ch 21 Sensation & Perception Ch. 2: Physiology of Perception © Takashi Yamauchi (Dept. of Psychology, Texas A&M University) Main topics –Neurons –Vision –Transforming light into electricity –Pigments and perception

ch 22 Anatomy Lesson by Dr. Nicholaes (painted by Rembrandt Harmenszoon van Rijn in 1632)

ch 23 Some brief history “Anatomy of the Brain” by Thomas Willis (1664) Oxford physician The first major work on the brain. Present the results of dissections of a human brain. Staining By Gamillo Golgi (1873) Injecting dyes into the nervous system Enabled the visualization of neurons

ch 24 A nerve cell (neuron) shown by the Golgi method. nedPyramidalCell.jpg

ch 25 Doctrine of specific nerve energy –By Johannes Mueller (1842) –Our perceptions depend on “nerve energies” reaching the brain and that the specific quality we experience depends on which nerves are stimulated.

ch 26 Basic structure of the brain Modular organization –Specific functions are served by specific areas of the cortex. –Primary receiving areas: Occipital lobe (seeing) Temporal lobe (hearing) Parietal lobe (touching)

ch 27 Source: Kandel et al., 1994

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9 Human brain

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ch 212 Neuron Key components: –Cell body, dendrite, axon, and synapse

ch 213 Neuron I

ch 214 Neuron II

ch 215 Neurons Dendrites Cell body Axon

ch 216 Perception involves Transduction and neural processing And then behavior Inform ation Behavior /action

ch 217 Transduction –Different types of information (air vibration, light energy) is transformed into a common neural language in the brain  neural information –  this process is called “TRANSDUCTION.”

ch 218 Transduction: Examples –Touching a mouse, open a program, typing some words. –Driving a car

ch 219 Neural energy What is neural energy? –It is basically a conversation between neurons. Conversation? They talk to each other? Yap.

ch 220 How do neurons talk to each other? Neurons talk to each like a computer does. Neurons talk to each other by sending electrical signals.

ch 221 How so? A neuron is immersed in liquid rich in ions (molecules that carry electrical charge). This figure shows the high concentration of positively charged sodium (NA+) and the high concentration of positively charged potassium (K+).

ch 222 Ion? An ion is an atom or group of bonded atoms which have lost or gained one or more electrons, making them negatively or positively charged. A negatively charged ion has more electrons in its electron shells than it has protons in its nuclei. A positively-charged ion has fewer electrons than protons. An atom is the smallest particle still characterizing a chemical element; it is composed of various subatomic particles: Electrons have a negative charge; they are the least heavy (i.e., massive) of the three types of basic particles. Protons have a positive charge with a free mass about 1836 times more than electrons. Neutrons have no charge, have a free mass about 1839 times the mass of electrons. (Wikipedia.org) Atom?

ch 223 Neurons talk to each other electronically by sending chemicals (neurotransmitters) from one neuron to other neurons. Neurons are not directly attached but are connected indirectly at a juncture called “synapse.”

ch 224 Synapse

ch 225 DendriteAxon Synapse Neurons (schematic Illustration) When an electric signal reaches at the end of the axon of a neuron, that neuron releases “neurotransmitters”

ch 226 DendriteAxon Synapse Synapse and neurotransmitter The neurotransmitters reach a terminal of a dendrite of the other neuron, and change the neuron’s resting potential.

ch 227 Resting potential The electrical charge when a neuron is at rest is called “resting potential.”  -70millivolt

ch 228 Dendrites collect electrical signals from other neurons. Dendrites forward these signals to the cell body. axon dendrites

ch 229 axon dendrites Firing (spike) No Firing Accumulation of signals When the signals that gather at the cell body exceed a threshold, the axon triggers a new signal (i.e., spike).

ch 230 DendriteAxon Synapse Neurotransmitters can send positive or negative signals. Neurotransmitters can open positive or negative gates. Some neurotransmitters open positive gates. Some neurotransmitters open negative gates.

ch 231 axon dendrites Basically there are two types of neuro-transmitters. One that sends excitatory (+) signals (transmitter), and the other that sends inhibitory (-) signals. So, the excitatory neurons enhance the activity of other neurons; the inhibitory neurons suppress the activity of other neurons. axon dendrites

ch 232 Demonstration

ch 233 Activities of neurons can be schematically shown as B a1 a2 a3 a4 The firing rate of neuron B is determined by the activation sent by neurons a1-a4.

ch 234 Summary A neuron consists of dendrites, a cell body and an axon. Neurons are not directly attached but are indirectly connected by synapses. One neuron sends an electrical signal to another neuron by releasing neurotransmitters. Some neurons send excitatory signals (+); others send inhibitory signals (-).

ch 235 What does this tell? (1) Perception can be examined by the activity of neurons. –When we are perceiving something, some neurons are firing. When we see a picture like this, neurons that respond to different colors, shapes, texture,… are firing together.

ch 236 Bridging the activity of neurons and behavior (perception) Single cell recording ERP (Event related potential/evoked potentials) PET (Positron Emission Tomography) fMRI (functional Magnetic Resonance Imaging)

ch 237 Single cell recording

ch 238 ERP

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ch 240 Biofeedback Neurofeedback for attention deficit disorder UG6BDA8wI

ch 241 PET & fMRI

ch 242 fMRI Source: Kandel et al., 1994

ch 243 fMRI Setup

ch 244 fMRI Experiment Stages: Anatomicals 4) Take anatomical (T1) images high-resolution images (e.g., 1x1x2.5 mm) 3D data: 3 spatial dimensions, sampled at one point in time 64 anatomical slices takes ~5 minutes Source: Jody Culham’s fMRI for Dummies web sitefMRI for Dummies

ch 245 PET (Normal resting pattern) Source: Kandel et al., 1994

ch 246 PET (visual & auditory stimulation) Source: Kandel et al., 1994

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ch 248 fMRI and a lie detector 7YWK0WQ

ch 249 TMS Transcranial magnetic stimulation –Disrupt the electrical activity of neurons in a targeted area by a strong magnetic field (4:15) – iA

ch 250 ERP, PET, &MRI Subjects carry out some psychological tasks (e.g., visual perception) Trace neural activities of the brain. Identify the brain location in which the psychological function takes place. Bridge psychological functions and their brain locations.

ch 251 Visual perception What is the difference between (a) & (b)? What is going on in your head when you see (a) versus when you see (b)? (a) (b)

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ch 254 How about this?

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ch 261 What’s going on? When you see the square, what’s going on? How do you find out?

ch 262 In terms of the activity of neurons, what is the difference between A and B ? Any guess? A. B.

ch 263 Measuring the electrical activity of a neuron directly by inserting a thin needle into animal brains.

ch 264 Time 0t The frequency of action potential Time 0 t The number of action potential emitted by a neuron is correlated with the intensity of the stimulus. Time 0 t

ch 265 Questions: What happens to B? 0 t

ch 266 Questions: What happens to B? ExcitatoryInhibitory

ch 267 Specificity coding vs. Distributed coding How are objects represented in the visual system? Think about human faces. Every face is different. So do we need an infinite number of neurons to represent individual faces?

ch 268 Specific coding? A single neuron responds to each face?

ch 269 Specific coding? A single neuron responds to each face?

ch 270 Neurons in the hippocampus respond specifically to an individual person, such as Halle Berry, her face picture, her name, and pictures of her dressed as Catwoman from Batman. But the hippocampus is a memory storage site. So, these specific neurons are responding to specific memory of a familiar person.

ch 271 Distributed coding The same set of neurons respond to different faces but in different degrees.

ch 272 Combinations of neurons can express lots of different faces