LECTURE 2: Methods of Cognitive Neuroscience

What is Cognitive Neuroscience?

• Understanding the neurobiological foundations of cognitive functions.

• How the brain enables the mind.

• It is at the intersection of cognitive science and neuroscience.

Overview

• Cognitive science - a historical overview

• Neuroscience - a historical overview

• Cognitive neuroscience

• Methods

Cognitive Science

• Associationism - Associations

• Ebbinghaus, Weber, Fechner, Thorndike

• Behaviorism – Learning

• Watson, Skinner

• Cognitivism – Mental Models

• Miller, Chomsky, Simon

• Computational Science

• Information theory

• Mind as a computer
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Neuroscience - Historical Overview

• Egypt:

  • 18th century BC Edwin Smith Surgical Papyrus

  • First documented aphasia case

• Ancient Greece:

  • Hippocrates (460-370 BC)

  • Importance of the brain

  • “Men ought to know that from the brain, and from the brain only, arise our pleasures, joy, laughter and jests, as well as our sorrows, pains, griefs, and tears.”

• Middle Age

  • Ventricular theory

  • Sensory information is processed in the brain.

  • Realized by the ventricles in the brain – the soul cannot be material – ventricles are ”empty” spaces in the brain.

  • Three parts:

    • Collecting thoughts

    • Organizing thoughts

    • Storing certain thoughts

• Age of Enlightenment

  • René Descartes

  • Dualism: body (brain) and soul are separate entities; ventricles are the place of the soul

  • Connection with the body: pineal gland

• Phrenology

  • Franz Joseph Gall(19th century)

  • Mental functions (cca. 35) can be linked to the brain

  • Specific functions are linked to specific brain areas.

  • Functions utilized more lead to an enlargement of the brain area related to that function – bumps on the skull

  • Pseudoscience – no experiments

• The Cell

  • Second part of 19th century

  • Physiological studies

  • Santiago Ramón y Cajal

  • Neurons are discrete entities

  • Communication between neurons

  • Action potentials

  • Synapses

  • Neurotransmitters

• Functional localization

  • Wilder Penfield (neurosurgeon, 1891-1976)

  • Mapping the cortex

  • Electric stimulation before surgery

• '70's

  • Neuroscientists started to build models

  • Psychologists began to consider the brain

  • Bridging the gap

  • Different operating and analytical levels

  • Molecule, cell, network, etc.

• Big push in the '80s: "meteoric rise of brain imaging" (Gazzaniga, 2002)

  • Brain imaging procedures (PET, fMRI)

Methods of Cognitive Neuroscience

• methods of experimental psychology + models of cognitive science + neurobiology

Convergence and Complementarity

• Convergence

  • Combining results from several experimental paradigms to illuminate a theoretical concept

  • Series of experiments

  • Meta-analyses

• Complementarity

  • Complementary methods

Neuroscience Techniques

• Neuroscience techniques differ in their spatial and temporal resolution

• Spatial resolution:

  • Ranges from 1m to 0.1 μm

  • Scalp ERPs, TMS, MEG, PET, Human optical, fMRI, Human intracranial ERPs, Animal optical techniques, Single-unit recording, Patch-clamp recording are included.

• Temporal resolution:

  • Ranges from 1 ms to 1 yr

  • EEG, Drug manipulations, Lesion (human), Gyrus, Voxel (fMRI), Lesion (animal), Cortical column, Neuron, Axon (diameter), Synapse are included.

Approaches to Connect Cognitive Functions and Brain Processes

• Brain perturbation approach

  • Measure task performance after perturbation of the brain to understand cognition

• Neuromonitoring approach

  • Manipulate cognitive process and measure neural variable in the brain to understand cognition

Brain Perturbations That Elucidate Cognitive Functions

• Stroke, trauma, diseases - neurology

• Limitations

  • Many uncontrolled factors can lead to leasions

  • Variability: lesions and brain areas related to cognitive functions

• Pharmacological studies:

  • Chronic drug use/abuse (e.g., cocaine use)

  • Targeted research (e.g., nicotine effects)

• Brain stimulation - (ir)reversible lesions

  • Intracranial stimulation (electrodes)

  • Extracranial stimulation (e.g., transcranial magnetic stimulation (TMS), transcranial direct stimulation (tDCS)

Neuromonitoring

• Measuring neural activity during cognitive processing

• Direct electrophysiological recording from neurons

  • Single unit recording
    Electroencephalography (EEG)

• Event-related potentials (ERPs)

Brain Imaging Techniques

• Computer tomography (CT)

  • 3D images about the head

  • Slices – tomograms (tomo – cut, slice)

• Magnetic resonance imaging (MRI)

  • Magnetic: strong magnetic field – protons of hydrogen atoms become aligned with the magnetic field of the scanner

  • Resonance: radio wave excitation

• Positron emission tomography (PET) imaging

• Functional magnetic resonance imaging (fMRI)

  • BOLD (blood oxygenation level-dependent) signal

  • Oxyhemoglobin

  • Deoxyhemoglobin

• PET/fMRI experiment design

• Unilateral visual information processing