Psychology 161-1
Adoption Study
"Dose-Dependent" effect of poor caregiving on brain development 78 international children who were adopted to the U.S. Mean age of adoption (in months): 19.2 months (range: 2.5-60 months) Children who spent more time in orphanage had larger amygdala and higher anxiety
Does bilingualism provide a protective mechanism against age-related cognitive decline?
"cognitive reserve": idea that lifelong bilingual experience serves as a deterrent to the onset of age-related cognitive decline Evidence in support of this suggests greater gray matter volume in bilingual older adults vs monolinguals
The Physical Environment subscale of the Home Observation forMeasurement of the Environment (HOME) inventory (Caldwell & Bradley 1984)
1) the home has no potentially dangerous structural or health hazards; 2) the home has at least 100 square feet of living space per person; 3) The home and immediate surroundings are not overly noisy; 4) the house or apartment is clean; 5) interior of the house is not dark or perceptually monotonous; 6) Immediate external environment is esthetically pleasing and contains no obvious health or safety hazards. The strength of the income to needs ratio was mediated by the physical home environment on its effect on the surface area of the right superior frontal gyrus surface area The physical home environment's effect on WRAT reading composite standard score was mediated by left superior frontal gyrus cortical thickness.
Study Design
1,037 children Assessed at multiple ages (age 26 in study) Well-characterized life history Multiple methods to assess antisocial behavior
Important periods of prenatal development
1-2 weeks: not susceptible to teratogens. Dividing zygote, implantation, gastrulation. 3-8 weeks: common site of action of teratogen. CNS, heart, eye, limbs, genitalia, ears, teeth, etc. develop) 9-38 weeks: brain development
Outcome Measures
1. Conduct disorder (psychological interview) 2. Convictions for violent crimes (police reports) 3. Disposition toward violence (psychological assessment) 4. Antisocial personality symptoms (peer report)
Not all plasticity is the same
1. Developmental plasticity 2. Adult plasticity Are the plastic processes that operate during development the same as those that operate in adulthood? Does experience influence the brain in the same way across the lifespan?
Environmental Complexity Paradigm
1. Environmental Complexity (EC) Animals -Housed in groups in large cages -Access to objects to manipulate -Exposure to challenges (mazes) 2. Social cage (SC) Animals -Housed in pairs in standard cages -No objects 3. Individual Cage (IC) Animals -Housed Alone -No objects Animals in enriched environment (EC) perform better on complex tasks than animals reared in SC or IC
Changes in neuroanatomy that occur with second language learning Which neuroanatomical changes are measured?
1. Gray matter density -Believed to reflect changes in neuron size, neurogenesis and synaptogenesis 2. Cortical thickness -Measures the thickness of gray matter on the surface of the cortex 3. White matter integrity -A technique that measures the white matter tracts in the brain
Policy Implications
1. Highlights brain development as a new target for intervention and prevention programs -Targeting particular neurocognitive systems directly (e.g. game-based training) 2. Focus on policies that influence the broader environments in which childred are reared. -Enriching environments are important -Maternal well-being (e.g. stress reduction) is important to address.
Genetic variability contributes to behavior/trait variability
1. Rate of development 2. Individual traits 3. Abnormal development
Causes of Allostatic Load
1. Repeated frequency of stress responses to multiple novel stressors 2. Failure to habituate to repeated stressors of the same kind 3. Failure to turn off each stress response in a timely manner due to delayed shut down 4. Inadequate responses that leads to compensatory hyperactivity of other mediators.
First Trimester (Germinal Period)
1. Single-celled mature ovum discharged by ovary on days 9 to 16 of menstrual cycle. 2. Fertilization occurs usually within 24 hours 3. 2 cells @ 36 hours 4. 4 cells @ 48 hours 5. 16 to 32 cells @ 72 horus 6. Cell Division and formation of inner cell mass @ 4 to 5 days. 7. Implantation (8 to 14 days)
ADHD: A Maturational Delay
100% had ADHD Diagnosis at Baseline 21% "grew out of" ADHD 42% partially "grew out of" ADHD 37% still had ADHD diagnosis Parietal Cortex shows "normalization" -No difference from controls by late teens "Growing out" of ADHD may be the result of normalization of initial delays -Improvement in initial cognitive deficits Stable (lifelong) ADHD may be the result of a deviant trajectory -Persistent or worsening cognitive deficits
Longitudinal study to monitor changes in white matter integrity as adults learned a new language
11 participants enrolled in a 9 month modern chinese language course 16 control participants did not enroll in a language course White matter integrity increases during language learning and is predictive of how well they learned
In the united states, ?% of children live in poverty
20, but more than that are getting inadequate resources
Chromosomes
23 pairs Each gene has at least two possible versions (one on each chromosome). These alternative states are alleles.
Overproduction of synapses leads to pruning (elimination) around puberty
5 distinct waves: Phase 1/2 are mostly under genetic control (you aren't born yet), experience independent. Phase 3/4 (overproduction) are experience expectant and/or dependent. The brain is getting ready for the visual input it will receive at birth. Connections between neurons are relatively week in phase 3. In phase 4, density of synpases plateaus and the connections between some neurons become very strong. Phase 5 (pruning): experience dependent [and expectant]. Connections between some neurons become weak and eventually die. *diagram*
Who makes the object permanence errors?
