Cognitive Neuroscience

Voluntary vs. Involuntary Attention

• Voluntary Attention: Controlled, intentional focus on a stimulus (top-down).

• Involuntary Attention: Automatic, stimulus-driven focus (bottom-up).

Visual Neglect

• Definition: A neurological condition where individuals fail to attend to stimuli on one side of space, often due to brain damage (e.g., to the right parietal lobe).

• Why a Disorder of Attention: Involves deficits in allocating attention rather than sensory impairments.

Posner Cueing Paradigm

• Focus: Measures how attention shifts due to cues.

• Facilitation: Faster responses to cued locations at short intervals.

• Inhibition of Return (IOR): Slower responses to previously cued locations at longer intervals.

ERP Responses as Indices of Selective Attention 

• N1 and P1 Components: Larger amplitude for attended targets, reflecting early sensory selection in attention processing.

ERP Responses and Inhibition of Return (IOR)

• P1 Component: Enhanced for uncued trials at longer stimulus-onset asynchronies (SOAs), indicating IOR.

Source vs. Site of Attention Effects

• Source: Top-down mechanisms (e.g., executive control systems) that regulate attention.

• Site: The location or neural region where attention is focused.

Negative Priming (NP)

• Basic Paradigm: Slower response to a previously ignored stimulus when it becomes relevant.

• Theories of NP:

o Inhibition: Suppressed processing of ignored items.

o Episodic Retrieval: Conflict due to mismatch in previous and current stimulus relevance.

• Neural Basis: Involvement of specific brain regions like the prefrontal cortex (Enger & Hirsch, 2005).

• Implications for Schizophrenia: Deficits in NP may reflect impaired attention regulation (Unger et al., 2010)

Memory

Sensory Memory 

• Definition: Brief retention of sensory information.

• Echoic Memory: Auditory sensory memory, lasting a few seconds.

• Sensory Store: The initial stage of memory that briefly holds all incoming sensory information.

Working Memory

• Definition: Active processing and storage of information for short-term use.

• Neural Basis:

o Verbal: Associated with Broca’s and left prefrontal regions.

o Nonverbal: Linked to the right prefrontal and parietal regions.

• N-back Task: A cognitive test requiring participants to identify if a stimulus matches one presented 'n' steps earlier; measures working memory capacity.

• Monitoring vs. Manipulating Information:

o Champod and Petrides (2010):

▪ Monitoring: Linked to the frontal regions.

▪ Manipulating: Linked to the frontal and parietal regions.

Long-Term Memory

• Semantic vs. Episodic Memory:

o Semantic: Facts and general knowledge.

o Episodic: Personal experiences and events.

• Explicit vs. Implicit Memory:

o Explicit: Conscious recall (e.g., facts).

o Implicit: Unconscious memory (e.g., skills).

o HM Case Study: Surgical removal of medial temporal lobes impaired explicit memory but preserved implicit memory, highlighting the distinction.

Neural Basis of Implicit Memory

• Weather Prediction Task: A probabilistic learning task demonstrating the role of the basal ganglia in implicit memory.

Encoding Paradigms

• Ranganath, Yonelinas, & D’Esposito (2004):

o Differentiated familiarity (vague recognition) and source recollection (specific memory of the context).

Alzheimer’s Dementia

• Symptoms: Memory loss, confusion, difficulty with daily tasks.

• Progression: From mild memory lapses to severe cognitive impairment.

• Risk Factors: Age, genetics (e.g., APOE-ε4), lifestyle.

• Pathology:

o Beta Amyloid: Protein plaques disrupting neuronal communication.

o Tau Tangles: Protein tangles damaging neuron structure.

• Role of PET and fMRI: Imaging tools to study amyloid deposition, brain atrophy, and progression of the disease.

Speech Perception

Neuroanatomy of the Auditory Cortex

• Key regions:

o Heschl’s gyrus and planum temporale.

o Associated with language dominance and laterality(e.g., left hemisphere in most people).

• Tonotopic organization:

o The auditory cortex is organized by frequency.

o Binaural input representation: Evidence of bilateral neural representation of sound from both ears; however, LH > Sound from Right Ear and vice versa

Mismatch Negativity (MMN) in Speech Perception

• MMN basics:

o Brain response to deviations in auditory stimuli.

o Paradigm involves comparing standard and deviant sounds.

