Textbook Notes (362,790)
Canada (158,054)
Psychology (9,545)
PSYB65H3 (479)
Ted Petit (185)
Chapter 13

Chapter 13 Notes

8 Pages
Unlock Document

University of Toronto Scarborough
Ted Petit

Chapter 13: Neural Development and Developmental Disorders NEURALDEVELOPMENT Early Development Embryonic life 3 weeks after conception Neural plate forms from the ectoderm of the embryo it's a patch of cells on the dorsal surface of the embryo which eventually becomes the nervous system Cells in the neural plate are stem cells they are pluripotent meaning they have the potential to develop into different types of nervous system cells Neural plate starts to form a groove day 24 fuses to form the neural tube. Proliferation: Cells of the neural within ventricular zone starts dividing. Next, 3 bumos form on the anterior portion of the neural tube eventually forming the forebrain, midbrain, and hindbrain of the CNS. Cells start migrating following glia & once neurons migrate, they begin to grow axons & dendrites and differentiate into their final forms. Cell differentiation is essentially complete at birth. Problems with any phase of development can lead to significant abnormalities in the CNS. Brain is extrememly vulnerable during last 4 5 months but failures at any point can have a significant impact on the final form of the brain. Problems: can originate within neurons themselves, genetic/chromosomal abnormalities, or external factors. One common malformation = when neural tube fails to close or incomplete closure. Craniorachischisis: complete failure of the closure of the neural tube fatal Spina bifida: complete neural tube closure failure different subtypes mostly results in neurological difficulties that are associated with locomotion rather than cognitive difficulties syndrome has its primary effects on the spinal cord. Anencephaly: partial closure of the neural tube generally fatal. th 7 month Most neurons have migrated & have differentiated into their final forms but just the beginning of a long period of brain growth and change. Synaptogenesis & Dendritic Branching Neurons undergo long period of synaptogenesis & dendritic branching producing far more synapses & dendrites that are needed. Both continue to occur even after birth and sometimes well into adulthood. With time, dendrites become more complex. Birth to 2 yrs synapse formation enters a period of rapid growth. Soon after period of synapse reduction neural death is apoptic planned/programmed cell death critical feature of development. Synapses that do not make functional connections or that make incorrect connections are especially likely to die, leaving room for other synapses to sprout. Postnatal Development Emergence of behaviours such as sitiing, walking, or speaking correlated with extensive growth in cortical areas of the brain, which increases its volume by 4 times btwn birth & childhood. One way to study this relationship is to study the maturation of specific parts of the brain & observe whether or not certain behaviours become evident only when the brain reaches a certain level of maturation. CNS and the Environment Env't plays a huge role in CNS development. Plastic Change & Critical Periods Plastic change: the abilitiy of the CNS to alter itself in response to environmental stimuli. Critical Periods: There are critical periods of plastic change in which the environment can have a maximal effect on CNS. Duration and timing of these critical periods vary by species, but seems like human exhibit prolonged periods that often occur later in life after prenatal period. Shaping of the CNS during critical periods does not depend on random events in the environment. Plasticity occurs in response to specific experiences: Experience expectant plastictic changes Those CNS changes that are dependent on experience(s) during the critical period for specific synapses to develop as they should. Sensory cortex has these experience expectant critical periods Organism must experience sensory stimulation during the critical period to develop normally otherwise, sensory impairment. Experience-dependent plasticity: Idiosyncratic experiences that occur during critical periods that also affect brain development. Musical training in childhood has an affect on the increase in size of the auditory cortex later on in life. Until 4 yrs of age, cortical gray matter volumes increase Synaptogenesis and dendritic branching occur both prenatally & postnatally and are maximal during critical periods. Brain's ability to engage in plastic change is often reduced as we age, especially once the critical period has passed except for plastic changes related to learning which occurs throughout life. Although the factors underlying plastic change are not completely understood, it appears that neurotrophins (chemicals of neurons) and neurotransmitters play critical roles. Hypothesis that complex behaviours are associated with the myelination of cortical areas sensory and motor areas myelinate early on, therefore sensory and motor behaviours seem to emerge first. Parietal Lobe Development In comparison to the other lobes of the brain, relatively little is known about the development of parietal lobes. Inconsistent levels of development at birth; some parts of the parietal lobe are more mature than others. Babies 2-3 months large increases in glucose utilization in parietal lobes remain steady until about 2 to 3 yrs of age. Children under age 6 often unable to name or point to a finger that was just touched when they canot see their hands so although they can perceive touch, they have hard time localizing the point on their hands. 8-12 yrs adultlike levels of performance Parietal lobe is also a component of the dorsal visual stream visual stream involved in processing of spatial information & directing behaviours toward certain points in space & processing motion. To understand the mechanisms underlying the development of parietal lobes look at Williams Syndrome mild to moderate cognitive impairments sparing of verbal ability, frontal & temporal loves difficulties with tasks of visuospatial ability smaller brain volumes but reduction in brain size is not uniform throughout the CNS disproportionate reductions in parietal & occipital lobes. May be a result of missing gene on chromosome 7 Therefore, genes on chromosome 7 may underlie typical development of parietal, occipital and/or white matter in the CNS. Occipital Lobe Development Development of occipital lobe is incomplete at birth. Newborns do not actually have underdeveloped visual systems it's quite sophisticated actually capable of distinguishing btwn 2D and 3D stimuli. Also have form perception. Become competent with complex stimuli such as faces quickly. 3 months optic tract and optic radiations become heavily myelinated resembling adult patterns. 6 weeks emergence of binocular vision Development of the visual cortex is critically dependent on the environmental experiences of the individual. Stabismus: Eyes are misaligned problems with depth perception Those who get treatment for this after critical period often continue to have impaired depth perception st Critical period for binocular vision - 1 few months of life 1-3 yrs. More complex visual tasks longer to develop. Simple face & emotion recognition is performed at adult levels by children btwn the ages of 6 and 8 yrs. Complex tasks requiring participation of the frontal lobes may not develop until the teens. Temporal Lobe Development Develompment of temporal love appears to depemd on the specific structures and the function that is being studied. Development of speech production and comprehension is the result of the cooperation and development of the frontal and temporal lobes Develompment of linguistic competence involv
More Less

Related notes for PSYB65H3

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.