8-10 month old infants consistently make the error. Infants older than 12 months of age perform this task correctly (reach for B location) Why this significant shift in correct performance at this age? -Multiple causes for improved performance.
Socioeconomic status
A measure of an individual's or family's economic and social position in relation to others, based on income, education, and occupation. Environmental factors: -Neighborhood characteristics -Exposure to toxins and violence -Parental Care
Antisocial Behavior
A pervasive pattern of disregard for, and violation of, the rights of others Children who experience child abuse are at increased risk for developing antisocial behavior Common characteristics: -Deceit -Manipulation -Irritability and aggressiveness -Failure to conform to social norms -Lack of remorse -Superficial charm However, most maltreated children do not become delinquents or criminals What is the source of this variability?
How does the A-not-B Task relate to Dynamic Systems Theory?
A. It illustrates the meaning of multicausality B. It shows why babies crawl before they walk C. It proves that nonverbal children do not have object permanence D. It does not relate to dynamic systems theory
The Importance of Time and Timing in Brain Development
Absolute time that a neural event occurs -Days after conception -Days after birth Time relative to other events -Development occurs as a cascade of events -One event MAY influence those that follow but not precede it. Example: Mental retardation and high radiation levels. 1-8 weeks, no risk of developing mental retardation. 8-15 weeks *direct relationship between dose of radiation exposure and subsequent mental retardation. NEURONAL MIGRATION* After 15 weeks, reduced risk of developing mental retardation.
Two things happen when we learn the speech sounds of our native language:
Acquired distinctiveness: We become BETTER at perceiving stimulus properties that are critical for distinguishing native language sounds. Acquired similarity: we become WORSE at perceiving properties that are not.
Humans do not have the largest brains
African elephant brains are larger than humans But the human prefrontal cortex is proportionally largest in humans: -PFC is 25% of the cerebral cortex in humans -PFC is 15% in chimps Our evolved brain is the reason we have higher cognition: -Humans have the highest brain size to body size ratio -PFC is 7% in dogs
Disrupted Velocity
All children show same basic developmental trajectory: -Childhood phase of cortical thickening -Adolescent phase of cortical thinning However, speed of this process is altered. Acceleration of the course of typical development Pruning occurs sooner and faster Longitudinal study of 100 patients with Childhood-onset Schizophrenia (COS) Multiple assessments over time
Allostasis and Allostatic Load (McEwen and colleagues)
Allostasis: psychological and physiological adaptation in stressful situations (good consequence of stress) -Helps maintain homeostasis -Maintains "stability through change" Allostatic load: the physiological costs of chronic exposure to fluctuating or heightened neural or neuroendocrine response that results from repeated or chronic stress. (bad consequence of stress)
Characteristics of a Systems Approach
An appreciation that the nature of life (living beings) is dynamic (i.e. development is ongoing throughout life) Development is hierarchical Phenotypes can emerge from a complex and dynamic (ongoing) interplay of factors The "individual" constructs their phenotypes from an already existing developmental history Example: There is no preset hard-wired program for crawling in the brain. Instead, crawling is a self-organizing solution to a problem.
How can lab animals help us understand stress effects in humans?
Animal models provide the opportunity, usually not available in humans, for examination of stress effects at the cellular level
Lifecycle model of stress
Argues that stress has the highest impact on brain regions that are developing at the time of stress exposure Stress can have programming effects and/or interaction effects with the environment In childhood and adolescence, the hippocampus is most vulnerable to the effects of stress Amygdala, Frontal Cortex, Hippocampus are the most susceptible in general.
When do SES differences begin to emerge?
At 18 months, there is a statistically significant difference in child-directed speech, but it is different. At 24 months, the difference widens for child-directed speech. Starts in childhood! As early as 18 months (or when they start talking)!
Candidate Mechanisms: Cognitive Stimulation
Availability of books, computers, trips, parental communication Interventions that enhance cognitive stimulation to boost school readiness and promote academic achievement
Phase 5
Begins following puberty through adult years Experience-dependent (and expectant?) mechanisms Loss of synapses around puberty may be related to hormonal changes.
What are the structural brain changes that are induced by bilingualism in children and adults?
Bilinguals have greater Gray Matter Density in the inferior parietal lobule than monolinguals Higher GM Density varies by how long the person has been bilingual Higher GM Density in people more proficient in the second language Higher GM Density in people who acquired the second language earlier in life Why the inferior parietal lobule? -It has been implicated in vocabulary knowledge Research comparing white matter tracts in monolinguals and bilinguals in mid-adults is less consistent than the GM density research -Some of it finds greater white matter integrity in monolinguals and other research finds greater white matter integrity in bilinguals -Differences probably based on exact white matter tracts that were examined and age of participants
NIMH Study shows that gray matter follows inverted-U shaped trajectory
Boys 10% larger overall Girls peak earlier than boys
Japanese speakers: fMRI Study
Brain activation in Japanese speakers Left posterior superior temporal gyrus responds specifically to phonetic change in one's native language Neural sensitivity with /da/-/ga/ stimuli common to Japanese and English, but not one with /ra/-/la/ stimuli present in English only.
