Week four
Callosotomy
Surgical procedure in which the corpus callosum is severed (used to control severe epilepsy).
What is the difference between the action potential and EPSPs/IPSPs
The action potential is all or nothing. The other two are graded, varying in strength. The change in voltage during action potential is 100mV. In the other two, it varies between 0.1 -40mV, and they are measured by how far the membrane potentials diverage from the resting membrane potential.
Soma
cell body of neuron that contains the nucleus and genetic info and directs protein synthesis
Three basic parts of the brain
cerebral hemisphere, cerebellum, brain stem
nucleus
contains genetic info, directs protein synthesis, and supplies the energy and the resources the neuron needs to function
Contralateral
opposite side
Axon
the extension of a neuron, ending in branching terminal fibers, through which messages (action potential) pass to other neurons or to muscles or glands - main output of a neuron
corpus callosum
the large band of neural fibers connecting the two brain hemispheres and carrying messages between them
resting membrane potential
-An electrical potential established across the plasma membrane of all cells by the Na+/K+ ATPase and the K+ leak channels. IN most cells, the resting membrane potential is approximately -70 mV with respect to the outside of the cell. -
Two forces act to maintain a steady state when the cell is at rest : diffusion and electrostatic.
- Diffusion is the force on molecules to move from area of high concentration to areas of low concentration. - Electrostatic pressure is the force on two ions with similar charge to repel each other and the force of two ions with opposite charge to attract one another.
What does the statement mean that communication within and between cells is an electrochemical process?
- Neuronal communication is often referred to as an electrochemical event. The movement of the action potential down the length of the axon is an electrical event, and movement of the neurotransmitter across the synaptic space represents the chemical portion of the process. -. Action potentials are electrical signals carried along neurons. Synapses are chemical or electrical junctions that allow electrical signals to pass from neurons to other cells. Electrical signals in muscles cause contraction and movement
synaptic gap (synaptic cleft)
-5nm - excises between the presynaptic terminal button and the postsynaptic dendritic spine
transcranial direct current stimulation (tDCS)
-A neuroscience technique that passes mild electrical current directly through a brain area by placing small electrodes on the skull. - It has been shown to improve performance in things such as; math, memory, attention, and coordination.
frontal lobe
-A region of the cerebral cortex that has specialized areas for movement, abstract thinking, planning, memory, and judgement -larger in humans than any other animal
Metabolite
-A substance necessary for a living organism to maintain life. -Our brain uses 20% oxygen and calories we consume despite being only 2% our total weight. -the average human brain contains 100 billion neurons
How does diffusion and electrostatic pressure contribute to the resting membrane potential and the action potential?
-Due to this difference in concentration and charge, two forces act to maintain a steady state when the cell is at rest: diffusion and electrostatic pressure. -Diffusion is the force on molecules to move from areas of high concentration to areas of low concentration. -Electrostatic pressure is the force on two ions with similar charge to repel each other and the force of two ions with opposite charge to attract to one another. -both diffusion and electrostatic pressure are pushing Na+ inside the cells. However, Na+ cannot permeate the membrane when the cell is at rest. Now that these channels are open, Na+ rushes inside the cell, causing the cell to become very positively charged relative to the outside of the cell. This is responsible for the rising or depolarizing phase of the action potential
In addition to the neuron, there is a second type of cell in the brain called glia cells.
-Glia, also called glial cells or neuroglia, are non-neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system that do not produce electrical impulses. They maintain homeostasis, form myelin, and provide support and protection for neurons -
How does myelin increase speed and efficiency of the action potential?
-Myelin can greatly increase the speed of electrical impulses in neurons because it insulates the axon and assembles voltage-gated sodium channel clusters at discrete nodes along its length.
