W6L3.pdf: Brain Study Methods & Feeding Regulation
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Uploaded by FelicitousKazoo7765
University of Sydney
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Summary
This document describes various methods for studying the brain, including TMS, single-cell recording, electrical stimulation, and functional imaging techniques such as EEG, MRI, fMRI, and MEG. It also covers the regulation of feeding behavior, focusing on the role of the hypothalamus and different brain regions involved in hunger and satiety.
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# 5/a wb lecture 3 ## How We Study The Brain - Observing damage to certain areas of the brain allows us to find what that part of the brain does. ## Transcranial Magnetic Stimulation (TMS) - TMS briefly interferes with a part of the brain, allowing you to see what parts of the brain do what....
# 5/a wb lecture 3 ## How We Study The Brain - Observing damage to certain areas of the brain allows us to find what that part of the brain does. ## Transcranial Magnetic Stimulation (TMS) - TMS briefly interferes with a part of the brain, allowing you to see what parts of the brain do what. - **Magnetic Pulse** - **Electrical current in brain** - **Depolarizes neurons (action potential)** - Good temporal resolution - Good ## Single Cell Recording - Observes changes in voltage/current in a single neuron. ## Electrical Stimulation - Stimulates neurons and seeing what results if you disrupt something. ## More Modern Techniques - Optogenetics and fibre photometry (cat imaging) - Microinjections into specific regions of a brain ## Functional Imaging of the Brain - Measuring which part of the brain is active when. - Shows correlations between brain activity and psychological function, does not prove causal links. ## Methods ### 1) Electroencephalography (EEG) - Electrode plates against scalp record electrical fields from the brain. - Very good temporal resolution. - Bad spatial resolution. ### 2) Magnetic Resonance Imaging (MRI) - Bombarding head with high frequency radio waves while inside a strong magnetic field to measure orientation of protons in water. - Allows you to identify different types of brain tissue and allows for visualizations of brain structures. - Bad temporal resolution - Good special resolution ### 3) Functional MRI - Measures changes in O2 in blood. - Differences in magnetic properties between O2-rich blood and O2-poor blood are measured. - Good spatial resolution - Bad temporal resolution ### 4) Magnetoencephalography (MEG) - Measures magnetic fields emitted from your brain. - 3D reconstruction of electrical activity to create functional map of brain response. - High spatial resolution - High temporal resolution - Non-invasive - Magnetic fields pass through your scalp without being disrupted, electrical fields get disrupted. - Very expensive, extremely sensitive to any electromagnetic interference. - There isn't too many in use right now. ## The Regulation of Feeding - Hunger and the sensation of being full are triggered by contents of your stomach and substances circulating in your blood. - Actual sensations themselves are actually in our brain. - Hypothalamus is very involved in regulating hunger. ### Parts of Hypothalamus - **LH: Lateral Hypothalamus** - Destruction of LH causes rats to eat much less. - **VMH: Ventromedial Hypothalamus** - Destruction of VMH causes rats to overeat, but not lack satiety: normal-sized meals, just more frequently. - **PVN: Paraventricular Nucleus** - Rats with PVN damage eat BIGGER meals. - **ARL: Arcuate Nucleus** - Has 2 neurons: - **Promote feeding (LH)** - **Suppress feeding (VMH & PVN)** - Easily feeding can activate each class; stimulation can induce/stop feeding. - Leaky BBB - Neurons have receptors for hormones from gut (ghrelin, CCK) and fat (leptin).