Summary
Can use cognitive neuroscience tools to study gene-environment interactions in humans Genetic variations lead to phenotypic variations There is NOT a 1:1 correspondence between genes and behavior -Gene X will not specifically affect behavior Y -Multiple genes and gene-environment interactions influence specific behaviors Genes can be protective Environment can be protective
Ectoderm
Central Nervous System (Brain and Spinal Cord) Peripheral Nervous System Skin Hair Nails
First Trimester (Embryonic Period)
Certain hormones and organs are only produced during pregnancy -Hormone that maintains uterine lining (used for pregnancy tests) -Placenta: nutrients pass from mother to embryo ===Allows teratogens (viruses, medicine, drugs) to pass through ===Embryo is particularly vulnerable during weeks 3-9 to exposure of teratogens
How does this happen?
Changes in gene expression. How much contact the mom rodents have with their pups changes the expression of the genes in the brain. High licking and grooming increases GR expression in pups. When the body has a stress response, there are more GR receptors for the stress hormones to bind to (this is good). It means the stress hormones have somewhere to lock onto. In contrast to lower GR expression, the stress hormones float around in circulation. Stress > Alters parenting quality > Alters developmental outcomes
Synapses permit the passage of an electrical or chemical signal from one neuron to another
Chemical synpase (neurotransmitter) Presynpatic neuron: "sender neuron" Postsynaptic neuron: "receiver neuron" Synaptogenesis happens throughout life as a response to adapt to new situations. If there is no postsynaptic neuron, one gets created.
Phase 4
Childhood years (varies by region; visual cortex: 2-3 years; PFC: through adolescence) Experience-expectant and experience-dependent mechanisms Extended period of synaptic fine-tuning.
Family income is associated with children's brain structure 2
Children's scores on tests measuring cognitive skills, such as reading and memory ability, also declined with parental income The results do not imply that a child's future cognitive or brain development is predetermined by socioeconomic circumstances Nor do these data explain the cause of the neural and cognitive differences.
Children showed a greater interference effect
Children: 44.4 msec difference (44.4 msec faster for neutral) Adults: 21.9 msec difference (21.9 msec faster for neutral) More activation in adults during interference suppression in the right PFC Greater activation in both children and adults associated with less susceptibility to interference (distraction)
Summary
Cognitive control requires engagement of prefrontal regions More mature cognitive control is associated with a shift in neural representation of cognition in the prefrontal cortex -Increased functional connectivity also supports increased cognitive control Children and teens show immature cognitive control (more susceptibility to interference and emotional context) Distracting emotional information can inhibit good cognitive control/behavioral regulation but it can also be beneficial.
Emergence
Coming into existence in a new form through ongoing processes.
Critical and Sensitive are windows for higher levels of learning. Anything you experience after critical window shuts, it makes it more difficult to learn that thing.
Critical period: More rigid. -A limited period of time when experience can influence brain development (usually in sensory and motor domains) -Particular input is expected Sensitive Period: More sensitive. -Heightened sensitivity to certain environmental stimuli -Not as rigidly tied to a specific age -(e.g. learning a new language) The terms "sensitive"/"critical" periods do not describe the mechanism by which this phenomenon occurs. Mechanism: the way something happens, the process by which change occurs.
Are the effects of stress "reversible"?
Decreased functional connectivity in session 1 (during stress) that is reversed in session 2 In an acute, discrete stressor, the effect of the stress returned to baseline in the post-test, providing evidence for reversibility
Stress in Adults: The Effects of Traumatic Stress
Decreased hippocampal volume Memory deficits Increased glucocorticoids Chicken or the egg? Examined brain morphometry and function Participants: healthy adults who were at different distances from Ground Zero Adults with closer proximity to the World Trade Center had lower gray matter volume
In rodents, effects of stress hormones on offspring of mothers exposed to stress during pregnancy
Decreased neuronal complexity (decreased spine density)
Glucocorticoids can be harmful if prenatal levels are too high or too low
Decreased number of necessary stress hormone receptors (low) Delayed maturation of neurons and glia (high)
Stress in Adults
Decreases neurogenesis Hippocampal volume loss Effects of stress on adult brain are reversible Chronic stress reduces neurogenesis in rodent brain (hippocampus) [BrdU is a marker for new cells] Most human adult studies have focused on proxies of stress to examine its effects on the brain -Low self-esteem -Mental disorders/psychopathology -Post Traumatic Stress Disorder -Childhood abuse Most generally find decreased hippocampal volume and elevated stress hormones.
How can typical developmental paths go awry?
Delayed shifts Disrupted velocity Deviant trajectories
Development as a Dynamic System (Linda Smith and Esther Thelen) How do we explain that brain development occurs?
