the brain! unit 3b: biological basis of behaviour

THE BRAIN!UNIT 3B: BIOLOGICAL BASIS OF BEHAVIOUR

THE BRAIN!

• ENABLES THE MIND

• THINK ABOUT IT…. IF YOU WERE TO TRANSPLANT ALL OF YOUR ORGANS, EXCEPT FOR YOUR BRAIN, YOU WOULD STILL BE MUCH THE SAME PERSON.

• TRANSPLANT YOUR BRAIN… NOW WE HAVE A PROBLEM!

HOW DO NEUROSCIENTISTS STUDY THE BRAIN’S CONNECTIONS TO BEHAVIOUR AND

MIND? • HISTORICALLY BRAIN UNDERSTAND HAD BEEN VERY PRIMITIVE. WE SIMPLY

LACKED THE APPROPRIATE TOOLS FOR THE JOB.

• ALL OR NOTHING… NO MRI MACHINES, NO ULTRASOUNDS, ETC. IF YOU WANTED TO SEE THE BRAIN, YOU HAD TO CUT IT OUT OF THE PATIENTS HEAD.

• KNEW BASELINE IDEAS, SUCH AS:

• IF YOU INJURE THE LEFT SIDE OF YOUR BRAIN, THE RIGHT SIDE OF YOUR BODY WOULD BE AFFECTED.

• DAMAGE TO THE BACK OF YOUR HEAD HARD ENOUGH COULD CAUSE VISION PROBLEMS.

• DAMAGE TO THE LEFT-FRONT PART OF THE BRAIN LED TO SPEECH PROBLEMS.

SO… HOW DO WE MAP A BRAIN?

• LESION TISSUE DESTRUCTION; A BRAIN LESION IS A NATURALLY OR

EXPERIMENTALLY CAUSED DESTRUCTION OF BRAIN TISSUE.

• WE CAN SELECTIVELY DAMAGE TINY CLUSTERS OF NORMAL OR DEFECTIVE

BRAIN CELLS, LEAVING THE SURROUNDING TISSUE UNHARMED.

• EX) DAMAGED RAT HYPOTHALAMUS TO REDUCE EATING, RATS WERE

STARVING UNLESS FORCE FED. THEN DAMAGED ANOTHER AREA AND

PRODUCE OVER EATING.

• MOST OFTEN IN ANIMAL TESTING.

• HUMAN BODIES GIVE OFF ELECTRICAL, METABOLIC AND

MAGNETIC SIGNALS

• ELECTROENCEPHALOGRAM (EEG) AN AMPLIFIED

RECORDING OF THE WAVES OF ELECTRICAL ACTIVITY THAT

SWEEP ACROSS THE BRAIN’S SURFACE. THESE WAVES

ARE MEASURED BY ELECTRODES PLACED ON THE SCALP.

• THEY ARE SO FINITE, THEY CAN PICK UP THE SIGNAL FROM

A SINGLE NEURON.

• THESE WAVES ARE LIKE STUDYING HOW A CAR IS RUNNING

BY LISTENING TO IT’S ‘HUM’.

• STIMULUS IS PRESENTED REPEATEDLY AND A COMPUTER

FILTERS OUT ALL OTHER BRAIN ACTIVITY.

• CT (COMPUTED TOMOGRAPHY) SCAN A

SERIES OF X-RAY PHOTOGRAPHS TAKEN

FROM DIFFERENT ANGLES AND COMBINED

BY COMPUTER INTO A COMPOSITE

REPRESENTATION OF A SLICE THROUGH

THE BODY.

• ALSO CALLED CAT SCAN.

• USED TO REVEAL BRAIN DAMAGE.

• PET (POSITRON EMISSION

TOMOGRAPHY) SCAN A VISUAL

DISPLAY OF BRAIN ACTIVITY THAT

DETECTS WHERE A RADIOACTIVE

FORM OF GLUCOSE GOES WHILE

THE BRAIN PERFORMS A GIVEN

TASK.

