Unit 01 Flashcards
Although it was a pseudoscience, phrenology helped establish the concept of
localization of function
Neurons communicate with each other across tiny gaps called
synapses
Which part of the neuron receives information from other neurons and converts chemical signals to electrical signals?
dendrites
The presynaptic side of the synapse contains _____ filled with neurotransmitters.
The postsynaptic side of the synapse contains _______.
synaptic vesicles; receptors
Myelin is produced by ________ in the central nervous system and by _______ in the peripheral nervous system
oligodendrocytes; Schwann cells
(T/F) In the peripheral nervous system, sensory nerves transmit information from the central nervous system to the muscles and glands, and motor nerves transmit information from the body to the central nervous system
false
The longitudinal fissure separates the two hemispheres. Which lobe does not border it?
temporal lobe
Which layer of the meninges is the tough outermost layer?
dura matter
What is behavioral neuroscience?
behavioral neuroscience = physiological psychology = biological psychology (biopsychology) = brain and behavior
Definition of behavioral neuroscience
study of the biological bases of psychological processes and behavior
Why study behavioral neuroscience?
- can provide general knowledge about the brain and behavior
- fundamental discoveries in biological psychology research may contribute to a greater understanding of brain disorders and the development of effective treatments
List the stats for people with neurological/psychiatric illness
at least one person in five
What did the ancient egyptians, indians, chinese, and greeks thought was the center of thoughts and emotions?
the heart
During Greece 300s BCE, who wrote about the brain controlling thoughts, emotions, and intelligence?
Hippocrates
During Greece 300s BCE, who believed the heart was the root of consciousness?
Aristotle
What did Aristotle think the function of the brain was?
a cooling system for the blood
During Greece 100s CE, who treated brain-injured gladiators?
Galen
What did Galen propose after treating brain-injured gladiators?
behavior results from connections between the brain and the body
What happened during the scientific revolution?
major developments in math and science starting towards the end of the renaissance, where the scientific method was established
Which renaissance artist/scientist pioneered anatomical drawings by relying on direct observation?
Leonardo de Vinci
Which renaissance artist/scientist pioneered anatomical drawings by relying on direct observation?
Leonardo de Vinci
What did Rene Descartes propose?
concept of spinal reflexes and their neural pathways; explained control of behavior in terms of the nervous system acting as a machine
What is dualism?
concept that humans have a nonmaterial soul and material body; soul governs behavior through a point of contact (i.e. pineal gland)
What is phrenology?
belief that bumps on the skull result from enlargements of brain regions responsible for certain behavioral faculties
What is localization of function?
concept that different brain regions specialize in specific behaviors
What did Broca note that damage to a particular region on the left side of the brain can do?
impairs speech production (broca’s aphasia)
Who invented cell staining technique?
Golgi
Who made detailed drawings of many types of nerve cells using Golgi staining?
Ramon y Cajal
What did Hebb describe about neuronal connections in relation to experience?
neural connections strengthen as a consequence of experience
What are Hebbian synapses?
plastic neuronal connections; they change in strength through use
What is the basic unit of the nervous system?
neurons (nerve cells)
What is a neuron composed of?
dendrites (receptive extensions), soma (cell body), axon, and axon terminal
List the steps for cell communication
1) Input: dendrites receive information from other neurons
2) Integration: cell body integrates (decides to produce a neural signal) the information
3) Conduction: a single axon conducts information away from the cell body as an electrical signal
4) Output: axon terminals at the end of the axon communicate activity to other cells
What part of the neuron receives chemical signals from other neurons and then converts them to an electrical signal?
dendrites
What does the soma do?
- integrates/combines information that has been received at dendrites
- sums together the electrical signals
What is the function of the axon?
carries the electric signal (action potential) away from the cell body and to the terminals
Where is the action potential generated?
axon hillock
What is the function of the axon terminals?
makes synaptic contact with other cell’s dendrites
Are information signals BETWEEN neurons chemical or electrical?
chemical
Are information signals WITHIN a neuron chemical or electrical?
electrical
Describe a multipolar neuron
one axon, many dendrites
Describe a bipolar neuron
one axon, one dendrite
Describe a unipolar neuron
one extension branching in two directions
What is a synapse/synaptic cleft?
junction between two neurons
What is the presynaptic membrane?
axon terminal of the presynaptic neuron; releases neurotransmitters
What is the postsynaptic membrane?
dendrite or cell body of the postsynaptic neuron; receives neurotransmitters
What happens at the presynaptic side of the synapse?
axon terminal contains synaptic vesicles that contain neurotransmitter; neurotransmitter is released by an action potential
What happens at the postsynaptic side of the synapse?
receptors respond to the neurotransmitters
What are the four classes of glia?