Development is an emergent product of many decentralized and local interactions that occur in a specific time Development is self-organizing: -Systems generate novelty through their own activity
Summary
Development is the study of change Change occurs as a product of gene-environment interactions Development is an agent in the product Thelan emphasizes development as a dynamic system "Making something more from something less" Development is an emergent product -i.e. not laid out beforehand
Gene x Environment Influence Development
Development occurs because genetic information and the environment exert influence over it Both are influential throughout the lifespan, even prenatally
Summary
Developmental Plasticity -Building a new house -Experience-expectant processes produce a surplus of synapses which are pruned back by experience -Relatively irreversible -Very time sensitive -Abnormal input leads to abnormal neural pattern formation. Adult plasticity -Remodeling (adding-on) an existing house -Experience-dependent synapse formation in response to events -Sometimes reversible.
Is language "innate"?
Developmental path is universal Infant brain response to spoken speech is same as adult brain response
Greater teen activation in the ventral striatum (a reward-related region)
Difference between adolescent and adult brain activation
First Trimester (Fetal Period)
Differentiation of sex organs, guided by genetic information Both male and female embryos go through a bisexual stage, during which no sex-linked characteristics can be discerned. Both have a surfaces mass that becomes tests in males and eventually deteriorates in females. -In males, sperm ducts develop and female ducts dissolve. -In females, the fallopian tubes, uterus, and vagina develop Sex hormones direct male and female brains along slightly different paths -Amygdala, hippocampus, and hypothalamus in particular
Chromosomal Disorders
Down's Syndrome: Extra 21st chromosome Turner Syndrome: Lack of one X in Females Klinefelter syndrome: Extra X in males
Classic G x E interaction: Drosophila bristle number varies with changing temperatures
Each line represents a given genotype, and the slope of the line reflects the changing phenotype (bristle number) with changing temperature
Greater inferior frontal gyrus cortical thickness in bilinguals vs monolinguals
Early bilinguals acquired 2nd language by age 5 Late bilinguals acquired 2nd language by age 10
Studies in both animals and humans have show that the brain is particularly sensitive to stress during both early childhood and old age
Early childhood is amygdala/hippocampus most sensitive Adolescence-frontal cortex
Inner Cell Mass
Embryonic Stage -Endoderm -Mesoderm -Ectoderm (outer layer) Undifferentiated: final fate not yet determined Induction: process of transforming undifferentiated tissue
Enrichment effects neuronal morphology
Enriched environment Non-enriched environment has fewer dendrites
Prenatal Stress
Environmental Toxins Maternal Stress Deprivation of nutrients/protective prenatal environment Programming effects: when a stressor acts on the organism during a sensitive period, affecting the structure and function of the brain, leading to effects that persist throughout life
Stress in Adolescence
Evidence to suggest that the adolescent brain is more susceptible to stressors than in adulthood. Prolonged stress response in adolescent rats compared to adult rats
Social Causation Hypothesis
Experience (of poverty) leads to differences in brain and cognitive development Evidence: 1) cross-fostering studies (being adopted to a higher/lower SES bracket affects cognition) 2) negative effects of poverty are worse if poverty occurs earlier rather than later in childhood 3) some negative effects of low SES may be reversible (e.g. interventions)
Experience expectant vs dependent
Experience expectant: -Very early in life -"pruning" (removal) of excess synapses following experience-expectant events Experience dependent: -Later in development and adulthood -Generation of new synapses based on need.
Developmental Plasticity
Experience influences the basic architecture of the brain (i.e. how the brain is going to be organized) Alterations to the auditory and visual systems during development usually alters function (e.g. vision) Building a house from the ground up
Adult Plasticity
Experience influences the existing architecture of the brain (i.e. brain is reorganized to incorporate additions/deletions) Expertise and training influence brain function (e.g. somatosensory cortex is change in musicians) -Somatosensory cortex critical for finger movements Adding a room to an existing structure
Greenough et al proposed a new classification to replace "sensitive period"
Experience-expectant: -The organisms is EXPECTING input -Species have evolved neural mechanisms to take advantage of experiences that typically occur (e.g. visual input) to shape developing motor and sensory systems -Timing occurs at roughly the same time among individuals Experience-dependent: -Experience/input that is unique to the individual -Experience differs in timing among individuals
Facts that influence language-related brain changes
Experience-induced brain changes: -Can be found in all ages (children, adults, elderly) -Can occur rapidly with short-term (intensive) language learning or training -Are sensitive to age of acquisition and proficiency -Are sensitive to timing of input
Better cognitive control in high-delayers
False alarm: failure to inhibit response to "nogo" target More PFC activation in high delayers
Second Trimester
Fetus begins to explore his/her surroundings
Two types of genetic information
Gene pool (species-related characteristics) - Genetic information from the human species (e.g. patterns of motor behavior such as walking upright, brain size and body structure) Ancestry - Hair color, skin color, blood type, etc - Specific to each individual - Make up only 0.1% of all your DNA but account for all of the individual variability
What is G x E?
Gene-environment interaction (or genotype-environment interaction or G x E) is when two different genotypes respond to environmental variation in different ways.
1. Rate of Development
Genes help regulate the pace of maturation. Genes signal the onset of growth spurts, teeth, puberty, and menopause -Motor skills, intellectual capacity and timing of physical maturation are under strong genetic influence. -Interacts with environment to promote development
Summary
Genetic factors are critically involved in both trait characteristics and timing of development Each trimester of pregnancy is unique All organs develop along unique timescales Brain development begins right after conception and continues through mid-20s Genetic and environmental influences alter course of brain development Events and processes occur in a particular sequence and at particular times When a particular event occurs in development it can influence long-term outcomes.
