-Branch like fibers, taper at end

-Synaptic receptors line surface. Receive info from other neurons. Surface area- more info received. Increased by branching and dendritic spines.

-Structure big part in determining neuron's shape

Contains cell nucleus and mitochondria.

-Metabolic maintenance functions

-Receives synaptic terminations from other neurons

-Long, thin fiber. One per neuron

-Information carrier to neurons, glands or muscles

-Insulated by myelin sheath

-Ends are swollen and bulbous

-Neurotransmitters released here

-Longest axons from spinal cord to feet

Efferent- Carries info AWAY from structure (i.e. motor neurons to rest of nervous system)

Afferent- Carries info TO a structure (i.e. sensory neurons to rest of nervous system)

Can be relative to any structure

"difference in electric potential"

-Electric gradient around each neuron

-Difference of electrical charge between inside and outside of cell

-Gradient maintained by membrane

-Called polarization

-During resting potential, sodium does NOT enter cell because sodium channels are closed

(slightly more negative inside cell, -70millivolts)

Electrical Gradient and Concentration Gradient

Electrical: (+) sodium ions outside of cell drawn in towards negative charges inside cell.

Concentration: Sodium more concentrated outside, more likely to enter the cell

1) At rest, neuron is slightly negatively charged

2) When stimulated past threshold, channels open up and sodium rushes in, causing a region of positive charge in the action

3) The positive charge causes nearby channels to open. When the channels close, potassium channels open and potassium exits the axon

4) Process continues as chain-reaction along axon. Influx of sodium de-polarizes axon, and outflux of potassium repolarizes axon.

5) Sodium/potassium pump restores resting concentrations of sodium and potassium ions

Hyperpolarization: Negative charge inside axon increases

Depolarization: Negative charge inside axon decreases

Threshold of Excitation: Level that depolarization must reach for action potential to occur

Action Potential: Rapid depolarization and slight reversal of the usual membrane polarization

-In action potential

-A neuron will either fire or not fire

-Size, amplitude and velocity of an action potential is independent of the intensity of the stimulus that intiated it

-If threshold met or exceeded, action potential. If not, no action potential.

1) Neurotransmitters manufactured and transported down axon

2) Vesicles that have neurotransmitters break up and release the neurotransmitters into synaptic cleft

3) Neurotransmitters bind to receptors

4) Stimulation of post-synaptic neuron beyond threshold leads to action potential in the neuron

5) Excess neurotransmitters reuptaken by presynaptic neuron

Set of axons within the CNS

-Also known as projection

-If axons extend from cell bodies in structure A to synapse in structure B, fiber "projects" from A onto B

Autonomic Nervous System: Nerves controlling heart, intestines and other organs

Somatic Nervous System: Nerves carrying infro from sense organs to CNS and from CNS to muscles and glands

-Carries messages from CNS to skeletal muscles controlling bodily movements (voluntary and involuntary)

-Receives incoming info from sense organs, muscles, joints and skin and transmits info to CNS

-Essential Bodily Functions: automatically control heartbeat, breathing, digestion, sweating and sexual arousal

-Emotion: Activated by emotional states, by throwing the internal organs out of balance in a minor way (i.e. anxiety can produce rapid heart beat, stomach ache, etc.)

1) Sympathetic: Nerves that prepare organs for VIGOROUS ACTIVITY. Axons connect SNS to spinal cord. Activate organs for fight or flight. Increase breathing and heart rate, decreasing digestive activity.

2) Parasympathetic: Vegetative, non-emergency responses by organs. Decreases heart rate, increases digestive activity.

Dorsal: Toward the back, away from the stomach side. Top of brain is dorsal because it has that position in 4-legged animals

Ventral: Toward the stomach, away from the back.

