Cognitive Neuroscience: Fetal Alcohol Spectrum Disorders

Fetal Alcohol Spectrum Disorders

• Intellectual disabilities arise from maternal alcohol consumption during pregnancy.
• Severity varies along a continuum, with Fetal Alcohol Syndrome (FAS) being the most severe.

Fetal Alcohol Syndrome (FAS)

• Symptoms include hyperactivity, poor impulse control, social and emotional difficulties, learning and memory issues, and executive dysfunction.
• Physical manifestations: slowed growth, facial and cranial abnormalities.
• Brain structural changes: reduced gray matter volume, altered white-matter development, particularly affecting frontal lobe connections throughout childhood and adolescence.

Dyslexia

• Identified as a specific reading disability; significant difficulty in reading despite appropriate training and intelligence.
• Primarily characterized by phonological understanding deficits: struggle to connect letters with sounds and decode words into phonemes.
• Potential issues with perceptual mechanisms essential for phonological awareness and communication among sensory and language regions.

Autism Spectrum Disorder (ASD)

• Diagnosis requires meeting two main criteria: impairment in social interaction across contexts.
• Demonstrates variability in behavioral manifestations, requiring a nuanced understanding for effective diagnosis and support.

Brain Plasticity in Adulthood

• The somatosensory cortex can reorganize following amputation, with areas previously assigned to the lost limb becoming responsive to adjacent body parts.
• Maps in sensory cortex rely on ongoing sensory input; systematic input changes can lead to remapping and phantom sensations in amputees.

Cross-Modal Plasticity

• Cortex regions can adapt for different functions; areas dedicated to one purpose may be repurposed for another, including compensation by regions in the opposite hemisphere.

Recovery of Function

• Damage to primary motor areas affects sensory and premotor cortices, altering inter-regional connectivity.
• Recovery from brain damage varies among individuals, with physical and cognitive therapies playing key roles.

Recovery vs. Compensation

• True recovery involves restoring original function, while compensation refers to finding alternative methods to complete tasks.
• The recovery window is shorter compared to the period for compensation, with true recovery primarily achievable within the first few months post-injury.

Interventions to Promote Recovery

• Specific training programs, such as physical therapy for motor issues post-stroke, emphasis on repetitive limb use or speech enhancement.
• Stimulation methods, including Transcranial Magnetic Stimulation (TMS) and Transcranial Direct Current Stimulation (tDCS), target damaged hemispheres or inhibit opposite ones to reduce competitive interference.

Kennard Principle

• Suggests earlier damage to the brain results in better recovery outcomes.
• Evidence indicates early left-hemisphere damage may not lead to aphasia but might affect phonology and syntax; early right-hemisphere damage can cause spatial cognition difficulties similar to those in adults.

Crowding Hypothesis

• Children experiencing early brain damage may show improved recovery, but later developmental demands can reveal deficits as they tackle more complex tasks.
• Intact brain regions must assume roles originally managed by damaged areas, potentially leading to cognitive overcrowding.

Cognitive Changes with Aging

• General decline hypothesis posits all cognitive abilities deteriorate with age, attributed to reduced mental resources or slowed processing.
• Reality is selective decline: fluid intelligence diminishes while crystallized intelligence remains stable; emotional regulation tends to improve.
• Greater cognitive decline observed in frontal and temporal regions compared to other areas.