Prenatal Development
Genetic factors guide the tempo of growth and the emergence of individual characteristics The psychosocial environment provides both resources for an challenges to healthy development
Genotype vs Phenotype
Genotype: genetic information about a trait Phenotype: the observed characteristics of the trait
Songbirds generate new neurons seasonally in the "song learning" area
HVC is the part of the brain that represents new songs. HVC grows and shrinks according to song learning (new neurons created every spring) BrdU= dye to label neurons. HVC shoots up in January to prepare to attract mates in the spring.
Deaf Individuals (Atypical language learning)
Hearing subjects (english) Deaf subjects (ASL) Both groups extensively recruit the left temporal lobe but deaf individuals also recruit the right hemisphere
Glucocorticoids are important for normal brain maturation
Help strengthen axons and dendrites; help cells survive.
Compared to people who were low-delayers at age 4, high delayers had the following as adults:
Higher -Sat Scores (210 points) -Income Lower -Friendship/relationship problems -Obesity -Criminal Behavior -Drug addiction
Bilingual cognitive advantage hypothesis
Hypothesis that bilingualism leads to advantages in -Cognitive control (better executive functions) -Conflict monitoring abilities (selective attention, inhibition of irrelevant information, task switching) Based on the idea that bilingual's have a lifelong experience of monitoring, switching between, and selecting among competing languages.
Experience-Expectant
If "expected" visual input is not received during the critical periods in development, alterations develop in: -Behavior (e.g. trouble with visual discrimination tasks) -Physiology (.e.g neurons only respond to stimuli they have been reared with) -Morphology (e.g. neurons make fewer and aberrant interconnections with other neurons)
Development of Axons and Dendrites
If neuron doesn't die, it develops axons and dendrites Purpose is to communicate with other neurons
Questions addressed by Bunge et al Does neural representation (i.e. brain activity) for cognitive control change across development? -Do children and adults differ in their brain activity when performing interference suppression and response inhibition tasks?
In the fMRI, participants performed a task that intermixed the go-no/go task and flanker (arrows) task Accuracy: adults more accurate on No-go and Incongruent trials
Incentive improves performance for teens but not for adults
In this case, being more susceptible (receptive) to external information is beneficial. The reason teens are more susceptible than adults to incentives is because their brain is more sensitive to rewards.
Why are social factors critical for vocal learning?
Increased Attention Increased Arousal Feedback During vocal learning, social interactions help integrate necessary cognitive processes -Social factors are the glue for attention, arousal and feedback -Direct infants to what they should attend to
White Matter
Increases speed of transmission Greater integration of disparate brain regions Modulates timing/synchrony Linear Development -VS inverted U shape
National Institute of Mental Health Longitudinal study of brain structure
Individuals aged 5-25 years Multiple scans (every ~2 years) ~2500 research participants ~7000 scans 50% clinical populations
Interpreter Academy Students
Interpreter academy of the Swedish military. Starting from scratch, the interpreters learn a new language to fluency within 10 months. The extreme learning rate requires the acquisition of 300 to 500 new words each week
Is language development/learning an experience-expectant or experience-dependent process?
It's both: the neural system is expecting language input but neural commitment is dependent on the native language of the rearing environment in which you grow up.
Categorical Perception
Learn not to hear the difference between two sounds in a second language.
How does the brain deal with bi(multi)lingualism?
Learning a second language changes the brain Bilingual brain is a highly adaptive and flexible system
Does prenatal stress influence behavior in adulthood?
Learning impairments -Prenatally stressed rats were tested on a spatial learning task at 6, 15, and 21 months of age. Prenatal stress doesn't have to have immediate effects. Evidence for delayed effects. Increased responsiveness to drugs of abuse -Prenatally stressed rats showed increased locomotor activity in response to amphetamine and greater self-administration of amphetamine. Increased depression an anxiety-related symptoms
Immature Cognitive Control
Limited ability to control behavior in the face of distraction, emotion, challenge etc. Ability to regulate behavior improves throughout childhood Functional development of the PFC supports maturation of cognitive control
Delayed Shifts Example: ADHD
Longitudinal study of ADHD Most common neurodevelopmental disorder in the U.S. (5-10% prevalence rate in school-aged children) -223 children were assessed repeatedly (at least twice) over several years -Age range: 4-20 years -Examined Marker for Cortical Maturation (peak cortical thickness) ADHD: By age 10, ~65% (45% in PFC) of regions reached cortical maturation Typical: By age 10, ~90% (95% in PFC) of regions reached cortical maturation No group differences in primary sensory and motor regions Suggesting that ADHD is not simply a deviation in cortical maturation but a delay in specific regions These findings suggest that the neuroanatomic signature of ADHD is dynamic and not the disorder is characterized by a shift along the age axis.
Rate of Gray Matter Loss
Loss rate was faster in kids with schizophrenia
Ocular Dominance Columns: Normal Development
Lots of overlap at birth. As an adult, they become distinct columns. Column shrinks as neurons die off/become less integrated. Nondeprived eye makes up for the difference.
