Neural Development Flashcards
Anencephaly
Failure of anterior neuropore to close
Spina bifida
Failure of posterior neuropore to close
Formation of Nervous System
Neural plate –> neural grove –> neural tube
4th Week
Primary Vesicles Forebrain (prosencephalon) Midbrain (mesencephalon) Hindbrain (rhombencephalon) Spinal Cord
5th Week
Secondary Vesicles
Forebrain (prosencephalon): Cerebral Hemispheres (telencephalon)
Thalamus & Hypothalamus (diencephalon)
Midbrain: (mesencephalon)
Hindbrain (rhombencephalon)
Spinal Cord
9th Month
Developed Brain
5th Month
Development of convolutions and sulci
6th Month
6 cortical layers developed
Teratogens
Agents capable of producing congenital abnormalities/interfering with development (infections, drugs, alcohol, environmental pollutant, radiation)
Pre-embryonic Period and Teratogens
Toxic agents interfere with all cells and results in death
Embryonic Period and Teratogens
As this is the time of tissue/organ differentiation, there is extreme sensitivity to teratogens and results in most severe functional and morphological deficits
Fetus and Teratogens
Little differentiation of tissues, less vulnerability to effects of teratogens; decreased cell size and number
Cell Proliferation
Development of new neurons
Cell Differentiation
Different types of neurons generated
Cell Migration
Neurons travel to ultimate location in CNS. Develops in an inside-out function with deeper layers produced first
Synaptogenesis
Creation of synapses with other neurons and the increase in the complexity of dendritic trees and number of dendritic spines
Selective Cells Death
As particular brain areas develop, they loss synapses in order to create circuits that are most effective/efficient
Myelination
Starts with most primitive areas and extends to more complex areas (spinal cord and brain stem first followed by midbraind and diencephalon and then telencephalon)
Prenatal Development
Primarily genetically-determined structural development; largely experience independent; sequence of development varies little among individuals
Postnatal Development
Dramatic increase in the role of experience in neural development; largely experience dependent
Reticular Activating System (Brain Stem)
Functioning at birth; serves vital life functions: breathing, heart rate, blood pressure, etc; role in alertness and consciousness
Diencephalon (Thalamus, Hypothalamus)
Functioning at birth; regulates internal environment/needs (hunger, sleep)
Limbic system (Amygdala, Hippocampus)
One of first to develop prenatally, but neurogenesis continues postnatally; close relationshipp between limbic and hypothalamus
Auditory System (Ear to Heschl’s gyrus)
Mechaical aspects reasonably mature at birth but not finished myelinating until 4
Visual System (Retina to Calcarine Fissure)
Fovea not finished developing until after birth and visual cortex develops rapidly during first year
Somatosensory System (Skin/muscle receptors to postcentral gyrus in parietal lobe)
Thermal, tactile and positional information (crucial for infant’s early exploration of the world by touch)
Pyramidal Motor System (Precentral gyrus in frontal lobe to muscles)
responsible for initiation of voluntary, rapid, precise control of extremities
Extrapyramidal Motor System (basal ganglia & cerebellum)
Responsible for alteration and adjustments in posture and coordination of movements initiated by the pyramidal system
Motor System
Locomotion and manipulation abilities develop throughout childhood with increased ability associated with integration of both motor systems
Association Areas
Cortical area where information from other areas is integrated
Commissural - Interhemipheric Pathways
Transmit refined information from one side of brain to the other - integrative function; late development postnatally
Critical Period
Developmental windows during which specific brain areas are developing and associated functions are emerging; genetically-determined periods of rapid neural development
Plasticity
Capacity of brain to adapt or change after environmental stimulation
Focal Injury
Circumscribed brain area is affected (hemispherectomy); better when younger
Diffuse Injury
Whole brain is effected (TBI, toxic exposure); better when older
