Chapter 4 – The Brain

•Evolution•Baby Theresa•Brain Injury•Play Dough Brains revisited•The Brain

•Cortex/Four Lobes•Hemispheres – Left and Right•Fore Brain•Mid Brain – Limbic System•Hind Brain

Evolution(p. 69)

Baby Theresa (p.74)

Infants born with anencephaly have either a severely underdeveloped brain or total brain absence. A portion of the brain stem usually protrudes through the skull, which also fails to develop properly. (Gale Group)

Baby Theresa II

The infants are kept alive by the developed midbrain and the hindbrain.

The medulla is key in maintaining life.

The BrainThe Brain

Cerebrum

(Cortex)

Corpus callosum

Cerebellum

Medulla

Pituitary gland

Hypothalamus

Thalamus

Cortex (Cerebrum)

Neurons and Glials

The Neurons make up the outside layers of the cortex. The wrinkles that are made on the brain are wrinkles in the Neuron layer of the cortex.

Making the damage to the outside layer (concussion/injury) ever present

The Glial cells are under the Neurons.

Functions of the cortex are localised into discrete areas:

Sensory Areas- these receive impulses via sensory neurones from receptors that detect the stimuli reaching the body. The skin has more receptors in some parts of the body than others.Motor areas send impulses to skeletal muscles along nerve fibres passing down the brain stem and spinal cord. As with the sensory areas the part of the body is represented by an area of the motor cortex.

Association areas make decisions and send impulses through the motor areas.

The Lobes

Prefrontal Lobe

Frontal Lobe p.74

Function: This lobe is divided into three different areas and is responsible for cognition, memory and emotional intelligence. Prefrontal Area – This area is responsible for planning, complex ideas, behaviors,  concentration and the ability to focus. This area is also responsible for emotional traits, judgment and inhibition. Motor – The rear-most portion of the frontal lobe, this area is responsible for voluntary motor activity. Premotor –This area is involved with volitional movement (storage of motor patterns) and motor activity to the opposite side of the body. In other words, the right side of the brain is responsible for the left side of the body.

Frontal Lobe Injury

Injury to this area, or a lack of accurate sensory information from the lower levels of the brain, causes among other things: inability to retrieve recent memories, inattentiveness, lack of focus, difficulty learning new information, lack of inhibition, and inappropriate sexual and social behavior.

Frontal Lobotomy

Was a surgical procedure in which about one-third of the frontal part of the frontal lobe was cut away from the rest of the brain.

This was to help those people with sever emotional problems.

18,000 done in the 1940s and 1950s.

Frontal Lobotomy

http://www.answers.com/topic/lobotomy-1

Follow the link to learn more about

prefrontal lobotomies

Temporal Lobe

This lobe is responsible for receiving auditory information and recognizing words; it is thus central to the process of learning and understanding language. It is also an important structure for emotions, for making new memories, and for short-term memory. Other parts of this lobe appear to integrate memories of taste, sound, sight, and touch.

Injury to the temporal lobe, or a lack of accurate sensory information from the lower levels of the brain, impairs the ability to process auditory information accurately, as well as other hearing impairments. Injury to this area can also cause a person to become overly agitated or irritable, and to exhibit childish behavior.

Parietal LobeThis lobe is responsible for processing sensory input and sensory discrimination. It is also called the ‘association area’.  It is responsible to receive and utilize from the lower levels of the brain, information about: temperature, taste, touch, and movement from the rest of the body – such as distance and position of objects.  It is also responsible for reading and arithmetic.

Injury to this area, or lack of accurate sensory information from the lower levels of the brain, create an inability to discriminate between different stimuli, locate and recognize parts of the body, inability to write and disorientation in environmental space.

Occipital LobeThis is the primary visual center of the brain. It processes information from the eyes, and links that information with images stored in memory. In other words, this area helps you determine what you are looking at.

The most common effect of injury to the occipital lobe is visual impairment; severe injury to this lobe can cause blindness. Along with visual impairment, injury to the occipital lobe can cause hallucinations, can cause objects to appear larger or smaller than they are, and can cause colors to appear abnormal.

