Copyright © 2010 Pearson Education Canada4-1 The Brain: Source of Mind and Self Chapter 4

Copyright © 2010 Pearson Education Canada 4-1

The Brain: The Brain: Source of Mind and SelfSource of Mind and Self

Chapter 4Chapter 4


Chapter OutlineChapter Outline

• The Nervous System: A Basic BlueprintThe Nervous System: A Basic Blueprint

• Communication in the Nervous SystemCommunication in the Nervous System

• Mapping the BrainMapping the Brain

• A Tour Through the BrainA Tour Through the Brain

• The Two Hemispheres of the BrainThe Two Hemispheres of the Brain

• Two Stubborn Issues in Brain ResearchTwo Stubborn Issues in Brain Research

• Using Our Brains about Brain ResearchUsing Our Brains about Brain Research

The Nervous SystemThe Nervous System

• Two main parts:Two main parts:

– Central nervous system (CNS): Central nervous system (CNS): receives, receives, processes, interprets, & stores incoming sensory processes, interprets, & stores incoming sensory information; sends out messages to muscles, information; sends out messages to muscles, glands, organsglands, organs

– Peripheral nervous system (PNS): Peripheral nervous system (PNS): handles input & handles input & output from the CNS; all portions of the nervous output from the CNS; all portions of the nervous system outside the brain & spinal cordsystem outside the brain & spinal cord


Central Nervous SystemCentral Nervous System• Two components: brain & Two components: brain &

spinal cordspinal cord

• Spinal cord Spinal cord is a bridge between is a bridge between the brain and parts of the body the brain and parts of the body below the neckbelow the neck

• Spinal nerves protected by the Spinal nerves protected by the spinal columnspinal column

• Enables spinal reflexesEnables spinal reflexes


Peripheral Nervous SystemPeripheral Nervous System

• Contains two subdivisions (messages carried Contains two subdivisions (messages carried through through sensorysensory & & motor nervesmotor nerves):):

1.1. Somatic nervous system: Somatic nervous system: nerves connected to nerves connected to sensory receptors and skeletal musclessensory receptors and skeletal muscles

2.2. Autonomic nervous system: Autonomic nervous system: regulates functioning regulates functioning of blood vessels, glands, & internal organsof blood vessels, glands, & internal organs

• Contains the Contains the sympathetic & parasympathetic sympathetic & parasympathetic nervous systemsnervous systems


Autonomic Nervous SystemAutonomic Nervous System


Communication in the Communication in the Nervous SystemNervous System

• Nervous system made up of:Nervous system made up of:

– Neurons:Neurons: cells that conduct electrochemical cells that conduct electrochemical signals; basic unit of the nervous systemsignals; basic unit of the nervous system

– Glia:Glia: cells that support, nurture, and insulate cells that support, nurture, and insulate neurons, remove debris when neurons die, enhance neurons, remove debris when neurons die, enhance the formation & maintenance of neural connections, the formation & maintenance of neural connections, and modify neural functioningand modify neural functioning


Structure of the NeuronStructure of the Neuron

• DendritesDendrites– Branch-like fibres that Branch-like fibres that

receive information from receive information from other neurons & transmit other neurons & transmit towards cell bodytowards cell body

• Cell bodyCell body– Keeps neuron alive & Keeps neuron alive &

plays key role in plays key role in determining whether determining whether neuron will “fire” neuron will “fire”

• AxonAxon– Extending fibre that Extending fibre that

conducts impulse away conducts impulse away from cell body and from cell body and transmits to other cellstransmits to other cells

– Branches at end called Branches at end called axon terminalsaxon terminals

– May be collected May be collected together in bundles together in bundles called called nervesnerves


Structure of the NeuronStructure of the Neuron


The Myelin SheathThe Myelin Sheath

• Many axons are insulated by surrounding Many axons are insulated by surrounding layer of fatty material called layer of fatty material called myelin sheathmyelin sheath

– In the CNS, this is made up of glial cellsIn the CNS, this is made up of glial cells

– Divided into segments due to constrictions in covering Divided into segments due to constrictions in covering ((nodesnodes))

– Purpose to speed conduction of neural impulses & Purpose to speed conduction of neural impulses & prevent interference from neighbouring signalsprevent interference from neighbouring signals


Neurons in the NewsNeurons in the News

• NeurogenesisNeurogenesis– Production of new neurons from immature stem cellsProduction of new neurons from immature stem cells

