Studying the Brain, Studying the Brain, the Old Brain, and the Old Brain, and the Limbic Systemthe Limbic System

AP PsychologyAP Psychology

Mr Tulper 2013Mr Tulper 2013

How do we study the How do we study the brain?brain?

There are many methods.There are many methods. lesionlesion: tissue destruction. A brain : tissue destruction. A brain

lesion is a naturally or experimentally lesion is a naturally or experimentally caused destruction of brain tissue.caused destruction of brain tissue.

Scientists and doctors can selectively Scientists and doctors can selectively lesion small areas of normal or lesion small areas of normal or defective brain cells, leaving the defective brain cells, leaving the surrounding brain unharmed. surrounding brain unharmed.

Clinical ObservationClinical Observation

The oldest method of studying the The oldest method of studying the brain-mind connection, by observing brain-mind connection, by observing the effects of specific brain diseases the effects of specific brain diseases and injuries.and injuries.

There are records of thousands of There are records of thousands of brain-injured patients across the brain-injured patients across the country.country.

These stories provide clues to our These stories provide clues to our own brains’ inner workings. own brains’ inner workings.

Manipulating the BrainManipulating the Brain

Scientists can electrically, Scientists can electrically, chemically, or magnetically chemically, or magnetically stimulate various parts of the brain stimulate various parts of the brain and note effects.and note effects.

They also surgically lesion specific They also surgically lesion specific brain areas in animals. brain areas in animals.

Video: Video: Transcranial Magnetic Stimulation

Recording the brain’s Recording the brain’s electrical activityelectrical activity

Scientists can stick Scientists can stick a tiny a tiny microelectrode microelectrode into a single into a single neuron to measure neuron to measure its activity.its activity.

Recording the brain’s Recording the brain’s electrical activityelectrical activity

electroencephalogram electroencephalogram (EEG): (EEG): an amplified an amplified recording of the waves recording of the waves of electrical activity that of electrical activity that sweep across the brain’s sweep across the brain’s surface. These waves are surface. These waves are measured by electrodes measured by electrodes placed on the scalp.placed on the scalp.

Repeated study of the Repeated study of the read-out can help read-out can help researchers filter out researchers filter out brain activity and find brain activity and find the electrical wave the electrical wave caused by the specific caused by the specific stimulus.stimulus.

Neuroimaging Neuroimaging TechniquesTechniques

Ways to observe the brain in a living Ways to observe the brain in a living person.person.

PET ScanPET Scan PET (positron emission tomorgraphy) PET (positron emission tomorgraphy)

scanscan: a visual display of brain activity that : a visual display of brain activity that detects where a radioactive form of glucose detects where a radioactive form of glucose goes while the brain performs a given task.goes while the brain performs a given task.

Active neurons hog the glucose (the brain’s Active neurons hog the glucose (the brain’s chemical fuel), and the PET scan tracks chemical fuel), and the PET scan tracks where in the brain the radioactive glucose where in the brain the radioactive glucose goes.goes.

Researchers can have participants think Researchers can have participants think about certain topics or do activities to see about certain topics or do activities to see where the glucose goes (thereby showing where the glucose goes (thereby showing what part of the brain is active during that what part of the brain is active during that activity). activity).

PET ScanPET Scan

MRIMRI MRI (magnetic resonance imaging):MRI (magnetic resonance imaging): a a

technique that uses magnetic fields and radio technique that uses magnetic fields and radio waves to produce computer-generated images that waves to produce computer-generated images that distinguish among different types of soft tissue; distinguish among different types of soft tissue; allows us to see structures within the brain.allows us to see structures within the brain.

Putting one’s head into a strong magnetic field Putting one’s head into a strong magnetic field aligns the spinning atoms.aligns the spinning atoms.

A pulse of a radio wave disorients the atoms A pulse of a radio wave disorients the atoms briefly.briefly.

When the atoms return to their normal spin, they When the atoms return to their normal spin, they release signals that give us a detailed image of the release signals that give us a detailed image of the body.body.

Video: Video: MRI

fMRIfMRI

fMRI (functional magnetic resonance fMRI (functional magnetic resonance imaging):imaging): a technique for revealing a technique for revealing blood flow and, therefore, brain activity blood flow and, therefore, brain activity by comparing successive MRI scans. MRI by comparing successive MRI scans. MRI scans show brain anatomy; fMRI scans scans show brain anatomy; fMRI scans show brain functions.show brain functions.

Researchers compare images taken less Researchers compare images taken less than a second apart, they can see which than a second apart, they can see which parts of the brain “light up” with parts of the brain “light up” with increased blood flow. increased blood flow.

fMRIfMRI

fMRI (functional magnetic resonance fMRI (functional magnetic resonance imaging):imaging): a technique for revealing a technique for revealing blood flow and, therefore, brain activity blood flow and, therefore, brain activity by comparing successive MRI scans. MRI by comparing successive MRI scans. MRI scans show brain anatomy; fMRI scans scans show brain anatomy; fMRI scans show brain functions.show brain functions.