Anterior: towards front end

Posterior: towards back end

Superior: above

Inferior: below

Lateral: Toward the side, away from the midline

Medial: Toward the midline, away from the side

Proximal: located close to point of origin or attachment

Distal: More distant from point of origin or attachment

Ipsilateral: On the same side of the body (2 parts on left or 2 parts on right)

Contralateral: On opposite side of body

Coronal: Plane that shows brain structures as seen from the front

Sagittal: Plane that shows brain structures as seen from the side

Horiztonal: Plane that shows brain structures as seen from above.

Forebrain: thalamus, hypothalamus, cerebral cortex, hippocampus, basal ganglia

Midbrain: Tectum, tegmentum, superior colliculus, inferior colluculus, substantia nigra

Hindbrain: Medulla, pons, cerebellum

-Controls vital reflexes (breathing, heart rate, vomiting, salivation, coughing, sneezing)

-via cranial nerves

-Damage often fatal

-Some opiates suppress activities of medulla

-Bridge

-Spinal crossover point

-nuclei for many cranial nerves

-Made of medulla and pons working together

-Descending neurons: control motor areas of spinal cord

-Ascending neurons: Output to cerebral neurons and greater forebrain to increase arousal and attention

-Modulates brain readiness to respond

-Control of movement, balance and coordination

-Also involved with switching/shifting of attention and sensory timing

-12 pairs

-Connects muscles of head to brain

-Connects some internal organs to brain

-Nucleus integrates sensory info and regulates motor output

-Nuclei for 1-4 in midbrain and forebrain, 5-12 in hindbrain

-VERY small area on top of hindbrain

-Tectum is roof of midbrain

-Superior and Inferior Colliculi are swellings on each side of the tectum for sensory information

-Tegmentum is under tectum. Middle of midbrain

-Has substantia nigra, from which stems a dopamine containing pathway)

-Most anterior part of brain

-Outer part is cerebral cortex ("bark" or "brain")

-Under the cortex: thalamus, basal ganglia, limbic system

-"inner chamber" or "bridal bed"

-At center of forebrain, looks like 2 pears put together.

-Forms diencephalon with hypothalamus

-"relay station" provides main input to cortex

-A lot of sensory info (except olfactory) goes to thalamus first and then cortex

-Made up of many nuclei (specialized processing centers)

-Primary sensory input goes to thalamus and then single cortical area

-Thalamus gets some feedback from cortex to update thalamic output

-Wide connections to forebrain and midbrain areas

-Made up of a number of nuclei

-Sends messages to pituitary gland to release hormones

-Damage effects motivated behaviors: eating, drinking, sexual behavior, temperature regulation, etc.

-Part of the endocrine system

-Attached by stalk to base of hypothalamus

-Responds to messages from hypothalamus

-Synthesizes hormones and releases them into the bloodstream which then travel to organs

-"Sea horse"

-Between thalamus and cortex

-in posterior forebrain

-memory storage and consolidation

-Particularly anterograde memory

-Lateral to thalamus

-made of 3 major structures: caudate nucleus, plutamen and globus pallidus.

-Many divisions share info with many parts of cortex

-Many connections with frontal lobes (planning, memory, reasoning, attention, depression)

-Has stayed about the same in evolution

-Interlinked structures including olfactory bulb, hypothalamus, hippocampus, amygdala, and cingulate gyrus

-border around brainstem

-Role in motivated behavior (eating/drinking), emotion, sexual arousal/nature of activity, anxiety, aggression, etc.)

-fluid-filled spaces within the brain

-Choroid Plexus in ventricles produce cerebrospinal fluid (CSF)

-Some CSF goes down to central canal, most to spaces between brain and meninges

-CSF buffers the brain

-Obstruction can lead to hydrocephalus

-Gross anatomical features vs. cellular arrangement

-Biggest division: 2 hemispheres

-Cellular layer on outer surface of hemisphere makes up the cortex (gray matter)

-White matter: inward extending axons from cortex

-Mostly through corpus callosum

-Also in small part via anterior commisure and other subcortical commissures

Gyri: Postcentral and Precentral

Sulci: Central and Lateral

-Posterior aspect of brain

-Target of visual input

-primary visual cortex or "striate" cortex

-Posterior to central sulcus.

