Lec4 Post Notes PDF

The nervous system -- review X.Liu PSYC5130 Resting Potential & Action Potential X.Liu PSYC5130 EPSP IPSP Resting Potential & Action Potential X.Liu PSYC5130 EPSP IPSP Resting Potential & Action Potential X.Liu PSYC5130 Synaptic Transmission EPSP IPSP Resting Potential & Action Potential Synaptic Tr...

The nervous system -- review X.Liu PSYC5130 Resting Potential & Action Potential X.Liu PSYC5130 EPSP IPSP Resting Potential & Action Potential X.Liu PSYC5130 EPSP IPSP Resting Potential & Action Potential X.Liu PSYC5130 Synaptic Transmission EPSP IPSP Resting Potential & Action Potential Synaptic Transmission Neurotransmitter Drug Effects Millions of such loops NS at large scale (CNS, PNS) X.Liu PSYC5130 Sensory System EPSP IPSP Resting Potential & Action Potential Synaptic Transmission X.Liu PSYC5130 Neurotransmitter Drug Effects Motor System Surface Features Meninges Tough material that covers the brain Three layers of meninges Dura mater is the outer layer Arachnoid membrane is the middle layer Pia mater is around every surface (they P.A.D. the brain…) Gap called the subarachnoid space, filled with cerebrospinal fluid (CSF) X.Liu PSYC5130 Three layers of meninges Dura mater is the outer layer Arachnoid membrane is the middle layer Pia mater is around every surface (they P.A.D. the brain…) Gap called the subarachnoid space, filled with cerebrospinal fluid (CSF) X.Liu PSYC5130 Meninges X.Liu PSYC5130 Ventricles & CSF Ventricles, a series of hollow, interconnected chambers Produce and contain the CSF X.Liu PSYC5130 Brain is fragile Brain is very soft and jellylike Needs protection Around the brain… Bath of Cerebrospinal Fluid Shock absorption Reduces net weight, less pressure on base X.Liu PSYC5130 Concussion and CTE Chronic Traumatic Encephalopathy (CTE) a brain condition thought to be linked to repeated head injuries and blows to the head. It slowly gets worse over time and leads to dementia. X.Liu PSYC5130 Neurotransmitters and drugs Some Examples X.Liu PSYC5130 Psychoactive Drugs alter mood, thought, or behavior used to manage neuropsychological illness. have an effect on the brain. X.Liu PSYC5130 Psychoactive Drugs To be psychoactive, the drug must reach and influence the nervous system Not all drugs are psychoactive because of the BLOOD BRAIN BARRIER X.Liu PSYC5130 The Blood–Brain Barrier Small molecules such as oxygen and CO2 are not ionized and are fat soluble – can pass right through. Glucose, amino acids and other components can be carried across by ACTIVE TRANSPORT SYSTEMS. It is like a pump. BB Barrier halts more substances than it lets through… X.Liu PSYC5130 Why Have a Barrier Electrical activity of neurons depends upon rather precise extracellular concentrations of ions. If ions could cross freely, would upset the balance. Protects from toxic and infectious substances X.Liu PSYC5130 A Clinical Example Treating Parkinson's disease Dopamine Small enough Chemical composition is wrong L-DOPA Slightly different composition Can pass through active transport X.Liu PSYC5130 Effects of Psychoactive Drugs Mostly at the synapses Increase effectiveness - AGONIST Decrease effectiveness – ANTAGONIST Stimulate the release of Dopamine Block the reuptake of Dopamine Block the inactivation of Dopamine All are Dopamine agonists X.Liu PSYC5130 Alcohol as an Example X.Liu PSYC5130 Alcohol: A Tale of Two Neurotransmitters Glutamate Excitatory NT: When active, encourages APs, increases firing Widespread throughout the brain GABA Inhibitory NT: When active, inhibits APs, decreases firing Also widespread throughout the brain Alcohol affects both Alcohol prevents glutamate from acting (antagonist) Alcohol makes GABA even more inhibitory (agonist) Biggest effect in frontal brain regions Impulse control, decision making, memory… X.Liu PSYC5130 GABA - Major inhibitory NT of CNS Influences chloride channels Excitation of the receptor by GABA produces an influx of Cl- ions Influx of