Transcript Eagleman Ch 1. Introductionx

1: Introduction
Cognitive Neuroscience
David Eagleman
Jonathan Downar
Chapter Outline
Who Are We?
 In Pursuit of Principles
 How We Know What We Know
 Thinking Critically about the Brain
 The Big Questions of Cognitive
Neuroscience
 The Payoffs of Cognitive Neuroscience
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Who Are We?
The Mission of Cognitive Neuroscience
 Neuroscience is a Relatively New Field
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Who Are We?
The brain is made of neurons and glia,
each containing a copy of the genome.
 There are nearly 100 billion of each of
these types of cells.
 A typical neuron makes about 10,000
connections to other cells.
 Together, they form a three-pound organ
that has the consistency of Jell-O.
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Different Views of the Brain
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The Mission of Cognitive
Neuroscience
Determine how the brain processes
information, builds memories, and makes
decisions.
 Figure out what makes us who we are.
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The Mission of Cognitive
Neuroscience

Emergent Properties
 Characteristics
of a system that are not part of
the individual components that make up the
system.
 Arranging all of the molecules into a cell, then
into organs, and into a body can produce a
living, conscious individual.
 Cognitive neuroscience seeks to understand
these emergent properties.
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Neuroscience is a Relatively
New Field
Combines biology and psychology to
connect neural functions to behaviors.
 “Neuroscience” was first used in the
1960s.
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Neuroscience is a Relatively
New Field
Every year, nearly 30,000 researchers, fellows, students, and health
professionals attend the annual meeting of the Society for Neuroscience.
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Neuroscience is a Relatively
New Field

Rapid growth of the field due to
 Greatly
increased research in and
understanding of biology.
 Greatly increased computing power at everlower prices.
 New theoretical approaches to the study of
perception, learning, reasoning, and disease
states.
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In Pursuit of Principles
The Functions behind the Form
 Which Parts Matter?
 What Is the Brain For?
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Which Parts Matter?
Explanations in cognitive neuroscience
can be at the level of individual molecules
or at the level of systems or neurons.
 All thoughts, memories, moods, and
decisions are brought about by the
physical substance of the brain.
 Alterations to the anatomy or chemistry of
the brain result in changes to behaviors.
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Which Parts Matter?
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What Is the Brain For?
The brain and therefore our thoughts and
behaviors are shaped by evolution.
 Adaptations

 Mechanisms
such as behaviors or physical
traits that enhance the reproductive success
of organisms that possess them.
 Our current thoughts or behaviors are
adaptations that benefitted our ancestors.
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What Is the Brain For?
The “mind” seems separate from the brain,
apparently non-physical.
 Research suggests that the mind is a
product of the brain.
 All of our thoughts and behaviors result
from the interactions of the physical parts
of the brain.
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How We Know What We Know
Connectional Methods
 Correlational Methods
 Lesion Methods
 Stimulation Methods
 A Toolbox of Complementary Methods
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How We Know What We Know
Scientists have studied the brain for 150
years, trying to link the brain with behavior.
 Such studies have used techniques from
microscopes to inserting genes into
existing cells.
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How We Know What We Know
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Connectional Methods
The function of a neuron depends on its
input and output.
 Tracing these connections can tell
neuroscientists what the cell does.
 It is possible to label cells that provide
input to the neuron as well as the cells that
the neuron sends messages to.
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Connectional Methods

Diffusion tensor imaging provides a way to
map these connections in a nondestructive way in living brains.
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Connectional Methods
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Correlational Methods
Researchers observe brain activity while
the subject performs a particular behavior.
 Observing how brain activity changes as
behavior changes provides information
about the brain regions that are important
for that behavior.
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Correlational Methods

Invasive Methods
 Microelectrodes
can be implanted in the brain
to record the electrical activity of individual
neurons or groups of neurons.
 Microdialysis samples the chemical makeup
and concentration of fluid in the brain.
 Voltammetry measures the levels of
neurotransmitters in a tissue by monitoring
voltage changes in the probe.
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Correlational Methods

