| Day | Event | Reference |
|---|---|---|
| 33 | posterior commissure appears | Ashwell et al. (1996) [2] |
| 33 | medial forebrain bundle appears | Ashwell et al. (1996) [2] |
| 44 | mammillothalamic tract appears | Ashwell et al. (1996) [2] |
| 44 | stria medullaris thalami appears | Ashwell et al. (1996) [2] |
| 51 | axons in optic stalk | Dunlop et al. (1997) [3] |
| 56 | external capsule appears | Ashwell et al. (1996) [2] |
| 56 | stria terminalis appears | Ashwell et al. (1996) [2] |
| 60 | optic axons invade visual centers | Dunlop et al. (1997) [3] |
| 63 | internal capsule appears | Ashwell et al. (1996) [2] |
| 63 | fornix appears | Ashwell et al. (1996) [2] |
| 70 | anterior commissure appears | Ashwell et al. (1996) [2] |
| 77 | hippocampal commissure appears | Ashwell et al. (1996) [2] |
| 87.5 | corpus callosum appears | Ashwell et al. (1996) [2] |
| 157.5 | eye opening | Clancy et al. (2007) [4] |
| 175 | ipsi/contra segregation in LGN and SC | Robinson & Dreher (1990) [5] |
Studies report that three primary structures are formed in the sixth gestational week. These are the forebrain, the midbrain, and the hindbrain, also known as the prosencephalon, mesencephalon, and the rhombencephalon respectively. Five secondary structures originate from these in the seventh gestational week. These are the telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon; the lateral ventricles, third ventricles, cerebral aqueduct, and upper and lower parts of the fourth ventricle in adulthood originated from these structures. [6] The appearance of cortical folds first takes place during 24 and 32 weeks of gestation. [7]
Cortical white matter increases from childhood (~9 years) to adolescence (~14 years), most notably in the frontal and parietal cortices. [8] Cortical grey matter development peaks at ~12 years of age in the frontal and parietal cortices, and 14–16 years in the temporal lobes (with the superior temporal cortex being last to mature), peaking at about roughly the same age in both sexes according to reliable data. In terms of grey matter loss, the sensory and motor regions mature first, followed by other cortical regions. [8] Though it is a controversial psychometric, adult IQ also begins to be tested around this age range, with the Raven's Progressive Matrices test beginning at age 14 and the Wechsler Adult Intelligence Scale test beginning at age 16, though scores between 14 and 16 on the Weschler test have differences so small that they are considered unreliable. This may bring into question the effectiveness of brain development studies in treating and successfully rehabilitating criminal youth. [9]
Major development in the brain, like prefrontal cortex, continues to around 25 [10] and sometimes even up to 30 [11] years of age. The brain continues to develop thoroughout life, however, major changes in the brain are usually completed at mid-to late 20s. [12] [ citation needed ]
The central nervous system (CNS) is the part of the nervous system consisting of the brain and spinal cord, the retina and optic nerve, and the olfactory nerve and epithelia. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric and triploblastic animals—that is, all multicellular animals except sponges and diploblasts. It is a structure composed of nervous tissue positioned along the rostral to caudal axis of the body and may have an enlarged section at the rostral end which is a brain. Only arthropods, cephalopods and vertebrates have a true brain, though precursor structures exist in onychophorans, gastropods and lancelets.
White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelinated axons, also called tracts. Long thought to be passive tissue, white matter affects learning and brain functions, modulating the distribution of action potentials, acting as a relay and coordinating communication between different brain regions.
Grey matter, or gray matter in American English, is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil, glial cells, synapses, and capillaries. Grey matter is distinguished from white matter in that it contains numerous cell bodies and relatively few myelinated axons, while white matter contains relatively few cell bodies and is composed chiefly of long-range myelinated axons. The colour difference arises mainly from the whiteness of myelin. In living tissue, grey matter actually has a very light grey colour with yellowish or pinkish hues, which come from capillary blood vessels and neuronal cell bodies.
The thalamus is a large mass of gray matter on the lateral walls of the third ventricle forming the dorsal part of the diencephalon. Nerve fibers project out of the thalamus to the cerebral cortex in all directions, known as the thalamocortical radiations, allowing hub-like exchanges of information. It has several functions, such as the relaying of sensory and motor signals to the cerebral cortex and the regulation of consciousness, sleep, and alertness.
Holoprosencephaly (HPE) is a cephalic disorder in which the prosencephalon fails to develop into two hemispheres, typically occurring between the 18th and 28th day of gestation. Normally, the forebrain is formed and the face begins to develop in the fifth and sixth weeks of human pregnancy. The condition also occurs in other species.