-primary somatosensory cortex

-Receives sensations about touch and info from muscle stretch receptors and joint receptors

-4 bands of cells parallel to central sulcus

-Light touch information goes to 2 bands, deep pressure to 1, combined to 4th

-Multimodal inputs

-Synthesizer of information

-Creates spatial and representational maps

-specialized for 3D coordinate transformations

-Extensive connections to all other parts of the brain

-Complex aspects of vision, motion, perception, face recognition

-Understanding spoken language

-Phenomena!

-From central sulcus to anterior end of brain

-Prefrontal cortex and primary motor cortex

-Posterior part is precentral gyrus, or primary motor cortex.

-Precentral gyrus

-90% contralateral control

-How much motor cortex devoted to a particularl motor function indexes the extent/complexity of motor control

-In frontal lobe

-massive in large brain species

-Receives sensory data (to different parts of frontal cortex)

-The neurons are the largest and greatest number of dendritic spines

-massive capacity for data integration

-top down control of some cortical areas

-important in working memory

-impulsivity, mood changes, loss of "executive control"

-Six distinct cell layers (laminae)

-Varying thickness of laminae; thickest in motor cortex

-Hierarchy among the layers

-Connections between the layers

-Differential spread of laminae across cortex

-Cells also arranged in columns

-Cells carrying similar properties and functions (veritcally through the laminae)

-Specialized to absorb light and transduce it into an electrochemical pattern in the brain

-What we see isn't an exact picture of the object in front of us

Pupil: opening in the center of the eye that allows light to pass through

Lens: focuses light on retina

Retina: back surface of eye lined by visual receptors. Light from above strikes bottom and light from below strikes top. Light from left strikes right and vice versa.

-Cornea: protective coating in surface

-Iris: Regulates amount of light entering

-Pupil: opening formed by iris

-Lens: focuses light on retina

-Ciliary Muscle: Controls lens shape

-Retina: Image falls onto it, contains rods and cones

-Fovea: Central spot on retina. (has heavy concentration of cones; blind spot)

1) Receptors send messages to bipolar and horizontal cells

2) They send messages to amacrine and ganglion cells

3) Axons of the ganglion cells loop together to exit the eye at the blind spot

4) They form the optic nerve which continues to the brain

-Rods and cones synapse to horizontal and bipolar cells

-Horizontal cells make inhibatory cells synapse onto bipolar cells

-BIpolar cells synapse to amacrine and ganglion cells

-Axons of ganglion cells leave back of eye

Macula: center with greatest ability to resolve detail. Fovea, at center of macula, provides most detail. Each visual receptor has a direct pathway to the brain through to one bipolar cell and one midget ganglion cell. Provides exact location of a point of light.

Periphery: Provides better sensitivity to dim light. Multiple receptors converge onto bipolar and ganglion cells. Can't detect exact location of shape of light, but convergence enables detection of very faint light

Rods: Visual receptors abundant in periphery of retina. Repond best to low light conditions, bleached by bright light

Cones: Visual receptors abundant in and around the fovea. Respond best to bright light conditions, essential for color vision

-Area of the visual field that strikes that receptor

-Where the inside half of the axons of each eye cross over

-most visual info goes through the lateral geniculate nucleus of thalamus, but some goes to superios colliculus.

-Lateral geniculate: inputs to other parts of thalamus and to visual areas of cerebral cortex, which sends back axons to modify input.

