NEUR2020 – Research Methods of Neuropsychology (Comprehensive Lecture 1 Notes)

Assessment Overview

  • Quizzes (3) – total weighting 65\%

    • Quiz 1 (Week 5), Quiz 2 (Week 9), Quiz 3 (Week 13)

    • Content focuses: Clinical, Social, Developmental respectively.

  • Tutorial Worksheets – total weighting 35\%

    • Completed in the final 20 min of 8 tutorial weeks (Weeks 2, 4, 6, 7, 8, 10, 11, 12).

    • Best 7 of 8 count (one free miss without penalty).

    • Submitted hand-written; no devices permitted.

  • Tutorial Attendance Policy

  • All graded work (except research participation) occurs in tutorials.

  • You must attend your allocated session; assessments done in other classes receive 0.

  • Rationale: class sizes make ad-hoc movement unmanageable.

Orientation & Neuro-anatomical Terminology

  • Body axes

    • ANTERIOR (rostral) ↔ POSTERIOR (caudal)

    • DORSAL (superior) ↔ VENTRAL (inferior)

    • MEDIAL (toward midline) ↔ LATERAL (away from midline)

  • Additional paired terms

    • CONTRALATERAL vs IPSILATERAL; BILATERAL vs UNILATERAL; PROXIMAL vs DISTAL.

  • Synonym overload

    • "Inferior / Sub / Hypo / Infra" all mean “below.”

    • "Tract / Fasciculus / Funiculus / Lemniscus" all denote CNS fibre bundles; e.g., solitary tract ≡ fasciculus solitarius ≡ funiculus solitarius.

  • Reference planes

    • Sagittal (mid vs para-), Frontal/Coronal, Horizontal/Transverse, Oblique, Cross-section.

Research Methods: Big Picture

  • Primary question themes

    1. Structure vs Function

    2. Invasive vs Non-invasive

    3. Spatial Resolution (SR): “WHERE?”

    4. Temporal Resolution (TR): “WHEN?”

    5. Correlation vs Causation

    6. Practicalities: cost, resources, participant comfort, directness of measure.

1. Structure vs Function

  • Structure = morphology; tells form

    • Example: CT or structural MRI reveals tumours.

  • Function = activity; tells process

    • Example: EEG demonstrating seizure discharges.

  • Visual sample EEG states:

    • Relaxed (alpha 8\text{–}12\ \text{Hz} ), deeper sleep (delta <4\ \text{Hz}), etc.

2. Invasive vs Non-invasive

  • Definition: breaches skin or introduces foreign material.

  • Gradient examples

    • Highly invasive: single-cell electrode implants.

    • Moderately invasive: PET (radio-isotope injection).

    • Non-invasive: EEG electrode cap.

  • Surgical photo illustration: recording grid (R), stimulator (S), cooling probe (C) directly on cortex.

3. Spatial Resolution (SR)

  • Analogy: locating where Frank lives.

    • "Brisbane" → low SR; "101 Smith St Toowong" → high SR.

  • Brain technique hierarchy

    • Single-cell recording: micrometre-level (super-high SR).

    • fMRI: millimetre-level (high SR).

    • EEG: centimetre-level (low SR).

4. Temporal Resolution (TR)

  • Analogy: specifying birth dates.

    • Year (low TR) vs exact day (high TR).

  • Technique hierarchy

    • Single-cell: microseconds.

    • EEG/MEG: milliseconds (high TR).

    • fMRI/PET: seconds (low TR).

5. Correlation vs Causation

  • Correlation = reliable relationship; may reflect:

    1. Direct causation (volume knob → sound level).

    2. Common cause (shoes-on-in-bed ↔ hangover from alcohol).

    3. Coincidence (pirates & global warming comic example).

  • Causal criteria

    1. X reliably precedes Y.

    2. Removing X eliminates Y.

  • Neuro example

    • fMRI activation and behaviour ≈ correlational.

    • TMS disruption causing behavioural deficits → causal inference.

Behavioural Measures (Psychophysics)

  • Reaction time, detection thresholds, discrimination accuracy.

  • Psychophysics: formal study of stimulus → sensation relations.

Physiological Measures (Peripheral)

  • Startle Reflex

    • Brainstem-mediated eyelid blink; fear-potentiated startle when conditioned with aversive cue (index of fear learning).

  • Electrodermal Activity (EDA/SCR/GSR/EDR/PGR/SSR)

    • Sympathetic arousal momentarily increases skin conductance.

  • Other measures: pupilometry, heart-rate & variability, EMG muscle tension, polygraph composites.

Brain Damage Approaches

  • Acquired Brain Injury (ABI)

    • Strokes, TBI, substance toxicity.

