Psych 2210 1st Edition Lecture 9 Outline of Last Lecture I. AddictionII. Dopamine: NeurotransmitterIII. Brain Reward CircuitIV. Other Neurotransmitter SystemsV. Neuronal DendritesVI. Risk FactorsOutline of Current Lecture I. Measuring Electrical ActivityII. Review of Neuronal Electrical ActivityIII. MethodsIV. Place Cells and Grid CellsV. What about HumansVI. Link to Alzheimer’s VII. Digital vs. PaperVIII. Hippocampal Activity Codes for MemoryCurrent LectureMethods: The different methods of measuring electrical activity in the brain. I. Measuring Electrical Activitya. Single cell recording, EEG, ERPII. Review of Neuronal Electrical Activity These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. Neurons communicate via electrical signalsi. Inputs to dendrites, post synaptic potentialsii. Action potentialsb. This activity can be measuredi. Individual neuronsii. Summed activity of thousands of neurons III. Methodsa. Single Cell Recordingi. Invasiveii. Records number of action potentials/secondiii. Records neural activity but does not stimulate itiv. Two types of designs1. Correlate activity with behavior2. Measure activity after stimulusv. Ex: stereotaxic procedure to implant electrodes 1. Electrode signal is amplified and recorded during behavior vi. Research applications1. Hubel & Wiesel: mapping the visual cortex 1981 Nobel Prizea. Simple cells: respond to particular orientationb. Complex cells: specific for orientation and direction c. “What pathway” cells respond to more complex stimulid. Visual neurons in “what pathway” e. Neurons can represent concepts i. Cellular basis for cognition2. O’Keefe, Moser, & Moser: Nobel 2014—Identifying cognitive mapsa. Recording cells in hippocampus b. “Place cells” code for where we arec. Place cells: mental map of environmenti. Cells code for a particular place in the environment,generating internal mapii. Hippocampus generates numerous maps represented by the collective activity of place cells that are activated in different environments iii. Memory of an environment can be stored as a specific combinationd. Grid cells: how we find the way from one place to anotheri. A place cell fires in one place in a square boxii. A grid cell fires in evenly spaced peaks all over the boxiii. Activated when rat passes certain locationsiv. Locations form hexagonal gridv. Grid cells form coordinate system that codes for neural version of “dead reckoning”b. Electroencephalograph (EEG)i. Non-invasiveii. Measures summed electrical potentials from millions of neurons (sensitive to dendritic currents)c. Event Related Potentials (ERP)i. Non-invasiveii. Average of summed electrical potentials in response to stimulusIV. Place Cells & Grid Cellsa. Neural version of “dead reckoning” i. Ship will “take a sighting” via cues such as the stars or landmarks to determine where the ship is on a mapii. As the ship moves, “dead reckon” to update location on the map paying attention to speed and directioniii. Keeping track of location on a mapb. Place cells and grid cells work togetheri. Hippocampal “dead reckoning”: ability to keep track of our position in space as we move with eyes closed or not attending to landmarks ii. Place cells: behave as a navigator on the ocean, updating the estimate of location using two types of inputs: dead reckoning and sightings—internalmapiii. Grid cells: as the rate moves, the grid cell system is consistently updating distance and directionV. What About Humans? a. Neurosurgical patients who had electrodes implanted in preparation for surgeryb. Entorhinal single cell recordings were made while subjects played a laptop computer game that involved simulated movement through a simulated village.c. Results—firing rate maps constructed on the layout of the simulated town…d. Memory is a spatial processVI. Link to Alzheimer’sa. Memory is deeply and physically connected to our perception and encoding of spaceb. First symptoms of Alzheimer’s is that patient gets lostc. Place where a patient’s brain cells begin to die is in the entorhinal cortex (grid cell location)d. Lose your ability to find your way and your ability to recall all other types of memoriesVII. Digital vs. Papera. Teens understood more with physical book and paperb. Why? Perceptible, direct experience gives you a mental map of the entire text. VIII. Hippocampal Activity Codes for Memorya. Internal Maps and Memoryb. Pastalka & Buzsaki (2008) Rats—i. Trained to alternate between left and right armsii. Between runs, rats ran in the same direction in the wheeliii. Recorded hippocampal activity during maze and wheeliv. Results: 1. Hippocampal neuron activity patterns similar during maze and wheel 2. Activity likely represents the brain’s internal mechanism for planning (or reminding itself) what it has to do. c. Fried, et al. (2008) Humans—i. Intracranial recording from hundreds of neurons in and around the hippocampus of 13 human patients with epilepsyii. Stage 1: watching clips1. Patients watched several 5-10 second clips with variety of landmarks, people, and animalsiii. Stage 2: free recall of clips1. Patients were asked to then think of any clip they’d just seen and call them out as they came to mind. Key terms: Single cell recordingElectroencephalograph (EEG)Event Related Potentials (ERP)Grid cellsPlace cellsHippocampal "dead reckoning" Alzheimer's