Chapter 49 (1)

In all vertebrates, three anterior bulges ofthe neural tube- the __, _, and __ - become evident as the embryo develops. By the fifth week of embryonic development in humans tehre are five brain regios. Three of htese regions- those derived from hte __ and _- give rise to the __, a set of structures that form the lower part of the brain. The __ also gives rise to a major brain center, the __, that isn't part of hte brainstem.

As __ proceeds, the most profound hange in the human brain occur in the __, the region of the forebrain that gives rise to the adult __. Rapid, expansive growth of the __ during the 2nd and 3rd months causes hte outer portion of the cerebrum, called the __, to extend over and around much of hte rest of the brain. Major centers that develop from the __ are the __, __, ad __.

The __ functions in homeostasis, coordnation of movement and conduction of info to and from higher brain celnters. Sometimes scalled the "lower brain", it forms a stalk with cap like swellngs at the anterior end of the spinal cord. The adult brainstem consists of the __, the __, and the __.

The transfer of info between the PNS and the midbrain adn forebrain is one of the most imp functions of the medulla and pons. All axons carrying sensory info to and motor instructions from higher brain regions pass through the __.

The __ and __ also help coordinate large-scale body movements, like runnig and climbing. In carrying instructions about these movements from cell bodies in the midbrain and forebrain to synapses in the spinal cord, most axons cross in the medulla from one side of the CNS to the other. As a result, the right side of the brain controls much of the movement of the left side of the body and vice versa.

The __ contains centers for receiveing and integrating several types of sensory info. It also sends coded sensory info along neurons to specific reigons of the forebrain. All sensory axons involved in hearing either terminate in the midbrain or pass through it on their way to the __.

In nonmammalian vertebrates, portions of the midbrain form prominent __ that in some cases are the animal's only visual centers. In mammals, vision is integrated in the __, not in the __. THE __ INSTEAD COORDIATES VISUAL REFLEXES, LIKE PERIPHERAL VISION REFLEX: THE HEAD TURNS TOWARD AN OBJECT APPROACHING FROM THE SIDE W/O THE BRAIN HAVING FORMED AN IMAGE OF THE OBJECT

Signals from the __affect attention, alertness, and motivation.

The __ contains centers that control several automatic, homeostatic functions, including breathing, heart and blood vessel activity, swallowing, vomiting, and digestion. The __ also participates in some of these activities; for example, it regulates the breathing centers in the medulla.
These activities of hte __ rely on axons that reach many areas of the __ and __, releasing neurotransmitters such as norepinephrine, dopamine, serotonin, and acetylcholine.

Transitions of attentiveness and mental alertness are regulated by the __ and __, which control both arousal and sleep. __ is a state of awareness of the external world. __ is a state in which external stimuli are received but not consciously perceived.

The brainstem contains several centers for controlling arousal and sleep. One such regulator is the __, a diffuse netowrk of neurons in the core of the brainstem.

Acting as a sensory filter, the __ determines which incoming info reaches the cerebral cortex. The more info the cortex receives, the more alert and aware a person is, although the brain often ignores certain stimuli while actively processing other inputs. Sleep and wakefulness are also regulated by specific parts of hte brainstem: the __ and __ contains centers tha tcause sleep when stimulated, and the midbrain has a center that causes arousal.

__, a hormone produced by the pineal gland, appears to play an imp role in b ird and mammal sleep/wake cycles. Peak __ secretion occurs at might.

__ has been promoted as a dietary supplement to treat sleep disturbances; synthesized from __, which itsepf may be the neurotransmitter of hte sleep-producing centers. __ in turn is synthesized from the amino acid __.

__ is an active sleep, at least for hte brain. By placing electrodes at multiple sites on the scalp, we can record patterns of electrical activity called brain waves in an __. These recordings reveal that brain wave frequencies change as the brain progreses through distinct stages of sleep. One hypothesis: sleep and dreams are involved in consolidating learning and memory.

True or False:
Some animals display volutionary adaptations that allow for substantial activity during sleep.
True False

The __, which develops from parth of the hindbrain, coordinates movements and balance. The __ recieves sensory info about the position of the joints and the length of the muscles, as well as input from the auditory (hearing) and visual systems. It also monitors motor commands issued by the __.