SES has effects on cognition, academic achievement and mental health
Low SES associated with higher rates of -Worse health -Impaired psychological well-being -Impaired cognitive development -Worse emotional development -Academic obstacles Greater poverty earlier in life is worse than later in life because thats when neural development happens. If you build a house on a bad foundation, it won't develop correctly.
Candidate Mechanisms: Prenatal Influence
Low ses = high stress, infection rates, low nutrition = high stress hormones = impairs fetal growth, trigger premature birth
Candidate Mechanisms: Prenatal Care
Low ses= greater irritability and depressed/anxious moods in parents = harsher and inconsistent discipline; reduced verbal communication=behavioral and emotional problems in the child High quality parent-child relationships are associated with resilience and better outcomes among children who live in stressful, low SES environments
Postnatal Stress
Maternal (Parental) Care -Abuse or neglect Maternal Separation Better maternal care reduces stress response in pups
What does daily stress do to adolescent cognition?
Middle and late adolescence reported their daily stress during a two-week study They visited the lab to perform cognitive tasks on a high-stress and a low-stress visit Teens made riskier choices on high-stress vs low-stress days Teens are worse at regulating their behavior Teens engage the PFC less on high-stress days during a self-regulation task Under high stress, teens who took more risks had less PFC activation
How does A-not-B relate to Dynamic Systems Theory?
Multicausality- multiple causes for error. Knowledge about correct location is emergent: -It emerges from multiple components of the task and previous history of the infant (e.g. what happened right before) -Infants self-organize based on what information is available to them and their ability to hold that information online.
Summary
Multiple factors mediate the relationship between SES and brain and cognitive development Cognitive stimulation best predicts child's cognitive development Parental care best predicts child's emotional development Effects in some domains are reversible
Myelination
Myelin is a fatty protein that wraps itself around an axon as a form of insulation Increases communication speed between neurons
Are the plastic processes that operate during development the same as those that operate in adulthood?
NO! -Local environment is vastly different -Wiring vs Rewiring the brain
Experience-Dependent Processes
Neural plasticity based on changing environment Why? -A species cannot count on certain important experiences to occur at particular points in the lifespan -Experience unique to individual's own environment How can we learn about these processes? -Change the rearing environment.
Environmental input can change phenotype
Neural tube defects associated with deficiency in folic acid (spina bifida) in 1992, the U.S. Public Health Service recommended that women of childbearing age increase consumption of the vitamin folic acid to reduce spina bifida and anencephalus. In 1996, the U.S. F.D.A. authorized that all enriched cereal grain prodcuts be fortified with folic acid.
National Institute of Mental Health study of brain structure in clinical populations
Neurodevelopmental disorders are not stable Rather, they change over time -Atypical development has distinct developmental trajectories (paths) ===I.e., there are multiple ways a neurodevelopmental disorder can rise.
Proliferation
Neurogenesis: birth of new neurons 100,000+ per minute Occurs by process of cell division Some continue to divide, others stop dividing; migrate to final destination
How does neuroplasticity occur?
Neurogenesis: the birth of new neurons. Does not generally occur after you are born. Synaptogenesis: the birth of new synpases. Happens though our lifetime, all the time.
Neuronal Migration (6-24 prenatal weeks)
Neurons are born in a different place from where they end up. Active Method: Neurons move in an inside-out direction to form six cortical layers
How does experience change the brain?
Neuroplasticity (aka brain plasticity/cortical plasticity): -Changes that occur in the neural pathways or synapses of the brain as a result of experience -Refers to how the brain adapts to different types of experience or input
Stress effects on the brain: chicken or egg?
Neurotoxicity hypothesis: excess exposure to stress hormones reduces neuronal integrity and strength Vulnerability hypothesis: effects of stress are result of interaction of stressors and pre-existing vulnerabilities (e.g. genetics) to stress Not mutually exclusive
Inside-Out Migration
New neurons come and stack on the old ones. (blue stays bottom layer)
These type of studies suggest:
Newborn brain is prepared and organized to learn language Newborn brain and adult brain represents language similarly
Deviant Trajectories
No resemblance to typical development (flat line)
Phases 1 and 2
Occur prenatally (phase 1: 2 months gestation; Phase 2: 3-4 months gestation) Dominated by genetic mechanisms Experience-Independent -Process can be influenced by genetic mutations, infections, toxins -Cannot (easily) be influenced by experience from the external world.
Phase 3
Occurs right before birth, during birth and early postnatal months (8 months gestation-1 year postnatally) Experience-expectant and experience-dependent mechanisms Experience-expectant -Input from the external world are necessary for proper final adjustment Experience-Dependent -Organization of synaptic contacts related to the experience of each individual.
Monocular Deprivation
One eye is sutured shut during the sensitive period Deprived eye becomes functionally disconnected from visual cortex neurons: -"Use it or lose it" Open eye becomes more functionally integrated with both sides of visual cortex.
Evidence for better cognitive control in adult bilinguals
Only bilinguals perform better in the second session Bilinguals need less brain activation to exert effective cognitive control than monolinguals
Multicausality
Organisms are complex systems composed of many individual elements No executive agent: No single element has causal priority (hence: Multicausality) Self-organization: Developmental change occurs because of relationships between organic components of the system. Development is a series of evolving and dissolving patterns of stability (changing) - rather than an "inevitable march" towards maturity.