• SHOWS EACH BRAIN AREA’S CONSUMPTION OF IT’S CHEMICAL FUEL – GLUCOSE

• ACTIVE NEURONS ARE GLUCOSE HOGS

• SHOWS ‘HOT SPOTS’, OR WHICH BRAIN AREAS ARE MOST ACTIVE AS THE PERSON PERFORMS SET TASKS, SUCH AS MATHEMATICAL EQUATIONS, OR LOOKS AT FACES.

• MRI (MAGNETIC RESONANCE IMAGING) A TECHNIQUE THAT USES MAGNETIC

FIELDS AND RADIO WAVES TO PRODUCE COMPUTER-GENERATED IMAGES OF

SOFT TISSUE. MRI SCANS SHOW BRAIN ANATOMY.

• SOME THINGS MRI’S HAVE REVEALED:

• MUSICIANS WITH PERFECT PITCH HAVE A LARGER NEURAL AREA IN THEIR

LEFT HEMISPHERE.

• SCHIZOPHRENIA PATIENTS HAVE LARGE AREAS OF FLUID FILLED AREAS IN

THEIR BRAINS.

• FMRI (FUNCTIONAL MRI) A TECHNIQUE FOR REVEALING BLOODFLOW AND,

THEREFORE, BRAIN ACTIVITY BY COMPARING SUCCESSIVE MRI SCANS. FMRI

SCANS SHOW BRAIN FUNCTION.

• COMPARES MULTIPLE MRI SCANS AT A TIME TO TRACK BLOOD FLOW, WHICH

INDICATES BRAIN ACTIVITY LOCATION.

BRAIN IMAGING

OLDER BRAIN STRUCTURES

• HUMAN BRAINS ARE ABOUT 1/45TH OF BODY WEIGHT, COMPARE TO 1/10,000TH IN WHALES AND 1/600TH IN ELEPHANTS.

• IN MORE PRIMITIVE ANIMALS, LIKE SHARKS, THE BRAIN IS FOCUSED ON AND DIVIDED INTO BASIC SURVIVAL FUNCTIONS – BREATHING, RESTING AND FEEDING.

• IN LOWER MAMMALS, LIKE RODENTS, A MORE COMPLEX BRAIN ENABLES EMOTION AND MEMORY.

• BRAINSTEM THE OLDEST PART OF THE CENTRAL

CORE OF THE BRAIN, BEGINNING WHERE THE SPINAL

CORD SWELLS AS IT ENTERS THE SKULL; THE

BRAINSTEM IS RESPONSIBLE FOR AUTOMATIC

SURVIVAL FUNCTIONS.

• BRAINSTEM IS A CROSSOVER POINT, WHERE NERVES TO AND FROM EACH SIDE OF THE BRAIN CONNECT WITH THE BODY’S OPPOSITE SIDES.

• MADE OF 3 PARTS:

• MEDULLA THE BASE OF THE BRAINSTEM; CONTROLS

HEARTBEAT AND BREATHING.

• PONS – HELPS COORDINATE MOVMENTS.

• RETICULAR FORMATION A NERVE NETWORK IN THE

BRAINSTEM THAT PLAYS AN IMPORTANT ROLE IN

CONTROLLING AROUSAL.

• FILTERS SIGNALS TO REPLAY IMPORTANT

INFORMATION TO THE BRAIN.

• THALAMUS THE BRAIN’S

SENSORY SWITCHBOARD,

LOCATED ON TOP OF THE

BRAINSTEM; IT DIRECTS

MESSAGES TO THE SENSORY

RECEIVING AREAS IN THE

CORTEX AND TRANSMITS

REPLIES TO THE CEREBELLUM

AND MEDULLA.

• ALL SENSES EXCEPT SMELL.

• HUB THROUGH WHICH TRAFFIC PASSES EN ROUTE TO DIFFERENT DESTINATIONS.

• CEREBELLUM THE “LITTLE BRAIN” AT

THE REAR OF THE BRAINSTEM;

FUNCTIONS INCLUDE PROCESSING

SENSORY INPUT AND COORDINATING

MOVEMENT OUTPUT AND BALANCE.

• HAS 2 WRINKLED HALVES, JUST LIKE OUR

BRAIN.

• HELPS US TO JUDGE TIME, DISCRIMINATE

SOUNDS AND TEXTURES.

