Research Methods in Cognitive Neuroscience Lecture 2 PDF

Research Methods in Cognitive Neuroscience Lecture 2: Dissociation vs. Association Correlational Methods Causal Methods  Dissociation vs. Association & Correlational Methods Topics covered in Lecture 2 01 Double Dissociation: Broca’s vs. Wernicke’s...

Research Methods in Cognitive Neuroscience Lecture 2: Dissociation vs. Association Correlational Methods Causal Methods  Dissociation vs. Association & Correlational Methods Topics covered in Lecture 2 01 Double Dissociation: Broca’s vs. Wernicke’s Aphasia’s (1), Functions of the Ventral vs. Dorsal Streams (II) 02 Association: Example of the prefrontal cortex (I); Luria’s theory of functional systems (II) 03 Correlational Methods: Pros & Cons Overview: Anatomical & Behavioural Methods 04 Anatomical Methods: Animal models (I); Post-Mortem Examination of Key Cases [Gage & HM] (II) 05 Behavioural Methods: Combining cognitive tasks with neuroimaging 06 Causal Methods: Overview (I); Transcranial Magnetic Stimulation (II) ; Drug Administration (III) 2  Dissociation (I) Example using Broca and Wernicke’s Aphasias Double Dissociation: This concept demonstrates that two related cognitive functions, such as speech production and comprehension, are handled by distinct neural systems. This method strengthens the argument for functional specialization within the brain. Example: Broca’s Aphasia Damage to Broca’s area affects speech production but spares comprehension. Broca Wernicke’s Aphasia: Damage to Wernicke’s area affects comprehension but spares fluent speech. Wernicke 3  Dissociation (II) Example using the Ventral and Dorsal Streams in Visual Processing Double Dissociation: Patient with damage to area X (Ventral Dorsal Stream Y Stream) is impaired in function A B Visuospatial Processing (object recognition) but not in function B (visuo-spatial processing). Patient with damage to area Y (Dorsal Ventral Stream A Object Recognition X Stream) is impaired in function B (visuospatial processing) but not in function A (object recognition). 4  Association (I) Example of the Prefrontal Cortex (PFC) Association: Co-occurrence of deficits from damage to a single brain region, which suggests that one neural substrate underpins multiple distinct cognitive functions. Example: Prefrontal Cortex Damage: Lesions here often result in impairments in working memory, decision-making, Dorsolateral PFC - Working memory and inhibitory control, all of which are - Cog nitive Flexibility Ventrolateral PFC higher-order cognitive processes reliant - Motor In hibition - Decision Making on the frontal lobe. Orbitofrontal PFC This association suggests that these - Inhibiting res ponses - Social behaviour related functions share overlapping neural systems within the prefrontal Ventral Stream Object cortex Recognition 5  Association (II) Luria’s theory of functional systems Historical shift: From localization to understanding distributed processing (Lecture 1) Early models: Cognitive functions mapped Luria to isolated brain areas Pluripotentiality Example: Modern view: Functions involve interaction Thalamus has multiple distinct fx: across multiple brain regions. - Sensory Processing - Motor Function - Cognitive Functions Luria’s theory of functional systems: - Emotion & Arousal Cognitive functions emerge from networks, not static regions. Concept of pluripotentiality: Brain areas often perform various functions or adapt to various functions (Neuroplasticity) 6  Correlational Methods (I) Pros & Cons Overview: Anatomical & Behavioural Methods Correlation methods: Observe relationships between brain structure and behaviour Not causal: Focus on naturally occurring variations Key for linking neural structures to cognitive functions Techniques: Anatomical & behavioural methods Method Pros Cons Important Issues: Post-Mortem - Direct examination of brain - Cannot observe real-time function Practice Effects Examinations structures - Retrospective Ecological Validity Anatomical Ethical Concerns - Limited generalizability (i.e. lack of - Detailed insights Cross Species Translation Case Studies Ecological validity) - Study rare/unique conditions Indirect Measurement - Single-case bias - Controlled experiments - Ethical concerns Animal Models Ecological Validity: - Neuroplasticity - Cross-species translation Practice Effects: Laboratory settings don’t Confound for cognitive often perfectly mimic the Behavioural Cognitive - Non-invasive - Practice effects assessments, where complexity of real-world Assessments - Direct cognitive measurement - May lack real-world relevance repeated exposure to the environments, raising same tasks can artificially concerns about how well improve performance over Functional - Real-time brain activity - Indirect measures the findings apply to time, skewing results. Neuroimaging - Brain networks - Expensive & time-consuming everyday cognition. 