Week 2 Psychobiology of Learning and Memory Notes
Week 2 Psychobiology of Learning and Memory Notes Psych 5600
Popular in Psychobiology of Learning and Memory
Popular in Psychlogy
This 10 page Class Notes was uploaded by alvey.15 Notetaker on Sunday January 24, 2016. The Class Notes belongs to Psych 5600 at Ohio State University taught by Derek Lindquist in Spring 2016. Since its upload, it has received 62 views. For similar materials see Psychobiology of Learning and Memory in Psychlogy at Ohio State University.
Reviews for Week 2 Psychobiology of Learning and Memory Notes
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 01/24/16
Psychobiology of Learning and Memory Notes Ch 2122 ll 81612116 Dr Lindquist Notes by Alexandra Alvey The neuron 3 main parts dendrites soma axon The dendrites form a dendritic tree branching from the soma The dendritic tree receives electrical information from many other neurons and passes the accumulation of electrical signals to the soma of the neuron The soma of the neuron then passes the electrical signal on to the axon The axon carries the electrical signal to other neurons A neuron can have more than one axon Sometimes the axons innervate the soma or axon of another neuron Axons can also innervate the neuron of where it originated from When the axon fires there is a retrograde electrical signal back through the entire neuron Dendritic spines density increase when an animal is placed in an enriched environment rather than just a cage Dendritic spines density increase when animals are ovulating DNA is contained within the nucleus of the soma RNA polymerase transcribes and strand of DNA within the nucleus and translation occurs outside the nucleus to form proteins Membrane Potential and The Axon Proteins are embedded in the neuronal semipermeable membrane The proteins act as channels for ions Ions move across the neuronal membrane by diffusion or electricity Diffusion ions move from an area of high concentration to low concentration Ex Potassium is high inside the neuron so will move outside the neuron to equalize the potential of the neuron Electricity positive ionic charges attract negative ionic charges and like charges repel Opposites attract and likes repel Ex The inside of the neuron is more negative than the outside of the neuron If potassium is high inside the neuron and has a positive charge then because of the electrical difference of the membrane the potassium will want to stay inside the neuron Potassium is the only ion high inside the cell Na sodium high outside neuron so diffusion and electrical forces will be attracting the ion in the cell K potassium high inside the cell so diffusion will be attracting the ion out and electrical forces will be keeping it in Cl chloride high outside the cell so diffusion will be attracting the ion in while electrical forces will be keeping it out Ca 2 calcium high outside the cell so diffusion and electrical forces will be pulling the ion inside the cell Resting membrane potential is 70 mV The inside of the neuron is more negative that the extracellular uid outside This can be determined by a voltmeter that uses microelectrodes to measure the inside on an axon compared to a solution of sea water Depolarization of an axon requires the axon to reach a threshold of 65 mV Threshold is reached by sodium entering the neuron Once threshold is reached more sodium channels open down the axon and while sodium rushes Remember like repels like The electrical charge moves from the axon hillock beginning axon propermiddle and axon terminal end Three Properties of Action Potential Rising phase Sodium enters the neuron and depolarizes makes more positive the neuron Overshoot The neuron is around 40 mV and sodium channels are open Potassium is leaving the neuron because of the positive charge inside Falling phase Sodium channels close The potassium channels close later than the sodium channels and cause an undershoot of the resting potential so the neuron is slightly more negative than 70 mV until the potassium channels close The neuron can not re another action potential until 70 mV is reached again and this is called the refractory period The action potential is an all or nothing phenomenon This means that the threshold has to be reached before an action potential is red If 65 mV is not reached by the neuron an action potential will not happen The synapse was theorized by Santiago Ramon y Caj a1 with his Neuron Doctrine stating that neurons are individual discrete units It was not until 1897 that Charles Sherrington named the area between two neurons the synapse Soups vs Sparks debate of whether neurons communicated by chemicals or electricity Today we know that the majority of neurons communicate with neurotransmitters but some can communicate with electricity via gap junctions Gap junctions form a channel between two neuronal somas Myelin on the axon increases the conduction speed of an action potential and the nodes of Ranvier are not myelin covered The nodes of Ranvier have the densest areas of sodium and potassium channels and the action potential jumps from one myelinated area of axon to the next via