- oligodenrocytes
- schwann cells
- astrocytes
- microglia
Which two types of glia cells wrap around axons to provide a fatty insulation layer (myelin) and where are they located?
- oligodendrocytes (in the central nervous system)
- schwann cells ( in the peripheral nervous system)
What is the function of astrocytes?
stretches around neurons, synapses, and sometimes blood vesicles = secrete chemicals
WHat is the function of microglia?
removes debris from injury
What is the central nervous system (CNS)?
brain and spinal cord
What is the peripheral nervous system (PNS)?
all other parts of the nervous system aside from the brain and spinal cord
What does the PNS consist of?
- motor nerves: transmits info from CNS to muscles + glands
- sensory nerves: convey info from body to the CNS
What are the two distinct systems of the PNS?
- somatic nervous system (SNS): nerves that interconnect the brain and the major muscles and sensory systems of the body
- autonomic nervous system (ANS): nerves that connect to the internal organs
What does the SNS includes?
- cranial nerves (12 pairs): connects brain = head, neck, visceral organs
- spinal nerves (31 pairs): connects spinal cord = muscles, organs
What components do cranial nerves have?
motor and sensory
What components do spinal nerves have?
- motor fibers project from the spinal cord
- sensory fibers enter the spinal cord
What are the two divisions of the ANS?
- symapthetic nervous system: prepares the body for action = fight-or-flight
- parasympathetic nervous system: helps the body relax = rest-and-digest
Describe horizontal plane of dissection
divides the body/brain into upper and lower
Describe sagittal plane of dissection
divides body/brain into right or left hemisphere
Describe coronal plane of dissection
divides body/brain into front and back
Describe medial/lateral
toward middle/toward side
Describe ipsilateral/contralateral
same/opposite side
Describe proximal/distal
near/far
Describe superior/inferior
up/down
Describe anterior/posterior
front/back
Describe rostral/caudal
beak/tail
Describe dorsal/ventral
back/belly
What is the outermost, convoluted layer of the brain?
cerebral cortex
Describe the cortex’s gyri
ridged or raised portions
Describe the cortex’s sulci
furrows
List and describe the four lobes of each cerebral hemisphere
1) frontal lobe: attention, planning, motor (most anterior)
2) parietal lobe: touch, other (b/w frontal and occipital lobe)
3) occipital lobe: visual processing (posterior)
4) temporal lobe: auditory processing, memory (lateral)
Describe longitudinal fissure
separates left/right hemispheres
Describe sylvian fissure
boundary of temporal lobe
Describe central sulcus
divides frontal/parietal lobes
Describe precentral gyrus
located in the frontal lobe; important for motor control
Describe postcentral gyrus
located in the parietal lobe; important for touch
Describe gray matter
- mostly cell bodies and dendrites that lack myelin
-nuclei
Describe white matter
- mostly axons with white myelin sheaths (fatty)
- tracts (bundles of axons)
What is a bundle of axons that connects the two cerebral hemispheres?
corpus callosum
What three subdivisions does the neural tube develop into?
- forebrain
- midbrain
- hindbrain
What does the forebrain develop into?
- telencephalon
- diencephalon
What does the midbrain develop into?
midbrain
What does the hindbrain develop into?
cerebellum, pons, and medulla
What is the function of the cerebral cortex?
sensory, motor, associative, cognitive
What is the function of the basal ganglia?
control of movement and actions
What is the limbic system important for? Name its parts
important for emotion and learning
- hippocampus and fornix
- amygdala
- cingulate gyrus
- olfactory bulb
What is the function of hippocampus and fornix?
learning
What is the function of the amygdala?
emotional regulation; perception or odor
What is the function of the cingulate gyrus?
attention
What is the function of the olfactory bulb?
sense of smell
What is the function of the thalamus?
relays almost all sensory information to the cortex
What is the function of the hypothalamus?
motivated behavior, homeostasis, regulating autonomic nervous system + controls pituitary gland
What are the two parts of the tectum in the midbrain and their functions?
- superior colliculi: visual processing
- inferior colliculi: auditory processing
Name the part of the tegmentum in the midbrain and describe its function
- substantia nigra: source of dopamine to basal ganglia
What are “other” midbrain systems? What are their functions?
- reticular formation: involved with sleep and arousal
- periaqueductal gray: pain perception
What is the pons in the hindbrain?
sensory and motor nuclei
What is the function of the medulla in the hindbrain?
- essential processes such as respiration and heart rate
Where is the medulla located in the brain?