Cognitive control is susceptible to emotional interference
Overall, kids have worse cognitive control when faced with emotional distractions (cognitive control is more disrupted by emotional information) Kids and teens perform worse during negative emotion trials However, emotional susceptibility can be adaptive.
Synaptogenesis
Overproduction, eliminating, and strengthening.
Outside-in Migration
Passive: neurons are displace by new neurons Thalamus, hypothalamus, spinal cord, hippocampus.
What is the role of the physical home environment?
Physical home environments influence opportunities for enrichment, development of healthy habits, and social interactions among members of the household. Youth from lower SES are more likely to experience homes characterized by: -a lack of cleanliness -high levels of clutter -potentially hazardous interiors and exteriors, crowding -excessive noise -poorly lit spaces
What is stress?
Physiological, biological, and emotional reactions to particular events. It's the body's way of rising to a challenge.
An example of multicausality: Object Permanence
Piaget: 'when do infants acquire the concept of object permanence?' Object Permanence: the understanding that objects continue to exist even when they cannot be seen, heard, or touched. A-not-B task as task to test object permanence Multicausality to explain A-not-B error
Largest SES effects are on language processing and vocabulary
Positive correlation between language skill and SES
The brain develops from the back to the front
Prefrontal cortex (PFC) is the last brain region to develop PFC is the last brain region to undergo synaptic pruning
What are the ways in which SES influences brain development?
Prenatal factors Parental care Cognitive stimulation Other factors? Brain development: -Childhood SES affects some neurocognitive systems more than others. Cognition, academic achievement, mental health
Experience-dependent neuroplasticity
Production of new synapses through activity-dependent mechanisms (LTP) experience expectant= pruning away
Summary of Visual Deprivation experiments
Prove that the organism expects visual input If one eye does not receive expected input by a certain age (developmental stage), the other eye (and related neural processes) compensates.
How do neurons know where to go?
Radial Glial cells provide guidance -Glia are supporting (helper) cells Molecular signals provide "stopping" signal
Monoamine oxidase A (MAOA)
Removes DA, NE, 5-HT from the synapse MAOA deficiencies associated with aggression, antisocial behavior, hyperreactivity to threat Low MAOA activity (excess DA, 5-HT levels) High MAOA activity (normal DA, 5-HT levels) Evidence that a functional polymorphism (allelic variant) in MAOA moderates the impact of childhood maltreatment on the development of antisocial behavior Genes may have a protective role (rather than a vulnerability)
Maternal Separation Influences offspring behavior
Repeated maternal separation in infant monkeys increases anxiety
Delayed Shifts
Same general shape of healthy developmental path Curve is shifted to the right Peak values are reached at a later age in the pathological group (~age 11.5) compared to the healthy group (~age 10) This suggests that the disorder is characterized by a delay in the pattern of typical development. Note: these are hypothetical data representing cortical thickness
What is cognition?
Self-regulation Cognitive control Reasoning abilities Attention Memory Decision-making Abstract thought Morality Religion Humor Friendships Language
Why do we need a prefrontal cortex?
Serves an integrative function to link sensory, motor and higher cognitive regions Guides relevant neural activation and behavior based on inputs from the environment Cognitive Control: -Goal-driven behavior in the face of distraction (e.g. challenge, thoughts, temptation, emotion)
Third Trimester
Significant maturation of the nervous system Sensitive to musical sounds, changes in speech sounds, stories
2. Individual Traits
Sociability, inhibition, and neuroticism have strong genetic components. This also interacts with environment -I.e., a parent who is temperamentally sociable is more likely to have a sociable child, which may be due to genetics and/or by modeling the parents social behavior. -Healthy teeth -Attractive people
3. Abnormal Development
Spontaneous abortion (15-20% of pregnancies) Birth Defects -Genetic Disorders: linked to specific genes (e.g. Albinism, sickle cell anemia, color blindness, hemophelia) -Chromosomal Disorders (e.g. Down syndrome, Turner's syndrome)
Summary
Stress exerts effects on development via stress hormones Stress effects are additive -Development is hierarchical Some stress is good -Inverted-U shape for optimal amount of stress Stress is adaptive Timing of stressor is critically involved in brain development outcome
How does maternal stress "get into" the developing fetus?