Less Invasive Methods
 Electroencephalography
(EEG) places
electrodes on the scalp to monitor electrical
activity in the brain.
 Magnetoencephalography (MEG) monitors
the very small changes in the magnetic field
around the head that result from the electrical
activity of the brain.
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Correlational Methods
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Correlational Methods

Indirect Methods
 Positron
emission tomography (PET) studies
inject small quantities of radioactive
molecules into the body and monitoring how
they are distributed in the body.
 Magnetic resonance imaging (MRI) enables
researchers to visualize the structure of the
brain in detail without exposing the subject to
radiation.
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Correlational Methods

MRI Techniques
 Functional
Magnetic Resonance Imaging
(fMRI) can map blood flow and oxygenation to
identify what parts of the brain are active
during particular tasks.
 Diffusion Tensor Imaging (DTI) identifies
connections between different regions.
 Voxel-based morphometry (VBM) maps the
shape and thickness of brain regions.
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Correlational Methods
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Lesion Methods
Lesions are areas of the brain that are
damaged by disease or injury.
 Traumatic brain injuries, stroke, or tumors
can result in lesions that affect behaviors.
 In the 1860s, the neurologist Paul Broca
studied patients who had difficulties
producing speech.
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Lesion Methods
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Lesion Methods
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Caveats to Lesion Studies
 Lesions
are rarely small enough and specific
enough to affect just one brain area.
 The lesion may spare enough of the tissue
that the function is preserved, making it
appear that that brain region is not involved in
the behavior.
 Researchers must be careful to characterize
the deficit precisely.
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Stimulation Methods
Researcher stimulate or increase the
activity in a brain region and observe how
behaviors change.
 Penfield and Jasper used electrical
stimulation of brain regions to map the
sensory and motor areas.
 Transcranial magnetic stimulation (TMS)
uses electromagnetic coils to activate
neurons in a particular region of the brain.
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Stimulation Methods
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Stimulation Methods
Repetitive transcranial magnetic
stimulation (rTMS) can be used to treat
depression.
 Transcranial direct current stimulation
(tDCS) applies a direct current to the scalp
to inhibit neurons adjacent to the
positively-charged cathode and stimulate
neurons adjacent to the negativelycharged anode.
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Thinking Critically About the
Brain
Is the Brain Equipped to Understand
Itself?
 Biases and Pitfalls in Human Cognition
 A Toolbox of Critical-Thinking Techniques
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Is the Brain Equipped to
Understand Itself?
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The brain has evolved to control three
specific classes of behaviors:
 Homeostatic
behaviors, which maintain a
normal range of survival parameters.
 Agonistic behaviors, which defend against
rivals.
 Reproductive behaviors, which promote the
continuation of the species.
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Is the Brain Equipped to
Understand Itself?
Maintaining the
body’s balance of
energy,
temperature,
hibernation, and
other critical
parameters for
one’s own
survival
Defending against
hostile rivals or
predators, establishing
territory or dominance
over rivals, and seeking
out prey to sustain
one’s own survival
Seeking out mates,
procreating, and
prompting the
survival of one’s
own offspring
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Biases and Pitfalls in Human
Cognition
The anchoring bias refers to the tendency
to be overly influenced by a single
observation, typically the first observation.
 The confirmation bias is the tendency to
seek out and emphasize information that
matches our existing beliefs.
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Biases and Pitfalls in Human
Cognition
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Biases and Pitfalls in Human
Cognition
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There is a long list of biases and heuristics
that adversely affect our ability to observe
and draw accurate conclusions about our
own brain.
 Availability
heuristic
 Affect heuristic
 Illusory correlation
 Belief bias
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A Toolbox of Critical-Thinking
Techniques
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The scientific method provides a
systematic way to study a process and
avoid biases and heuristics.
 Make
observations about the world.
 Develop a hypothesis to explain the
observations.
 Generate testable predictions about the
hypothesis.