Researchers compare images taken less Researchers compare images taken less than a second apart, they can see which than a second apart, they can see which parts of the brain “light up” with parts of the brain “light up” with increased blood flow. increased blood flow.

Video: Video: fMRI

Older Brain StructuresOlder Brain Structures

The brain makes up 1/45th of a The brain makes up 1/45th of a person’s body weight. person’s body weight.

There are newer structures that help There are newer structures that help animals think in more complex waysanimals think in more complex ways

There are also older structures that There are also older structures that have not changed much over many, have not changed much over many, many years. many years.

The BrainstemThe Brainstem

The brainstem: The brainstem: The oldest part and The oldest part and central core of the central core of the brain, beginning brain, beginning where the spinal where the spinal cord swells as it cord swells as it enters the skull; the enters the skull; the brainstem is brainstem is responsible for responsible for automatic survival automatic survival functions.functions.

The BrainstemThe Brainstem medullamedulla: the base of : the base of

the brainstem; controls the brainstem; controls heartbeat and heartbeat and breathing.breathing.

ponspons:: right above the right above the medulla, it helps medulla, it helps coordinate movementcoordinate movement

The brainstem is a The brainstem is a crossover point, where crossover point, where most nerves to and from most nerves to and from each side of the brain each side of the brain connect with the body’s connect with the body’s opposite side. opposite side.

Reticular FormationReticular Formation

reticular formationreticular formation: a nerve network : a nerve network in the brainstem that plays an in the brainstem that plays an important role in controlling arousal.important role in controlling arousal.

finger-shaped network of neurons that finger-shaped network of neurons that extends from the spinal cord right up extends from the spinal cord right up to the thalamus.to the thalamus.

filters incoming stimuli and relates filters incoming stimuli and relates important information to other areas important information to other areas of the brain. of the brain.

Reticular FormationReticular Formation

ThalamusThalamus thalamus: thalamus: the the

brain’s sensory brain’s sensory switchboard, located switchboard, located on top of the on top of the brainstem; it directs brainstem; it directs messages to the messages to the sensory receiving sensory receiving areas in the cortex areas in the cortex and transmits replies and transmits replies to the cerebellum to the cerebellum and medulla.and medulla.

receives information receives information from all the senses from all the senses exceptexcept smell. smell.

CerebellumCerebellum Cerebellum: Cerebellum: the “little brain” attached to the “little brain” attached to

the rear of the brainstemthe rear of the brainstem Its functions include processing sensory Its functions include processing sensory

input and coordinating movement output input and coordinating movement output and balance.and balance.

It also enables one type of nonverbal It also enables one type of nonverbal learning and memory.learning and memory.

Helps us judge time, modulate our Helps us judge time, modulate our emotions, and discriminate sounds and emotions, and discriminate sounds and textures.textures.

Coordinates voluntary movement. Coordinates voluntary movement.

CerebellumCerebellum

Older Brain StructuresOlder Brain Structures

***Most of these older brain ***Most of these older brain functions occur without any functions occur without any conscious effort conscious effort

DO NOW:DO NOW:

What are three ways scientists can What are three ways scientists can study the brain?study the brain?

The Limbic SystemThe Limbic System

A doughnut-shaped system of neural A doughnut-shaped system of neural structures at the border of the structures at the border of the brainstem and cerebral brainstem and cerebral hemispheres.hemispheres.

Associated with emotions such as Associated with emotions such as fear and aggression, and drives such fear and aggression, and drives such as those for food.as those for food.

Includes the hippocampus, Includes the hippocampus, amygdala, and hypothalamus. amygdala, and hypothalamus.

AmygdalaAmygdala Amygdala: Amygdala: two lima bean-sized neural two lima bean-sized neural

clusters that are components of the limbic clusters that are components of the limbic system and are linked to emotion.system and are linked to emotion.

Associated with both rage and fearAssociated with both rage and fear BUT, other areas of the brain are involved BUT, other areas of the brain are involved

as well, not just the amygdala.as well, not just the amygdala. Research has shown that lesioning the Research has shown that lesioning the

amygdala in violent monkeys has amygdala in violent monkeys has transformed them into peaceful creatures.transformed them into peaceful creatures.

However, people with the same damage However, people with the same damage may have been calmer, but lost other may have been calmer, but lost other forms of functioning as well. forms of functioning as well.

AmygdalaAmygdala

HypothalamusHypothalamus

Hypothalamus: Hypothalamus: a neural structure lying a neural structure lying below the thalamus.below the thalamus.

