Neuroscience Lecture Notes: Brain Structure, Function, Development, and Memory
Brain and the Nervous System
The brain is interconnected by the corpus callosum, which is primarily axons, enabling communication between the left and right hemispheres.
The brain is covered by the cerebral cortex, where the four lobes sit.
The brain uses neurotransmitters to communicate as electrochemical messages; drugs can modify these signals (e.g., SSRIs affect serotonin).
Common neurotransmitters discussed: serotonin (SSRI), epinephrine, acetylcholine; these influence alertness, mood, cognition, and memory.
When you perform a movement (e.g., waving your right hand), the controlling signals originate on the left side of the brain and control the opposite side of the body (contralateral control).
The brain’s energy use is high, but it is efficient: it’s not that we use only 10% of the brain; we use a lot of it, but energy is conserved via selective activation in task-relevant regions.
Consciousness and the nature of mind are complex and not fully understood; we infer mental states but cannot truly know another mind.
The four major lobes: frontal, parietal, occipital, temporal.
The frontal lobe is involved in executive functions, planning, decision-making, and future planning (prefrontal cortex).
The parietal lobe handles body sensation and spatial awareness; helps judge distances and body position.
The occipital lobe contains the primary visual cortex; it is the initial cortical processing area for vision.
The temporal lobe handles auditory processing and memory; it contributes to language and recognition.
The cortex functions as a distribution center (a filing system) for sensory information that is then routed to other areas for interpretation and response.
The cortex processes visual input: signals travel from the retina to the primary visual cortex in the occipital lobe, then to other regions for object recognition (e.g., identifying a water bottle).
The cerebrum consists of two hemispheres connected by the corpus callosum; the majority of the cortex is folded, increasing processing surface area in a compact volume.
Some people hypothesize about brain evolution and cortical expansion; such ideas are speculative and not established science.
Neurons, Synapses, and Neural Communication
Neurons consist of: dendrites (receive signals), cell body (soma; integrates signals), axon (sends signals), synaptic terminal buttons (release neurotransmitters).
The synapse (synaptic cleft) is the communication space between neurons; neurotransmitters cross this space and bind to receptors on the receiving neuron.
Binding sites are like locks and keys: different transmitters bind to specific receptors, triggering downstream effects.
If a neurotransmitter is released but not received (reuptake), the signal ends; medications like selective serotonin reuptake inhibitors (SSRIs) keep serotonin in the synaptic cleft longer to improve signaling.
An action potential travels along the axon to the synapse, releasing neurotransmitters into the synaptic cleft.
The myelin sheath speeds up signal transmission along the axon; it is primarily fatty and produced by glial cells.
Myelin is crucial for motor control (e.g., in Parkinson’s disease, myelin-related signaling may be impaired, contributing to motor symptoms).
Myelin development is particularly important in infancy; fats in diet (including DHA) support myelination.
The synaptic receptor landscape can change with drugs, learning, and experience; receptor binding and receptor availability influence mood and cognition.
Brain Development and Lifespan Dynamics
In utero, the brain begins neural activity; auditory and light responsiveness can be present before birth.
After birth, vision is limited; newborn visual acuity is poor, with preference for high-contrast patterns (e.g., red on black, blue on yellow).
Rods and cones: rods handle low light; cones handle color; color vision develops gradually; full color perception emerges as the infant matures (~6–12 months for fuller color discrimination).
Prefrontal cortex (frontal lobe) development continues well into childhood; robust executive function tends to emerge around ages 3–5 as schooling and planning demands increase.
Cognitive development is guided by use: the brain develops as it is used (experience-dependent plasticity).
By late adolescence and early adulthood, many cortical regions are still maturing; the prefrontal cortex is particularly prolonged in development.
Substance exposure (e.g., cannabis) in young people can impact developing prefrontal cortex and memory circuitry, with potential long-term effects on memory and executive function.
Primary vs. secondary cortical development: early development relies on sensation and motor coordination, followed by increasingly complex cognitive functions as language and memory networks mature.
Language Areas and Speech
Broca's area (left hemisphere generally) is primarily responsible for speech production and motor aspects of speaking; damage can lead to aphasia with fluent but nonsensical speech or telegraphic speech.