The brain is the central organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It controls most of the activities of the body, processing, integrating, and coordinating the information it receives from the sense organs, and making decisions as to the instructions sent to the rest of the body. The brain is contained in, and protected by, the skull bones of the head.
Aging of the brain is a process of transformation of the brain in older age, including changes all individuals experience and those of illness. Usually this refers to humans.
In the human brain, the diencephalon is a division of the forebrain. It is situated between the telencephalon and the midbrain. The diencephalon has also been known as the tweenbrain in older literature. It consists of structures that are on either side of the third ventricle, including the thalamus, the hypothalamus, the epithalamus and the subthalamus.
Neuroscience and intelligence refers to the various neurological factors that are partly responsible for the variation of intelligence within species or between different species. A large amount of research in this area has been focused on the neural basis of human intelligence. Historic approaches to studying the neuroscience of intelligence consisted of correlating external head parameters, for example head circumference, to intelligence. Post-mortem measures of brain weight and brain volume have also been used. More recent methodologies focus on examining correlates of intelligence within the living brain using techniques such as magnetic resonance imaging (MRI), functional MRI (fMRI), electroencephalography (EEG), positron emission tomography and other non-invasive measures of brain structure and activity.
In psycholinguistics, language processing refers to the way humans use words to communicate ideas and feelings, and how such communications are processed and understood. Language processing is considered to be a uniquely human ability that is not produced with the same grammatical understanding or systematicity in even human's closest primate relatives.
The size of the brain is a frequent topic of study within the fields of anatomy, biological anthropology, animal science and evolution. Measuring brain size and cranial capacity is relevant both to humans and other animals, and can be done by weight or volume via MRI scans, by skull volume, or by neuroimaging intelligence testing. The relationship between brain size and intelligence remains a controversial although frequently investigated question.
FreeSurfer is a brain imaging software package originally developed by Bruce Fischl, Anders Dale, Martin Sereno, and Doug Greve. Development and maintenance of FreeSurfer is now the primary responsibility of the Laboratory for Computational Neuroimaging at the Athinoula A. Martinos Center for Biomedical Imaging. FreeSurfer contains a set of programs with a common focus of analyzing magnetic resonance imaging (MRI) scans of brain tissue. It is an important tool in functional brain mapping and contains tools to conduct both volume based and surface based analysis. FreeSurfer includes tools for the reconstruction of topologically correct and geometrically accurate models of both the gray/white and pial surfaces, for measuring cortical thickness, surface area and folding, and for computing inter-subject registration based on the pattern of cortical folds.
The development of the nervous system in humans, or neural development, or neurodevelopment involves the studies of embryology, developmental biology, and neuroscience. These describe the cellular and molecular mechanisms by which the complex nervous system forms in humans, develops during prenatal development, and continues to develop postnatally.
Posterior cortical atrophy (PCA), also called Benson's syndrome, is a rare form of dementia which is considered a visual variant or an atypical variant of Alzheimer's disease (AD). The disease causes atrophy of the posterior part of the cerebral cortex, resulting in the progressive disruption of complex visual processing. PCA was first described by D. Frank Benson in 1988.
Gyrification is the process of forming the characteristic folds of the cerebral cortex.
In brain anatomy, the lunate sulcus or simian sulcus, also known as the sulcus lunatus, is a fissure in the occipital lobe variably found in humans and more often larger when present in apes and monkeys. The lunate sulcus marks the transition between V1 and V2.
The causes of schizophrenia that underlie the development of schizophrenia, a psychiatric disorder, are complex and not clearly understood. A number of hypotheses including the dopamine hypothesis, and the glutamate hypothesis have been put forward in an attempt to explain the link between altered brain function and the symptoms and development of schizophrenia.
The dual systems model, also known as the maturational imbalance model, is a theory arising from developmental cognitive neuroscience which posits that increased risk-taking during adolescence is a result of a combination of heightened reward sensitivity and immature impulse control. In other words, the appreciation for the benefits arising from the success of an endeavor is heightened, but the appreciation of the risks of failure lags behind.
Bradley S. Peterson is an American psychiatrist, developmental neuroscientist, academic and author. He is the Inaugural Director of the Institute for the Developing Mind at Children's Hospital Los Angeles (CHLA), and holds the positions of Vice Chair for Research and Chief of the Division of Child & Adolescent Psychiatry in the Department of Psychiatry at the Keck School of Medicine at the University of Southern California.