    • Classic case: Broca’s patient “Tan.”

    • Lesion in posterior inferior frontal gyrus → expressive aphasia.

  • Lesion / Ablation Studies (animals)

    • Aspiration, radio-frequency, knife-cuts.

    • Caveats: neighbouring tissue damage, incomplete removal, functional compensation.

  • Causality strength: high.

Stimulation & Disruption Techniques

  • tDCS

    • \text{Anode} (+) depolarises, \text{Cathode} (-) hyperpolarises neurons.

    • Low-amplitude current; behavioural changes often polarity-specific.

  • Drug Blocks

    • Wada test: intracarotid sodium amobarbital → temporary hemispheric shut-down to assess speech lateralisation.

  • Cryogenic Block

    • Probe cools tissue; creates reversible “virtual lesion.”

  • Transcranial Magnetic Stimulation (TMS)

    • Single-pulse: transient excitation/disruption (timing critical; e.g., 70\text{–}130\ \text{ms} post-stimulus disrupts letter recognition).

    • Repetitive TMS (rTMS): longer-lasting changes (potential LTP/LTD analogues); therapeutic use in depression & neuropathic pain.

    • Enables causal inference of regional necessity.

Recording Neural Activity (Correlational)

  • Magneto-encephalography (MEG)

    • Measures tiny magnetic fields from intracellular currents.

    • Excellent TR (ms), reasonable SR for cortex; limited for deep/buried sources; costly.

  • Electro-encephalography (EEG)

    • Surface electrodes capture summed electrical potentials.

    • Characteristic rhythms: Alpha 8\text{–}12\ \text{Hz}, Beta 16\text{–}31\ \text{Hz}, Delta <4\ \text{Hz}.

    • Event-Related Potentials (ERPs)

    • Small, time-locked signals; average across trials.

    • Naming: polarity + latency (e.g., N100, P300).

    • Functional associations: N200 =mismatch, P300 =attended stimulus, P400 =surprise, etc.

    • Pros: high TR, non-invasive, low cost.

    • Cons: low SR, poor subcortical coverage, low SNR → many trials/subjects.

Brain Imaging Techniques

  • Positron Emission Tomography (PET)

    • Radio-labelled biologically active molecules (e.g., 2\text{-}DG) accumulate in metabolically active regions.

    • Half-life <3\ \text{h} isotopes; moderate SR/TR; invasive (injection).

  • Magnetic Resonance Imaging (MRI)

    • Structural: H-proton alignment → density map; high SR (sub-mm).

  • Diffusion Tensor Imaging (DTI)

    • Variant of MRI; gauges anisotropic water diffusion along axons; maps white-matter tracts.

  • Functional MRI (fMRI)

    • Blood-oxygen-level-dependent (BOLD) contrast.

    • Neurovascular coupling: active neurons ↑ flow of oxy-Haemoglobin (paramagnetic difference from deoxyHb).

    • Subtraction logic: task – baseline.

    • Advantages: no radiation, whole-brain coverage, combined structural+functional.

    • Limitations: low TR (seconds), indirect measure, interpretational complexity, correlational only.

Method Comparison (Condensed)

  • Psychophysics: Non-invasive, Functional, Low SR/TR, Correlational.

  • SCR/Peripheral: as above.

  • ABI/Lesions: Invasive (Y for animal lesions), Functional, Low SR/TR, Causal.

  • tDCS/Cryo/TMS: Mostly non-invasive (except cryo), Functional, causal.

  • MEG/EEG: Non-invasive, Functional, High TR, Low SR, Correlational.

  • PET: Invasive, Functional, Moderate SR/TR, Correlational.

  • MRI/DTI: Non-invasive, Structural, High SR, Low TR.

  • fMRI: Non-invasive, Functional, High SR, Low TR, Correlational.

Key Learnings & Exam Tips

  • Master anatomical directions, planes, and naming conventions; synonyms matter on tests.

  • For any method, be able to specify:

    1. Structural vs Functional focus.

    2. Degree of invasiveness.

    3. Spatial/Temporal resolution rankings.

    4. Whether it supports correlation or causation.

    5. Practical pros/cons (cost, comfort, availability).

  • Recognise which peripheral physiological measures index autonomic arousal vs central processes.

  • Understand lesion logic (both natural ABI & experimental animal lesions), plus limitations (collateral damage, plasticity).

  • TMS & tDCS: concept of "virtual lesion" and causal testing.

  • EEG basics: frequency bands, ERP components, averaging necessity.

  • fMRI: BOLD mechanism, subtraction designs, limitations (hemodynamic delay, indirectness).

  • Always consider building a convergent evidence base using multiple complementary techniques.