Wernicke's area (left hemisphere) handles language comprehension (spoken and written); damage leads to fluent but nonsensical speech with poor comprehension.
Language is predominantly localized in the left hemisphere for about 90% of people; the right hand is typically used for language expression. About 10% of left-handed individuals have language localization in the right hemisphere.
Language processing involves multiple networks, including comprehension, syntax, and semantics, and can be affected by strokes or lesions in Broca's or Wernicke's areas.
The Limbic System: Amygdala and Hippocampus
Amygdala: emotional processing center; involved in fear, fight-or-flight responses, and emotional evaluation of stimuli.
Hippocampus: critical for forming new long-term memories; not the storage site for all memories, but essential for consolidation and creating new long-term memory traces.
The limbic system (including amygdala and hippocampus) contributes to emotion, memory, and behavior; memory consolidation is improved with sleep.
In memory disorders or after hippocampal damage (e.g., in Memento or 50 First Dates scenarios), the ability to form new long-term memories can be disrupted while older memories remain intact.
Memory distribution: memories are stored across multiple brain regions (distributed storage) rather than in a single localized site.
Sensation, Perception, and the Senses
Sensation vs. perception: sensation is the raw input from sensory receptors; perception is how the brain interprets and makes meaning of that input.
The five senses: sight, smell, hearing, taste, touch.
In utero capabilities: babies can respond to sound and light while in the womb; vision is immature at birth but stimulation helps development.
Vision: newborns see high-contrast patterns best; acuity improves over the first 6–12 months; color vision develops with age.
Taste and smell: fetuses and newborns show preferences in taste/smell after birth; some evidence for prenatal taste exposure; nasal passages and olfaction are functional postnatally.
Touch: tactile sensation is present; infants explore with mouth and hands; reflexes guide early feeding and social bonding.
Infant Development: Senses, Reflexes, and Motor Milestones
Reflexes serve survival functions early in life (e.g., rooting, sucking, grasping); most reflexes fade as voluntary control develops.
Primary circular reactions (birth to ~4 months) involve repetitive actions that are pleasurable or self-stimulating (e.g., mouth movements, grasping).
Secondary circular reactions (~4 to ~8 months) involve repeating actions that produce effects outside the body (e.g., shaking a rattle to produce sound).
Around 6–8 months, infants develop the understanding of object permanence: the realization that objects continue to exist even when out of sight; this reflects memory and representation abilities.
Memory and recall: recall (accessing memory without cues) vs recognition (cue-based retrieval) develop with time and language.
Sensorimotor stage (Piaget) ends around age 2; language development begins to accelerate understanding and representation of the world.
Differentiate gross motor (big movements like walking) vs fine motor (small movements like finger coordination).
Gross motor milestones: walking around ~12 months; gross motor skills improve with age as motivation and opportunity increase.
Fine motor milestones: grasping, pincer grip, writing readiness; these develop with practice and neural maturation.
Piaget and Schemas: Assimilation, Accommodation, and Affordances
Piaget proposed stages of cognitive development: sensorimotor, preoperational, concrete operational, formal operational; development continues into adolescence.
All knowledge begins with physical interaction with the world (sensorimotor foundation).
A schema is a mental structure for organizing knowledge and expectations about the world; can be stereotypes or general rules.
Assimilation: incorporating new information into existing schemas (e.g., calling an 80-year-old an octogenarian but initially mislabeling as an eight-legged creature).
Accommodation: adjusting schemas to fit new information when assimilation fails (e.g., realizing octogenarian means an 80-year-old, not an eight-legged creature).
Equilibrium and disequilibrium drive learning; learning occurs as the organism adapts to new information to regain balance.
Affordances: perceived possibilities for action offered by objects; sometimes people use objects in unintended ways (e.g., Band-Aids for purposes other than covering a booboo, using a container for storage).
In early development, infants explore with their mouths and hands to learn about objects; language and mental representation emerge as schemas become more abstract.
The role of culture is emphasized in later theories (not fully addressed in Piaget’s original framework); learning is socially mediated and context-specific (Vygotsky).
Dynamic Systems Theory and Motivation in Learning
Dynamic systems theory emphasizes that development is self-organizing and driven by multiple interacting factors, including motivation, environment, and social context.