 Perform experiments to test the predictions.
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A Toolbox of Critical-Thinking
Techniques
The results of one experiment help to
refine the hypotheses for the next
experiment.
 Experiments are repeated and extended to
show they are reproducible.
 Results are subjected to independent peer
review to reduce the biases that may have
been introduced by the experimenter.
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A Toolbox of Critical-Thinking
Techniques
Findings are
reviewed by peers
and replicated or
refuted by further
experiments.
4. Experimental
testing of
predictions:
requires careful
measurement and
comprehensive
efforts to control for
any additional
factors that could
influence the
observations.
Experiments are
designed to test the
predictions of the
hypothesis against
alternatives.
1. Observation:
Careful, repeated
measurements using
standardized
techniques
Overcoming bias:
Standardization of
measures;
Disconfirmation of
hypothesis; Peer
review of findings;
Replication of
results; Progress
by iterations
2. Generation of specific
and testable predictions:
if our hypothesis X is true,
then we ought to be able to
observe other phenomena
A, B, and C.
Observations
lead to research
questions.
2. Development of
a hypothesis: a
proposed
explanation for the
observations in
question; a good
hypothesis should
be falsifiable.
Competing
hypotheses lead
to competing
predictions.
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The Big Questions in Cognitive
Neuroscience
2.
3.
4.
5.
Why Have a Brain at All?
How is Information Coded in Neural
Activity?
How Does the Brain Balance Stability
against Change?
How Does Vision Have So Little to Do
with the Eyes?
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The Big Questions in Cognitive
Neuroscience
6.
7.
8.
9.
How Does the Brain Stitch Together a
Picture of the World from Different
Senses?
How Does the Brain Control Our Actions?
What is Consciousness?
How Are Memories Stored and
Retrieved?
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The Big Questions in Cognitive
Neuroscience
What Do Brains Sleep and Dream?
11. How Does the Human Brain Acquire Its
Unique Ability for Language?
12. How Do We Make Decisions?
13. What Are Emotions?
14. How Do We Set Our Priorities?
10.
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The Big Questions in Cognitive
Neuroscience
How Do I Know What You’re Thinking?
16. What Causes Disorders of the Mind and
the Brain?
15.
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The Payoffs of Cognitive
Neuroscience
Healing the Disordered Brain
 Enhancing Human Abilities
 Blueprints for Artificial Cognition
 Brain-Compatible Social Policies
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Healing the Disordered Brain
Depression affects as many as 1 in 10
individuals.
 Techniques such as rTMS and deep brain
stimulation have been identified that can
help alleviate the symptoms of conditions
such as depression, Parkinson’s disease,
and obsessive-compulsive disorder.
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Healing the Disordered Brain
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Enhancing Human Abilities
Understanding how humans make
decisions can provide insight into how to
encourage us to make better decisions.
 Brain interface devices, such as cochlear
implants and implanted electrodes to
enable paralyzed patients to move devices
outside their own body, can restore lost
functions to individuals.
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Enhancing Human Abilities
Can we create new senses for humans?
 https://ted.com/talks/david_eagleman_can
_we_create_new_senses_for_humans
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Blueprints for Artificial Cognition
Researchers are learning from the brain to
improve the abilities of our computing
devices, such as speech recognition,
locomotion, and object recognition.
 Such artificial “neural networks” are now
being used to recognize patterns of brain
activity in brain imaging studies.
 Much remains to be done to find artificial
equivalents to much human cognition.
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Brain-Compatible Social Policies
Eyewitnesses are very compelling in the
courtroom, but are notoriously unreliable.
 Cognitive neuroscience can help
understand and explain the factors that
influence the memory of such witnesses.
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Brain-Compatible Social Policies
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Brain-Compatible Social Policies
An increased understanding of the
neuroscience of addiction can inform our
policies regarding punishment and
treatment of addicts.
 Such research suggests ways to attack
the demand for the drugs within the
reward system of the brain.
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Brain-Compatible Social Policies
Modern neuroscientific research has
important implications for criminal
punishment and rehabilitation.
 It is estimated that about 25% of the
American prison population has a mental
illness, so providing appropriate care is
important.
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