the brain! unit 3b: biological basis of behaviour
TRANSCRIPT
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.