• Language specificity studies:

o Näätänen et al., 1997: Finnish and Estonian participants showed MMN differences tied to native phoneme categories.

o Highlights the role of MMN in understanding:

▪ Language development.

▪ Second-language (L2) learning.

Neuroanatomy of Speech Processing

• Differentiation between:

o Speech without understanding (auditory processing without semantic interpretation).

o Semantic understanding of speech (involves higher-level cognitive and language processing).

Second Language (L2) Learning

Factors Impacting L2 Proficiency

• Study by Jakoby et al., 2011:

o Variations in L2 proficiency linked to:

▪ Neural differentiation of phoneme categories.

▪ MMN as a potential marker of phoneme discrimination abilities.

• Implications:

o Individual differences in neural plasticity and auditory processing affect L2 learning outcomes.

Reading

Reading for Meaning

Pathways in Reading

• Phonological pathway: O – P - S

o Involves decoding written text into sounds.

• Orthographic pathway: O - S

o Direct recognition of word forms without phonological decoding.

o Essential for fluent reading.

Homophone Error Paradigm

• Logic: Errors arise when phonologically identical words (homophones) are misinterpreted (e.g., "flour" vs "flower"), which is evidence for the phonological pathway

• ERP (Event-Related Potential) studies:

o Focus on N400 component:

o Used to understand time course of phonological activation during reading.

Neuroanatomy of Reading

• Inferior frontal gyrus:

o Phonological processing with emphasis on subvocal articulation.

• Temporo-parietal regions:

o Phonological processing at the whole word level.

o Integration with semantic processing.

• Occipitotemporal area:

o Houses the visual word form area (VWFA).

o Critical for recognizing written words and letter patterns.

Reading Disabilities

Developmental Dyslexia

• Key theories:

o Phonological Theory: Suggests a deficit in phonological awareness as the core issue in reading difficulties (e.g., developmental dyslexia).

o Magnocellular Theory: Proposes that reading disabilities are due to a deficit in the magnocellular system, which is involved in processing visual and auditory motion.

• Neurobiology:

o Comparison:

▪ No history of reading troubles: Efficient neural connections for reading.

▪ Developmental dyslexia: Disruptions in phonological and orthographic pathways.Reduced activation in the left frontal, temporoparietal and VWFA; compensatory activation in the right hemisphere

Diffusion Tensor Imaging (DTI)

• Focuses on white matter pathways:

o Integrity of connections impacts reading ability.

o Individuals with reading challenges often show reduced white matter integrity in key reading-related pathways.

Cognitive Control

Frontal Lobe Pathology

• Overview: Damage to the frontal lobes can result in impairments in cognitive, emotional, and social behaviors.

• Key Syndromes:

o Dorsolateral Syndrome:

▪ Symptoms: Poor planning, organization, and goal-directed behavior.

▪ Associated deficits: Working memory and cognitive flexibility.

o Orbitofrontal Syndrome:

▪ Symptoms: Disinhibition, impulsivity, socially inappropriate behavior.

▪ Associated deficits: Emotional regulation and decision-making.

Importance of the Frontal Lobes (Prefrontal Cortex)

• Central to cognitive control:

o The ability to regulate thoughts and actions in pursuit of goals.

• Key functions of the prefrontal cortex:

o Forming goals and objectives.

o Developing and sequencing plans to achieve those goals.

o Monitoring progress and making adjustments.

o Shifting gears (cognitive flexibility) when needed.

o Evaluating successes and failures for future adaptation

Cognitive Control

• Definition: The capacity to coordinate mental processes to achieve a specific objective.

• Daily Examples:

o Planning your day.

o Adapting when unexpected events disrupt plans.

o Tracking progress toward completing a project.

o Evaluating why a task succeeded or failed.

Clinical and Experimental Measures of Cognitive Control

Wisconsin Card Sorting Task (WCST):

o Tests cognitive flexibility and problem-solving.

o Patients must sort cards based on shifting rules, requiring them to adapt when the rules change.

o Deficits in performance (perseverating on an old rule)often linked to dorsolateral prefrontal cortex (DLPFC) damage.

fMRI Adaptations of WCST:

o Highlights the role of the DLPFC in:

▪ Rule maintenance.

▪ Working memory (WM) integration for cognitive control.

o Working Memory (WM):

▪ Critical for holding task-relevant information during problem-solving.

Task-Switching Paradigm:

o Evaluates the ability to shift between tasks or rules.

o Shows strong overlap between cognitive control and WM demands.