terminal buttons (axon terminals)
-The terminal buttons are located at the end of the neuron and are responsible for sending the signal on to other neurons. At the end of the terminal button is a gap known as a synapse. Neurotransmitters are used to carry the signal across the synapse to other neurons -
Golgi stain
-a neural stain that completely darkens a few of the neurons in each slice of tissue, thereby revealing their silhouettes -see 1-2% of neurons
inhibitory postsynaptic potential (IPSP)
-an inhibitory hyperpolarization of the postsynaptic membrane of a synapse caused by the liberation of a neurotransmitter by the terminal button -An inhibitory postsynaptic potential (IPSP) is a kind of synaptic potential that makes a postsynaptic neuron less likely to generate an action potential. -A hyperpolarizing postsynaptic current that causes the membrane potential to become more negative and move away from the threshold of excitation
Neurotransmitters
-chemical messengers that cross the synaptic gaps between neurons - they activate ion channels on the postsynaptic spine by binding to receptor sites
Synapse
-the place at which the axon of one neuron comes in close contact to the dendrite of another neuron -typically the axon is covered in an insulating substance, myelin sheath, that allows the signal and communication of one neuron to travel rapidly to another.
brain stem
-the trunk of the brain comprised of the medulla, pons, midbrain, and diencephalon. -It is responsible for regulating respiration, heart rate, digestion.
cerebral hemispheres
-two halves of the cerebral cortex, each of which serve distinct yet highly integrated functions -It gives the Braine its gray and convoluted appearance. The folds are groves of the cortex are called gyrus and sulcus. -The two hemispheres are divided into four lobes; occipital, temporal, parietal, and frontal lobes.
How many neurons are in the human brain?
100 billion
excitatory postsynaptic potentials
A depolarizing postsynaptic current that causes the membrane potential to become more positive and move towards the threshold of excitation.
myelin sheath
A layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.
cell membrane
A lipid belayer of fat molecules, separates the cell from the surrounding extracellular fluid.
Diffuse Optical Imaging (DOI)
A neuroimaging technique that infers brain activity by measuring changes in light as it is passed through the skull and surface of the brain.
Transcracial magnetic stimulation (TMS)
A neuroscience technique where a brief magnetic pulse is applied to the head that temporarily induces a weak electrical current that interferes with ongoing activity. TMS allows very precise study of when events in the brain happen so it has good temporal resolution
Action potential
A transient all-or-nothing electrical current that is conducted down the axon when the membrane potential reaches the threshold of excitation.
action potential
A transient all-or-nothing electrical current that is conducted down the axon when the membrane potential reaches the threshold of excitation. There is no half way. It is all or nothing.
Electroencephalogram (EEG)
An amplified recording of the waves of electrical activity that sweep across the brain's surface. These waves are measured by electrodes placed on the scalp.
Presynaptic terminal button ( neuron sending the signal) and the postsynaptic membrane ( neuron receiving the signal)
At the synapse, the firing of an action potential in one neuron—the presynaptic, or sending, neuron—causes the transmission of a signal to another neuron—the postsynaptic, or receiving, neuron—making the postsynaptic neuron either more or less likely to fire its own action potential.
temporal lobe
Auditory processing Memory Multi sensory integration (convergence of vision and audio)
gray matter
Brain and spinal cord tissue that appears gray with the naked eye; consists mainly of neuronal cell bodies (nuclei) and lacks myelinated axons.
Name and describe the basic function of the brain stem, cerebellum, and the cerebral hemispheres
Cerebrum: is the largest part of the brain and is composed of right and left hemispheres. It performs higher functions like interpreting touch, vision and hearing, as well as speech, reasoning, emotions, learning, and fine control of movement. Cerebellum: is located under the cerebrum. Its function is to coordinate muscle movements, maintain posture, and balance. Brainstem: acts as a relay center connecting the cerebrum and cerebellum to the spinal cord. It performs many automatic functions such as breathing, heart rate, body temperature, wake and sleep cycles, digestion, sneezing, coughing, vomiting, and swallowing.
Deplorization
In biology, depolarization is a change within a cell, during which the cell undergoes a shift in electric charge distribution, resulting in less negative charge inside the cell. Depolarization is essential to the function of many cells, communication between cells, and the overall physiology of an organism.
Neurons
Individual cells in the nervous system that receive, integrate, and transmit information.
Membrane potential
Membrane potential is the difference in electric potential between the interior and the exterior of a biological cell. With respect to the exterior of the cell, typical values of membrane potential, normally given in units of millivolts and denoted as mV, ranges from -40 mV to -80 mV
synaptic vesicles
Membrane-bounded compartments in which synthesized neurotransmitters are kept within the terminal button
What is the difference between neurons and glia? The two main cell classes in the brain.