The visual sensory area is at the back of the brain and receives sensory input from the optic nerve. Neurones from the left half of the retinas of both eyes go to the visual sensory area in the left hemisphere and likewise for the right half of the retina. Therefore the two hemispheres see slightly different images from opposite sides of the visual field, these differences help judge distance.

p. 76-79

Midbrain p.80

The Midbrain p.80

The Midbrain – is a sub cortical level of the brain. Through the body of the midbrain pass a substantial number of various fiber tracts especially related to vision, voluntary muscle activity and other important functions. The midbrain contains:Thalamus HypothalamusHippocampus Basal GangliaPineal Body Corpus Callosum

Thalamus

Thalamus - A main sensory relay and integrative center connecting with many areas of the brain, including the cerebral cortex.

Hypothalamus

Hypothalmamus – The master control of the autonomic nervous system, parasympathetic and sympathetic. This system stimulates and controls structures such as the heart, most glands and smooth muscles. In effect, this system allows your systems to excite and relax, as needed. This system integrates the autonomic and endocrine functions with behavior.

Hippocampus

Hippocampus – This area of the brain, apart from its other functions, is primarily responsible for short term memory.

Amygdala (part of Basal Ganglia)

Amygdala –is involved in forming, recognizing, and remembering emotional experiences, especially fear as well as emotional facial expressions.

Hindbrain p.73

Pons

Pons—functions as a bridge to interconnect messages between the spinal cord and brain. The pons also makes involved in sleep.

Medulla (Oblongata)

Medulla—located at the top of the spinal cord, including a group of cells that control vital reflexes, such as respiration, heart rate and blood pressure.

Cerebellum

Cerebellum—located in the back and under the brain. Involved in coordinating movements but not in initiating voluntary movement. Key in timed motor activities like sports

Hemispheres (Cortex) p. 87

Left – Right Brain …

Characteristics of Right Brain:RandomIntuitiveSubjectiveLooks at wholesHolisticSynthesizingThis part is more interested in challenge, risk, new ideas, imagination, and whole picture.

Characteristics of Left Brain:LogicalSequentialRationalLooks at partsAnalyticalObjectiveIn addition, this part likes technicalities, numbers, data, facts, logic and precision.

Right Brain vs. Left Brain

http://www.news.com.au/dailytelegraph/story/0,22049,22535838-5012895,00.html

Split Brain Operation

Splitting the corpus callosum (the tissue connecting the left and right halves of the brain – 200 million nerve fibers).

This is done especially with epileptic patients. It splits the two halves into independent parts of the brain.

This takes some therapy to find out what each half can do.

Right Brained or Left Brained

When reading your left side actually reads the words and allows you to decode the words.

Your right side keeps track of the story and visualizes the details and recalls related personal experiences.

Both is the most likely answer.

The upper part of the brain, the cerebrum is responsible for all voluntary activities, it is connected to the nervous system.

The cerebrum is divided down the middle by a deep cleft into two cerebral hemispheres connected by the nerve fibres of the corpus callosum

The inside contains fluid and only the outer few mm of the cerebral hemispheres contains neurones and this is called the cerebral cortex.

The cortex is highly folded providing a large surface area.

Parts of the brain in relationship to your face …

MRI Brain Images p. 70

http://www.lahey.org/Medical/Radiology/MRI_CommonTypes_Brain.asp

MRI p. (70)

Magnetic resonance imaging involves passing nonharmful radio frequencies through the brain.

MRIs are used to study the structure of the brain.

PET Brain Scans (p. 71)

Positron emission tomography (PET) is a nuclear medicine medical imaging technique which produces a three-dimensional image or map of functional processes in the body.

PET Scans (p. 71)

Done by injecting slightly radioactive solution into the blood and then measuring the absorption by the brain.

Indicating the activity of neurons.

Other uses of PET ScansA normal PET scan which shows the difference in brain activity between reciting a set of well memorized and practiced words; and a set of words not practiced much.

PET scans of a schizophrenia sufferer's brain (left) and normal

brain (right).

