Transcript Cognitive Neuroscience Methods

Methods of Cognitive
Neuroscience
How do we accomplish our goals?
Science
• What is science?
• What is the purpose of science?
• Is Science about finding Truth?
Whither Cognitive Science?
• How do we “observe” something that can’t
be seen?
• How do we theorize about something that
cannot be observed?
• We have to really know what it is we’re
analyzing.
What we’re studying
• What we’re looking at is how the mind
processes information.
• What does that mean?
• Process and Representation
Representation
• The manner in which information is stored
in the mind.
• Analogous to different representations on a
computer - text, JPG, MP3, WMV, etc.
Process
• The means by which those representations
are manipulated.
• Once again, we can use the computer
analogy: e-mail, Word, iTunes, Quicktime,
etc.
Cognitive Research Methods
• Task Difficulty - Different combinations of
processes and representations should make
different types of tasks more or less difficult.
Determining which properties of tasks make them
easier or harder can shed light on what processes
and representations are being used.
– Reaction time
– Error rate
– Task performance time
• Ex: the Chinese Ring puzzle
More methods
• Task Performance - examine how people
perform various tasks to try and understand
the underlying processes and
representations
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Verbal protocols
Eye tracking
Mouse tracking
Brain-damaged patients
Two Goals
• Localization of function - At the macro
level, Cognitive Neuroscience tries to
examine where in the brain various
cognitive operations take place.
• Neural computation - At the micro level, we
try to understand how the brain performs
various operations.
Localization of function
• Post-mortem lesion studies - Find someone who
displays an interesting cognitive deficit. When
they die, study their brain for where the damaged
tissue was. (Phineas Gage, Broca’s & Wernicke’s
areas)
• Human-lesion studies - These days, we can take
pictures of the brain while it’s still in the skull
(CAT, MRI) an determine where the lesions are
while someone is still alive. (Prosopagnosia, optic
aphasia)
More localization
• Animal lesion studies - Human lesions are messy and
uncontrolled. No two people ever have the exact same lesion.
With animals, we can control the characteristics of the lesions.
(Area MT)
• Single-cell recording - Also with animals, we can attach
electrodes to neurons and measure the firing pattern of
individual neurons. (Feature detectors in area V1)
But wait! There’s more
• Brain imaging - Modern technology provides us
the ability to, in very broad strokes, examine
what the brain is doing while a person is actively
performing a cognitive task. (Face recognition,
spatial processing)
• Brain stimulation - People are kept awake during
brain surgery. Use the opportunity. (Motor and
somatosensory homunculi)
Neural computation
• Physical modeling - Understand the properties of
neurons, how they share information and whatnot, and try to understand how these properties
can lead to complex computations. (opponent
processes, how feature detectors are calculated).
• Computational modeling - Neural networks are
computer models of how groups of neurons
behave. Use these models to try and better
understand cognitive processing in the brain.