NRSC 2100 1st Edition Lecture 18 Receptive Field Concept 1 Receptive field Area of retina that when stimulated with light changes a cell s membrane potential Light always hyperpolarizes photoreceptors reducing neurotransmitter glutamate release 1 Off bipolar cells depolarize during light off periods dark On bipolar cells depolarize during lights on periods light Antagonistic center surround receptive fields 1 On center Bipolar Cells Presence of light on center receptive field depolarization Presence of light on surround receptive field hyper polarization Off center Bipolar Cells Display the reverse responses to light compared to On center cells Ganglion Cell Receptive Fields 1 First cells that produce action potentials and send their axons to brain via Optic nerve 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 2 On Center and Off Center ganglion cells driven by similarly responsive bipolar cells 3 Responsive to differences in illumination Types of Ganglion Cells 1 M type Magno large and P type Parvo small ganglion cells Different in appearance connectivity and electrophysiological properties Color Opponent Ganglion Cells Linked colors Center surround receptive fields responsive to colors P type ganglion cells mostly Red green opponents Blue yellow opponents Visual Hemifields 1 Right and Left Visual Hemifields Left hemifield projects to right side of brain and vice versa Ganglion cell axons from nasal retina cross temporal retinal axons stay ipsilateral Central Pathway for Conscious Visual Perception Retinal Ganglion cells Optic Nerve Optic Tract Lateral Geniculate Nucleus Optic radiation Primary Visual cortex Occipital lobe Non Thalamic Central Visual Pathways 1 Hypothalamus suprachiasmatic nucleus Biological rhythms including sleep and wakefulness Pretectum Size of the pupil certain types of eye movement Superior colliculus Orients the eyes in response to new stimuli Lateral Geniculate Nucleus Organization 1 Eye segregation into different layers 1 6 2 M layers 1 2 ventral derived from M type ganglion cells 3 P layers 3 6 dorsal derived from P type ganglion cells 4 LGN cells retain characteristic properties of retinal cells projecting to them Striate Primary Visual Cortex Organization 1 V1 recipient of LGN axon terminals 2 Neocortex generally divided into 6 layers Layer V VI deepest output Layer IV C recipient of major LGN inputs M P Ctr Srd org Layer I contains few cells and is next to pia Striate Primary Visual Cortex Organization 1 Ocular Dominance Columns Present in layer IV alternating inputs from two eyes 1 brown one eye blue other eye each column 0 5 mm Striate Primary Visual Cortex Organization Orientation selective cells outside layer IVC neighboring patches respond to closely related angles simple cortical cells Extra Striate Cortex and Visual Information Dorsal stream Analysis of visual motion and the visual control of action Ventral stream Perception of the visual world and the recognition of objects Chemical Senses Taste and Smell Smell Olfaction olfactory system Taste Gustation gustatory system called chemical senses because their function is to monitor the chemical content of the environment Flavor of food is a composite of both taste and smell sensation In many species including humans taste especially of bitterness and sourness is used to protect against poisoning