Other PET Scans

PET Scans can be used to view activity in other

parts of the body

PET scans are used most often to detect cancer and to examine the effects of cancer therapy by

characterizing biochemical changes in the cancer.

Divisions of the Nervous System

Central NervousSystem

Peripheral Nervous System

Somatic Nervous System

Automatic Nervous System

Network of nerves to move voluntarily

Regulates heart rate, breathing, blood

pressurewithout conscience

effortSympathetic DivisionTriggered by a threat

Parasympathetic DivisionReturns body to

calmer/relaxed state

Sympathetic Nervous System

Autonomic nervous system is triggered by a threatening or challenging physical stimuli – =Increases blood pressure=dilate pupils=heightened physiological

Autonomic Nervous System p.81Regulates Physiological responses to stimuli

Sympathetic Nervous System-Fight or Flight response to stimuli

Parasympathetic Nervous System-Relaxed state (Often following a stressful period or event)

Parasympathetic Nervous System

Decreasing physiological arousal and calming your body down. The body triggers the hypothalamus

Homeostasis

Homeostasis means that sympathetic and parasympathetic systems work together to keep the body’s level of arousal in balance for optimum functioning.

Amygdala

Amygdala – limbic structure involved in many brain

functions, including emotion, learning and memory. It is

part of a system that processes "reflexive" emotions like fear and

anxiety.

Cerebellum

Cerebellum – governs movement. Coordinates (but

not initiates) voluntary movement.

Cortex/Cerebrum

Cortex or Cerebrum – are the four lobes of the “gray” matter. It is dived unto four major lobes and is the part of the brain used in high level brain activities.

Frontal Lobe

Frontal Lobe – helps control skilled muscle movements,

mood, planning for the future, setting goals and

judging priorities.

Hippocampus

Hippocampus – plays a

significant role in the formation of

long-term memories.

Medulla (Oblongata)

Medulla (Oblongata) – contains centers for the

control of vital processes such as heart rate, respiration,

blood pressure, and swallowing.

Limbic System

Limbic system – a group of interconnected structures that

mediate emotions, learning and memory.

Occipital Lobe

Occipital Lobe – helps process

visual information.

Parietal Lobe

Parietal Lobe – receives and processes information about temperature, taste, touch, and movement coming from the rest of the body. Reading and arithmetic are also processed in this region.

Pons

Pons – contains centers for the control of vital processes,

including respiration and cardiovascular functions. It

also is involved in the coordination of eye

movements and balance.

Thalamus

Thalamus – a major relay station between the senses

and the cortex (the outer layer of the brain consisting of the parietal, occipital, frontal and

temporal lobes).

Temporal Lobe

Temporal Lobe – processes hearing, memory and language functions.

The Different Regions of the Brain

The medullamedulla controls heart rate, breathing, peristalsis, and reflexes such as sneezing.

The hypothalamushypothalamus controls temperature and water homeostasis. Also controlling the release of hormones by the pituitary gland.

The thalamusthalamus is a relay station, integrating sensory input and channelling it to the sensory areas of the cerebrum.

The cerebellumcerebellum co-ordinates muscle movement and so controls balance, posture and movement.

The main motor area controls the main skeletal muscles of the body and the main sensory area receives input from the various skin receptors all over the body.

The areas are duplicated onto the two cerebral hemispheres, which control opposite sides of the body.

Therefore, those situated on the left cerebral hemisphere are linked to the right side of the body and vice versa.

The regions of the body with many sensory neurones have correspondingly large areas of the cortex linked to them. For example, the lips occupy a larger region of the sensory cortex than the shoulder, because they have more sensory neurones.

Theses are involved in advanced kills such as visual recognition , language understanding, speech and memory retrieval.

The frontal lobes are particularly large in humans, they are thought to responsible for higher functions such as abstract thought, personality and emotion.

The association areas are not duplicated in the two hemispheres. The right hemisphere has association area for face recognition, spatial skills and musical sense. The left hemisphere has association areas for speech language and language mathematical logical and analytical