Psychology 224: Neuroscience Lecture 12 PDF

Psychology 224: Neuroscience Methods and Research Strategies; Sensory Systems: Vision Reading: Carlson, Chapter 5 &6  Announcement Exam #3 Exam 3 will be on 11/7, not 11/4. What if we want to manipulate specific circuits?  Targeted Mutations In...

Psychology 224: Neuroscience Methods and Research Strategies; Sensory Systems: Vision Reading: Carlson, Chapter 5 &6  Announcement Exam #3 Exam 3 will be on 11/7, not 11/4. What if we want to manipulate specific circuits?  Targeted Mutations In Mice  Mutated genes can be producedBad Hair Day (Bhrd) Mouse in the laboratory and inserted into the chromosomes of mice Constitutive Knockout mice: The target of the mutation prevents the production of a Spontaneous Mutation certain protein -Limitation: Compensatory mechanisms Conditional knockout mice: Temporal control over the gene -Advantage: Mice can develop normally 5-HT1B Receptor Knockout  Manipulating Circuits Using Optogenetics  Channelrhodopsin-2 (ChR2) -A photosensitive protein found in green algae -Controls ion channels -Responds to blue light by opening sodium and calcium channels  Manipulating Circuits Using Optogenetics  Channelrhodopsin-2 (ChR2) -A photosensitive protein found in green algae -Controls ion channels -Responds to blue light by opening sodium and calcium channels Natronomonas pharaonis halorhodopsin (NpHR) -A photosensitive protein found in bacterium -Controls a transporter -Responds to yellow light by moving chloride into the cell Manipulating Circuits Using Optogenetics Videos How is light delivered to those brain cells? How do we get the opsin into the brain?  Targeted Mutations In Mice  Mutated genes can be producedBad Hair Day (Bhrd) Mouse in the laboratory and inserted into the chromosomes of mice Constitutive Knockout mice: The target of the mutation prevents the production of a Spontaneous Mutation certain protein -Limitation: Compensatory mechanisms Conditional knockout mice: Temporal control over the gene -Advantage: Mice can develop normally 5-HT1B Receptor Knockout The Visual System  Sensory Systems: Receptors & Transduction Sensory receptors are specialized neurons that detect physical stimuli in the external world Sensory transduction is the process whereby stimuli from the external world are transformed into electrical changes – e.g. transformed into changes in membrane potential – these changes are called receptor  The Eye The eye is part of the CNS (the retina is actually part of the brain) The eye is suspended in the orbits of the skull Six extraocular muscles attach the eye to the skull  Lens-like 5. structure that Location of focuses light on 7. sensory receptors the retina & sensory 2. transduction Transparent 6. part of sclera Output to 3. 8. the brain Muscular ring that controls how much light gets in Hole where 4. light enters 1. Outer white covering (no entry of light)  Photoreceptors Lightthat passes through the pupil travels through the vitreous humor to the retina, which houses the sensory receptors called photoreceptors A photoreceptor converts light (electromagnetic radiation) into electrical signals (sensory transduction)  Photoreceptors There are 2 types of photoreceptors: – 1) Cones (6 million) – provide us with most of the visual information about our environment  Responsible for our daytime vision; high visual acuity  Process color – 2) Rods (120 million) –more sensitive to light  Better for nighttime vision  Provide vision of poor acuity  The Fovea The central region of the retina Almost all of the cones in the retina are concentrated in the fovea Mediates our most acute vision When we look at something, our ocular muscles work to position the light emitted from the object directly on our fovea Cones vs. Rods  Optic Disk The part of the retina where axons carrying visual information leave the eye to form the optic nerve Contains NO receptors, so produces a blind spot Close your left eye and focus on the + with your right eye. Move book closer and further away until green circle hits your blind spot.  Retina Anatomy There are the 3 major types of cells in the retina forming different layers: – 1) Photoreceptors – the cones and rods – 2) Bipolar cells – neurons that synapse with the photoreceptors – 3) Ganglion cells – neurons that synapse with the bipolar cells and whose axons give rise to the optic nerve  Carries visual information into the brain https://www.google.com/search? sca_esv=576600514&rlz=1C5CHFA_enUS9 74US974&sxsrf=AM9HkKkZdPUE6ypNgM8 XJ9VH8d- GW1ATLQ:1698269679610&q=retina+neu roscience&tbm=vid&source=lnms&sa=X& ved=2ahUKEwjHqfHHk5KCAxWyhIkEHWKD AhUQ0pQJegQICBAB&biw=1674&bih=109 3&dpr=2#fpstate=ive&vld=cid:7f1361af,v id:fZDAwXh54is,st:0