What is Critical Period A critical period is a phase during which the brain cell connections are more plastic and receptive to the influence of a certain kind of life experience. These connections, called synapses, can form or strengthen more easily during this period.
What does the phrase critical period refer to?
More specifically, the "Critical Period" refers to the period of time following the end of the American Revolutionary War in 1783 to the inauguration of George Washington as President in 1789. During this time, the newly independent former colonies were beset with a wide array of foreign and domestic problems.
What is the difference between critical period and sensitive period?
What is the difference between a critical period and a sensitive period? Sensitive periods generally refer to a limited time window in development during which the effects of experience on the brain are unusually strong, whereas a critical period is defined as a special class of sensitive periods where behaviors and their neural substrates do not develop normally if appropriate stimulation
What is the definition of critical period?
In general, a critical period is a limited time in which an event can occur, usually to result in some kind of transformation. In developmental psychology and developmental biology, a critical period is a phase in the life span during which an organism has heightened sensitivity to exogenous stimuli that are compulsory for the development of a particular skill.
What is an example of a sensitive period?
An example of a sensitive period occurs in vision development. Infants are born with the basic ability to see (unless their vision is impaired by prenatal damage or genetic defects), but a newborn’s vision is not as good as the vision of an 8-month-old. Likewise, what is the difference between a critical period and a sensitive period?
What is a critical period of development?
Critical period is an ethological term which refers to a fixed and crucial time during the early development of an organism when it is able to learn things which are essential to survival. These influences impact the development of processes such as hearing and vision, social bonding, and language learning.
What is a critical period quizlet?
What is a critical period? A critical period is a specific period in development during which an organism is most vulnerable to the deprivation or absence of certain environmental stimuli or experiences.
What does critical periods mean in psychology?
1. an early stage in life when an organism is especially open to specific learning, emotional, or socializing experiences that occur as part of normal development and will not recur at a later stage.
What happens during the critical period?
What is the critical period? Also known as the sensitive period, the critical period is a time during early postnatal life when the development and maturation of functional properties of the brain, its 'plasticity', is strongly dependent on experience or environmental influences.
What is the critical period and what is it meant to explain?
The critical period hypothesis (CPH) states that the first few years of life constitute the time during which language develops readily and after which (sometime between age 5 and puberty) language acquisition is much more difficult and ultimately less successful.
Why was it called the critical period?
The "Critical Period" of American history—the years between the end of the American Revolution in 1783 and the ratification of the U.S. Constitution in 1789—was either the best of times or the worst of times.
What is the role of the critical period in imprinting quizlet?
What are critical periods and what does imprinting refer to? Imprinting is the process by which certain animals form attachments during a critical period very early in life. The reflex that causes an organism to respond immediately to a change in its environment.
What is a critical period in early brain development?
Children's brains develop in spurts called critical periods. The first occurs around age 2, with a second one occurring during adolescence. At the start of these periods, the number of connections (synapses) between brain cells (neurons) doubles. Two-year-olds have twice as many synapses as adults.
What is a critical period in adolescence?
3. Critical periods of cortical development. Critical periods are specific windows during development when both genetic driven processes and environmental processes, e.g. nature and nurture, interact to establish functional characteristics.
What is a critical item quizlet?
critical items. -all invasive instruments. -items that enter a sterile area of the body or the vascular system; condition at time of use (sterile) -surgical instruments, IV catheters, implanted devices, -items can be purchased sterile, or sterilzed.
What is the critical period Apush?
More specifically, the "Critical Period" refers to the period of time following the end of the American Revolutionary War in 1783 to the inauguration of George Washington as President in 1789. During this time, the newly independent former colonies were beset with a wide array of foreign and domestic problems.
What is the difference between a critical period and a sensitive period quizlet?
What is the difference between a critical period and a sensitive period of development? A critical period is a time when something must occur to ensure normal development, while a sensitive period is a time when a particular development is most likely but doesn't have to occur at that time.
How does GAD65 affect the eye?
Both GAD65 KO mice (at any age) as well as immature wild-type animals just after eye opening (around postnatal day P12 in mice) exhibit weak GABA release and no loss of visual responsiveness to an eye deprived of vision. However, plasticity can be rapidly “switched on” by just 2 days of local diazepam infusion into V1 ( Iwai et al., 2003 ). This represents the first direct control over critical period timing in any system, and is surprisingly dictated by the late maturation of inhibitory function. Unless a favorable E–I balance is achieved, plastic changes are not engaged. Recently, this principle has been extended to the cerebellum, where elimination of excessive climbing fiber inputs onto Purkinje cells during an early critical period is regulated by GABA levels ( Nakayama et al., 2012 ).