• Stem cellsStem cells– Immature cells that Immature cells that

renew themselves & renew themselves & have the potential to have the potential to develop into mature develop into mature cellscells

– Stem cells from early Stem cells from early embryos can develop embryos can develop into any cell typeinto any cell type


Stem-Cell ResearchStem-Cell Research

• Embryonic stem cells can differentiate into any type of Embryonic stem cells can differentiate into any type of cell; adult stem cells limitedcell; adult stem cells limited

• Use is controversial and surrounded by ethical debates Use is controversial and surrounded by ethical debates regarding extraction*regarding extraction*

• Most promising in developing treatments for cancer, Most promising in developing treatments for cancer, blood, organ, and brain disorders (e.g., Parkinson’s)blood, organ, and brain disorders (e.g., Parkinson’s)

• Canadian researchers have had some success with Canadian researchers have had some success with adult stem cells transforming to brain cellsadult stem cells transforming to brain cells


Brain PlasticityBrain Plasticity

• PlasticityPlasticity

– The brain’s ability to change and adapt in The brain’s ability to change and adapt in response to experience (e.g., reorganizing or response to experience (e.g., reorganizing or growing new neural connections)growing new neural connections)

– Behavioural deficits that occur as a result of Behavioural deficits that occur as a result of brain damage may be lessened by enriching brain damage may be lessened by enriching environments people live in environments people live in (e.g., Kolb et al., 1991)(e.g., Kolb et al., 1991)


How Neurons CommunicateHow Neurons Communicate

• No direct contact No direct contact between neuronsbetween neurons

• Communicate Communicate through the through the synapsesynapse

– Includes the axon Includes the axon terminal, terminal, synaptic synaptic cleftcleft, and receptor , and receptor sites in the sites in the membrane of the membrane of the receiving cellreceiving cell


How Neurons CommunicateHow Neurons Communicate

• When nerve is stimulated, produces an electrical potential When nerve is stimulated, produces an electrical potential between the inside & outside of a cellbetween the inside & outside of a cell

• If enough stimulation, produces an If enough stimulation, produces an action potential action potential that that sends an impulse down the axon (speed depends on sends an impulse down the axon (speed depends on myelination)myelination)

• Axon terminals release neurotransmitters from Axon terminals release neurotransmitters from synaptic synaptic vesiclesvesicles into synaptic cleft into synaptic cleft

• NeurotransmittersNeurotransmitters bind to post-synaptic receptor sites that bind to post-synaptic receptor sites that they fit (causing excitatory or inhibitory inputs)they fit (causing excitatory or inhibitory inputs)


Chemical MessengersChemical Messengers

• NeurotransmittersNeurotransmitters

– A chemical substance that is released by a A chemical substance that is released by a transmitting neuron at the synapse and that transmitting neuron at the synapse and that alters the activity of a receiving neuronalters the activity of a receiving neuron

• Major neurotransmitters:Major neurotransmitters:

– Serotonin, dopamine, acetylcholine, Serotonin, dopamine, acetylcholine, norepinephrine, GABA, glutamatenorepinephrine, GABA, glutamate



• EndorphinsEndorphins

– Chemical substances in the nervous system that Chemical substances in the nervous system that are similar in structure and action to opiatesare similar in structure and action to opiates

– Involved in pain reduction, pleasure, and Involved in pain reduction, pleasure, and memorymemory

– Technically known as Technically known as endogenous opioid endogenous opioid peptidespeptides



• HormonesHormones

– Chemical substances, secreted by organs called Chemical substances, secreted by organs called endocrine glandsendocrine glands, that affect the functioning of other , that affect the functioning of other organsorgans

• Regulate growth, metabolism, sexual development & Regulate growth, metabolism, sexual development & behaviour, and other functionsbehaviour, and other functions

– Major hormones:Major hormones:• Melatonin, oxytocin, adrenal hormones, sex Melatonin, oxytocin, adrenal hormones, sex

hormones (androgens & estrogens)hormones (androgens & estrogens)


Mapping the BrainMapping the Brain

• Many ways scientists can study the brain:Many ways scientists can study the brain:

– Patients with brain damagePatients with brain damage

– Lesion methodLesion method• Involves damaging or removing section of brain in Involves damaging or removing section of brain in

animals and then observing the effectsanimals and then observing the effects

– Electrical & magnetic detectionElectrical & magnetic detection

– Brain scansBrain scans


Electrical & Magnetic DetectionElectrical & Magnetic Detection

• Electroencephalography (EEG)Electroencephalography (EEG)

