The Biology of Mind. Consciousness and the

Two-Track Mind.

Neuroscience and BehaviorNeuroscience and Behavior BBiological psychology iological psychology is the scientific study ofis the scientific study of the the

biological bases of behavior and mental processes. biological bases of behavior and mental processes. This area of research isThis area of research is also called also called biopsychology. biopsychology. Both terms emphasize the idea of a biological Both terms emphasize the idea of a biological approachapproach to the study of psychological processes. to the study of psychological processes.

Biological psychology is one of the scientificBiological psychology is one of the scientific disciplines that makes important contributions to disciplines that makes important contributions to neuroscienceneuroscience—the—the scientific study of the nervous scientific study of the nervous system. As system. As neuroscientists, neuroscientists, biopsychologists bringbiopsychologists bring their expertise in behavior and behavioral research to their expertise in behavior and behavioral research to this scientific endeavor.this scientific endeavor.

Some of the other scientific disciplines that contribute Some of the other scientific disciplines that contribute to neuroscience includeto neuroscience include physiology, pharmacology, physiology, pharmacology, biology, biology, and and neurology.neurology.

NNeuronseurons

Communication Communication throughout the throughout the nervous system nervous system takes place via takes place via neuronsneurons—cells—cells that are highly that are highly specialized to specialized to receive and receive and transmit transmit information from information from one part ofone part of the the body to another.body to another.

GGlial cellslial cells

Along with Along with neurons, the human neurons, the human nervous system is nervous system is made up of other made up of other types oftypes of specialized cells, specialized cells, called called glial cellsglial cells between neurons between neurons and blood vesselsand blood vessels in the brain.in the brain.

Glia and Blood-Brain BarrierGlia and Blood-Brain Barrier

BBasic typesasic types of neuronsof neurons There are three basic typesThere are three basic types of neurons, each of neurons, each

communicating different kinds of informationcommunicating different kinds of information:: Sensory neurons Sensory neurons convey information about theconvey information about the

environment, such as light or sound, from specialized environment, such as light or sound, from specialized receptorreceptor cells in the sense organs to the brain. cells in the sense organs to the brain. Sensory neuronsSensory neurons also carry information from the skin also carry information from the skin and internaland internal organs to the brain. organs to the brain.

Motor neurons Motor neurons communicate informationcommunicate information to the to the muscles and glands of the body. blinking your eyes muscles and glands of the body. blinking your eyes activates thousands of motor neurons. activates thousands of motor neurons.

IInterneuronsnterneurons communicate information communicate information between between neurons. By far, most of the neurons in theneurons. By far, most of the neurons in the human human nervous system are interneurons, and many nervous system are interneurons, and many interneurons connect tointerneurons connect to other interneurons.other interneurons.

Characteristics of the Neuron

• Most neurons have three basic components: a cell body, dendrites, and an axon. The cell body contains the nucleus, which provides energy for the neuron to carry out its functions. The cell body also contains genetic material and other structures that are found in virtually all the cells in the body

Components of the neuronComponents of the neuron The The cell body cell body contains the nucleus, which provides energycontains the nucleus, which provides energy for for

the neuron to carry out its functions. The cell body also the neuron to carry out its functions. The cell body also contains geneticcontains genetic material and other structures that are found in material and other structures that are found in virtually all the cells in thevirtually all the cells in the body.body.

Extending out from the cell body are many short, branching Extending out from the cell body are many short, branching fibers, calledfibers, called dendrites. dendrites. Dendrites Dendrites receive receive messages from messages from other neurons orother neurons or specialized cells.specialized cells.

The The axon axon is a single, elongated tube that extends from the cell is a single, elongated tube that extends from the cell body inbody in most, though not all, neurons. Axons carrymost, though not all, neurons. Axons carry information information from from the neuron the neuron to to other cells in the body, other cells in the body, including other neurons,including other neurons, glands, and muscles.glands, and muscles.

The axons of many, though not all, neurons are surrounded by The axons of many, though not all, neurons are surrounded by the the myelinmyelin sheath. sheath. The myelin sheath is a white, fatty The myelin sheath is a white, fatty covering covering anufactured by specialanufactured by special glial cells.glial cells.

The NeuronThe Neuron

Axon

DendritesSoma

Axon Terminals

Myelin Sheath

Function of ion gate

Action PotentialsAction Potentials

Communication Between NeuronsCommunication Between Neurons

In theIn the brain, as in brain, as in the rest of the the rest of the nervous system,nervous system, information is information is transmitted by transmitted by electrical impulseselectrical impulses that speed from that speed from one neuronone neuron to the to the next.next.

