Unit 4 The Brain PDF

Unit 4 The Brain Likitha S (Department of Psychology)  The human central nervous system begins to form when the embryo is about 2 weeks old. At birth, the average human brain weighs about 350 grams. By the end of the first year, it weighs 1000 g, close to the adult weight of 1200 to 1400g...

Unit 4 The Brain Likitha S (Department of Psychology)  The human central nervous system begins to form when the embryo is about 2 weeks old. At birth, the average human brain weighs about 350 grams. By the end of the first year, it weighs 1000 g, close to the adult weight of 1200 to 1400g The brain and spinal cord begin as folding lips surrounding a fluid-filled canal. The stages shown occur at approximately age 2 to 3 weeks. Likitha S (Department of Psychology)  The development of the nervous system naturally requires the production and alteration of neurons. Likitha S (Department of Psychology)  Neuroscientists distinguish these processes in the development of neurons: proliferation, migration, differentiation, myelination, and synaptogenesis. Proliferation is the production of new cells. Migrate (move) toward their eventual destinations in the brain. Differentiates, forming the axon and dendrites that provide its distinctive shape Myelination, the process by which glia produce the insulating fatty sheaths that accelerate transmission in many vertebrate axons Synaptogenesis, or the formation of synapses, Likitha S (Department of Psychology)  The brain and the spinal cord are the central nervous system, and they represent the main organs of the nervous system A person’s conscious experiences are based on neural activity in the brain. Brain-scanning techniques provide a window into the living brain. Likitha S (Department of Psychology)  Brain imaging techniques allow investigators to sneak into the brain's internal workings without having to cut open a person’s skull. The most important scanning techniques are the electroencephalogram (EEG), positron emission tomography (PET), functional magnetic resonance imaging (fMRI), and transcranial magnetic stimulation imaging (TMS). Likitha S (Department of Psychology) Likitha S (Department of Psychology)  The brain and spinal cord (the CNS) are the most protected organs in the body. They are encased in bone covered by three protective membranes, the three meninges (pronounced “men-IN-gees”). The outer meninx (which, believe it or not, is the singular of meninges) is a tough membrane called the dura mater (tough mother). Immediately inside the dura mater is the fine arachnoid membrane (spider-web-like membrane) Beneath the arachnoid membrane is a space called the subarachnoid space, which contains many large blood vessels and cerebrospinal fluid; then comes the innermost meninx, the delicate pia mater (pious mother), which adheres to the surfaceLikitha ofS (Department the CNS of Psychology) The central core: old brain Likitha S (Department of Psychology) Likitha S (Department of Psychology)  Thalamus: the part of the brain located in the middle of the central core that acts primarily to relay information about the senses. Hypothalamus: a tiny part of the brain, located below the thalamus, that maintains homeostasis—a steady internal environment for the body— and produces and regulates behavior critical to the basic survival of the species. Eating, drinking, and sexual behavior. Likitha S (Department of Psychology)  Reticular formation The brainstem also contains networks of neurons, known collectively as the reticular formation, that project up into the cerebral cortex and basal ganglia and affect general arousal. The reticular formation is also involved in inducing and terminating the different stages of sleep. The autonomy of the brain stem can be dramatically illustrated by severing an animal’s brain stem from the entire brain above it, including its entire cerebral cortex. Cats that receive this treatment can still walk around and direct attacks at noises; if they then find themselves holding on to food, they will eat it. Some cases have been reported of humans born without cerebral cortices, and their behaviors are extremely basic and reflexive. Such infants tend not to develop normally and also do not tend to survive Likitha S (Department of Psychology)  Parts of the Brain THALAMUS amygdala hippocampus → Relays messages pituitary CEREBELLUM → Coordination and balance BRAINSTEM → Heart rate and breathing Likitha S (Department of Psychology) Likitha S (Department of Psychology) Likitha S (Department of Psychology)  CEPHALON: REGION OF THE HEAD! Before birth, the initial three swellings in the neural tube become five This occurs because the forebrain swelling grows into two different swellings, and so does the hindbrain swelling. From anterior to posterior, the five swellings that compose the developing brain at birth are the telencephalon, the diencephalon, the mesencephalon (or midbrain), the metencephalon, and the myelencephalon encephalon means “within the head”). These swellings ultimately develop into the five divisions of adult brain Likitha S (Department of Psychology) Likitha S (Department of Psychology) Thank you Likitha S (Department of Psychology)