PSB3340 Exam 1

Neuroscience

the study of the nervous system

Behavioral Neuroscience

the study of the neural mechanisms underlying behavior and mental processes

Five Viewpoints of Behavioral Neuroscience

1. Describing Behavior

2. Otogeny (development of behavior)

3. Mechanisms of Behavior

4. Application of Behavior

5. Evolution of Behavior

Somatic Intervention

alterations to brain/body structure/function to see how behavior is exchanged/affected

ex.) intervene with "administering a hormone", affects "strength of mating behavior"

-If there is no functional specialization, them amount of behavioral impairment should correspond to the size (not the location) of damage

Behavioral Intervention

alter behavior implemented to see how brain structure/function is changed/affected

-how does experience change the brain?

ex.) "change hormone levels" caused by behavioral intervention of "putting male in presence of female"

Correlation

extent to which a neural measure varies with a behavioral measure

-correlation is not causation

-suggests direct or indirect link

-Comparing different species, there is a this term (a statistical relationship; can substitute the more general term association) between brain size and higher cognitive processing

-Within the human species, only weak correlations between IQ (or other measures) and brain size or degree of connectivity between regions

-does not necessarily mean that one causes the other (it may, but cause is much harder to demonstrate)

We usually rely on controlled experiments (as opposed to just observation), where one independent variable (IV) is manipulated to observe the effects upon a dependent variable (DV), to investigate cause-effect

-If the variables of interest can not be manipulated—as they can in a controlled experiment—but only observed, usually we settle for measuring an association (such as a correlation) between them

Neuroplasticity

the structure of the brain is changing with experience and the environment

-not just restricted to the developing brain

-occurs in response to stressors, damage, the environment, learning new hobbies

-ex.) aversive conditioning (prev. neutral stimulus is paired with an aversive outcome repeatedly and reliably)

-occurs with social experiences (Cooke et al (2000), Rainville (1997))

Levels of Analyzing the Link of Brain and Behavior

social level>organ level>neural systems level>brain region level>circuit level>cellular level>synaptic level>molecular level

-reductionism= breaking down system into units to better understand it

Reductionism

breaking down system into units to better understand it

-Studying complex systems with many interacting parts—like brains or cities—usually necessitates this type of approach

daVinci

anatomical drawings of body and brain

Rene Descartes ~1650

-Hydraulic machines were th4e latest in technology

-Proposed that the body operated hydraulically, pushed by fluid within the hollow chambers of the brain (ventricles)

-wrote "De Homme" (On Man)

-animal behavior is similar to the workings of a machine while humans had non-material soul that could initiate actions in the material body

-proposed spinal reflexes and their neural pathway

-mind/body connection to pineal gland

-Philosophers argued that there would be no free with and there is a mind body problem but descartes answer was dualism

-"dualism"= soul and body are separate -although located within- the brain

Franz Joseph Gall

rejects dualism

-proposes "localization of function"

-phrenology= bumps on head

Paul Broca

-Discovered stroke damage to a small region of the left side of the brain disrupted only a person's ability to speak (could still understand speech, walk, etc.)

-localization of language production after seeing evidence of regional atrophy

Brodmann

52 cortical functioning areas

Ebbinghaus/James

E: wrote "On Memory"

-measured learning and memory in ppl

J: wrote "The Principles of Psychology"

-furthered idea that conciousness and human experience exist to the nervous system

Pavlov

"conditional reflex"

-classical conditioning

Donald Hebb

"Organization of Behavior"

-complex behavior is accomplished via networks of activated neurons

-"cells that fire together, wire together"

Carmillo Golgi

"neurons are continuous"

-developed stain to dye a minority of neurons in great detail

Santiago Ramon y Cajal 1906

Established The neuron doctrine -

the nervous system is comprised of billions of individual cells called neurons instead of being a continuous sheet

The Neuron Doctrine

1. cells are independent from one another structurally, functionally, and metabolically

2. info is transmitted via tiny gaps in between two neurons (synaptic)

Structural Divisions of a Neuron (4 zones)

1. Input

2. Integration

3. Conduction

4. Output

3 Principle Forms of Neurons

-multipolar: multiple dendrites, one axon, most common

-bipolar: 1 dendrite, 1 axon, in sensory system

-unipolar/monopolar: single processes branch from soma, are somatosensory neurons

