How our brain works and does not work

David SpaffordAssociate ProfessorDirector of Undergraduate NeuroscienceDepartment of Biology,University of Waterloo

ORGANIZATION OF THE TALK

1. The brain is complex2. The brain is highly sensitive to injury3. The brain interprets the sensory information it receives4. The brain lives in its own virtual reality5. Our divided brain6. Critical brain feature for human culture – Mirror neurons.

Purkinje Neuron

human brain

post-synaptic neuron

pre-synaptic neuron

synapse

100 trillion synaptic connections

dendriticspine

dendrite

nerve terminals

100 billion neurons

nerve fascicle (wrapped by perineurium)

neuron

neuron(wrapped in myelin sheath)

neuron(wrapped in endoneurium)

nerve

nerve(wrapped by epineurium)

peripheral nervous system

The Brain Stem – The Primitive Brain- produces automatic, survival behaviors

• midbrain

• pons

• medulla

Cerebellum – body movement center

– coordinates body movements – helps maintain equilibrium

Cerebellar cortex

MORE ADVANCED BRAIN Diencephalon on top of the Brain stem

hypothalamus “master control gland of autonomic activities” epithalamus “pineal gland” – circadian rhythmsthalamus “relay center of sensory information”

Basal ganglia (Basal nuclei) internal islands of gray matter (help regulate voluntary motor activities)

thalamus

(basal ganglia)

(basal ganglia)

(basal ganglia)

PROJECTION FIBERS

AND CORPUS COLLOSUM

Projection fibers”

corpus callosum

CEREBRAL CORTEX

• 2-4 mm thick gray matter• accounts for 40% of the mass of the brain; cortical folds triples size of cortex• “home of our conscious mind” and information processing of the brain• enables sensation, voluntary and skilled skeletal muscle activity, language,

memory, personality, self-awareness• Each hemisphere has functional regions

white matter

gray matter

• Primary olfactory cortexA

• Orbitofrontal cortexB

• Prefrontal cortexC

• Motor association areaD

• Primary motor areaE

• Primary somatosensory areaF

• Somatosensory association areaG

• Visual association areaH

• Primary visual cortexI

• Wernicke’s areaJ

• Primary gustatory cortexK

• Primary auditory cortexL

• Auditory association areaM

• Broca’s areaN A

M

C

D

EF

G

H

I

JL

N

K

B

1. The brain is complex2. The brain is highly sensitive to injury3. The brain interprets the sensory information it receives4. The brain lives in its own virtual reality5. Our divided brain6. Critical brain feature for human culture – Mirror neurons.

Internal carotid arteryA

Cerebral arteries (anterior, middle)BCircle of WillisC

AA

A

B

B

AA

B

A

B

B

B

B

B

B C

Stroke

• Caused when blood circulation to the brain is blocked and brain tissue dies

• Most commonly caused by blockage of a cerebral artery

• Other causes include compression of the brain by hemorrhage or edema, and atherosclerosis

Cerebral aneurism is a weak or thin spot on a blood vessel in the brain that balloons

out and fills with blood.

may leak or rupture, hemorrhaging into the surrounding tissue

Sidney Crosby concussion

Muhammad Ali Punch drunk syndrome

Concussions or traumatic brain injury

Cerebrospinal fluid (CSF)

Brain surrounded by bone (skull)

1. The brain is complex2. The brain is highly sensitive to injury3. The brain interprets the sensory information it receives4. The brain lives in its own virtual reality5. Our divided brain6. Critical brain feature for human culture – Mirror neurons.

Sensory Integration:

Our brains can fill in the gaps…

Multimodal Sensory Integration(vision-hearing-touch-taste-smell)

The brain makes use of multiple sensory inputs simultaneously to provide the “best” understanding possible.

McGurk Effect

image of a man uttering “ga ga” audio of him pronouncing “ba ba”our brains mesh these two to come up with “da da”.

Amygdala – the emotional center

fear, anger, pleasure

Capgras syndrome

The brain injured patient's mother came to see him, he exclaimed, "Who is this woman? She looks just like my mother, but she's an impostor! She's some other woman pretending to be my mother.

Daniel Tammet

Synaesthesia – “Jointed perception”

Tammet set a record on March 14th 2004 when he recited the famous mathematical constant Pi (3.141...) to 22,514 decimal places from memory in a time of 5 hours, 9 minutes.

Everyone has a limited form synaesthesia

- important for metaphorical thinking , abstraction, creativity

- 8x more likely for poets, artist, and novelists to have synaesthesia

Alien language:“Booba” and “Kikki”

1. The brain is complex2. The brain is highly sensitive to injury3. The brain interprets the sensory information it receives4. The brain lives in its own virtual reality5. Our divided brain6. Critical brain feature for human culture – Mirror neurons.

George: Jerry, just remember, it's not a lie if you believe it.

Phantom limb pain

Sensory and Motor Areas of the Cerebral Cortex

• Spatial map of somatic sensory area / primary motor area

Vilayanur Ramachandran

The Divided Brain

Brain halves are asymmetrical

Brain halves talk with one another through the corpus callosum

Original interpretation of the divided brain

Left to write: normal conditions, right hemisphere inactivated, left hemisphere inactivated

man, bicycle and house drawn by subject with right pareito-occipital lesion)

Left side of brain can’t interpret the whole

Hemi-neglect - inability to pay attention to or notice stimuli from one-half of the visual field

Morning in 1996 Jill Taylor: “I realized, ‘Oh my gosh! I’m having a stroke! I’m having a stroke!’ The next thing my brain says to me is, ‘Wow! This is so cool! How many brain scientists have the opportunity to study their own brain from the inside out?’”

In her case, although the stroke damaged the left side of her brain, her recovery unleashed a torrent of creative energy from her right

Dr. Jill Bolte Taylor Harvard-trained and published neuroanatomist

RIGHT BRAIN LEFT BRAIN

Left brain - needed to manipulate things in the worldRight brain – provides the broader context

Right brain – provides broad perspective

Left brain – execution of tasks

Left brain – execution of tasks

1. The brain is complex2. The brain is highly sensitive to injury3. The brain integrates and interprets the sensory information it receives4. The brain lives in its own virtual reality5. Our divided brain6. Critical brain feature for human culture – Mirror neurons

IMITATION, EMULATION, LANGUAGE, MOTOR PLANNING

ORIGINS OF HUMAN EMPATHY

HUMAN CIVILIZATION AND CULTURE

= MIRROR NEURONS- mirror neurons for action- mirror neurons for touch

Discovery of Mirror Neurons in Monkeys

Giacomo Rizzolatti,Italy, early 1990s

Monkey grabs food pellet

Brain recording of mirror neurons in prefrontal cortex

Monkey watches human grab food pellet

Mirror Neurons for action

= experience another other persons point of view, virtual simulation of action

Imitation / emulation – learn language, learning to hold a pencil, feeling their pain,

- discovery of culture moves rapidly through the population

- discover of culture carried through the generations

Mirror Neurons for touch

- Somatosensory neuron will fire when I simply watch another person being touched (empathy)

- feedback from receptors in skin prevent you from feeling someone else's experience of touch

- Remove skin receptor connection to the brain, you then remove the barrier between what that person feels and what you feel

Mirror neurons connects people as a whole creating human empathy and the development of human culture