What is the critical period in the visual cortex?
Perhaps the best-studied model of a critical period is the enduring loss of responsiveness in primary visual cortex (V1) to an eye deprived of vision. The behavioral consequence, amblyopia (poor visual acuity), afflicts 2–5% of the human population and remains without a known cure in adulthood ( Holmes and Clarke, 2006 ). From the initial discovery by Hubel and Wiesel 50 years ago, a picture has emerged that inputs from the two eyes compete with each other when they first converge in V1 onto individual neurons ( Wiesel and Hubel, 1963 ). With the advent of gene targeting in mice, it has become possible to directly manipulate the factors which may mediate such functional and structural rewiring in response to imbalanced sensory experience.
How does social context affect plasticity?
Social context may provide information that affects plasticity of traits in different ways during different critical periods, and together these will contribute to an integrated set of phenotypic traits that may be employed in a particular set of conditions.
Why are critical periods important?
Such periods are needed to establish an optimal neural representation of the surrounding environment to guide future action. Given the extraordinary biological resources that must be devoted to rewiring neural circuitry, concentrating the construction of accurate, immutable maps early in life for use throughout adulthood may be an efficient strategy. However, this poses limitations on future revisions to the circuitry. Recent cellular and molecular insights indicate that biological mechanisms are expressed to ensure that adaptive changes are preferentially set in place early in life while leaving the door open for lifelong plasticity.
What is the role of miRNA in ocular dominance?
miRNAs are small non-coding RNAs that regulate post-transcriptional gene expression. Visual experience induces histone mark modifications at CRE loci close to the miR-132 coding sequence ( Tognini et al., 2011 ). Such modifications may underlie the developmental upregulation of miR-132 that occurs after eye opening and persists throughout the critical period. Manipulating miR-132 in vivo, by either increasing levels with a double-stranded mimic ( Tognini et al., 2011) or decreasing them with a competitive inhibitor (sponge)-expressing lentivirus that sequesters endogenous miR-132 ( Mellios et al., 2011 ), completely blocks ocular dominance plasticity during the critical period. miR-132 elevates the percentage of mushroom/stubby spines, suggesting that it may play a role in the structural modifications that occur during critical periods.
What is the critical period of the brain?
In humans, critical periods are extended over years and there are different critical periods for different brain functions (for example binocular vision or language acquisition) and unless a certain function is learned during this period, the function will remain poor. The well-known classic experiments by Hubel and Wiesel showed how early sensory deprivation dramatically affects anatomy and functional organization of the visual cortex. These authors reported that occluding one eye (monocular deprivation) early in development led to a severe reduction in the number of visual cortical cells responding to that eye, with a very strong increment in the number of neurons activated by the open eye. They termed this the critical period during which synaptic connections in the primary visual cortex are modified by visual experience. The critical period shown by Wiesel and Hubel (1963) has remarkably influenced not only biologists but also psychologists, philosophers, physicians, politicy makers, parents, and educators. In fact, this sensitive period is also considered present in humans, involving language, music, sport, and even sociability. The brain continues to develop throughout infancy, childhood, and adolescence and psychologists assert that, through the same periods, one acquires increasingly higher mental functions. During growth, the brain accumulates information about the external world in order to build an internal world in the temporo-parietal association cortex. In thinking, the frontal association cortex exerts its executive function on the internal world to manipulate thought models such as images, ideas, and concepts to simulate what could happen in the external world. In fact we acquire knowledge and new skills over our entire lives; it is likely that there are differently timed sensitive periods for acquiring different types of knowledge and skills such as literacy, numeracy, music, art, and physical education. A new field of research, called “nurturing the brain,” is expected to provide accurate knowledge about sensitive periods, which will help formulate an efficient learning timetable for curricula in nurseries and schools ( Hensch, 2004; Ito, 2004; Konishi, 2004 ).
What are the phases of plasticity?
Thus, three phases of plasticity define the critical period: (1) pre-critical period: the initial formation ...
How does critical period closure work?
Critical period closure has been shown to be modulated by the maturation of inhibitory circuits, mediated by the formation of perineuronal nets around inhibitory neurons. Perineuronal nets (PNNs) are structures in the extracellular matrix formed by chondroitin sulfate proteoglycans, hyaluronan, and link proteins. These structures envelop the soma of inhibitory neurons in the central nervous system, appearing with age to stabilize mature circuits. PNN development coincides with the closure of critical periods, and both PNN formation and critical period timing is delayed in dark-rearing. For example, PNN digestion by ABC chondroitinase in rats leads to a shift in ocular dominance upon monocular deprivation, which is normally restricted to its critical period much earlier in development.