-Specific range of frequencies that humans can hear

-20hz-20,000hz

-Magnitude of auditory sensation

-Associated with sound pressure of stimulus (increasing pressure increases loudness)

1) Deliver sound stimulus to receptors

2) Transduce stimulus from pressure changes into electrical signals

3) Process electrical signals so they can indicate qualities of the sound source, such as pitch, loudness, timbre and location

-Pinnae: obvious part of ear

-Sound waves first pass through it

-Pinna and Auditory Canal

-Protects delicate structures of the middle ear

-Protects eardrum

-Helps keep the membrane and structures of the middle ear at a constant temperature

-Sound waves reach ear drum at end of ear

-sound waves send eardrum into vibrations

-vibtrations travel to structures on other side of eardrum

-Influenced by smell

-Taste receptors: modified skin cells sloughed off and replaced every 10-14 days. Have excitable membranes and release neurotransmitters.

-Located in papillae

-Along outside edge of tongue

-Some on tip and posterior third of tongue

-virtually nonexistent in center of tongue

-Papillae: give tongue rough appearance. 4 kinds, each with different shape.

-Make up taste bud

-Many cells per bud, tip sticks out into a taste pore

-one or more nerve fibers associated with each cell

1) Sweet, bitter and (likely) glutamate/umami. Activates protein that releases second messenger within the cell.

2) Salty. Detects presence of sodium. Higher concentration, stronger response

3) Sour. Closes potassium channels, preventing potassium from leaving the cell creating a depolarization

-Branch of 7th cranial nerve

-Carries atnerior 2/3 of tongue to brain

-Loss of taste here and posterior of tongue can still taste sensations

-Posterior becomes more active and may release tastes when nothing is there

-In medulla; taste nerves project to it

-Branches to pons, lateral hypothalamus, amygdala and ventral-posterior thalamus

-Then to 2 areas of cortex, one for taste, one for touch

-Monitors movement of head, directs eye compensation and maintains balance

-When head tilts, otolith organs (utricle and saccule) push against different haircells. Also, jellylike substance in 3 semicircular canals cause bending of hair cells.

-Action potentials from cells travel through 8th cranial nerve to brain stem and cerebellum

1) Kinesthetic receptors and 2)vestibular organs

Vestibular organ: composed of 2 semicircular canals and keep the body informed about orientation in 3 planes

Somatosensory receptors vary in complexity and stimuli that they respond to.

Different names based on specialized functions

Pacinian: Detects sudden displacements or high-frequency vibrations on the skin

Meissners: Elaborate neuronal endings detect sudden displacement and low frequency vibrations on skin

Ruffini: detect stretch of skin

Merkels: detect indentation of skin

-Touch information from head enters CNS through cranial nerves

-Below head, info enters enters through 31 spinal nerves connecting to 31 dermatomes

-Reduce pain

-Found in brain

-Responsive to opiate drugs (i.e. morphine)

-Brain chemcicals that attach to the same receptors as morphine

-bind to opiate receptors

-Stimulated by pain, sex, long-distance running and loud music

-Constantly changing within limits

-Major changes during development, growth milestones, learning/experience, and response to brain damage

1) Production of Neurons

2) Growth of axons

3) Fine tuning by experience

-Start of formation of NS

-Dorsal surface thickens, long thin lips rise, curl and merge

-Neural tube forms containing fluid-filled cavity

-Forward end enlarges, becomes hind, mid and forebrain

-Remaining tube becomes spinal cord

-Tube's cavity becomes central canal of SC and brain's ventricle

-Proliferation

-Myelination

-Migration

-DIfferentiation

-Synaptogenesis

-Production of new cells

-Start with cells lining ventricles, then divide and redivide

-Some become primitive neurons and glia

-Primitive neurons move to eventual destinations

-Different kinds of neurons: different points of origination, different timing, migrate over large distances, radial and tangential migration

-possible interference by genes or toxins

-Primitive neuron initially looks like an ordinary cell; gradual differentiation into its basic parts

-Axons grow before dendrites

-Axons may grow during migration

-Dendrites grow after axon reaches destination

-Dendrite growth slow; faster when more axons arrive.

