdala, and the fornix
Klüver & Bucy (1938)
Early support for the limbic model of emotion
Studies of monkeys after the removal of their temporal lobes
Klüver-Bucy syndrome
A condition brought about by bilateral amygdala damage that is characterized by dramatic emotional changes, including reduction in fear & anxiety
11.2.2) The amygdala is crucial for emotional learning
Fear conditioning
A form of classical conditioning in which a previously neutral stimulus is repeatedly paired with an unpleasant stimulus until the previously neutral stimulus alone elicits the responses seen in fear
Allowed researchers to develop a map of the neural circuitry of emotional learning
Revealed the amygdala to be a key structure
Amygdala
A group of nuclei in the medial anterior part of the temporal lobe
Crucial for adverse conditioning & appetitive learning
Conditioned positive emotional reactions to attractive stimuli
On the way to the amygdala, sensory information about emotion-provoking stimuli reaches a fork in the “low road,” bypasses conscious processing & allows for immediate emotional reactions to stimuli
“Low road” - a direct projection from the thalamus to the amygdala
The “high road” pathway routes the incoming information through the sensory cortex, allowing for processing that, while slower, is conscious, fine-grained, and integrated with higher-level cognitive processes
11.2.3) Different emotions activate different regions of the human brain
Several forebrain areas are consistently implicated in varying emotions
Each emotion involves differential patterns of activation across a network of brain regions associated with emotion
Activity of the cingulate cortex is altered in sadness, happiness, & anger, while the left somatosensory cortex is deactivated in both anger & fear
Although different emotions are associated with different patterns of activation, there is a good deal of overlap among patterns for different emotions
Love, compared with friendship, involved increased activity in the insula & anterior cingulate cortex & reduced activity in the posterior cingulate and prefrontal cortices
11.3) Neural circuitry, hormones, and synaptic transmitters mediate violence and aggression
Agression
Behavior that is intended to cause pain or harm to others - whether physical, emotional, or mental
Intermale aggression is observed in most vertebrates
Aggression between males of the same species
Males are 5x as likely as females to be arrested on charges of murder in the US
11.3.1) Androgens seem to increase aggression
In seasonally breeding animals, inermale aggression waxes and wanes in concer with seasonal changes in levels of tesosterone
A hormone produced by male gonads that controls a variety of bodily changes that become visible at puberty; one of a class of hormones called andrgogens
Conversely, castrating males to remove the source of testosterone usually reduces aggressive behavior profoundly, and treating castrated males with testosterone restores fighting behaviors
More complicated in humans
Treating adults with extra testosterone didn’t increase aggression
Young men going through puberty experience a sudden large increase in circulating testosterone, yet they don’t show a correlated increase in aggressive behavior
Some studies report that testosterone levels correlate with hostility, as measured by behavior rating scales, and are also associated with unprovoked versus defensive violence in both men & women
At least 2 variables confound the correlations between testosterone and aggression
The observation that experience can affect testosterone levels
Dominance
11.3.2) Brain circuits mediate aggression
Modulated by brain activity associated with several neurotransmitter systems
Dopamine, GABA, vasopressin, serotonin
Medial amygdala
A portion of the amygdala that receives olfactory & pheronomonal information
Ventromedial hypothalamus (VMH)
The hypothalamic region is involved in sexual behaviors, eating, and aggression
Serves as a trigger to activate aggressive behavior
A direct input to the VMH from the SCN appears to regulate the daily variation in aggression seen in many species, including humans
Maternal aggression
Aggression of a mother defending her nest/offspring
Controlled by the neural circuits in the VMH, as well as other regions, including the preoptic area (POA), the premammillary nucleus, and a serotonergi projection originating from the midbrain
11.3.3) The biopsychology of human violence is a controversial topic
Some forms of human violence are characterized by sudden & intense physical assaults
Long-standing controversy surrounds the idea that some forms of intense human violence are caused by temporal lobe disorders
Aggression is sometimes a prominent symptom in people with temporal lobe seizures
A significant percentage of people arrested for violent crimes have abnormal EEGs or other indicatos of temporal lobe dysfunction
Psychopath
Not a psychiatric disorder with formal diagnostic criteria in the DSM-V
An individual incapable of experiencing remorse
