2-Basics Neurons RFs.pdf

Perception: The Basics Steps to Perceptual Processing Neurons & Receptive Fields Laying the foundation for our study of the perceptual system Perceptual Receptor Experience...

Perception: The Basics Steps to Perceptual Processing Neurons & Receptive Fields Laying the foundation for our study of the perceptual system Perceptual Receptor Experience cells in sensory Sense surface organs Neurons/Brain Physical Stimulus Information Encoding and Transmission Transduction  Physical Stimulus Energy Light Vibrations Chemicals Pressure/heat Need specialized sensory systems to DETECT these stimuli.  Sense organs They funnel the physical stimulus to specialized receptor cells, located inside the sense organs, that can detect that stimulus EAR EYE NOSE & TONGUE SKIN/BODY  Receptors Receptors are cells in the sense organs. Their 1st job is to detect the physical stimulus VIBRATIONS CHEMICALS LIGHT PRESSURE/HEAT/POSITION Their 2nd job is to transduce physical stimuli into neural signals Neural signals li ght sound che m ic a ls P re ssu re / he at  Signal chain: stimulus to neuron Receptors Neurons The neuron’s RECEPTIVE FIELD Receptive Field of a Neuron The receptive field of a neuron is the area on a sensory surface containing receptor cells from which the neuron gets signals The receptive field of a neuron could consist of one receptor cell, or thousands of sensory cells, spread out or close together Any given receptor cell could be a part of one or more neurons’ receptive fields The signal can be conveyed directly from the receptor cells themselves, or via other neurons that are connected to those cells A neuron that receives signals from multiple neurons will have an RF equal to the total RFs of those neurons Receptive field size can vary over sensory surface and depending on the brain areas that are receiving the signals brain Receptive Field size can vary across the sensory surface: An Experiment What do we observe? Smaller Receptive Field – Few receptor cells – High resolution (lots of fine detail) – Lower sensitivity (less likely to respond to weak stimulus) Larger Receptive Field – More receptor cells – Lower resolution (grosser, fine detail not important) – Higher sensitivity  = No stimulus Receptive Fields = Low-intensity stimulus = High-intensity stimulus Sensory surface Receptor cells Baseline firing  = No stimulus Receptive Fields = Low-intensity stimulus = High-intensity stimulus Sensory surface  = No stimulus RFs and Resolution = Low-intensity stimulus Two-point test = High-intensity stimulus  = No stimulus RFs and Sensitivity = Low-intensity stimulus Very light pressure on surface = High-intensity stimulus ulus sti m s i ster e reg pons es edr m S um g ne firin li base te from a cri min dis d to Har Receptive Field Size can vary as you move up in processing Neurons in higher brain areas can put together detailed information from multiple neurons to identify the object anywhere on the stimulus surface This means that RFs of these neurons are larger and can be high resolution as well – they get the details from earlier in processing and put them together.  Putting it all together: The brain Modular: Different areas associated with different functions Laying the foundation for our study of the perceptual system Perceptual Receptor Experience cells in sensory Sense surface organs Neurons/Brain Physical Stimulus Information Encoding and Transmission Transduction HOW CAN WE KNOW WHAT’S GOING ON AT EACH STEP?