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
    *

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