– Recording neural activity detected by electrodesRecording neural activity detected by electrodes– Limited precision as recording multiple cells Limited precision as recording multiple cells – Recent techniques include needle & micro-electrodesRecent techniques include needle & micro-electrodes

• Transcranial magnetic stimulation (TMS)Transcranial magnetic stimulation (TMS)

– Uses a powerful magnetic field produced by a wire coil Uses a powerful magnetic field produced by a wire coil placed on person’s head to stimulate cellsplaced on person’s head to stimulate cells

– Can cause neurons to fire & inactivate othersCan cause neurons to fire & inactivate others


Brain ScansBrain Scans

• PET scan (positron-emission tomography)PET scan (positron-emission tomography)

– Method for analyzing biochemical activity in the brain, Method for analyzing biochemical activity in the brain, using injections of a glucose-like substance containing a using injections of a glucose-like substance containing a radioactive elementradioactive element

• MRI (magnetic resonance imaging)MRI (magnetic resonance imaging)

– Method for studying body and brain tissue, using Method for studying body and brain tissue, using magnetic fields and special radio receiversmagnetic fields and special radio receivers

• Performance assessed by Performance assessed by functional MRI or fMRI functional MRI or fMRI


Brain ScansBrain Scans


Touring the BrainTouring the Brain

• Localization of function Localization of function

– Specialization of particular brain areas for Specialization of particular brain areas for particular functionparticular function

• Major areas/structures:Major areas/structures:

– Brain stem, cerebellum, thalamus, Brain stem, cerebellum, thalamus, hypothalamus & pituitary gland, amygdala, hypothalamus & pituitary gland, amygdala, hippocampus, cerebrum & cerebral cortexhippocampus, cerebrum & cerebral cortex


The Brain StemThe Brain Stem• MedullaMedulla

– Responsible for automatic functions such as breathing & Responsible for automatic functions such as breathing & heart rateheart rate

• PonsPons– Involved in sleeping, Involved in sleeping,

waking, & dreamingwaking, & dreaming

• Reticular activating Reticular activating system (RAS)system (RAS)– Extends from brain stem; Extends from brain stem;

arouses cortex & screens arouses cortex & screens incoming informationincoming information


The CerebellumThe Cerebellum

• CerebellumCerebellum

– Regulates movement Regulates movement & balance& balance

– Involved in learning of Involved in learning of certain kinds of simple certain kinds of simple skills & acquired skills & acquired reflexesreflexes

– Role in complex Role in complex cognitive tasks cognitive tasks (e.g., problem solving)(e.g., problem solving)


The ThalamusThe Thalamus• ThalamusThalamus

– Brain structure that relays sensory messages to the Brain structure that relays sensory messages to the cerebral cortexcerebral cortex

• Includes all Includes all sensory sensory messages messages except those except those from olfactory from olfactory bulbbulb


Hypothalamus & Pituitary GlandHypothalamus & Pituitary Gland• HypothalamusHypothalamus

– Involved in emotions & drives vital to survival, such as fear, Involved in emotions & drives vital to survival, such as fear, hunger, thirst & reproduction; regulates autonomic nervous hunger, thirst & reproduction; regulates autonomic nervous systemsystem

• Pituitary glandPituitary gland– Endocrine gland at Endocrine gland at

base of brain that base of brain that releases many releases many hormones & hormones & regulates other regulates other endocrine glandsendocrine glands


The Limbic SystemThe Limbic System

• AmygdalaAmygdala– Involved in Involved in

arousal and arousal and regulation of regulation of emotion; initial emotion; initial emotional emotional response to response to sensory sensory informationinformation

• HippocampusHippocampus– Involved in the storage of new information in memoryInvolved in the storage of new information in memory


The CerebrumThe Cerebrum

• CerebrumCerebrum

– Largest brain structureLargest brain structure

– Divided into two Divided into two cerebral hemispherescerebral hemispheres, connected by , connected by corpus callosumcorpus callosum

– Hemispheres specialized for certain tasks (Hemispheres specialized for certain tasks (lateralizationlateralization))

– Contains layers of densely packed cells called Contains layers of densely packed cells called cerebral cerebral cortexcortex (divided into lobes) (divided into lobes)


Lobes of the CortexLobes of the Cortex


Lobes of the CortexLobes of the Cortex

• Occipital lobesOccipital lobes– Includes Includes visual cortexvisual cortex

• Parietal lobesParietal lobes– Includes Includes

somatosensory cortex somatosensory cortex (pressure, pain, touch, (pressure, pain, touch, temperature)temperature)