• VOLUNTARY MOVEMENT – EX. PERFECTLY

TIMED SOCCER KICK.

• DAMAGED CEREBELLUM CREATES SHAKY

WALKING, BALANCE AND OVER

EXAGGERATED MOVEMENTS.

• OCCUR WITHOUT CONSCIOUS EFFORT –

OUR BRAIN PROCESSES MOST

INFORMATION OUTSIDE OF OUR

AWARENESS.

• LIMBIC SYSTEM DOUGHNUT-

SHAPED NEURAL SYSTEM

(INCLUDING THE

HIPPOCAMPUS, AMYGDALA,

AND HYPOTHALAMUS)

LOCATED BELOW THE

CEREBRAL HEMISPHERES;

ASSOCIATED WITH EMOTIONS

AND DRIVES.

• HIPPOCAMPUS IS INVOLVED IN PROCESSING MEMORY, IF REMOVED, THEY ARE UNABLE TO PROCESS MEMORIES OF NEW FACTS/EPISODES.

• AMYGDALA TWO LIMA BEAN-SIZED

NEURAL CLUSTERS IN THE LIMBIC

SYSTEM; LINKED TO EMOTION.

• AGGRESSION AND FEAR

• NEUROSURGEONS LESIONED THE AMYGDALA OF AN AGGRESSIVE CHIMP, BECAME COMPLETELY DOCILE.

• NOT THE MEANS TO AN END OF AGGRESSION BECAUSE THERE ARE LOTS OF OTHER NEURAL LINKS ATTACHED.

• HYPOTHALAMUS A NEURAL STRUCTURE LYING BELOW

(HYPO) THE THALAMUS; IT DIRECTS SEVERAL

MAINTENANCE ACTIVITIES (EATING, DRINKING, BODY

TEMPERATURE), HELPS GOVERN THE ENDOCRINE

SYSTEM VIA THE PITUITARY GLAND, AND IS LINKED TO

EMOTION AND REWARD.

• INFLUENCE ON THE PITUITARY GLAND

• REWARD CENTERS

• ELECTRODES ATTACHED TO HYPOTHALAMUS IN

RATS. WHEN PRESSING A PEDAL, REWARD

STIMULUS. RATS WOULD PUSH THE PEDAL SO MUCH

(7000 TIMES PER HOUR) AND DROP FROM

EXHAUSTION.

• REWARD DEFICIENCY SYNDROME –ADDICTIVE

DISORDERS MAY STEM FROM THIS (EX ALCOHOLISM).

A GENETICALLY DISPOSED DEFICIENCY IN THE

NATURAL BRAIN SYSTEMS FOR PLEASURE AND

WELL-BEING THAT LEADS PEOPLE TO CRAVE

WHATEVER PROVIDES THE MISSING PLEASURE OR

RELIEVES NEGATIVE FEELINGS.

BRAIN STRUCTURES

MAPPING THE BRAIN THROUGH ELECTRICAL STIMULATION

THE CEREBRAL CORTEX• CEREBRAL CORTEX THE INTRICATE

FABRIC OF INTERCONNECTED

NEURAL CELLS COVERING THE

CEREBRAL HEMISPHERES; THE

BODY’S ULTIMATE CONTROL AND

INFORMATION-PROCESSING

CENTER.

• SMALLER CORTEX =

PREPROGRAMMED GENETIC

INSTRUCTIONS (EX FROGS)

• LARGER CORTEX = INCREASED

LEARNING AND THINKING (EX

MAMMALS)

• PART OF THE CEREBRUM, OR LARGE

2 LOBES OF THE BRAIN.

STRUCTURE OF THE CORTEX

• GLIAL CELLS CELLS IN THE NERVOUS SYSTEM THAT SUPPORT, NOURISH, AND

PROTECT NEURONS. THINK GLUE CELLS, NEURONS ARE QUEEN BEES, GLIAL ARE WORKER BEES

• LOBES:

• 1) FRONTAL LOBE PORTION OF THE CEREBRAL CORTEX LYING JUST BEHIND THE

FOREHEAD; INVOLVED IN SPEAKING AND MUSCLE MOVEMENTS AND IN MAKING PLANS

AND JUDGMENTS.