It directs several maintenance activities It directs several maintenance activities (eating, drinking, body temperature), (eating, drinking, body temperature), helps govern the endocrine system via helps govern the endocrine system via the pituitary gland, and is linked to the pituitary gland, and is linked to emotion.emotion.

It both monitors blood chemistry and It both monitors blood chemistry and takes orders from other parts of the takes orders from other parts of the brain.brain.

Is a “reward center” in the brain.Is a “reward center” in the brain.

HypothalamusHypothalamus

HypothalamusHypothalamus

May be related to “reward deficiency May be related to “reward deficiency syndrome” – a genetically disposed syndrome” – a genetically disposed deficiency in the natural brain deficiency in the natural brain systems for pleasure and well-being systems for pleasure and well-being that leads people to crave whatever that leads people to crave whatever provides that missing pleasure or provides that missing pleasure or relieves negative feelings. relieves negative feelings.

The Cerebral CortexThe Cerebral Cortex

The intricate fabric of The intricate fabric of interconnected neural cells that interconnected neural cells that covers the cerebral hemispheres; covers the cerebral hemispheres; the body’s ultimate control and the body’s ultimate control and information-processing center.information-processing center.

Like the bark of a tree, this is the Like the bark of a tree, this is the brain’s outer layer.brain’s outer layer.

The Cerebral CortexThe Cerebral Cortex

Adaptability increases as the Adaptability increases as the cerebral cortex expands and genetic cerebral cortex expands and genetic controls relax.controls relax.

Larger cortex = increased Larger cortex = increased capabilities for learning and thinkingcapabilities for learning and thinking

What makes humans different from What makes humans different from animals is the complex functions of animals is the complex functions of our brain’s cerebral cortex.our brain’s cerebral cortex.

Structure of the CortexStructure of the Cortex

80% of the brain’s weight comes 80% of the brain’s weight comes from the left and right cerebral from the left and right cerebral hemispheres.hemispheres.

They are filled with mostly axon They are filled with mostly axon connections between the surface connections between the surface and its other regions.and its other regions.

The cortex contains around 20 to 23 The cortex contains around 20 to 23 billion nerve cells.billion nerve cells.

Structure of the CortexStructure of the Cortex

The wrinkled surface greatly The wrinkled surface greatly increases the overall surface area of increases the overall surface area of the brain, and therefore increases its the brain, and therefore increases its complexity.complexity.

Lower mammals have smoother Lower mammals have smoother cortexes, and therefore simpler cortexes, and therefore simpler brains. brains.

Glial CellsGlial Cells

Cells in the nervous system that support, Cells in the nervous system that support, nourish, and protect neurons.nourish, and protect neurons.

a.k.a “glue cells”a.k.a “glue cells” They guide neural connections, provide They guide neural connections, provide

nutrients and insulating myelin, and mop nutrients and insulating myelin, and mop up ions and neurotransmitters.up ions and neurotransmitters.

They may play a role in learning and They may play a role in learning and thinking by “talking” to neurons.thinking by “talking” to neurons.

Fun fact: Einstein’s brain didn’t have larger Fun fact: Einstein’s brain didn’t have larger or more than normal amount of neurons, or more than normal amount of neurons, but it did have a larger concentration of but it did have a larger concentration of glial cells.glial cells.

Lobes of the BrainLobes of the Brain

Divided by prominent fissures, or Divided by prominent fissures, or folds, in the brain.folds, in the brain.

Frontal lobesFrontal lobes: start at the front of : start at the front of your brain and go over the top of it, your brain and go over the top of it, behind your forehead.behind your forehead.

Parietal lobesParietal lobes: at the top and to the : at the top and to the rear of the head.rear of the head.

Lobes of the BrainLobes of the Brain

Occipital lobesOccipital lobes: the back of your : the back of your head.head.

Temporal lobesTemporal lobes: on the sides of : on the sides of your head, just above your ears.your head, just above your ears.

Each lobe does specific functions, Each lobe does specific functions, and many functions are completed and many functions are completed with the interaction of several lobes. with the interaction of several lobes.

Functions of the CortexFunctions of the Cortex

Where do certain functions take Where do certain functions take place in the cortex?place in the cortex?

It is hard to say where complex It is hard to say where complex activities take place (most likely in activities take place (most likely in several areas), but scientists have several areas), but scientists have localized some simple functions.localized some simple functions.

Motor FunctionsMotor Functions

Motor Cortex: an area at the rear of Motor Cortex: an area at the rear of the frontal lobes that controls the frontal lobes that controls voluntary movements.voluntary movements.

Researchers have found that when Researchers have found that when they stimulate specific parts of the they stimulate specific parts of the motor cortex in the left or right motor cortex in the left or right hemispheres, specific body parts hemispheres, specific body parts moved on the opposite side of the moved on the opposite side of the body.body.

