Chapter 4 study guide: The Brian and Consciousness

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-epilepsy is the debilitating (devastating) affliction in which seizures (uncontrolled storms of electrical
activity) begin in some part of the brain and spread throughout much of it, often causing violent life-
threatening convulsions of the entire body
-Parkinsons disease is when specific parts of the brain control specific mental and physical capabilities
-have difficulty learning tasks that require repetition because of damage to their basal ganglia, which is
crucial for planning and producing movement
-mental activities and behaviours are produced by biological processes within the brain, such as the action of
nerve cells and associated with chemical reactions
-the coordinated action of a number of different brain regions contributes not only to consciousness, but also to
variations in conscious experience, from being highly aware of our surroundings to being fast asleep and
-brain is always active, functioning at every moment to keep us alive as it processes information from the
external world and in doing so, creating our mental world
-the brain wasnt always recognized as the home of the mind
-ie. Egyptians viewed the hear as more important
-they elaborately embalmed (preserved) the hearts of their deceased but the brains they simply threw
-the heart was to be weighted in the afterlife to determine the deceaseds fate
-in early 19th century, Franz Gall and Johann Spurzheim proposed their theory of phrenology
-phrenology is the practice of assessing personality traits and mental abilities by measuring bumps on the human
-based on the idea that the brain operates on a principle of functional localization
-one of its most vigorous critics was Pierre Flourens, a French scientist
-believed that the brain functions as a single unit, with al parts working together
-conducted experiments in the 1820s on birds and rodents in which he removed brain regions and observed
the effects on behaviour
-Karl Lashley used a similar method to identify the place sin the brain where learning occurred
-conceded that specific brain regions were involved in motor control and sensory experiences
-believe that all parts of the cortex contributed equally to mental abilities (ie. Problem solving and memory,
a concept called equipotentiality)
-his theory has been discredited now
-the brain consists of a patchwork of high specialized areas
-evidence came from the work of French scientist Paul Broca
-performed an autopsy on a man who was a patient that lost the ability to say anything other than the
word tan, but could still understand language
-Broca found substantial damage to the front left side caused by a large lesion
-observation led him to conclude that this particular region was important for speech
-the frontal region to become known as Brocas area
-since the invention of brain imaging methods in late 1980s, there has been various experiments and researches
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done at different levels of analysis, linking specific brain areas with particular behaviours and mental processes
-allowed psych scientists to examine mental states, such as consciousness
What are the Basic Brain Structures and their Functions
-today, the brain is best viewed as a collection of interacting neuronal circuits that have accumulated and
developed throughout human evolution
-through the process of adapting to the environment, the brain has evolved specialized mechanisms to regulate
breathing, food intake, sexual behaviour and bodily fluids, as well as sensory systems to aid in navigation and
assist in recognizing friends and foes
-nervous system is involve din almost every aspect of an organisms maintenance, regulation and behaviour
-composed of vast number of interacting brain circuits
-ie. ranging from those controlling the contractions of the intestines, to those allowing a child to play with a
dog, to those allowing college students to choose their majors
-all orchestrated by parts of the brain that are as different in their structure and organization as the roles they
-some roes have remained essentially the same through our evolution
-the neural circuits responsible for such basics as breathing have changed correspondingly a little
-human nervous system has a fundamental layout shared with all other vertebrates,
-developed an impressive elaboration of structures responsible for our enormous capacities for communication
and thought
-PAGE 121, FIGURE 4.4
The Spinal Cord is Capable of Autonomous Function
-the spinal cord is a rope of neural tissue that runs inside the hollows of the vertebrae, from just above the
pelvis up into the base of the skull
-segmented, with each segment marked by its own pair of spinal nerves emerging for the sides of the cord
and communicating info to and from the rest of the body
-the cord is seen to be composed to two distinct tissue types
-the gray matter, which is dominated by the cell bodies of neurons
-the white matter, which consists mostly of axons and the fatty sheaths that surround them
-gray and white matter are clearly distinguishable throughout the brain as well
-sensory info from the body enters the spinal cord and passed up to the brain
-besides relaying info, spinal cord is able to take action on its own
Stretch Reflex
-spinal cord handles one of the simplest behaviours, the spinal reflex
-conversion of sensation into action by a handful of neurons and the connections between them
-ie. Consider the stretch reflex. When the tendon attached to your kneecap is tapped with a rubber hammer,
the leg gives a little reflexive kick
-the reflex is present throughout the skeletal musculature and functions to maintain the position of the
joins under varying loads
-stretching the muscle causes the stretch receptor neurons to fire, which cause the motor neurons to increase
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their firing, which contracts the muscle
-all muscles have stretch receptors inside them to sense changes in length
-receptors are actually the dendritic tips of receptor neurons whose cell bodies are located in the spinal
-stretching the muscle causes the receptor neurons connected to it to fire
-receptor neurons axons enter the spinal cord and transmit their signal directly to motor neurons, which
lead back out to the same muscle
The Brainstem Houses the Basic Programs of Survival
-spinal cord becomes thicker and more complex as it transforms into the brainstem, which houses the most
basic programs of survival
-ie. Breathing, swallowing, vomiting, urination and orgasm
-the brainstem is simply the spinal cord continued up to the head
-performs functions for the head similar to those that the spinal cord performs for the rest of the body
-a whole complement of reflexes are housed here, analogous (similar) to the spinal reflexes
-ie. Gagging
-the brainstem has nerves that connect it to the skin and muscles of the head
-as well as to the specialized sense organs of the head such as eyes and ears
-these nerves each have distinct, dedicated clumps of cells within the brainstem that handle their needs
-brainstem uses reflexes of the spinal cord to produce useful behaviour
-ie. Electrically stimulating a part of the brainstem ca cause an anesthetized animal (or one whose spinal
cord and brainstem have been disconnected from the rest of its brain) to begin walking,
-increasing the frequency of the stimulation causes the animal to go from a walk to a trot, and even
more causes the animal to gallop
-stimulating another area will cause the animal to turn to one side
Reticular Formation
-the brainstem also contains networks of neurons known as the reticular formation, that project up into the
cerebral cortex and affect general arousal
-reticular formation is also involved in inducting and terminating the different stages of sleep
-the autonomy of the brainstem can be dramatically illustrated by severing an animals brainstem from the
entire brain above it, including its entire cerebral cortex
-some case have been reported of humans born without cerebral cortices and their behaviours are extremely
basic and reflexive
-such infants tend not to develop normally and also do not tend to survive
The Cerebellum is Essential for Movement
-the cerebellum is a large protuberance connected to the back of the brainstem
-its size and convoluted surface make it look like a supplementary brain
-lesions to different parts of the cerebellum produce very different effects
-its cellular organization appears to be identical throughout
-suggest that the cerebellum is performing identical operations on al of its inputs with different effects
resulting from the difference in origin and destination of the information
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