• 2) PARIETAL LOBE PORTION OF THE CEREBRAL CORTEX LYING AT THE TOP OF THE

HEAD AND TOWARD THE REAR; RECEIVES SENSORY INPUT FOR TOUCH AND BODY

POSITION.

• 3) OCCIPITAL LOBE PORTION OF THE CEREBRAL CORTEX LYING AT THE BACK OF THE

HEAD; INCLUDES AREAS THAT RECEIVE INFORMATION FROM THE VISUAL FIELDS.

• 4) TEMPORAL LOBE PORTION OF THE CEREBRAL CORTEX LYING ROUGHLY ABOVE THE

EARS; INCLUDES THE AUDITORY AREAS, EACH RECEIVING INFORMATION PRIMARILY

FROM THE OPPOSITE EAR.

HEMISPHERIC BALANCE

• CURVES IN LOBES ALLOW FOR INCREASED SURFACE AREA (3 TIMES AS LARGE).

• FUN FACT! AFTER DISSECTING EINSTEIN'S BRAIN, IT WAS FOUND THAT HE HAD A MUCH HIGHER CONCENTRATION OF GLIAL CELLS.

• MOTOR CORTEX AN

AREA AT THE REAR OF

THE FRONTAL LOBES

THAT CONTROLS

VOLUNTARY

MOVEMENTS.

• USED IN PROSTHETIC

LIMB CONTROL.

MOTIONS ARE

PREDICTED 1/10TH OF A

SECOND BEFORE

THEY ARE

TRANSMITTED, THIS

PREDICTION ALLOWS

FOR MOVEMENT

USING THOUGHT.

• SENSORY CORTEX AREA AT THE

FRONT OF THE PARIETAL LOBES

THAT REGISTERS AND PROCESSES

BODY TOUCH AND MOVEMENT

SENSATIONS.

• MORE SENSITIVE A BODY REGION, THE LARGER THE AREA OF THE SENSORY CORTEX IS ALLOTTED TO IT.

Functions of the Cortex

• ASSOCIATION AREAS AREAS OF THE CEREBRAL CORTEX THAT ARE NOT INVOLVED IN PRIMARY MOTOR OR SENSORY FUNCTIONS; RATHER, THEY ARE INVOLVED IN HIGHER MENTAL FUNCTIONS SUCH AS LEARNING, REMEMBERING, THINKING, AND SPEAKING.

• PARIETAL LOBES –ENABLE MATHEMATICAL AND SPECIAL REASONING.

• TEMPORAL LOBES – FACE RECOGNITION

• FRONTAL LOBES

• PHINEAS GAGE

PHINEAS GAGE

LANGUAGE PROCESSING

• SPEAKING, READING, WRITING, SINGING, SPEAKING, ETC ARE ALL PART OF LANGUAGE.

• APHASIA IMPAIRMENT OF LANGUAGE, USUALLY CAUSED BY LEFT HEMISPHERE DAMAGE

EITHER TO BROCA’S AREA (IMPAIRING SPEAKING) OR TO WERNICKE’S AREA (IMPAIRING

UNDERSTANDING).

• SOME PEOPLE WITH APHASIA CAN:

• SPEAK FLUENTLY BUT CANNOT READ

• COMPREHEND WHAT THEY READ BUT CANNOT SPEAK

• WRITE BUT NOT READ

• READ BUT NOT WRITE

• READ NUMBERS BUT NOT LETTERS

• SING BUT NOT SPEAK

• BROCA’S AREA CONTROLS LANGUAGE EXPRESSION THAT

DIRECTS THE MUSCLE MOVEMENTS INVOLVED IN SPEECH.

• WERNICKE’S AREA CONTROLS LANGUAGE RECEPTION – A

BRAIN AREA INVOLVED IN LANGUAGE COMPREHENSION AND

EXPRESSION; USUALLY IN THE LEFT TEMPORAL LOBE.

• IN PROCESSING LANGUAGE, JUST LIKE IN OTHER FORMS OF INFORMATION PROCESSING, THE BRAIN OPERATES BY DIVIDING IT’S MENTAL FUNCTIONS – SPEAKING, PERCEIVING, THINKING, REMEMBERING – INTO MANAGEABLE SUB FUNCTIONS.