Cl- increases the concentration of negative charges on the inside of the cell membrane Hyperpolarizing it and making it less likely to propagate an action potential. X.Liu PSYC5130 Alcohol Acts like GABA Produces greater inhibition in CNS. Not as quickly reabsorbed as GABA – long lasting X.Liu PSYC5130 Rohypnol (Roofies) + Alcohol = Very Bad Rohypnol is a benzodiazepine that is used in the short-term treatment of insomnia and as a sedative-hypnotic medication. X.Liu PSYC5130 X.Liu PSYC5130 X.Liu PSYC5130 Another Example -- where does the “high” come from? X.Liu PSYC5130 The “Reward” Circuit When dopamine is released, feeling of pleasure/satisfaction Natural rewards or “drives” Food, sex, thirst Less natural drives play on this system, too Gambling Drugs X.Liu PSYC5130 A “Natural High” We have natural opiate receptors that serve a natural painkilling role under circumstances of extreme pain. Ordinarily, GABA actively inhibits Dopamine release. pink = dopamine receptor blue = dopamine (released from neuron on left) X.Liu PSYC5130 Heroin When an NT binds to an opiate receptor Decrease in GABA More dopamine released Heroin mimics very effectively, too effectively Other opiate-like drugs – opioids oxycodone (OxyContin), hydrocodone (Vicodin), methadone, Fentanyl X.Liu PSYC5130 X.Liu PSYC5130 Cocaine Also works on Dopamine receptors. Inhibits reuptake of dopamine from the synaptic cleft into the pre-synaptic axon terminal X.Liu PSYC5130 How We Study Brain X.Liu PSYC5130 First Things First --- Research Ethics Animal Studies Human Studies X.Liu PSYC5130 Research with Animals Animal Research Use of animals for scientific research to learn more about ourselves Requires strict regulations and approval of the experimental procedures In the U.S., Institutional Animal Care and Use Committee (IACUC) At CUHK, Animal Experimentation Ethics Committee (AEEC) Most effective way to understand and treat diseases in complex, living organisms X.Liu PSYC5130 Research with Humans Human Research Research with human volunteers to advance knowledge of the brain in health and disease Regulated by the Institutional Review Board (IRB) At CUHK, Clinical Research Ethics Committee (CREC) Voluntary participation Informed consent coercion and undue influence Neuroethics studies the implications of, and develops best practices in, ethics for neuroscience research X.Liu PSYC5130 Imaging This is 1800s What can you do to learn about the brain? Hong Kong, 1865 X.Liu PSYC5130 Imaging This is 1800s What can you do to learn about the brain? Neuropsychology: Study what happens with brain injury If someone loses behavior X after damage to brain lesion Y, presume that Y was involved in the generation of X. X.Liu PSYC5130 Phineas Gage Man who began neuroscience X.Liu PSYC5130 Song Time! X.Liu PSYC5130 Imaging This is 1800s What can you do to learn about the brain? Neuropsychology: Study what happens with brain injury If someone loses behavior X after damage to brain lesion Y, presume that Y was involved in the generation of X. Anatomy: Dissect the brain X.Liu PSYC5130 At the beginning of the 1900s… The primary technique was staining and brain sectioning Staining identifies neuron cell bodies of different types A slice of rodent hippocampus, revealing multiple types of neurons and glia. X.Liu PSYC5130 Brodmann’s Areas A Brodmann area is a region of the cerebral cortex defined based on its cytoarchitecture, or organization of cells. Continues to define how we discuss neural anatomy X.Liu PSYC5130 Today Manipulating & Measuring Brain-Behavior Lesion Stimulation X.Liu PSYC5130 Dr. Wilder Penfield, 1940s X.Liu PSYC5130 X.Liu PSYC5130 X.Liu PSYC5130 Relatively noninvasive brain stimulation Transcranial Magnetic Stimulation (TMS) A small wire coil is placed adjacent to the skull High-voltage current pulsed through the coil Magnetic field passes through the skull Causes a population of neurons to depolarize or hyperpolarize X.Liu PSYC5130 X.Liu PSYC5130