At the transition from brain to spinal cord
What is the function of the cerebellum?
motor coordination/control
What are meninges?
protective membranes that surround the brain and spinal cord
List and describe the three layers of the meninges
1) dura mater: tough
2) arachnoid membrane: lies b/w pia and dura; filled with cerebrospinal fluid (CSF)
3) pia mater: delicate innermost layer
What membrane in the lateral ventricle produces CSF?
choroid plexus
Which system consists of a series of chambers filled with CSF?
ventricular system
Describes the directional flow of CSF
from the lateral ventricles into the third ventricle at the midline = into the fourth ventricle = then exists to circulate over the brain and spinal cord
What is the function of CSF?
provides buoyancy, protection, exchange of nutrients/waste b/w blood and brain
Besides CSF, what else does the brain depend on?
oxygenated blood from the cerebral arteries
What are strokes caused by?
rupture or blockage of blood vessels = causes insufficient oxygen supply
What is the function of the blood-brain barrier (BBB)?
filters blood before it enters brain tissue; it is selectively permeable
Why is the BBB selectively permeable?
keep the brain environment as stable as possible + keep bacteria/viruses out
Define computerized axial tomography (CAT/CT)
map of the brain based on tissue density and X-ray absorption; best for strokes, tumors
Define magnetic resonance imaging (MRI)
uses magnetic fields and radio waves to map tissue density; best for high resolution images
Define diffusion tensor imagine
variant of MRI, can visualize axon fiber tracts
Define functional MRI (fMRI)
detects small changes in brain metabolism in active brain areas; can show how networks of brain structures collaborate
Define position emission tomography (PET)
gives images of brain activity using radioactive chemicals in the bloodstream; identifies wich brain regions contribute to specific functions
What can magnetism be used for?
study brain activity
Describe transcranial magnetic stimulation (TMS)
briefly stimulate discrete cortical regions; scientists can record observed changes in behavior
Describe magnetoencephalography (MEG)
measures the tiny magnetic fields given off by active neurons during cognitive processing
What happens at dendrites (input zone)?
neurotransmitter binding causes local changes in electrical activity (post synaptic potentials)
What happens when the change in electrical activity enough to reach the soma (integration zone)?
an action potential is generated down the axon (condition zone)
How would you describe the electrical signal of an action potential?
all-or-nothing
How would you describe a resting neuron?
polarized = difference in electrical charge when comparing inside vs. outside of the cell
Is the inside of a resting neuron negative or positive?
negative
How many mV is the resting potential?
-50 to -80
How do ions pass through the cell membrane?
via ion channels
Which ion channels are gated?
sodium channels open and close in response to signals
Which ion channels stay open all the time?
potassium channels allow for K+ to enter and leave freely
Describe chemical pressure (diffusion)
causes ions to spread out in a uniform manner (concentration gradient)
Describe electrostatic pressure
causes ions to flow towards oppositely charged areas (electrical gradient)
Describe the function of the sodium potassium pump
pushes Na+ ions out; pulls K+ ions in
What does the sodium-potassium pump cause?
causes K+ ions to accumulate inside the cell + Na+ ions outside the cell
What kind of pressure drives K+ ions out?
chemical
What kind of pressure pulls k+ ions in?
electrical
What is the equilibrium potential?
electrical charge that balances the two opposing forces: concentration gradient and electrostatic pressure
What is the resting potential of a neuron and what is it based on?
- around -65 mV
- based on equilibrium potential for K+ created by Na+/K+ pumps and K+ ion channels
Describe hyperpolarization
interior of the cell becomes more negative
Describe depolarization
interior of the cell becomes less negative
Describe a graded response
greater the stimulus, greater the response
Describe a local potential
in dendrites and soma, the signal diminishes as it spreads further away
What happens when the stimulus depolarizes the membrane to the threshold (about -40 mV)?
triggers a brief action potential/spike
What happens during an action potential?
membrane potential reverses, and the inside of the cell becomes more positive
Where do action potentials originate?
in the initial segment of the axon, just after axon hillock
What is the relation of the amplitude to the action potential?
independent of stimulus size; increased stimulus strength = more action potentials
What is the action potential caused by?
a sudden rush of Na+ ions into the axon
At its peak, where does the action potential approach?
equilibrium potential for Na+
What triggers voltage-gated Na+ channels to open?
sufficient depolarization (threshold); for Na+ ions there are strong ionic forces to drive it into the cell
What pressure(s) drives for Na+ ions to enter?
chemical and electrostatic pressure
After the Na+ ions enter, what mV does the membrane potential reach?