• EVEN DIFFERENT TYPES OF JOKES ARE PROCESSED DIFFERENTLY IN THE BRAIN… EXPLAINS DIFFERENT SENSES OF HUMOR.

Language

Language

Language

Language

Language

Language

THE BRAINS PLASTICITY!!!! (COOL STUFF YO!!!)

• OUR BRAIN IS EXTREMELY MOULDABLE. FOR EXAMPLE, PIANISTS HAVE MORE DEVELOPED AUDITORY CENTRES.

• IT IS ALSO ABLE TO MODIFY AND HEAL ITSELF AFTER TRAUMA OR DAMAGE.

• PLASTICITY THE BRAIN’S ABILITY TO CHANGE, ESPECIALLY DURING CHILDHOOD, BY

REORGANIZING AFTER DAMAGE OR BY BUILDING NEW PATHWAYS BASED ON EXPERIENCE.

• THE BRAIN IS MOST PLASTIC IN EARLY CHILDHOOD –USE OF CONSTRAINT-INDUCED

THERAPY IS COMMON.

• AIMS TO REWIRE BRAINS BY RESTRAINING A FULLY FUNCTIONING LIMB, FORCING THE USE

OF A ‘BAD’ HAND OR LEG. GRADUALLY THE THERAPY REPROGRAMS THE BRAIN,

IMPROVING DEXTERITY OF A BRAIN DAMAGED CHILD, UP TO A STROKE SUFFERING ADULT.

• BLINDNESS OR DEAFNESS MAKES UNUSED BRAIN AREAS AVAILABLE FOR OTHER USES.

EX) WHEN A BLIND PERSON USES THEIR FINGER TO READ BRAILLE, THE BRAIN AREA

DEDICATED TO THAT FINGER EXPANDS AS THE SENSE OF TOUCH INVADES THE VISUAL

CORTEX.

• PHANTOM LIMB SYNDROME – FEELING A SENSATION ON A LIMB THAT IS NO LONGER THERE.

• SENSORY FIBRES IN THE BRAIN THAT WERE ORIGINALLY ASSOCIATED WITH THAT AREA, HAVE INVADED AN ADJACENT AREA.

• NEUROGENESIS THE FORMATION OF NEW NEURONS.

• MADE DURING SLEEP, EXERCISE AND NON STRESSFUL BUT STIMULATING

ENVIRONMENTS.

• ALTHOUGH SMALL `BABY NEURONS`, THERE IS EVIDENCE THEY CAN HEAL OVER DAMAGED AREAS.

• JODY MILLER – GIRL WITH HALF A BRAIN

• HTTP://WWW.YOUTUBE.COM/WATCH?V=VADLLD97CLM

BRAIN PLASTICITY

LANGUAGE AND BRAIN PLASTICITY

OUR DIVIDED BRAIN

• SPLITTING THE BRAIN

• OUR BRAIN HAS 2 SIDES AND EACH SIDE SERVES DIFFERENT FUNCTIONS.

• EX) DAMAGE TO LEFT AFFECTS READING, WRITING, SPEAKING, ARITHMETIC, REASONING AND UNDERSTANDING. SAME DAMAGE ON THE RIGHT, VISIBLY LESS DRAMATIC AFFECTS.

• 2 NEUROSURGEONS, VOGEL AND BOGEN, FIGURED OUT THAT MAJOR EPILEPTIC SEIZURES WERE CAUSED BY AMPLIFICATION OF ABNORMAL BRAIN ACTIVITY, BOUNCING BACK AND FORTH BETWEEN BRAIN HEMISPHERES…. SO WHY NOT CUT THE CORPUS CALLOSUM (THE LARGE BAND OF NEURAL FIBERS CONNECTING

THE TWO BRAIN HEMISPHERES AND CARRYING MESSAGES

BETWEEN THEM) TO REMEDY THIS?

• VOGEL AND BOGEN KNEW THAT OTHER NEUROSURGEONS, MYERS AND GAZZANIGA, HAD DONE THIS ON CATS AND MONKEYS… SO THEY TRIED IT ON HUMANS.