Why are PNNs negatively charged?
Additionally, PNNs are negatively charged, which is theorized to create a cation-rich environment around cells, potentially leading to an increased firing rate of inhibitory neurons, thereby allowing for increased inhibition after the formation of PNNs and helping to close the critical period.
What is a weak critical period?
'sensitive' periods) — defining 'weak critical periods' / 'sensitive periods' as more extended periods, after which learning is still possible. Other researchers consider these the same phenomenon.
Why is language important in the CPH?
According to Pinker, language must be viewed as a concept rather than a specific language because the sounds, grammar, meaning, vocabulary, and social norms play an important role in the acquisition of language. Physiological changes in the brain are also conceivable causes for the terminus of the critical period for language acquisition. As language acquisition is crucial during this phase, similarly infant-parent attachment is crucial for social development of the infant. An infant learns to trust and feel safe with the parent, but there are cases in which the infant might be staying at an orphanage where it does not receive the same attachment with their caregiver. Research shows that infants who were unable to develop this attachment had major difficulty in keeping close relationships, and had maladaptive behaviors with adopted parents.
How does PSA affect PV cells?
PSA acts, in part, by preventing Otx2 interaction with PV cells. Soon after the opening of the critical period, PSA levels decrease, allowing PV cell maturation by activating inhibitory GABAa receptors that facilitate inhibitory circuit remodeling.
What happens if an organism does not receive the appropriate stimulus during this critical period?
If, for some reason, the organism does not receive the appropriate stimulus during this "critical period" to learn a given skill or trait, it may be difficult, ultimately less successful, or even impossible, to develop certain associated functions later in life.
Why do adults have more permanent language impairment than children?
Other evidence comes from neuropsychology where it is known that adults well beyond the critical period are more likely to suffer permanent language impairment from brain damage than are children, believed to be due to youthful resiliency of neural reorganization.
Overview
Linguistics
The critical period hypothesis (CPH) states that the first few years of life constitute the time during which language develops readily and after which (sometime between age 5 and puberty) language acquisition is much more difficult and ultimately less successful. The hypothesis that language is acquired during a critical period was first proposed by neurologists Wilder Penfield and Lamar Roberts in 1959 and popularized by linguist Eric Lenneberg in 1967. Lenneberg argued for the hyp…
Strong versus weak critical periods
Examples of strong critical periods include monocular deprivation, filial imprinting, monaural occlusion, and Prefrontal Synthesis acquisition. These traits cannot be acquired after the end of the critical period.
Examples of weak critical periods include phoneme tuning, grammar processing, articulation control, vocabulary acquisition, music training, auditory processing, sport training, and many othe…
Critical period mechanisms
Critical periods of plasticity occur in the prenatal brain and continue throughout childhood until adolescence and are very limited during adulthood. Two major factors influence the opening of critical periods: cellular events (i.e. changes in molecular landscape) and sensory experience (i.e. hearing sound, visual input, etc). Both need to coincide for the critical period to open properly. At the cellular level, critical periods are characterized by maturation of the inhibitory circuits. More …
Vision
In mammals, neurons in the brain that process vision actually develop after birth based on signals from the eyes. A landmark experiment by David H. Hubel and Torsten Wiesel (1963) showed that cats that had one eye sewn shut from birth to three months of age (monocular deprivation) only fully developed vision in the open eye. They showed that columns in the primary visual cortex receiving inputs from the other eye took over the areas that would normally receive input from th…
Imprinting
In psychology, imprinting is any type of rapid learning that occurs in a particular life stage. While this rapid learning is independent of the behavioral outcome, it also establishes it and can affect behavioral responses to different stimuli. Konrad Lorenz is well known for his classic studies of filial imprinting in graylag geese. From 1935 to 1938, he presented himself to a group of newly hatched gosling and took note of how he was instantly accepted, followed, and called to as if he …
Auditory processing
Many studies have supported a correlation between the type of auditory stimuli present in the early postnatal environment and the development on the topographical and structural development of the auditory system.
First reports on critical periods came from deaf children and animals that received a cochlear implant to restore hearing. Approximately at the same time, both an electroencephalographic stu…
Vestibular system
In our vestibular system, neurons are undeveloped at neuronal birth and mature during the critical period of the first 2-3 postnatal weeks. Hence, disruption of maturation during this period can cause changes in normal balance and movement through space. Animals with abnormal vestibular development tend to have irregular motor skills. Studies have consistently shown that animals with genetic vestibular deficiencies during this critical period have altered vestibular phe…