-see notes for illustrations

Interneuron

-Only in the CNS

-Connect sensory and motor systems

-multiple dendrites, short axons

-receive, process, pass info to other neurons

-make up networks and circuits

Motor Neuron

-Transmit info from the CNS to muscles, organs, and glands

-governs movement

-long axons carry info from brain to muscles, organs, and glands

Sensory Neurons

carry info from peripheral tissue to CNS (brain and spinal cord)

Presynaptic Axon Terminal

info transmission

-synaptic vesicles (30-140nm) hold neurotransmitters

-vesicles fuse with presyn. membrane to release neurotransmitters into synaptic cleft

Across Synaptic Cleft

info transmission

-NTs diffuse across and encounter postsynaptic receptors

Postsynaptic Dendritic Spines

info transmission

-NT bind to receptors, create local changes to electrical system

-most NT not taken by postsyn; diffuse away, taken up by support cells

Info Processing

dendritic arborization determines complexxity of connections

axon hillock

cone-shaped projection of soma, acts as an integration zone

-integration zone determines whether electrical signals will travel down axon

-0.2-20micrometers in diameter

Transport: Anterograde

from soma to terminals

-substance packed in transport vesicles that "walk" along microtubule

-carried by kinesin (motor protein)

Transport: Retrograde

from terminals to soma

-carried by dynein (motor protein)

-fast (200-400mm/day) v.slow (

Glial Cells

the "glue" of the nervous system

-function as support cells, provide raw materials and chemical signals to neurons

-4 forms: 75% oligo, 17% astro, 7% microglia

Astrocyte- Glial Cell

star-shaped, weave among neurons

-have end feet to regulate local blood flow to provide materials to active neurons

-evidence of tripartites synapses in which astrocytes directly influence info transmission

-involved in forming new synapses and pruning old ones

Microglia- Glial Cell

small cells, brain's clean-up crew

-move to site of injury/disease to clear debris

-involved in pain perception and neuronal remodeling

Schwann Cells- Glial Cells

provide myelin to nerves in peripheral nervous system

-insulates a limited length of an axon

Oligodendrocyte- Glial Cells

myelination of neurons of CNS

-wrap around axon in layers for signal transmission

-makes "nodes of Ranvier"=cracks in myelin where AP occurs

-1 cell= multiple axons; provide trophic signals to enhance structural integrity of neuron

Glial Dysfunction

-edema: swelling, cell's response to injury, prone to tumors (astrocytes)

-epilepsy: astrocytes affect local brain chemistry

-Alzheimer's Parkinson's, amyotrophic lateral sclerosis= astrocytes and microglia

-multiple sclerosis: loss of myelin

-schizophrenia: change in all kinds of glial cells

Myelination

increase speed of signal down axon, allows signal to jump from node to node

-PNS=schwann

-CNS=oligo

Peripheral Nervous System (PNS)

All parts of the nervous system found outside the skull and spinal column

Somatic Nervous System (PNS)

connects brain and major muscles/sensory system

-sensory/motor system of head/neck, not of the spinal cord

-Cranial Nerves: 12 pairs*Some are sensory, some are motor, some have both functions-separate axons in the nerve carry the sensory and motor signals

-Spinal Nerves: 31 pairs*Each spinal nerve composed of two branches or roots (dorsal root and ventral root)

-Pairs=left & right sides

-Also called voluntary nervous system; voluntary control of the body

Autonomic Nervous System (PNS)

connect brain and viscera

--Spans the Central and Peripheral Nervous system and includes sympathetic NS, parasympathetic NS, enteric NS

-Operates mostly unconsciously, controlling functions such as heart rate, digestion, and constriction/dilation of the pupil

-controls viscera/organs; neurons innervate ganglia which sends axons to innervate major organs

Ganglia

bundles of neurons outside CNS

-preganglianic autonomic neurons arise in CNS

-postganglianic autonomic neurons arise in ganglia

Enteric NS (Autonomic NS)

-Local network of neurons that governs function of the gut and maintains fluid-nutrient balance

-Controlled by the CNS but functions semi-autonomously

Sympathetic Nervous System (Autonomic NS)

preganglionic cells in the thoracic/lumbar region

-innervate sympathetic chain along spinal cord

-Expenditure of Energy

-postganglionic cells send axons to major organs to prepare the body for action (fight v. flight)

-Main neurotransmitter is norepinephrine (noradrenaline)