TThehe SSynapseynapse The point of The point of

communication communication between two between two neuronsneurons

is called the is called the synapse.synapse.

The transmission The transmission of information of information between two between two neurons occurs in neurons occurs in one of twoone of two

ways: electrically ways: electrically or chemically.or chemically.

Chemical Signals Chemical Signals One neuron will transmit info to another neuron or to a muscle or One neuron will transmit info to another neuron or to a muscle or

gland cell by releasing chemicals called neurotransmitters.gland cell by releasing chemicals called neurotransmitters. The site of this chemical interplay is known as the synapse.The site of this chemical interplay is known as the synapse.

An axon terminal (synaptic knob) will abut another cell, a An axon terminal (synaptic knob) will abut another cell, a neuron, muscle fiber, or gland cell.neuron, muscle fiber, or gland cell.

This is the site of transduction – the conversion of an electrical This is the site of transduction – the conversion of an electrical signal into a chemical signal.signal into a chemical signal.

Synaptic Synaptic TransmissionTransmission An AP reaches the axon An AP reaches the axon

terminal of the terminal of the presynaptic cell and presynaptic cell and causes V-gated Cacauses V-gated Ca2+2+ channels to open.channels to open.

CaCa2+2+ rushes in, binds to rushes in, binds to regulatory proteins & regulatory proteins & initiates NT exocytosis.initiates NT exocytosis.

NTs diffuse across the NTs diffuse across the synaptic cleft and then synaptic cleft and then bind to receptors on the bind to receptors on the postsynaptic membrane postsynaptic membrane and initiate some sort of and initiate some sort of response on the response on the postsynaptic cell.postsynaptic cell.

Important Neurotransmitters

AcetylcholineAcetylcholine -l -learning, earning, memorymemory, muscle contractions, muscle contractions

DopamineDopamine – m – movementovement, , tthought processeshought processes, r, rewarding ewarding sensationssensations

SerotoninSerotonin - e - emotional statesmotional states, , ssleepleep

NorepinephrineNorepinephrine - p - physical hysical arousalarousal, l, learningearning, m, memoryemory

GABAGABA - - Inhibition of brain Inhibition of brain activityactivity

Endorphins Pain perception Endorphins Pain perception Positive emotionsPositive emotions

CCentral entral & & peripheral peripheral nervous systemnervous system

The The central nervous central nervous system system includes the brain includes the brain and the spinal cord.and the spinal cord.

Bundles of neuron axons Bundles of neuron axons that carry informationthat carry information in the in the peripheral nervous peripheral nervous systemsystem..

ReflexReflex a simple, automatic, inborn response to a sensory stimulusa simple, automatic, inborn response to a sensory stimulus

Skinreceptors

Muscle

Sensory neuron(incoming information)

Motor neuron(outgoing information)

Brain

Interneuron

Spinal cord

Neural NetworksNeural Networks interconnected interconnected

neural cells neural cells with experience, with experience,

networks can networks can learn, as feedback learn, as feedback strengthens or strengthens or inhibits inhibits connections that connections that produce certain produce certain results results

computer computer simulations of simulations of neural networks neural networks show analogous show analogous learninglearning

Inputs Outputs

Neurons in the brain connect with one

another to form networks

The brain learns by modifyingcertain connections in response to feedback

Specialized Cortical RegionsSpecialized Cortical Regionsrevealed with PET scanrevealed with PET scan

Brain scan images Brain scan images have

become so commonplace in news articles and popular magazines that it’s easy to forget just how revolutionary brain imaging technology has been to the field of neuroscience

Looking at Brain-Scan Images

The ‘Split Brain’ studiesThe ‘Split Brain’ studies Surgery for epilepsy : cut Surgery for epilepsy : cut

the corpus callosumthe corpus callosum Roger Sperry, 1960’sRoger Sperry, 1960’s Special apparatusSpecial apparatus

picture input to just picture input to just one side of brainone side of brain

screen blocks objects screen blocks objects on table from viewon table from view

Nonverbalrighthemisphere

Verballefthemisphere

Nonverbalrighthemisphere

Verballefthemisphere

??

“What didyou see?”

Picture to left brainPicture to left brain can name the objectcan name the object left hand cannot identify left hand cannot identify

by touchby touch

Picture to right brainPicture to right brain can’t name the objectcan’t name the object

left hand can identify by left hand can identify by touchtouch

“Using your left hand,Pick up what you saw.”

The ‘Split Brain’ studiesThe ‘Split Brain’ studies

I saw anapple.

“What didyou see?”

Nonverbalrighthemisphere

Verballefthemisphere