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– 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 what-not, 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.