Stress to mom increases glucocorticoid secretion, which then pass through the placenta Glucocorticoids have significant effects on brain organization
Stress in the brain
Stressors activate the hypothalamus-pituitary-adrenal (HPA) axis 1. Amygdala triggers stress response 2. Hypothalamus releases CRH and AVP 3. Pituitary releases ACTH 4. Adrenal gland releases GCs (cortisol in humans) 5. Once stressor has passed, feedback loops (hippocampus) are supposed to "turn off" the stress response. Stress becomes maladaptive when stress response does not diminish and there are too many stress hormones flooding the brain/body
Stress is not always bad
Stressors can serve to mobilize an organism Stress is useful 'Fight or flight' response
Summary of HOME study
Study demonstrates that adolescents' physical home environment (PHYS) is a significant factor in explaining how socioeconomic disparities are represented in the adolescent brain and relate to cognitive achievement. This study differs from the majority of neuroscientific studies of SES, which have relied on just one (income) or two (income/education) indices of SES rather than more proximal factors directly impacting daily experience, and were conducted in infants or children
Brain changes in adult language learners
Study examining individuals studying a foreign language Received MRI immediately before and after the interpreters first 3 months of language studies
Heightened stress response in human adolescents
Teens have larger stress response following a public speaking challenge than younger kids Some plausible explanations: -Interaction of stress hormones with pubertal hormones -Adaptive to be more responsive to the environment during this developmental period -Stress interacts with changing emotional systems during adolescence
Sensitive period for language
The ability to acquire language changes over time Raised in isolation from ~20 months old to ~12 years After extensive language training, learned to speak at 2-year-old level *Genie* Why does the ability to acquire language change over time? Native language neural commitment (NLNC) Hypothesis: initial coding of native language eventually interferes with the learning of new languages -"sensitive period" for language acquisition
Family income is associated with children's brain structure
The association between parent education and cortical surface area was mapped to visualize regional specificity (language and decision-making areas) The brains of children from the lowest income bracket - less than US$25,000 - had up to 6% less surface area than did those of children from families making more than US $150,000
Making the error vanish by changing:
The attention-grabbing properties of the covers of the well The attention-grabbing properties of the hiding event The delay The past activity of the infant The position of the infant during hiding event of B
Experience-expectant processes differ from later developmental processes
The degree to which they are age-dependent -Must occur early in life And irreversible -Neurons become committed to a particular pattern of organization
Why is it adaptive for an organism to rely on expected input?
The environment is already there Take advantage of what should be there anyway -Genes sketch an outline an environment fills in the details ===There are "eye" genes ===There aren't "visual input" genes -Fine-tuning occurs by eliminating unnecessary synapses/strengthening necessary synapses.
Experience-expectant information storage
The organism is expecting some sort of experience -Sensory information -For example, the organism expects to receive visual information
How does multicausality relate to brain development?
There are multiple causes for acquisition of a new skill, for development. Development is finding a solution to a problem that works within your constraints.
Language is learned. Social influence on language learning
There is a strong learning component to language: -Infants learn the lagnuage they were born into (i.e. and not some 'generic' universal language) Social deprivation has devastating effects on language learning Social feedback modulates language learning
Why is this classification better?
This classification considers: -The evolutionary origins of a process -Its adaptive value for the individual -The required timing for the process -The organism's active role in obtaining appropriate experience for itself
Role of Genotype in the Cycle of Violence in Maltreated Children Caspi study
This study examined the contribution of Gene x Environment Interactions on a complex behavioral phenotype Are you doomed to have antisocial personality disorder if you have a particular allele of a gene? or if you grow up in a particular environment? Can genes be protective? Can the environment be protective?
Bilingualism in the elderly
Tracts with greater WM integrity in bilinguals vs monolinguals
Expected experience participates in the organization of a detailed neural pattern
Typical Pattern of experience = Typical Neural organization Atypical Pattern of Experience = Atypical Neural organization. Reason: nerve cells of visually deprived animals make fewer connections and altered patterns.
Neurulation (18-24 prenatal days)
Undifferentiated tissue becomes the brain and spinal cord. Neural plate to neural tube. "Making something more from something less"
What is unique about speech and language?
Unique to humans Humans learn it with remarkable speed Strong social component to learn Reduction in ability with development (i.e. you get worse at learning new languages as you age) Language is a relatively evolutionarily new invention How does the brain solve the problem of dealing with a construct that previous, related species, have not faced?
Norm of reaction
Variation in environment will lead to variation in behavior. 3rd dimension is genetics Genotype, Phenotype, and Environment can all be affected differently. No one genotype is "best" for all environments
Hypothesis
Variations in MAOA alleles lead to variations in antisocial behavior Antisocial behavior can be predicted by an interaction between genes and environment (MAOA and maltreatment)
Evidence from Rodents
Variations in maternal care (licking and grooming in rat pups) are associated with changes in neural systems that regulate behavior and stress reactivity More neurogenesis and less stress reactivity in pups with good maternal care
Increases in cortical thickness and hippocampal volume accompany foreign language acquisition
Word meaning selection Lexical retrieval, syntactic processing Acoustic and phonetic processing
More evidence for language is learned. Atypical language learning Can children who have lesions to "language regions" still learn language?
Yes Do much better in terms of language and speech than adults with equivalent damage.
Does prenatal stress influence behavior in adulthood?
Yes Stress experienced early in life will undoubtedly influence the individual later in life In humans, prenatal stress is linked to: -Lower birthweight -Preterm delivery -Increased stress response in offspring -Increased rates of mental health issues in offspring
Synaptogenesis
Your brain gets rid of synapses it does not need Critical event in the maturation of the neocortex 5 distinct waves of synaptogenesis Highly orchestrated
Long-term Potentiation (LTP):
long-lasting increase in signal transmission between two neurons
Inverted-U Relationship between stress and performance
low stress=boredom high stress= anxiety and unhappiness optimum= area of best performance.