these nodes When the action potential reaches the axon terminal neurotransmitter is released from the vesicles containing it The neurotransmitter leaves the presynaptic neuron travels in to the synaptic cleft and the receptors on the postsynaptic neuron receive the neurotransmitter How do action potentials convey information Neural information code has a temporal and frequency component How often temporal or pattern of ring an action potential is red will have a certain amount of information and how fast frequency or rate of ring an action potential is red will have other information We do not know what this information translates to yet but we do know that a strong stimulus such as a bright light will increase the rate of ring of an action potential A weak stimulus such as a dull light will not have as fast a ring rate as the strong stimulus Neurotransmitters First neurotransmitters have to be synthesized and packaged in to vesicles then they are released in to the synaptic cleft by exocytosis and then they bind to a speci ed receptor GABA and glutamate are the two amino acid neurotransmitters we will be focusing on GABA is the main inhibitory neurotransmitter or in other words when it binds to the postsynaptic receptors it stops the neuron from ring an action potential Glutamate is the main excitatory neurotransmitter and when it binds to the postsynaptic receptors it triggers an action potential Too much GABA can cause sedation and too much glutamate can cause seizures Peptide neurotransmitters enhance the signal to the postsynaptic neuron and can be released simultaneously with amino acid neurotransmitters out of different vesicles As long as the postsynaptic neuron has receptors for both neurotransmitters dual transmission is possible Gases are retrograde neurotransmitters and send a signal from the axon to the soma and then to the dendrites This can cause brain damage in to high of doses such as what happens with carbon monoxide poisoning We won t spend a lot of time on neuropeptides Termination of the post synaptic signal happens by inactivation reuptake or diffusion Inactivation is the breaking down of neurotransmitter in to small parts reuptake is when the presynaptic neuron recycles the neurotransmitter by taking it back in and diffusion is when neurotransmitter diffuses to multiple neurons so the signal is too weak to cause an action potential Synaptic Transmission Ionotropic receptor when a neurotransmitter binds it will open and close quickly Whether the receptor lets positive or negative ions in the postsynaptic neuron depends on the neurotransmitter binding to it Glutamate is an excitatory neurotransmitter so it will let sodium in to depolarize the neuron GABA is an inhibitory neurotransmitter so it will let chloride ow in and potassium ow out to hyperpolarize the neuron Post Synaptic Potential EPSP excitatory postsynaptic potential IPSP inhibitory postsynaptic potential Post synaptic potentials are graded which means there is a range in which EPSP and IPSP can occur An action potential is binary and either occurs or doesn t occur Action potentiall and no action potential0 Synaptic Integration Multiple action potentials can be added together by spatial summation or temporal summation Spatial summation depends on the closeness of neurons within the brain and temporal summation depends on if the action potentials are ring within 10 milliseconds of each other One neuron could be receiving many IPSPs and many EPSPs and whether the neuron res or not depends on the strength of the summed IPSPs versus the strength of the summed EPSPs The combination of excitatory and inhibitory neurons is important For example if we wanted to make sure a neuron did not re and action potential the most ideal place to put an inhibitory neuron would be at the axon hillock Neuromodulators These are neurotransmitters that effect not just a single synapse but entire brain regions Many neuromodulators work through metabotropic receptors that don t have channels but G proteins attached to the inside of the neuron When the G protein is activated by the neuromodulator it can open other receptors in other areas of the neuron or even control gene expression Neuromodulators are important for general neuronal function as well and when individuals don t have enough of a certain neuromodulator it can be a major contributor to neurodegenerative disorders like Alzheimer s and Parkinson s They change the signal to noise ratio by enhancing the action potential of a summation of neurons Acetylcholine epinephrine norepinephrine serotonin and dopamine are neuromodulators Long Term Potentiation and Synaptic Plasticity Caj al was the rst to come up with the general idea that neuronal connections strengthened or weakened based on the information transferred between the two neurons Although he did not have the technology to nd the biological basis and prove his theory When the electron microscope was invented Caj al s Neuron Doctrine was proven accurate Donald Hebb furthered Caj al s theory by stating if two neurons were to re close in time the connection between them would strengthen Hebbian Plasticity Neurons