Parasympathetic NS (Autonomic NS)

preganglianic cells exist in cervical (brainstem) and sacral regions

-Production/storage of energy

-axons terminate in parasympathetic ganglia throughout body

-postganglianic anxons are short and prepare the body to relax (rest and digest) and the activation is often in opposition to sympathetic activity

-Main neurotransmitter is acetylcholine

Ganglion

collection of neurons (cell bodies/somas) in PNS

Nerve

In the PNS: a bundle of axons

-A collection of the 'wiring' portion (axons/nerve fibers) of many neurons

Tract

bundle of axons in CNS

Nucleus

within the CNS, a collection of cell bodies (somas

saggital plane

divides the body into a right and left side

coronal plane

An imaginary plane where the body is cut into front and back parts.

axial plane

A horizontal flat surface dividing the body into upper and lower parts; also known as the transverse plane

Brain

3lbs of mostly fat from myelin tissue, 2 cerebral hemispheres

frontal lobe

front section of brain

-movement and high-level cognition

parietal lobe

middle and top sections of brain

-spatial cognition

occipital lobe

back section of brain

-visual processing

temporal lobe

middle and bottom sections of brain

-auditory processing, sense of smell, aspects of learning

Central Nervous System (CNS)

-The brain and the spinal cord

-develops from neural tube at head end, splits into four divisions

-forebrain

-midbrain

-hindbrain

-brainstem

Forebrain

-AKA the executive brain is the outermost covering and it has expanded the most

-"prosencephalon"

-includes diencephalon (thalamus and hypothalamus)

-includes telencephalon (cerebral hemispheres)

Midbrain

"mesencephalon"

Hindbrain

"rhombencephalon"

-includes "metencephalon" (cerebellum and pons)

-incldues myelecephalon (medulla)

Brainstem

cerebellum, pons, medulla

-part of hindbrain

Cerebral Cortex

6 layers based on type of neuron and patterns of dendrites and axons

-two cell types: pyramidal and cortical

1. telencephalon

2. diencephalon

3. mesencephalon

4. cerebellum

5. pons

6. medulla

Pyramidal Cells

of cerebral cortex

-most prominant neuron in neocortex

-layer 3 or 5

-1 aptypical dendrite

-extends from top of soma to outermost layer, several basal dendrites

Cortical Cells

of cerebral cortex

-info processing unit

-from surface thru the cortical layer

-synaptic connections are vertical

Telencephalon

subcortical structure=forebrain

-basal ganglia: reciprocally connected to cortex, motor control

-limbic system: structures important for learning and memory, cogn. functions, emotional responses, and sense of smell

Diencephalon

subcortical structure=forebrain

-thalamus: relay center for sensory signals, cluster of nuclei, signals move from sensory system to cortex and onward

-hypothalamus: cluster of discrete nuclei, controls hunger/thrist/sex drive/temperature regulation, controls pituitary gland, main interface with hormonal system

Mesencephalon

subcortical structure=midbrain

-tectum (roof), dorsal midbrain: superior colliculi (visual processing) and inferior colliculi (auditory processing)

-motor centers: substantia nigra, red nucleus, reticular formation

Cerebellum

subcortical structure=brainstem/hindbrain

-"little brain", 3 layers, key for motor control and coordination, important for learning and imagery

-molecular layer (parallel fibers)

-purkinje layer 2 (fan-shaped dendric pattern)

-granule cell layer 3

Pons

subcortical structure=brainstem/hindbrain

-part of brainstem, multiple cranial nerves, motor and sensory nuclei

Medulla

subcortical structure=brainstem/hindbrain

-all axons from brain to spinal cord pass through

-CN 6+7 arise here

-control neck and tongue

-reticular form ends here

-nuclei that regulate HR and breathing

CSF

cerebrospinal fluid; ventricular system

-cushion/shock absorber

-protection from sudden movements

-medium for nutrient exchange btw blood vessels and brain tissue

Lateral Ventricles

lined with choroid plexus (gen. CSF)

-ventricular system

Third Ventricle

midline structure

-ventricular system

Fourth Ventricle

between cerebellum and pons

-ventricular system

Neurovasculature: ACA/MCA

ACA: anterior cerebral artery, top of brain

MCA: middle cerebral artery, middle of brain

both come from internal carotid arteries

Neurovasculature: PCA

PCA: posterior cerebral artery, back and bottom of brain

comes from basilar artery

-branches of PCA support hindbrain

Neurovasculature: Circle of Willis

ACA and MCA here

-from basilar and internal carotid arteries

-seen in interior view, where all arteries are connected by the circle

Blood Brain Barrier

ventricular system

-endothelial cells in blood vessels have tight junctions (astrocyte and pericyte regulation

