PSYC 101 Week 3

Brain Development and Executive Function

  • Neuron

    • basic unit of the brain

  • Cell body (grey matter)

  • Dendrites

  • Axon

  • Synapse

  • Our cerebral cortex makes us human

  • Brain development begins: neurogenesis

    • proliferation of neurons by cell division complete before birth

    • growth, migration, and differentiation continue after birth

  • Myelination (white matter)

    • for fast communication

  • Brain maturation

    • the bluer the image, the more mature area of the cortex


Synaptogenesis

  • Results in an overabundance of connections (children have ~50% more than adults)

  • Synaptic pruning: use it or lose it

  • Neural Darwinism


Experience- expectant Processes

  • Result from experiences that are universal to the species

  • Sensitive periods


Experience-dependent Processes

  • Result from experiences that are specific to the individual

  • Continues into adulthood (but more flexible during early life)

  • London Taxi drivers


Review: Developmental Processes

  • Neurogenesis (high season: prenatal through 1st year)

  • Synaptogenesis (high season: infancy - early childhood)

  • Synaptic Pruning (high season: early childhood - adulthood)


Flexibility and Brain Damage

  • The “worst” time for brain damage?

    • neurogenesis (prenatal through 1st year)

  • The “best” time for brain damage?

    • synaptogenesis (early childhood)

  • Synanptic proliferation and pruning: why bother?

  • Adults: spotlight attention

  • Babies: lantern attention

    • are babies more conscious than we are?

  • Childhood as a model for the effects of psychedelics

  • Adolescents seek diversion, new experiences, and strong emotions, sometimes putting their health at serious risk

  • How does brain structure develop?

    • baby brains are unique and different from adult brains in important and adaptive ways

    • a second period of flexibility occurs during adolescence.

    • the structure of the brain is the product of the complex interaction between nature and nurture (experience-expectant and experience-dependent)


Prefrontal Cortex

  • Late development, “executive function”

  • Facilitates working memory / learning strategies

  • Cognitive flexibility (switching) / planning

  • Inhibition

  • Go-No Go: Kitten or Puppy?

    • clap for kittens, don’t clap for puppies

  • Multi-dimensional card sort

  • Delay of gratification

    • the marshmallow task

    • self-control predicts SAT score

      • children who delayed longer at age 4, at 14 were

        • more academically competent

        • more socially competent

        • more verbally fluent, rational and attentive

        • better able to plan for the future

        • better able to deal with frustration and stress


Short term vs. long term

  • Almost always in conflict!

  • Saving for retirement vs. enjoying life now

  • Studying for tests vs. having fun in college

  • Staying on a diet vs. eating the things you like

  • Staying faithful working through conflict vs. moving on when things we fall apart

  • Waiting for payday to spend money vs. using a credit card

  • Promise and perils of “brain training”


Training Executive Function

  • Executive function in preschool

  • Learning to be students

  • Taking tuns

  • Sharing toys

  • Monitoring others

  • Planning activities

  • Remembering events

  • Practicing symbols

  • Following rules

  • Improving self-control outside the classroom

    • concentration exercises

    • sports and martial arts

    • some computer games


Sensation vs. Perception

  • Sensation

    • the low-level processing of basic information from the external world by sensory receptors (e.g. eyes, ear, skin, nose, tongue)

    • the output of our senses alone is not enough information to create an accurate perception of the world

  • Perception

    • the process of organizing and interpreting sensory information about the objects, events, and spatial layout

    • you don’t see things how they reallly are

    • the mind makes educated guesses (perceptual constancy)


How do Infants Perceive the World?

  • William James (1890)

    • the baby, assailed by eyes, ears, nose, skin, and entrails at once, feels it all as one great blooming, buzzing confusion

  • Jean Piaget (1930)

    • the [infant’s] world is a world of pictures, lacking in depth or constancy, permanence or identity which disappear or reappear capriciously

  • How do we know these views are true?

    • problems? infants can’t do much

    • eat/sleep/poop/cry

    • look around

    • prefer to look at interesting things over boring things

    • solution → use looking time!

    • THEORIES NOT SO RIGHT

  • Two methods

    • method 1

      • preferential looking

        • measure looking time to each side

        • problem? side preferences

        • calculate % of time spent looking at bullseye

      • visual preferences in infants: some displays and findings

      • infants can see but how well

      • visual acuity

        • no preference when stripes are too narrow to see

        • at each age, find smallest width at which infants show a preference for stripes over gray

        • acuity results   

          • the sharpness of visual acuity develops rapidly, approaching adults by 8 months; reaches full adult acuity by 3 - 6 years

      • color vision

        • preferential looking method? but infants don’t always have color preferences and different infants have different preferences/ won’t work

        • how can we find out if infants perceive colors?

          • key: make baby very bored

          • show them the same thing over and over until they are bored of it

          • so bored that they prefer anything else

    • method 2

      • habituation

        • visual habituation procedure

        • dishabituation

          • getting bored, now change something

        • continued habituation         

          • same old, same old

        • color vision

          • limitations in the early moths (0-3 months)

            • poorer in 1st month, highly saturated red at birth

            • 3 months and older - similar to adults


Depth Perception

  • Wimpy kid

    • newborn goats on a rock won’t step off

  • The visual cliff

    • as opposed to a real cliff

    • results: animals

      • all baby goats crossed the shallow side

      • no baby goats crossed the deep side

      • an inborn capacity to perceive/avoid visual drop-offs

  • Comparative development

    • test: human infant

    • results: human infants

      • human infants avoid the visual cliff

      • early depth perception

  • Innate depth perception?

    • it’s always nature and nurture together

      • truly perceive depth at birth

      • need post-birth visual + motor experience, lined up

      • and this a 6 moth old

  • Object perception

    • Possible cues include:

      • Color

      • Shape

      • Texture

      • Gaps

      • MOTION

        • e.g. common motion: if things move together they are likely part of the same object

Auditory Perception

  • Begins prenatally

  • Recall → study

  • Well-developed at birth

    • method: auditory localization

  • Attend to speech

    • infant directed speech or motherese posody

  • Many aspects adult-like by 6 mos

    • frequency range, intensity, localization, etc.

  • Babies love music


Intermodal Perception

  • In addition to perceiving things from our individual senses we come to appreciate relationships between percepts

    • intermodal mapping?

  • Molyneux’s problems


Two Hypotheses

  • You have to learn the correspondence between touch and vision

  • The ability to recognize things across modalities is inborn, or innate

  • A test

    • tactile familiarization:

      • 1 month olds were allowed to mouth (but not see) either a bumpy or a smooth pacifiier

    • visual test

      • shown two pictures, one of a smooth object and one of a bumpy object

    • preferential Looking

      • Infants looked longer at the picture matching how the pacifier felt    

      • Ability to detect correspondence between tactile and visual modality doesn’t need to be learned

    • hearing and movement?