– HomunculusHomunculus

– Attention & mental Attention & mental operationsoperations

• Temporal lobesTemporal lobes– Includes the Includes the auditory cortex auditory cortex

& Wernicke’s area & Wernicke’s area (left)(left)

– Memory, perception, Memory, perception, emotionemotion

• Frontal lobesFrontal lobes– Includes the Includes the motor cortex & motor cortex &

Broca’s area Broca’s area (left)(left)

– Emotion, planning, creative Emotion, planning, creative thinkingthinking


The Case of Phineas GageThe Case of Phineas Gage

• 1848: Explosion at railroad construction site forced 1848: Explosion at railroad construction site forced steel tamping rod through Gage’s headsteel tamping rod through Gage’s head

• Survived accident Survived accident but some said he but some said he was “no longer was “no longer Gage”Gage”

• Problems with Problems with emotional processing emotional processing & rational decision & rational decision makingmaking


Two Hemispheres of the BrainTwo Hemispheres of the Brain

• Hemispheres have different areas of specialization Hemispheres have different areas of specialization & control opposite sides of the body& control opposite sides of the body

– Communicate through Communicate through corpus callosumcorpus callosum

– If severed through If severed through split-brain surgerysplit-brain surgery, perception & , perception & memory disturbed, although most other processing memory disturbed, although most other processing intactintact

• E.g., facial identification tasks by Sperry & E.g., facial identification tasks by Sperry & colleaguescolleagues


Split Brain ExperimentsSplit Brain Experiments


Hemispheric Allies or Opposites?Hemispheric Allies or Opposites?

• Studies of split-brain patients have demonstrated:Studies of split-brain patients have demonstrated:

– Most right-handed & the majority of left-handed people Most right-handed & the majority of left-handed people process language mainly in the left hemisphereprocess language mainly in the left hemisphere

– Many researchers believe in left hemisphere Many researchers believe in left hemisphere dominancedominance

– Right hemisphere important for problems involving Right hemisphere important for problems involving spatial-visual ability, facial recognition, music processing, spatial-visual ability, facial recognition, music processing, & some language abilities& some language abilities


Where is the Self?Where is the Self?

• Brain scientists consider the mind a physical Brain scientists consider the mind a physical product of cerebral cortexproduct of cerebral cortex

– Many actions & choices occur without conscious Many actions & choices occur without conscious awareness awareness

– Brain structures create sense of reality, interacting Brain structures create sense of reality, interacting mental modulesmental modules

– Frontal lobes may be critical in “self” experienceFrontal lobes may be critical in “self” experience

– Some still question relationship between subjective Some still question relationship between subjective experience & physical processes experience & physical processes


““His” and “Hers” Brains?His” and “Hers” Brains?

• Are there sex differences in the brain?Are there sex differences in the brain?

– Some evidence to suggest anatomical Some evidence to suggest anatomical differencesdifferences

– Differences in lateralization of language: Differences in lateralization of language:

• Males show left hemisphere activation only whereas Males show left hemisphere activation only whereas females show activation in both hemispheresfemales show activation in both hemispheres


Gender & Language LateralityGender & Language Laterality


Problems with Gendered Brains?Problems with Gendered Brains?

• What these sex differences What these sex differences meanmean with respect to with respect to behaviour or personality should be interpreted with behaviour or personality should be interpreted with caution:caution:

a)a) Supposed gender differences (e.g., intuition, abilities) Supposed gender differences (e.g., intuition, abilities) are stereotypesare stereotypes

b)b) A brain difference does not necessarily explain A brain difference does not necessarily explain behaviour or performancebehaviour or performance

c)c) Sex differences in the brain could be the result rather Sex differences in the brain could be the result rather than the cause of behavioural differencesthan the cause of behavioural differences


Using Our Brains about Using Our Brains about Brain ResearchBrain Research

• Study of the brain illuminates many aspects Study of the brain illuminates many aspects of functioning, but also raises many of functioning, but also raises many questions about future research questions about future research

– Neuroethics:Neuroethics: interdisciplinary specialty interdisciplinary specialty addressing the legal, ethical, and scientific addressing the legal, ethical, and scientific implications of brain researchimplications of brain research


End of Chapter 4End of Chapter 4


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Copyright © 2010 Pearson Education Canada4-1 The Brain: Source of Mind and Self Chapter 4