-Migrate over large distances

-Radial and tangential migration

-Can be affected by genes or toxins

-After formation, many vertebrate become insulated by fatty sheaths produced by glial cells (myelination)

-In humans, myelination is first in spinal cord, then in hindbrain, midbrain and forebrain

-Process continues gradually

-Formation of synapses

-Continues throughout life

-Cholesterol essential

-Sensitive to imbalances in local chemical environment

1) Right number of neurons in each part of the NS

2) Receive axons from right source

3) Neurons must send own axons to right places

4) Timing: neurons in some areas develop before others arrive

In a normal, healthy NS: no extra neurons!

-Nerve Growth Factor

-Delivered by muscle to synapsing axon

-Axons that don't receive enough NGF will degenerate; cell bodies die

-Built in suicide mechanism

-Neurotrophin, promoting growth and survival

-BDNF: brain derived neurotrophic factor, NS neurons respond to it

-Preprogrammed mechanism of cell death

-Cell goes through this that if it a certain point in time, it doesn't reach the right post-synaptic cell

-NGF cancels apotosis

-Early in development, secreted by target and axons grow towards them

-Axons that synapse target get more neurotrophins so that axons can survive

-Later in development, neurons secrete neurotrophins to stimualte branching of incoming axons

1) If some fail to reach targets, others will

2) More likely that with large number of neurons, CNS can match right number to number required by target region/organ

-How axons find their way

-Which axons attach to which region/organs does matter

Paul Weiss: Thought it didn't matter. Said that neurons attach to muscles randomly but muscles will only respond to some kinds of neurons

-Experiment with axons' pathfinding

-Cut newt's optic nerve and did 180degree rotation of eye. Regrowth of axons to tectum (from retina) follow original plan. Newt sees world upside down.

-Neurons grow back to where they originally were. Follow chemical signal.

-Not one separate chemical for each axon

-Growing axons first follow a path along cell surface molecules in the direction of target (chemical attraction and repulsion process)

-At a certain location, axons become no longer sensitive to this surface molecule path.

-Follow a new attractant chemical to get to final target

-Effects of experience on dendritic branching

-Effects of experience on brain structures

-Effects of experience on synapse structure

-Brain needs to meet some essential size/capacity to drive the body and its functions

-Beyond capacity, brain represents additional processing, which makes up "intelligence"

Quantitative: more columns in neocortex

Qualitative: patterns of connectivity between different cortical regions and different laminar layers, relative richness of laminar layers

many brain areas get larger. Some more disproportionately than others.

-Increased forebrain proportion comes primarily through expense of midbrain and medulla

-cerebellum proportion consistent among species.

-In humans, major speech area called Broca's area

-Apes have area similar to Broca's, but it is largely over-represented in humans. NOT specialized for language in apes

-Affect action potential

-Help neuron synthesize NTs or diminish production of NTs

-Help neuron transport NTs to axon terminal

-increase release of NT at terminal

-Help with transport of NT across synapses

-Help with reuptake of a NT
-ACT as NT and bind to receptor

Neurotransmitters: released in small quantities within proximity to neuron

Hormones: released in large quantities, flows through blood to various targets.

Some chemicals, like epinephrine, norepinephrine, insulin and oxytocin can work as hormones AND NTs

Amine group NH2 act as NTs

GABA, glycine, glutamate, aspartate

-Drugs that increase alertness and activity level and elevate mood

Examples: amphetamines and cocaine, clinical antidepressants, caffeine, nicotine

Drugs that counteract anxiety and/or decrease alertness and activity level

Examples: Benzodiazepines, alcohol

-Pain reducers, cause feelings of euphoria

Examples: opium, morphine, heroin, endorphins (natural)

-Prescribed mostly to treat schizophrenia

-decrease activity at synapse where dopamine is transmitter

Induce hallucinations and sensory distortions. Act either by mimicking or blocking transmitters they resemble.