Mapping the Motor Mapping the Motor CortexCortex

Otfrid Foerster and Wilder Penfield both Otfrid Foerster and Wilder Penfield both individually researched the motor cortex in individually researched the motor cortex in patients who were awake during the patients who were awake during the procedure.procedure.

This did not cause any pain because there This did not cause any pain because there are no sensory receptors in the brain.are no sensory receptors in the brain.

They stimulated different cortical areas and They stimulated different cortical areas and noted that different parts of the motor noted that different parts of the motor cortex caused different body parts to move.cortex caused different body parts to move.

Mapping the Motor Mapping the Motor CortexCortex

They created a map of the motor cortex, They created a map of the motor cortex, according to the body parts it controls.according to the body parts it controls.

The amount of cortex devoted to a body The amount of cortex devoted to a body part is not proportional to that part’s part is not proportional to that part’s size. Instead, the brain devotes more size. Instead, the brain devotes more tissue to sensitive areas and to areas tissue to sensitive areas and to areas requiring precise control.requiring precise control.

E.g. the fingers have more cortex E.g. the fingers have more cortex devoted to them than the arm.devoted to them than the arm.

Neural ProstheticsNeural Prosthetics

Research has been done on monkeys to Research has been done on monkeys to determine whether our knowledge of the determine whether our knowledge of the motor cortex could give movement to motor cortex could give movement to someone lacking mobility.someone lacking mobility.

They implanted electrodes into the monkeys They implanted electrodes into the monkeys brains and recorded activity (e.g. moving a brains and recorded activity (e.g. moving a joystick on a computer or reaching for a joystick on a computer or reaching for a specific spot on a computer screen).specific spot on a computer screen).

Then, the neural activity was recorded and Then, the neural activity was recorded and programmed into a computer.programmed into a computer.

Neural ProstheticsNeural Prosthetics

When the monkey thought about the When the monkey thought about the movement, the computer could now make the movement, the computer could now make the cursor move in response to the monkey’s cursor move in response to the monkey’s thoughts.thoughts.

The first human trial was approved by the US The first human trial was approved by the US Food and Drug Administration in 2004 for a Food and Drug Administration in 2004 for a 25-year-old paralyzed man.25-year-old paralyzed man.

They implanted a small (aspirin-sized) chip in They implanted a small (aspirin-sized) chip in his head on his cortex that records activity.his head on his cortex that records activity.

He can now mentally control a television, He can now mentally control a television, draw shapes on a computer screen, and play draw shapes on a computer screen, and play video games with only his thoughts to control video games with only his thoughts to control them.them.

Sensory FunctionsSensory Functions

Sensory cortex: the area at the front Sensory cortex: the area at the front of the parietal lobes that registers of the parietal lobes that registers and processes body touch and and processes body touch and movement sensations.movement sensations.

Runs parallel to the motor cortex Runs parallel to the motor cortex and just behind it.and just behind it.

It is the part of the cortex that It is the part of the cortex that receives the incoming messages.receives the incoming messages.

Sensory FunctionsSensory Functions If you stimulate a point on this cortex, If you stimulate a point on this cortex,

people may report feeling like they’re people may report feeling like they’re being touched somewhere else on the being touched somewhere else on the body.body.

Again, more sensitive areas have more Again, more sensitive areas have more cortex devoted to them.cortex devoted to them.

We also receive visual information in our We also receive visual information in our occipital lobes at the very back of our occipital lobes at the very back of our brains.brains.

Sound is processed in the auditory areas Sound is processed in the auditory areas of our temporal lobes.of our temporal lobes.

Association AreasAssociation Areas

Three-fourths of our cortex is Three-fourths of our cortex is dedicated to our association areas.dedicated to our association areas.

Areas of the cerebral cortex that are Areas of the cerebral cortex that are not involved in primary motor or not involved in primary motor or sensory functions.sensory functions.

They are involved in higher mental They are involved in higher mental functions, such as learning, functions, such as learning, remembering, thinking, and remembering, thinking, and speaking.speaking.

Association AreasAssociation Areas We cannot specify the functions of We cannot specify the functions of

association areas because stimulating association areas because stimulating these parts of the cortex does not these parts of the cortex does not produce an observable response.produce an observable response.

Association areas in our frontal lobes Association areas in our frontal lobes help us judge, plan, and process new help us judge, plan, and process new memories. memories.

Frontal lobe damage can also affect Frontal lobe damage can also affect personality, removing inhibitions.personality, removing inhibitions.

Take the case of Phineas Gage: his Take the case of Phineas Gage: his mental abilities and memories were mental abilities and memories were intact after his accident, but his intact after his accident, but his personality completely changed.personality completely changed.