that fire together wire together Hebb also theorized that memory perception and learning took place between a cell assembly that red close in space and time The mechanism for synaptic plasticity is LTP Lomo and Andersen demonstrated LTP by placing an electrode in a presynaptic neuron neuron A and an electrode in the postsynaptic cell neuron B and providing electrical stimulation to the presynaptic cell neuron A They noticed that when a weak stimulation was given to the neuron A neuron B responded with a weak response The same was true for a strong stimulus given to neuron A but after the initial high frequency stimulus neuron B would have a strong response even if a weak stimulus was produced to A Neuron B has been potentiated by the strong stimulus from neuron A which mean it will not need as strong of a stimulus to produce a strong EPSP This is why long term potentiation is an experience dependent change Chemical and Electrical Process of LTP The post synaptic neuron has to receptors NMDA and AMPA AMPA is an ionotropic receptor that lets sodium in the negatively charged postsynaptic neuron once glutamate binds to it As the postsynaptic neuron begins to depolarize from the sodium input the magnesium plug blocking the AMPA receptor is removed As long as the postsynaptic neuron is depolarized voltage gated and the AMPA receptor has glutamate bound to it ligand gated then the AMPA receptor will open and let calcium ow in to the neuron After potentiation of the postsynaptic neuron the neuron can increase the number of AMPA receptors increase the surface area of the dendritic spine andor phosphorylate the AMPA receptors to keep them open for longer The postsynaptic neuron might even be able to send a retrograde signal back to the presynaptic neuron to make it release more glutamate All of these options will lead to a stronger EPSP in the neuron and eventually the morphology of the brain will change by making new synapses Homosvnaptic LTP A weak stimulus is not strong enough to produce a EPSP in the postsynaptic neuron but if the weak stimulus is accompanied by a strong stimulus at the same time then a EPSP is produced and the weak stimulus bene ts Associative LTP Synapses of the same neuron are only potentiated if they are ring close in time with another synapse of a different neuron If a weak input occurs close in time with a strong input then an association can be made This explains fear conditioning when the weak CS or the tone is paired with the strong US of the shock Even though the CS of the tone is weak it produces a strong behavioral response because it occurred close in time with the strong US If the tone had occurred alone it would not be strong enough to produce a EPSP LTD When the presynaptic and postsynaptic neuron ring is not in sync LTD occurs Dephosphorization of AMPA receptors smaller dendritic trees and less glutamate being released will lead to a smaller EPSP There is good evidence to support that LTP and LTD are mechanisms of learning and forgetting but the results are not definitive Beginning of 22 lecture notes The CNS is composed of the brain and spinal cord In the middle of the spinal cord is gray matter Where somas of neurons are located Around the gray matter is White matter composed of axonal tracts The dorsal root is Where sensory axons enter the spinal cord via the dorsal root ganglion The ventral root is Where motor axons leave the spinal cord to innervate skeletal muscle Bell and Magendie Law of Neural Signaling The CNS and the PNS have distinct tracts for sensory information and motor information Afferent means signals from body to the brain so the dorsal root of the spinal cord receives afferent tracts Efferent exit the CNS means signals from the brain to the body so the ventral root of the spinal cord has efferent tracts Know divisions of the efferent CNS and afferent CNS on slide 6 Human Brain The somatosensory cortex in the parietal lobe and the motor cortex in the frontal lobe are topographically organized The lips tongue and hands comprise the largest area on the motor cortex because these areas require intricate movements The lips and genitalia comprise a large portion of the somatosensory cortex Neuroscience Techniques Neuroimaging is primarily used on humans and has a functional division and a structural division Structural Neuroimaging Computed Tomography CT radiopaque tissues bone absorb xrays and a 3D image is constructed Magnetic Resonance imaging MRI A strong magnetic eld causes hydrogen atoms in the brain to align in a particular direction When the magnetic eld is released the atoms move back to their original position and send out a signal The accumulation of signals produces a 3D image of the brain Both CT and MRI section the brain in to slices to view particular structures Great for seeing tumors or lesions Functional Neuroimaging Functional Magnetic Resonance imaging fMRI uses the ratio of oxygenated blood to deoxygenated blood in brain areas to determine which areas are most active during a speci c behavioral task Activitybaseline BOLD response BOLD stands for blood oxygen level dependent Positron Emission Tomography PET This