+40 mV (Na+ equilibrium potential)
What happens as the inside of the cell becomes more positive?
voltage-gated K+ channels open; K+ rushes out and the resting potential is restored
Describe absolute refractory phase
no action potentials can be produced; due to the voltage-gated Na+ channels being inactivated
Describe relative refractory phase
only very strong stimulation can produce an action potential; due to voltage-gated K+ channels still being open, which causes hyperpolarization (afterpotential or afterhyperpolarization)
How many directions can an action potential travel?
only one
Why can an action potential only travel in one direction?
due to the absolute refractory state of the membrane after depolarization (when voltage gated Na+ channels are inactivated)
What causes conduction velocity to vary?
- axon diameter; larger diameter = faster speed
- myelination; enhances speed and conduction
What are nodes of ranvier?
small gaps in the myelin; voltage-gated Na+ channels are located at the nodes
What is saltatory conduction?
term used to describe the action potential traveling down the axon and jumping from node to node
What happens once an action potential reaches the axon terminals?
causes the release of neurotransmitter into the synapse
Describe the direction neurotransmitters as they move across the synapse
FROM: the axon terminal of the presynaptic neuron
TO: receptors on the dendrites/soma of the postsynaptic neuron
What causes local postsynaptic potentials or brief changes in the membrane potential?
neurotransmitters binding to the receptors
Is excitatory depolarization or hyperpolarization?
depolarization
Is inhibitory depolarization or hyperpolarization?
hyperpolarization
What is excitatory postsynaptic potential (ESPS)?
small depolarizing local potential in the postsynaptic membrane that pushes the cell closer to the action potential threshold, increasing the likelihood that the neuron will fire an action potential
What channels are open in EPSPs?
sodium (Na+) ion channels; letting positive ions into the cell
What is inhibitory postsynaptic potential (IPSP)?
small hyperpolarizing local potential in the postsynaptic membrane that pushes the cell further away from the threshold, decreasing the likelihood of the neuron firing an action potential
What channels are open in IPSPs?
chloride (Cl-) ion channels open; making inside more negative
What is spatial summation?
summing of all the potentials that reach the axon hillock from locations across the soma and dendrites
What happens if the overall depolarization reaches/exceeds the membrane threshold?
action potential is produced
T/F: the closer together in time the potentials arrive, the greater their impact and likelihood of producing an action potential
true
What happens at the presynaptic side of synapse?
axon terminal contains synaptic vesicles that contain neurotransmitter
What happens at the postsynaptic side of synaose?
receptors respond to the neurotransmitters
List the sequence of transmission
1) action potential arrives at the presynaptic axon terminal
2) voltage-gated calcium (Ca2+) channels open in the terminal and calcium ions enter
3) calcium ions cause synaptic vesicles filled with neurotransmitter to fuse with the presynaptic membrane, releasing neurotransmitter into the synaptic cleft
4) transmitters bind to postsynaptic receptors, causing ion channels to open and leading to an EPSP or IPSP
5) EPSPs or IPSPs spread toward the postsynaptic axon hillock; if threshold is reached, an action potential will occur
6) synaptic transmission is rapidly stopped via reuptake or degradation
7) transmitter may also activate presynaptic receptors (autoreceptors) that decrease transmitter release (negative feedback)
List and describe the two ways neurotransmitter actions are rapidly halted
- degredation: the rapid breakdown and inactivation by an enzyme
- reuptake: when transmitter is cleared/recycled from the synapse by transporters (special proteins) in presynaptic terminal or nearby glia
What are ligands?
molecules that fit into receptors and activate/block them
T/F: ligands includes neurotransmitters and drugs
true
What determines the action of the transmitter?
receptor (excitatory or inhibitory)
How are ACh and nicotine agonists?
they activate the receptor = causes channels to open
How are curare and bungarotoxin antagonists?
they block the receptor
Describe axo-dendritic synapse
axon terminal synapses on a dendrite
Describe axo-somatic synapse
synapse between axon and cell body
Describe axo-axonic synapse
synapse between two axons
Describe dendro-dendritic synapse
synapse between two dendrites (not common)
What is an electroencephalogram (EEG)?
recording of spontaneous brain potentials
What is an event-related potentials (ERPs)?
EEG responses to a single stimulus
Is brain activity desynchronized or synchronized during brain activity?
desynchronized
What is a seizure?
a wave of abnormally synchronous electrical activity in the brain
What are the three cell layers that a human embryo develops?
- endoderm (inner layer): becomes internal organs, gut lining
- mesoderm: becomes muscles, bones, circulatory system
- ectoderm (outer layer): becomes nervous system, epidermis (skin)
What happens during embryonic development?
a groove forms at the midline = the crests of the neural groove join, forming the neural tube, the beginning of the central nervous system
What are the three subdivisions of the anterior part of the neural tube?