Learning and development depend on the child’s level of motivation to achieve a task; caregivers influence the pace and direction of development through scaffolding and support.
Avoidance of learned helplessness: balance between support and independence is key; over-scaffolding can hinder autonomous problem solving.
Language and Cognitive Development: Memory, Recall, and Recognition
Language networks underpin recall and comprehension; development of language accelerates cognitive processing and memory organization.
Recall requires deeper memory retrieval with fewer cues; recognition relies on cues and prior exposure.
Practical and Real-World Implications
Sleep and memory: adequate sleep supports memory consolidation and cognitive functioning.
Nutrition and brain development: adequate fat intake (e.g., DHA) is important for myelination and brain development in infancy; breastfeeding has immune and developmental benefits, including potential reductions in infections and allergies, though not universal.
Breastfeeding guidelines: exclusive breastfeeding for ~ when possible; continued breastfeeding with complementary foods through the first year or longer depending on circumstances; maternal and infant benefits include uterine involution for the mother and immune support for the infant.
Formula and breast milk considerations: formula provides nutrition when breastfeeding is not possible; cost and access are considerations; early feeding choices influence later development and family dynamics.
SIDS: risk reduction includes back-sleeping recommendations; weight at birth is a key health indicator, with heavier infants generally showing better outcomes, though not determinative.
Infant sleep patterns and breast milk are interconnected with growth and development; newborns sleep lengthy periods (often around and sometimes up to in some cases).
Observations about development (e.g., language onset around age ; walking around ) reflect typical developmental windows while acknowledging individual variability.
Ethical and philosophical notes: human consciousness and mind remain deeply complex; society debates about brain evolution, artificial intelligence (Matrix-like scenarios), and the ethics of neuromodulation and memory manipulation.
Quick Reference: Key Terms and Concepts
Corpus callosum: main communication bridge between hemispheres.
Cortex: outer layer of brain; processing and distribution hub.
Lobes: frontal (planning, decision-making), parietal (somatosensation, spatial), occipital (vision), temporal (hearing, memory).
Broca's area: speech production (left hemisphere, language expression).
Wernicke's area: language comprehension (left hemisphere, language interpretation).
Amygdala: emotion and fear processing.
Hippocampus: consolidation of new long-term memories.
Limbic system: emotion and memory integration.
Synapse: junction between neurons where neurotransmitters act.
Myelin: fatty sheath covering axons to speed signal transmission.
Assimilation: fitting new information into existing Schemas.
Accommodation: altering Schemas to fit new information.
Affordances: possible uses of objects beyond their intended purpose.
Dynamic Systems Theory: development driven by interaction of multiple factors and motivation.
Sensorimotor stage (Piaget): infancy learning through sensory and motor interactions (0–2 years).
Gross motor vs Fine motor: big vs small muscle movements.
Object permanence: understanding that objects continue to exist when not seen.
Recall vs Recognition: different memory retrieval processes.
SIDS: sudden infant death syndrome; back-sleeping recommendations reduce risk.
DHA, fat intake: supports myelination and brain development in infants.
Prefrontal cortex: executive function development; planning and self-control.
Exam Prep Tips (from lecture cues)
Know the four lobes and a primary function of each.
Be able to explain Broca's vs Wernicke's areas and what happens with aphasia.
Distinguish sensation vs perception and list the five senses.
Describe the roles of the amygdala and hippocampus in emotion and memory.
Explain how neurotransmission works at a synapse, including reuptake and receptor binding.
Distinguish gross motor vs fine motor skills with examples.
Summarize Piaget’s sensorimotor stage and the concepts of assimilation and accommodation with examples (e.g., octogenarian misinterpretation, dog vs horse example).
Define affordances and provide everyday examples.
Understand dynamic systems theory and the role of motivation in learning new skills (e.g., walking).
Recognize basic infant development milestones (walking ~; first words ~).
Recall how breastfeeding affects infant health and growth, and the general guidelines for duration and when to introduce solids (~ with continued feeding alongside solids).
Be able to discuss SIDS risk factors and prevention strategies.
Understand how memory consolidation is influenced by sleep and the distributed nature of memory storage in the limbic system.