LSD and psilocybin resemble serotonin

-Role in communication within the body and regulation of bodily processes

-Glands which secrete hormones into the bloodstream

-Hormones carried to various parts of the body

-Hormones influence many organ systems and some glands

-Directly regulated by brain (esp. hypothalamus)

-Aid nervous system's ability to control body by activating many organs during physical stress or emotional arousal, and influencing metabolism, blood-sugar level and sexual functioning

-Above kidneys

-secrete hormones important in metabolism

-important in emotional arousal

-secretes 3 hormones involved in reactions to stress: ephinephrine, norepinephrine and cortisol

-Embedded in pancreas

-Regulates amount of sugar in blood by secreting glucagon (causes lliver to convert its stored sugar and release sugar into blood) and insulin (reduces amount of blood sugar by helping body's cells to absorb the sugar)

-Produce sex cells (ova in female, sperm in male)

-Produce hormones involved in sexual arousal and development

-estrogen and testosterone most important

-Located below larynx

-Important in metabolism

-4 small glands embedded in thyroid gland

-Secretes parathormone (important for functioning of nervous system)

-Parathormone regulates ion levels in neurons and thereby controls excitability of the nervous system

-Located between 2 cerebral hemispheres on top of thalamus

-Secretes melatonin, which is important in biological rhythms

Circannual: internal calendar which prepares a species for annual SEASONAL changes

Circadian: Internal rhythms which last about a DAY.

SCN

-part of hypothalamus

-controls rhythm for sleep and temperature

-neurons generate impulses that follow circadian rhythm

-Bio clock is ROBUST- insensitive to many forms of interference

-Regulates amount of proteins which induce or inhibit sleepiness

-Hormone released by pineal gland.

-2-3 hours before bedtime

Free-running: rhythm that occurs when no stimuli are needed to reset or alter it

Zeitgeber: stimulus necessary for resetting circadian rhythm (i.e. light)

Noise, meals, temperature can affect resetting of circadian rhythms

-8-12 brain waves per second

-typuical of relaxed state of consciousness

-Also known as REM

-discovered in cats. brain active, muscles relaxed

-REM has repeated eye movements, fast low-voltage brain waves, breathing and heart rate similar to phase 1 of sleep.

Adenosine: Inhibitor substance in brain's arousal system. Caffeine increases arousal by inhibiting adenosine.

GABA: inhibitory NT, promotes sleepiness

1) Repair and restoration: body must repair itself from exertions during the day. rebuild protein, replenish supply of energy

2) Evolutionary theory. We need sleep to save energy when we would otherwise be energy defficient, such as during the night.

-Memory storage and consolidation (helps brain discard neuronal connections formed accidentally during the day)

-get oxygen to corneas by shaking eyeballs!

1) Activation-Synthesis Hypothesis: many brain regions activate, brain creates a story to make sense of the activity. Cortex combines haphazard input with other activity already occuring, synthesizes it, interprets sum

2) Clinico-Anatomical Hypothesis: Internal or external stimulation activates parts of the parietal, occipital and temporal cortex. no visual information to override stimulation or pre-frontal censorship, so develops as hallucinations.

-3 types of cells in primary visual cortex

1) Simple cells: fixed, small receptive field. Fixed excitatory and inhibatory zones, must have bar or edge shaped receptive fields

2) Complex cells: large receptive field. Respond to a particular orientation anywhere within large receptive field, receive input from combination of simple cells

3) End-stopped or hypercomplex cells: resemble complex cells with a strong inhibatory area at one end of its bar shaped recpetive field.

1) pathway originating mainly from magnocellular neurons

2) mixed magnocellular/parvocellular pathway

3) Mainly parvocellular pathway.

neurons sparsley connected with neurons of other pathways

-from ventral stream

-specialized for identifying and recognizing objects

-if damaged, we can find and pick up objects but cannot describe them

"what" path

-From dorsal stream

-"where" or "how" path, helps motor system find objects, move toward them and pick them up.

-damaged, we can describe objects but can't find and pick them up

-FFA

-specialized for faces and other complex objects

-neurons in FFA of people who are experts in objects like cars or birds can respond to humans AND to cars or birds.