Often, are intelligent individuals with superficial charm and have poor self-control, a grandiose sense of self-worth, and little to no feelings of remorse
Most people who score high on psychopathic tendencies lead normal, often highly successful lives
Don’t react as negatively to words about violence, and show blunted responses to averse cues associated with fear conditioning that typically causes strong reactions in other people
Imaging suggests that they have reductions in both the size & activity of the prefrontal cortex
11.4) Stress activates many bodily responses
Stress
Any circumstance that upsets homeostatic balance
11.4.1) The stress response progresses in stages
Alarm system
The hypothalamus activates the sympathetic nervous system to ready the body for action
Fight-or-flight
The sympathetic nervous system stimulates the adrenal medulla to release epinephrine and norepinephrine
Adrenal medulla - the inner core of the adrenal gland
Epinephrine -
aka adrenaline
A compound that acts both as a hormone and as a synaptic transmitter
Norephinephrine -
Aka noradrenaline
A neurotransmitter produced and released by sympathetic postganglionic neurons to accelerate organ activity
These hormones act on many parts of the body to boost heart rate, breathing, and other physiological processes that prepare the body for action
The hypothalamus stimulates the anterior pituitary to release the adrenal cortex
Adrenal cortex - the steroid-secreting outer rind of the adrenal gland
Activation of the hypothalamic-pituitary-adrenal axis (HPA axis) results in the release of adrenal corticosteriod hormones like cortisol
Adrenal corticosteroid hormones - a steroid hormone that is secreted by the adrenal cortex
Cortisol - a glucocortcoid stress hormone of the adrenal cortex
These hormones act slower than epinephrine, but they also ready the body for action
In general, childhood stress has an enduring impact on health in later life, including neural & cognitive development, emotional regulation, & measures of lifetime achievement
11.4.2) There are individual differences in the stress response
Why do individuals differ in their responses to stress?
One hypothesis focuses on early experience
Stress immunization
A little stress early in life seemed to make the animals more resilient to later stress
However, the rat pups in the study benefited because their mothers comforted them after the stress
suggests that this gentle tactile stimulation from Mom is crucial for the stress immunization effect
The immunizing benefit of early stressful experiences happens only if the children are promptly comforted after each stressful event
Maternal deprivation
Causes long-lasting changes in epigenetic regulation
Epigenetic regulation - changes in gene expression that are due to environmental effects rather than to changes in the nucleotide sequence of the gene
The brains of suicide victims revealed the same epigenetic change in expression of the adrenal steroid receptor, but only the victims who had a history of abuse or neglect as children
11.4.3) Stress & emotions affect our health
Psychosomatic medicine
A field of study that emphasizes the role of psychological factors in disease
Health psychology
Aka behavioral medicine
A field of study that focuses on psychological influences on health-related processes
Psychoneurolimmunology
The study of the immune system and its interaction with the nervous system and behavior
The brain influences responses of the immune system, and the immune cells and their products affect brain activities
Periods of elevated stress frequently suppress the immune system
11.4.4) Why does chronic stress suppress the immune system?
Brief stress doesn’t impair immune function - it may even enhance it
Longer-lasting stress has pronounced suppressive effects on the immune system
Adrenal steroids directly suppress the immune system
Relaxation training
Focusing one's attention on something calming while becoming more aware of one's body, trying to relax every muscle
Mindfulness-based stress reducation (MBSR)
Pairs relaxation with efforts to focus attention on the present moment, including sensations thoughts, and bodily sensations, in an open, nonjudgmental ways
Focused on results and doesn’t require practitioners to adopt any particular religious or spiritual views
Been shown to reduce activity in the amygdala and prevent relapses of anxiety disorders or depression
Figures to study
11.1; 11.8; 11.13; 11.18; 11.19
Ch. 12) Psychopathology
12.1) The toll of psychiatric disorders is huge
Diagnostic and Statistical Manual of Mental Disorders (DSM-V)
Provides a standardized system for diagnosing and classifying the major psychiatric disorders according to current knowledge
12.1.1) Schizophrenia is a major neurobiological challenge in psychiatry
Schizophrenia
A severe psychopathological disorder characterized by negative symptoms such as emotional withdrawal & flat affect, by positive symptoms such as hallucinations and delusions, and by cognitive symptoms such as poor attention span