Info fromt eh __ passes first to the pons and from there to the __. The __ integrates this info as it carries out coordination and error checking during motor and perceptual funcitons. Hand-eye coordination is an example of __ control; if the __ is damaged, the eyes can follow a moving object, but they will not stop at the same place as the object. Hand movement otward hte object will be erratic. The __ also helps in learnign and remembering motor skills.

The embryonic __- the forebrain division that evolvd earliest in vertebrate history- develps into three adult brain regions: the __, __ and __. The __ and __ are major integgrating centers that act as relay stations for info flow in the body. The __ includes the pineal gland, the source of melatonin. It also contains on of serveral clusters of capilaries that generate __ from blood.

The __ is the main inpu center for sensory info going to the cerebrum. Incoming info from all the senses is sorted in the __ and sent to the appropriate cerebral centers for further processing. The __ also receives input from the cerebrum and other parts of hte brain tha tregulate emotion adn arousall. The __ is formed by two masses.

Much smaller than the thalamus, the __ is one of hte most imp brain regions for the control of homeostasis. Besides thermostat, it regulates hunger, thirst, and many other basic survival mechanisms. The __ is the source of posterior pituitary hormones and of releasing hormones that act ont he anterior pituitary. In addition, __ centers play a role in sexual and mating behaviors, the flight-or-fight response and pelasure.

Specilaized nerve cells int he __ regulate circadian rhythms, daily cycles of bniological activity. Such cycles occur in organisms from bac to hums.
- In mammals, the cycles controlled by the __ influence a number of physiological processes, like sleep, body temp, hunger, hormone release. As in other organisms, circadian rhythms in mammals rely on a __, a molecular mechanism that directs periodic gene expressiona dn cellular activity.

Although __ are typically synthesized to the cycles of light and dark in the environment, they can maintain a roughly 24-hr cycle even in the absence of environmental cues.

In mammals, circadian rhythms are coordinaed by a group of neurons in the hypothalamus called the __. In response to transmission of sensory info by the eyes, the __ acts as a pacemaker, synchronizing the biological clock in cells throughout the bodyto the natural cycles of day length.

By surgically removing the SCN from lab animals, SCN is required for__: Animals without an __ lack rhythmicity in behaviors and in electrical activity of the brain. These experiments did not reveal whether rhythms oiginate in the SCN or elsewhere.

In mammals, info processing is largely centered int he __; the __dvelops ffrom the embryonic __, an outgrowth of the forebrain that arose early in vertebrate evolution as a region supporting olfactory reception as well as auditory and visual processing.

The __ is divided into teh right and left __; Each hemispehre consists of an outer covering of gray matter, the __; internal white matter, and groups of neurons collectively called __ that are located deep within the white mattter.

The __ are imp centers for planning and learning movement sequences. Damage in this brain region during fetal develpoment can result in __, adefect disrupting how motor commands are issued to the muscles.

The __ is part extensive in mammals, where it is vital for perception, vol movement, ad learning. In humans, it accounts for about 80% of total brain mass and is highly convoluted. The convolutions allow the cerebal cortex to have a large surface area and still fit inside the skull.

cerebral cortex

Like the rest of the __, the __ is divided into right and left sides, each o which is responsible for the opposite half of hte body. The left side of hte cortex receies info from, and controls the movement of, the right side of the body, and vice versa. A thick band of axons known as the __ enables the right and left cerebal cortices to communicate.

If damage occurs to the cerebrum early in development, the normal functions of hte damaged area are frequently redirected elsewhere. A dramatic example of this phenomenon results from a treatment for the msot extreme cases of __, a condition causing episodes of electrical disturbance, or seizures in the brane.

In humans, the outermost part of hte cerebral cortex forms the __, six parallel layers of neurons arranged tangential to the brain surface. It was long though that a large, highly convoluted neocortex was required for advancead __, the perceptiona dn reasoning that constitute knowledge.

The sophisticated cognitive ability of birds is based on an evolutionary variation on the architecture of hte __, the top or outer portion of brain.

- Whereas hte human __ the __- contains flat sheets of cells in 66 layers, the avian __ contains neurons clustered into neuclei. It is likely that hte common ancestor of birds and mammals had a __ in which neurons were organized into nuclei. Early in mammalian evolution, this nuclear organization was tranformed into a layered one.

Connectivity was maintained during this trasnformation such that the __ of both mammals and birsds recieve sensory input- sights, sounds and touch- from the __. The result was two dif arrangements, each of which supports complex and flexible brain function.