is more invasive than fMRI because they inject radioactive deoxyglucose in to the back of the neck They see which areas use up the most glucose during behavioral tasks Hotter colors mean more activity while cooler colors mean less activity Activitybaseline difference image In all structural imaging a baseline image is taken when the participant is just laying there When the behavioral task is done the activity image is taken To understand which areas are most active they subtract the baseline image from the activity image Lesions in Animals Ablation gross technique meaning there is not much precision in the areas removed or damaged Electrical or heat lesions Can ask if this brain region is involved in a speci c task and then damage the area and bers of passage Usually these are the rst lesion test to be done and then more speci c tests follow Neurotoxic lesions can be given to the animal in food or by exocytosis and can target speci c neurons Reversible lesions by cooling or inactivation The best technique for ablation because function can be taken away temporarily and then restored Brain Stimulation In Vivo Stimulation Patients receiving surgery for epilepsy had brain regions stimulated while they were awake in the 1940 s 50 s and 60 s These experiments helped map out the functions of certain brain regions Transcranial Magnetic Stimulation TMS Brain regions can be activated or interrupted by the magnetic coil when it is place over the skull Great because it is a non invasive procedure Neurophysiology EEG the amount of electrodes on the cap determines the spatial resolution of the neurons that are being recorded Aroused low amplitude and high frequency pattern this means that each neuron is ring asynchronously During sleep the patter is lower in frequency but higher in amplitude which means the neurons are beginning to synchronize ring rates Used to study mental states Event Related Potentials ERP The EEG is still used but in response to environmental stimuli Such as distinguishing between the sound of two words Neurophysiological Recordings In vitro recordings An animal is sacri ced and brain tissue is placed in a solution of nutrients to keep in alive A glass pipette electrode is injected in to a neuron and recorded Great for de ning the physiology of individual neurons or small group of neurons In vivo recordings The animal is living and an electrode is placed inside the animal s brain to record extracellular activity from groups of neurons Good for relating activity to ongoing behavior Neuropharmacologv Know what agonists and antagonists are and how the mechanisms that effect neuronal function Slides 3132 Autoreceptors sites on the presynaptic terminal that act as negative feedback to stop production of a neurotransmitter when there is too much Drug infusions See the effects of a drug on a particular brain region of an animal using a cannula Microdialysis A semipermeable tube is inserted in the brain that collects CSF The CSF contains chemicals proteins and neurotransmitters that can be studied Immunocytochemisty using the immune system of an animal by having their antibodies detect a speci c protein or antigen Withdrawing the blood from the animal and using the antibody that is now tagged with uorescence to detect the protein on a slice of the animal s brain Biochemistry know the difference between Western Blot and PCR Slide 37 Genetic Method Twin Studies concordance rate if one twin has a disorder what is the probability of the other having it The higher the concordance rate the more likely that the disorder is genetic Knockout or Knock in genes Can inject human variant of a gene in to animals The gene can be expressed from birth or expressed when the animal is an adult The Crelox gene inactivates a gene for knockout studies Both can be used on speci c brain regions Developing a neuron that is light sensitive by putting the DNA from algae in to the DNA of the animal An electrode shines different color lights that activate speci c neurons which are designed to respond a certain wavelength of light Localization of Function Gall and Spurzheim developed phrenology good idea because discrete regions are involved in different functions but the technique of feeling for bumps on the skull to find the brain functions was a bad idea Phineas Gage had a spike go through his medial frontal cortex and his personality changed drastically Good case study for localization of function Paul Broca encountered a woman who could only say tam tam but understood language and could write He named this Brocas aphasia when he found that she had a lesion in the frontal cortex Wernicke encountered a patient that could produce speech but it wasn t a comprehendible sentence Damage was localized to the temporal cortex Karl Lashley damaged the brains of mice in many regions and found that they could perform the maze task just the same He was looking for the engram but after many failures to find it he agreed with the theory of equipotentiality There is some evidence today that a small area of the cerebellum is the engram for classical conditioning
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'