• THE RESULTS WERE THAT THE SEIZURES WERE ALL BUT ELIMINATED! THESE PATIENTS NOW HAD SPLIT BRAINS A CONDITION RESULTING FROM

SURGERY THAT ISOLATES THE BRAIN’S TWO HEMISPHERES BY CUTTING THE

FIBERS (MAINLY THOSE OF THE CORPUS CALLOSUM) CONNECTING THEM.

• ONE BRAIN OR TWO? STUDY IN YOUR FORTY STUDIES BOOK, ALSO PAGES

84-85 IN TEXTBOOK.

• TRY DRAWING A CIRCLE WITH YOUR LEFT HAND AT THE SAME TIME AS

DRAWING A SQUARE WITH YOUR RIGHT HAND… SEE WHAT YOUR RESULT IS!

RIGHT LEFT DIFFERENCES IN THE INTACT BRAIN

• HEMISPHERIC SPECIALIZATION• PERCEPTUAL TASKS – RIGHT HEMISPHERE –

INTERPRETING PICTURES, ETC.

• LANGUAGE – LEFT HEMISPHERE

• SENSE OF SELF – RIGHT HEMISPHERE - WHO YOU ARE IN

RELATIONSHIP TO OTHER PEOPLE EX) SEEING MEDICAL

CAREGIVERS AS FAMILY.

Which face is happiest? Left or right?

SPLIT BRAIN

THE BRAIN AND CONSCIOUSNESS • CONSCIOUSNESS OUR AWARENESS OF OURSELVES AND OUR ENVIRONMENT.

• EVOLUTIONARY PSYCHOLOGIST MIGHT THINK CONSCIOUSNESS IS LINKED WITH REPRODUCTIVE ADVANTAGE…

• COMPARING LONG TERM CONSEQUENCES TO SHORT TERM GAINS

• HOW DO WE SEE OTHERS AND HELPING US TO ‘READ THEIR MINDS’ OR INTERPRET THEIR EMOTIONS FOR OUR BENEFIT.

• COGNITIVE NEUROSCIENCE THE INTERDISCIPLINARY STUDY OF THE BRAIN ACTIVITY

LINKED WITH COGNITION (INCLUDING PERCEPTION, THINKING, MEMORY AND

LANGUAGE).

• DUAL PROCESSING THE PRINCIPLE THAT

INFORMATION IS OFTEN SIMULTANEOUSLY PROCESSED

ON SEPARATE CONSCIOUS AND UNCONSCIOUS TRACKS.

• PRIMING -EXPOSURE TO ONE STIMULUS INFLUENCES A RESPONSE TO ANOTHER STIMULUS.

• EX) READ THE WORD TABLE.. THEN SEE A WORD

STARTING WITH ‘TA’, ALREADY STARTING TO FORM

WORDS IN YOUR HEAD THAT START WITH THAT…

INCLUDING TABLE.

• CONSCIOUS (EXPLICIT) LEFT BRAIN

• INTUITIVE (IMPLICIT) RIGHT BRAIN

NEUROIMAGING

PLANNING LIFE’S GOALS AND THE FRONTAL LOBE

BRAIN REWARD CENTERS

• TWO-TRACK MIND• VISUAL PERCEPTION TRACK – ENABLES

US TO CREATE THE ‘MENTAL

FURNITURE’ THAT ALLOWS US TO THINK

ABOUT OUR WORLD. TO RECOGNIZE

THINGS AND PLAN FUTURE ACTIONS.

• VISUAL ACTION TRACK – GUIDES OUR

MOMENT TO MOMENT ACTIONS.

• THINK OF DRIVING… SPACING OUT.. BUT

BODY STILL KNOWS HOW TO DRIVE.

• SOME TWO TRACK MIND ACTIVITIES –

• IF YOU ARE RIGHT HANDED, MOVE YOUR RIGHT FOOT IN A SMOOTH CLOCKWISE CIRCLE WHILE WRITING THE NUMBER 3 OVER AND OVER WITH YOUR RIGHT HAND. (SWITCH IF LEFT HANDED).

• TAP 4 TIMES WITH YOUR DOMINANT HAND WHILE TAPPING 3 TIMES WITH YOUR LESS DOMINANT HAND.