- forebrain (cortical regions, thalamus, hypothalamus)
- midbrain
- hindbrain (cerebellum, pons, medulla)
What part becomes the ventricles of the brain and the central canal of the spinal cord?
interior of neural tube
T/F: There is NOT dramatic brain growth during fetal development (cortex gyri/sulci in humans) and after birth also
false
List the stages of brain development
1) neurogenesis: the birth of new neurons
2) cell migration: cells move toward their destination
3) cell differentiation: cells change into distinctive types of neurons or glia
4) synaptogenesis: establishment of synaptic connections
5) neuronal cell death: selective death of many neurons
6) synapse rearrangement: pruning and fine-tuning of synapses
The sodium-potassium pump ________ and _________.
pushes Na+ ions out, pulls K+ ions in
In a resting neuron, chemical pressure ____ ____ K+ ions, whereas electrostatic pressure _____ ______ K+ ions.
drives out; pulls in
Na+/K+ pumps and open K+ ion channels are associated with
the resting membrane potential
Who drives Na+ to enter the neuron when Na+ ion channels open?
chemical and electrostatic pressure
Action potentials begin in the
initial segment of the axon
IPSPs are
inhibitory
The opening of voltage-gated K+ ion channels are associated with
the falling phase of the action potential
T/F: Synaptic transmission is rapidly stopped via reuptake or degradation of neurotransmitter
true
Which of the following is an example of neurotransmitter degradation?
A) curare is an antagonist at acetylcholine receptors
B) dopamine is cleared from the synapse by the dopamine transporter (DAT)
C) acetylcholine is inactivated by the enzyme acetylcholinesterase (AChE)
D) nicotine is an agonist at the acetylcholine receptors
C
________ are molecules that fit into receptors and activate or block them
ligands
T/F: neurogenesis can occur in adults, especially in the dentate gyrus of the hippocampus
true
Cell differentiation is the process of
stem cells becoming distinctive types of neurons or glia
What is released by target cells that encourage the survival of cells and synapses?
neurotrophic factors
What do neurons compete for at target structures?
synaptic connections
What is synapse rearrangement?
loss or development of synapses
T/F: Synapse rearrangement continues throughout adulthood
true
What results in postnatal brain growth?
growth in the size of neurons and branching, increased myelin, and new glia
T/F: In the human cortex, there is NO net loss of synapses from late childhood until mid-adolescence
false
Describe the direction of the thinning process
continues from caudal to rostral throughout maturation, reaching the prefrontal cortex last
What is the period during development, when visual experience is crucial for proper development?
sensitive period
What happens if there is binocular deprivation during development?
reduced synapses in visual cortex
T/F: After deprivation for several weeks during sensitive period, eyesight CAN be recovered
false
What happens if there is monocular deprivation?
ocular dominance is disrupted = cortical neurons respond to only one eye, not both
Describe Hebbian synapses
What is genotype?
sum of an individual’s intrinsic, genetic information; constant
What is phenotype?
physical characteristics and traits; changes constantly based on extrinsic effects on genes
Define epigenetics
study of the factors that change gene expression without changing the gene sequence
What was the result of poor maternal care in the brain during the animal experiment?
induces methylation of the glucocorticoid receptor gene
What happens as a result of induced methylation on rodent pups?
become hyperresponsive to stress
Since memory impairments are observed with aging, what does it correlate to in terms of the hippocampus?
severity of memory loss correlates with hippocampal shrinkage
Describe the process of Alzheimer’s disease as it is a form of dementia
- begins with memory loss of recent events
- eventually, memory impairment is so extensive that conversation is impossible
- cortex shows atrophy and reduced metabolism
List the cellular changes in Alzheimer’s
- amyloid plaques = formed by clumps of beta-amyloids in extracellular space
- neurofibrillary tangles = formed from filaments inside neurons
- loss of acetylcholine neurons in the basal forebrain
The electrical charge that balances the opposing forces of concentration gradient and electrostatic pressure is called
equilibrium potential
The opening of voltage-gated Na+ ion channels is associated with
the rising phase of the action potential
Postsynaptic potentials take place in the _________; action potentials take place in the __________
dendrites/soma; axon
T/F: The amplitude (size) of an action potential can change
false
When the inside of a neuron becomes even more negative, this is known as
hyperpolarization
On the postsynaptic side of the synapse, _______ respond to neurotransmitter
receptors
Which of the following developmental processes still continues on a large scale after birth in humans?
synaptic rearrangement
