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PSY2014/L01/01^ Mon Sep 30 09:05:00 BST 2024

Overview of Lecture 2: Cognitive Neuroscience Methods

  • Focus: Understanding methods used in cognitive neuroscience.

  • Related Textbook Chapters: Chapter 3 in 5th edition and Chapter 2 in earlier editions.

Key Focus Areas

  • This lecture aims to clarify the relevance of gathered information in the context of exam preparation.

  • Students are encouraged to focus on materials covered in lectures over textbook details.

  • Extra credit is given for further readings, but it is not mandatory to excel in exams and understanding.

Differences Between Cognitive Psychology and Cognitive Neuroscience

  • Cognitive Psychology:

    • Studies mental processes (e.g., perception, memory).

    • Relies on behavior to infer underlying mental functions, often described as a "black box" approach.

    • Seeks to understand mental representations and operational processes—how individuals interpret stimuli and respond.

  • Cognitive Neuroscience:

    • Investigates the biological substrates and mechanisms behind cognitive processes.

    • Strives for deeper understanding of the physiological and neurological basis of cognitive functions.

Understanding Mental Representations

  • Definition: Anything that has meaning to an individual—such as recognizing a tree based on various sensory inputs.

  • Levels of Representation: Different ways of mentally representing an object, e.g., seeing a tree vs. knowing its smell as wood.

  • Mental Processes: Involved in transforming sensory data into actions and responses.

Methods in Cognitive Psychology

  • Posner's Letter Matching Task (1970s-1980s):

    • Subjects identify if two displayed letters belong to the same category (vowel/consonant).

    • Reaction times measured for different categories reveal cognitive processing layers exhibit:

      • Physical identity (fastest response)

      • Phonetic identity (slower)

      • Categorizations (slowest)

    • Reaction times indicate cognitive processing complexity.

  • Stimulus Onset Asynchrony:

    • Technique to manipulate timing of stimuli presentation to observe reaction time differences and the transformation of mental representations.

Neurology and Brain Damage

  • Neurological Factors:

    • Brain damage may occur from trauma, strokes, tumors, or neurodegenerative diseases (e.g., Alzheimer's, Parkinson's).

    • Understanding effects of damage aids in identifying functions corresponding to specific brain areas.

  • Importance of Single and Double Dissociations:

    • Single Dissociation: When one cognitive function is impaired while others remain intact and helps infer brain function.

    • Double Dissociation: Compares two patient groups with different impairments which allows deeper inferences about brain functions and task complexities.

    • Requires careful experimental design and comparison.

Techniques in Cognitive Neuroscience

  • Electroencephalography (EEG):

    • Measures electrical activity across the scalp, recording brain responses via synchronized neuron activity.

    • Useful in identifying different brain conditions (e.g., seizures).

  • Functional Magnetic Resonance Imaging (fMRI):

    • Measures brain activity by detecting changes associated with blood flow, providing insights into brain functions during tasks.

    • BOLD response indicative of active areas (blood oxygenation level dependent).

    • Important in linking cognitive tasks to specific neural processes.

  • Transcranial Magnetic Stimulation (TMS):

    • Non-invasive method to stimulate small regions of the brain, helpful for understanding functional roles in cognitive tasks.

    • Can deactivate specific areas and assess impact on cognitive performance.

  • Optogenetics:

    • A modern technique to control neuron activity using light, allowing for precise manipulation of neural circuits—although it is primarily used in animal models.

  • Pros and Cons of Techniques:

    • Single-cell recordings provide high temporal and spatial resolution but are limited to specific contexts (often animal studies).

    • Techniques vary in their capability to map and measure brain functions, necessitating a combination of methods for comprehensive understanding.

Conclusion and Recap

  • Lecture emphasized understanding cognitive functions through a multi-method, multi-faceted approach.

  • Clarified the differences between cognitive psychology and neuroscience.

  • Discussed methods that reveal underlying mental processes and relationships.

  • Reinforced the importance of evidence from neuroscience to support cognitive theories.

Pros and Cons of Techniques in Cognitive Neuroscience

Electroencephalography (EEG)

Pros:

  • High temporal resolution (measures brain activity in milliseconds) allows for precise timing of neural processes.

  • Non-invasive and relatively easy to set up compared to other imaging techniques.

  • Useful for understanding event-related potentials (ERPs) associated with specific cognitive events.

Cons:

  • Limited spatial resolution; difficult to pinpoint exact locations of brain activity due to the smearing of signals.

  • Susceptible to noise from muscle activity and external electrical interference, which can complicate data interpretation.

Functional Magnetic Resonance Imaging (fMRI)

Pros:

  • Excellent spatial resolution (around 1-2 mm), allowing for detailed mapping of brain anatomy and activity during cognitive tasks.

  • Measures changes in blood flow (BOLD response), reflecting active neural regions during specific cognitive tasks.

  • Provides insights into dynamic brain functions and networks.

Cons:

  • Limited temporal resolution (typically several seconds); cannot measure immediate neural activity.

  • Requires a noisy environment, which can affect participants' focus and performance.

  • High cost and logistical complexity of MRI machines limit accessibility for some studies.

Transcranial Magnetic Stimulation (TMS)

Pros:

  • Non-invasive and allows for causal inferences about brain function by temporarily disrupting activity in targeted brain regions.

  • Can assess how impairments of certain areas affect cognitive performance in real-time.

Cons:

  • Limited to superficial brain areas; cannot target deeper structures effectively.

  • Repeated stimulation in the same area can lead to discomfort or pain for participants.

  • Experimental design must carefully consider potential confounding factors in assessing cognitive effects.

Optogenetics

Pros:

  • Allows for precise control of neuron activity using light, facilitating detailed studies of specific neural circuits.

  • Enables high temporal precision and manipulation of synaptic transmission in live subjects, often used in animal models.

Cons:

  • Primarily limited to animal studies; not applicable to human subjects due to technical and ethical constraints.

  • Requires sophisticated genetic modifications, which complicates the experimental setup.

  • Still emerging as a technique; long-term effects and reliability in brain function studies are being explored.