Positive symptoms
In psychiatry, an abnormal behavioral state
Hallucinations, delusions, and excited motor behavior
Negative symptoms
In psychiatry, an abnormality that reflects insufficient functioning
Emotional & social withdrawal, and blunted affect
For many, this lasts a lifetime; for others, it appears & disappears unpredictably
12.1.2) Schizophrenia has a heritable component
12.1.2.1) Family studies
12.1.2.2) Adoption studies
12.1.2.3) Twin studies
12.1.2.4) Individual genes
12.1.3) An integrative model of schizophrenia emphasizes the interactions of factors
Increases the likelihood of developing schizophrenia
Prenatal stress
Mother & baby have incompatible blood types
Mother becomes diabetic during pregnancy
If there is a low birth weight for the baby
Evidence indicates that schizophrenia results from a complex interaction of genetic factors & stress
12.1.4) The brains of some people with schizophrenia show structural and functional changes
12.1.4.1) Ventricular abnormalities
Enlarged cerebral ventricles, especially the lateral ventricles
Come at the expense of brain tissue
12.1.4.2) Cortical abnormalities
Ch. 13) Memory & Learning
13.1) There are several kinds of learning & memory
Learning
The process of acquiring new & relatively enduring information, behavior patterns or abilities, characterized by modifications of behavior as a result of practice, study, or experience
The process of acquiring new information
Memory
The ability to learn & neurally encode information, consolidate the information for longer-term storage, & retrieve or reactivate the consolidated information at a later time
The specific information that is stored in the brain
The ability to store & retrieve information
Cannot be sure that learning has occurred unless a memory can be elicited later
13.1.1) For Patient H.M., the present vanished into oblivion
Amnesia
Severe impairment of memory
Usually a result of an accident or disease
Retrograde amnesia
Difficulty in retrieving memories formed before the onset of amnesia
Not uncommon
Anterograde amnesia
Difficulty in forming new memories beginning with the onset of a disorder
Patient H.M.
Henry Molaison
A man who had anterograde amnesia because of the surgical removal of medial temporal lobe structures
Amygdala
Most of the hippocampus
Medial temporal lobe & structure that is important for learning & memory
Declarative memories
A memory that can be stated or described
Facts & information that can be learned
Delayed non-mathcing-to-sample task
A test in which the individual must respond to the unfamiliar stimulus in a pair of stimuli
Nondeclarative memory
Procedural memory
A memory that is shown by performance rather than by conscious recollection
13.1.2) Damage to the medial diencephalon can also cause amnesia
Patient N.A.
A still-living man who is unable to encode new declarative memories, because of damage to the dorsomedial thalamus & the mammillary bodies
Dorsomedial thalamus
A limbic system structure that is connected to the hippocampus
Mammillary bodies
One of a pair of limbic system structures that are connected to the hippocampus
Korsakoff’s syndrome
A memory disorder, caused by thiamine deficiency, that is generally associated with chronic alcoholism
Degenerative disease in which damage is found in the mammillary bodies and dorsomedial thalamus, but not in temporal lobe structures like the hippocampus
People often fail to recognize or sense any familiarity with some items, even those presented repeatedly, yet frequently they deny that anything is wrong
Confabulate
To fill in a gap in memory with a falsification
Frontal cortex damage is also seen and probably causes the denial & confabulation that differentiates them from other people who have amnesia
The mammillary bodies may serve as a processing system connecting the medial temporal lobes to the thalamus &, from there, to other cortical areas
A brain circuit that includes the hippocampus, the mammillary bodies, and the dorsomedial thalamus is needed to form new declarative memories
Established declarative memories are not stored in these structures for the long-term
13.1.3) Brain damage can destroy autobiographical memories while sparing general memories
At least some declarative memories are stored in the cortex
Patient K.C.
Lent Cochrane
Sustained damage to the cortex that rendered him unable to form and retrieve episodic memories
Episodic memory
Autobiographical memory
Memory of a particular incident or a particular time & place
Semantic memory
Generalized declarative memory, such as knowing the meaning of a word
Extensive damage to the left frontoparietal & right parieto-occipital cerebral cortex, as well as severe shrinkage of both right and left hippocampus & nearby cortex
The bilateral hippocampal damage probably accounts for the anterograde declarative amnesia; but it doesn’t account for the selective loss of nearly all his autobiographical memory
Damage to the frontal and parietal cortex may be what resulted in the loss of autobiographical memory