Neurons do the actual receiving and sending of info. Neurons have axons and dendrites. Glia do not. They provide support to the neurons.
Describe the cycle of communication within and between neurons
Neurons send signals to other neurons via specialized contacts known as synapses. The most common type of synapse in the nervous system is known as a chemical synapse. Typically a chemical synapse occurs between the axon terminal of the neuron sending the message, and the dendrite of the neuron receiving the message.
Explain the features and axonal and synaptic communication in neurons
Neurons send signals to other neurons via specialized contacts known as synapses. The most common type of synapse in the nervous system is known as a chemical synapse. Typically a chemical synapse occurs between the axon terminal of the neuron sending the message, and the dendrite of the neuron receiving the message.
What happens when the ESPS is strong enough?
Once it is strong enough to depolarize the membrane potential to reach the threshold of excitement, it initiates the action potential. THe actions potential travels down the axon until it reaches the end of it where the terminal button is. IN the terminal button, the action triggers the release of the neurotransmitters from the presynaptic terminal button into the synaptic gap. These neurotransmitters cause EPSP and IPSP in the postsynaptic dendritic spines to the next cell.
ion channels
Proteins that span the cell membrane, forming channels that specific ions can flow through between the intracellular and extracellular space.
spines
Protrusions on the dendrite of a neuron that form synapses with terminal buttons of the presynaptic axon.
Lesions or ablate
Remove parts of the brain in animals
converging evidence
Similar findings reported from multiple studies using different methods.
What happens with the ESPS or IPSP?
They either add together or cancel each other out.
lateralized
To the side; used to refer to the fact that specific functions may reside primarily in one hemisphere or the other (e.g., for the majority individuals, the left hemisphere is most responsible for language).
There are three neurons based on their number of dendrites
Unipolar - only one dendrite Bipolar - two dendrites Multipolar - three or more
white matter
Whitish nervous tissue of the CNS consisting of neurons and their myelin sheaths.
Stimulus
a signal to which an organism responds
excitatory postsynaptic potential (EPSP)
a slight depolarization of a postsynaptic cell, bringing the membrane potential of that cell closer to the threshold for an action potential
functional magnetic resonance imaging (fMRI)
an imaging technique used to examine changes in the activity of the working human brain by measuring changes in the blood's oxygen levels
Position Emission Tomography (PET)
an imaging technique used to see which brain areas are being activated while performing tasks Records blood flow in the brain
inhibitory postsynaptic potential (IPSP)
an inhibitory hyperpolarization of the postsynaptic membrane of a synapse caused by the liberation of a neurotransmitter by the terminal button - becomes more negative and goes further from the threshold of excitement
What structures of a neuron are the main input and output of that neuron?
axon - output dendrite - input
Each neuron has three main components
dendrites, soma, axon
Lambic system
neural system located below the cerebral hemispheres; associated with emotions and drives
Parietal lobe
portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position
ionotropic receptors
receptors that are coupled to ion channels and affect the neuron by causing those channels to open It allows some ions to enter or exit depending on what type of neurotransmitter it is The type of neurotransmitter and the permeability of the ion channel it activates will determine if an EPSP or IPSP occurs in the dendrite of the post-synaptic cell.
There are three types of neurons; sensory, motor, and inter neurons.
sensory - help us receive into about the world around us Motor - allow us to move and behave Inter- process the sensory input into meaningful representations, plan appropriate behavior responses, and connect to the motor neurons to execute it all.
Cerebellum
the "little brain" at the rear of the brainstem; functions include processing sensory input and coordinating movement output and balance
Dendrite
the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body - main source of input of the neuron
Phrenology
the detailed study of the shape and size of the cranium as a supposed indication of character and mental abilities.
resting membrane potential
the electrical charge of a neuron when it is not active (-70mV)
equilibrium potential
the point at which the movement of ions across the cell membrane is balanced, as the electrostatic pressure pulling ions in one direction is offset by the diffusion force pushing them in the opposite direction
threshold of excitation
the value of the membrane potential that must be reached to produce an action potential Typically around -50
occipital lobe
visual processing