-resistant to passage of large molecules, protects against blood borne toxins, impedes drug delivery

-includes glymphatic system: provides waste disposal, allows immune system access to brain

Structural Neuroimaging

-angiography: view of vasculature after injection of radiopaque

-CAT/CT scan: x-rays show tissue density, medium resolution

-MRI: radio frequency energy, high resolution

-DTI: shows fractional anistotropy of H2O molecules (uses protons in H2O) along myelin of axons; shows origin, orientation, course, and termination

Functional Neuroimaging

-PET: radioactive chemicals injected to see brain activity

-fMRI: good spatial resolution, decent temporal resolution; magnetic field gradients find changes in the brain metabolism (O2 used by active brain regions)

-optical imaging: near-infrared light shows brain activity

-TMS: magnetic currents stimulate the cortex (activate/interfere with); assesses behavior post-stimulation

-MEG: SQUIDS map neural activity, good temporal resolution

Functional Neuroimaging Speed/Accuracy Tradeoff

-fMRI v. M/EEG

-fMRI: structural is better than temporal

-M/EEG: temporal is better than structural

Neurophysiology

the study of electrical (intra-neuron) and chemical (inter-neuron) processes in neurons

Electrostatic Pressure

force driving ion mvmt across cell membrane

-ions flow to oppositely charged areas (opposite charges attract, like charges repel)

-eventually counteracts diffusion (equilibrium)

Diffusion

force driving ion mvmt across cell membrane

-ions are spread from a high ion concentration to a low ion concentration

-move down the concentration gradient

-eventually counteracted by electrostatic pressure (equilibrium)

Sodium-Potassium Pump

maintain resting cell potential, maintain ion gradient

-pumps 3 Na+ out for every 2 K+ in

Equilibrium Potential

electrostatic pressure counteracts force of ion diffusion

-Nernst Equation: =voltage needed to counterbalance diffusion and electrostatic pressure of flow of K+ ions; predicted at -80mv but typically at -65 mv

-Goldman Equation: takes into account the concentrations of K+ and Na+ and the degree of permeability of both ions

Concentrations of Ions Inside and Outside Cell

-3 Na+ out for every 2 K+ in

-K+ has higher concentration inside cell

-Na+ has higher concentration outside cell

-Ca2+ has low concentration inside cell, maintained by pumps

Action Potential (AP)

rapid, large changes in membrane potential at the axon hillock

-propogates down axon to terminals

-patterns of APs carry info to postsynaptic targets

Hyperpolarization

increase in membrane potential

-due to AP

-interior of cell becomes more negative

Depolarization

decrease in membrane potential

-due to AP

-brings membrane potential closer to zero

-if potential reaches threshold at -40mv an AP is triggered

-larger depolarization=more APs

-info coded in frequency of AP, not amplitude

Conduction Velocity

speed of propogation of AP

-speed varies with diameter of axon

-larger axon=faster conduction

Saltatory Conduction

AP travels inside axon and jumps from node to node

-Na+ channels open which depolarizes cell and creates AP, AP moves down axon interior barricaded from outside by myelin, gets to end of axon, Na+ channels here open which creates another AP, etc. as moves from node to node

Postsynaptic Potential

electrical signal of AP converts to chemical signal as NTs are released from presynaptic cell

-brief chnage in resting potential of postsynaptic cell

excitatory postsynaptic potential (EPSP)

depolarizes local postsynaptic membrane

-if cell gets enough EPSP from many presynaptic neurons, can trigger AP

inhibitory postsynaptic potential (IPSP)

hyperpolarizes local postsynaptic membrane

-results from opening ion channels that allow Cl- ions into the cell

Synaptic Delay

when NT diffuses across synaptic clefts

Spatial Summation

part of postsynaptic potential

-summing of potentials that all come from different parts of the cell

-sums EPSP and IPSP

-if sum can depolarize cell at axon hillock, AP is triggered

Temporal Summation

part of postsynaptic potential

-summing of potentials that arrive at axon hillock at different times

-sums EPSP and IPSP

-if sum can depolarize cell at axon hillock, AP is triggered