7  Anatomical Methods (I) Animal Modelling Methods Animal Methods : Rodent studies: Controlled lesions to study Animal methods involve controlled brain lesion to examine inks between brain & behaviour experiments in animals John O’Keefe: Discovered “place cells” in Allows researchers to study brain-behaviour hippocampus (spatial navigation) relationships that can't be ethically tested in humans. May-Britt & Edvard Moser: Found “grid cells” in the entorhinal cortex Animal Models Contributions: Understanding neuroplasticity and distributed brain fxs Pros: - Assess Neuroplasticity - Controlled Experiments Cons: - Cross-Species Translation - Animal welfare - Ethics 8  Anatomical Methods (II) Post-Mortem Examinations of Key Cases (Lesion Analysis) Post-Mortem Examinations of Key Cases: Henry Molaison (HM) By conducting post-mortem examinations of the Brain damage to the medial brains of individuals who suffered brain injuries temporal lobes (specific lesions) with distinct cognitive outcomes, Correlated with profound researchers have been able to establish correlations memory loss between specific areas of brain damage and Helped identify the role of corresponding cognitive functions. the hippocampus in memory Drawbacks of Lesion Analysis: Lesion studies may not account for the brain’s plasticity, where undamaged regions can compensate for lost fxs. Phineas Gage Additionally, the damage can affect multiple areas, Frontal lobe injury from a complicating the interpretation of results about railroad accident specific brain functions. Linked to personality and decision-making changes Case Study Cons: Case Study Pros: -Limited generalizability (Ecological validity) - Detailed insights Demonstrated the role of the - Single-case bias - Study rare/unique conditions frontal cortex in behaviour 9  Behavioural Methods Combining Cognitive Tasks with Neuroimaging Behavioural Studies: Brenda Milner These studies often link cognitive tasks (like Milner’s extensive cognitive testing memory tests) with brain activity using work with HM helped establish the neuroimaging techniques such as fMRI, EEG, hippocampus as essential for or TMS (Lecture III). memory. Behavioural studies often aim to correlate Michael Posner patterns of brain activity with specific Developed the Attention Network cognitive processes. Model, identifying three networks that govern alerting, orienting, and executive control of attention Cognitive Assessments Functional Neuroimaging through EEG and fMRI. Pros: Pros: -Non-invasive - Real-time brain activity - Direct cognitive measurement - Brain networks Joshua Greene His research on moral decision- Cons: Cons: making used fMRI to observe brain - Practice effects - Indirect measures - May lack real-world relevance - Expensive & time-consuming regions involved in ethical dilemmas. 10  Causal Methods (I) Pros & Cons Overview: TMS & Drug Administration Causal methods in Cognitive Neuroscience: Aim to establish direct links between brain activity and cognitive functions. Manipulate brain regions or neurotransmitter systems and observe the effects on behaviour. Unlike correlational methods, causal approaches provide definitive evidence of how specific neural mechanisms support cognition. Method Pros (advantages) Cons (Disadvantages) - Non-invasive Transcranial - Causal inference - Limited depth of brain stimulation Magnetic - Temporary brain disruption allows - Short-lasting effects Stimulation study of specific brain areas - Possible discomfort or side effects (TMS) (Reversibility) - Can study effects on specific - System-wide effects (not brain-specific) Drug neurotransmitter systems - Ethical concerns with certain drugs Administration - Longer-lasting effects compared to - May have lasting physiological/ TMS psychological side effects 7  Causal Methods (II) Transcranial Magnetic Stimulation Transcranial Magnetic Stimulation A coil placed on the scalp generates a magnetic field, inducing currents that can alter neuronal activity. Different protocols: Single-pulse TMS disrupts activity briefly. Repetitive TMS (rTMS) has longer-lasting effects. Theta-burst stimulation (TBS) can last up to an hour. Used to Treat: Major Depressive Disorder (MDD) - Prefrontal Cortex stimulation Obsessive Compulsive Disorder (OCD) – Anterior Cingulate stimulation Disadvantages (Cons): Advantages (Pros): - Short-lasting effects - Non-invasive - Discomfort / side effects - Causal inference - Reversibility 8  Causal Methods (III) Drug Administration Drug Administration: Advantages (Pros): - Can study effects on specific neurotransmitter systems Manipulates neurotransmitter systems to study - Longer-lasting effects compared to TMS effects on cognition and behaviour. Drugs used: Disadvantages (Cons): - System-wide effects (not brain-specific) Agonists enhance neurotransmitter activity - Ethical concerns with certain drugs (e.g., L-DOPA for dopamine). - May have lasting physiological/ psychological side effects Antagonists inhibit neurotransmitter activity (e.g., Haloperidol). Example studies: Mehta et al. (2000): Increased dopamine via methylphenidate enhances working memory. Robbins et al. (1996): Blocking acetylcholine receptors impairs memory. 8  ? Key terms ? Double dissociation Broca’s vs. Wernicke's Aphasias ? Ventral vs. Dorsal Stream Association Prefrontal Cortex QUESTIONS? ? Luria’s functional systems theory Pluripotentiality Neuroplasticity ? Correlational Methods Anatomical Methods Animal Studies Post-Mortem examinations (Lesion Analysis) Behavioural Methods Causal Methods NB: Pros & Cons TMS of different Drug Administration Methods 13