CHAPTER 2

The Anatomy and Evolution of the Nervous System

LECTURE OUTLINEI. Anatomical Directions and Planes of Section (pp. 26-28)

PowerPoint Slides 2-2 through 2-5

A. Anatomical directions help us locate structures in the nervous system.

Common directional terms must be established before undertaking a description of the nervous system. The anatomical directional terms may become confusing due to a 90-degree bend in the neuraxis of humans. Comparing the use of the terms between a four-legged animal and a human is a very useful tool to minimize confusion.

The rostral-caudal-dorsal-ventral set “moves” relative to the neuraxis, but the anterior-posterior-superior-inferior set does not. The rostral-caudal-dorsal-ventral set rotates at the junction of the midbrain and the diencephalon. Please point out to students that this change affects Figure 2.1 on p. 26 of their textbooks.

You can think of the anterior-posterior set naming the walls, floor, and ceiling of a room, whereas the rostral-caudal set applies to the animal in the room, as in this image.

To obtain a full-color version of this image for adding to a PowerPoint, please email me at laura@laurafreberg.com

*See the Supplemental Teaching Strategies and Tools section: Active Learning: Drawing Neuroanatomy.

The Anatomy and Evolution of the Nervous System

1. Rostral structures are located toward the head within the body region or the front of the skull within the head region.

2. Caudal structures are located toward the tail (feet in humans) within the body region or the rear of the skull within head region.

3. Dorsal structures are located toward the back within the body region or the top of the skull within the head region.

4. Ventral structures are located toward the belly within the body region or the bottom of the skull within the head region.

5. In humans, the dorsal parts of our brain form a 90-degree angle with the dorsal parts of the spinal cord.

6. Anterior structures are in front of the animal, which means the forehead and belly of a human. In other words, looking at the human spinal cord, anterior and ventral are equivalent.

7. Posterior structures are in back of the animal, which means the back of the head and the back of a human. In other words, looking at the human spinal cord, posterior and dorsal are equivalent.

8. Superior structures are located at the top of the animal, which means the top of the head in humans. Looking at the human spinal cord, the thoracic division is both superior and rostral to the lumbar division.

9. Inferior structures are located at the bottom of the animal. In the human spinal cord, the lumbar division is both inferior and posterior to the thoracic division.

10. Ipsilateral structures are on the same side of the midline, and contralateral structures are on opposite sides of the midline.

11. Structures near the midline are medial, and structures away from the midline are lateral.

12. In limbs, proximal structures are closer to the body center, and distal structures are farther away.

B. Anatomists make particular cuts or sections in the nervous system in order to view the structures in two rather than three dimensions.

1. Coronal or frontal sections divide the brain from front to back in a vertically cut plane as if from ear to ear. (Mnemonic: Think of a woman wearing a tiara—coronal means crown)

2. Sagittal sections are parallel to the midline and give us a “side” view of the brain in a vertically cut plane as if from the front to back of the head. A special sagittal section cut direction on the midline of the brain is called a midsagittal section.

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This is a common view used to describe the corpus callosum, the brainstem and midbrain structures, and the ventricle system. (Mnemonic: Sagittarius is usually depicted as a man getting ready to shoot an arrow from a bow, seen from the side)

3. Horizontal/axial sections divide the brain from top to bottom in a plane that is parallel to the floor in a human standing upright.

II. Protecting and Supplying the Nervous System (pp. 28-32)

PowerPoint Slides 2-6 through 2-10

Clicker Question #1

Film Clip #1: The Ventricles

Film Clip #2: Inserting a CSF Shunt

A. The Meninges (pp. 28-29)

1. Three layers of meninges protect the central nervous system: the dura mater, the arachnoid, and the pia mater.

2. Only the dura and pia mater layers are present in the peripheral nervous system.

B. The cerebrospinal fluid circulates through the four ventricles, the central canal of the spinal cord, and the subarachnoid space, floating and cushioning the central nervous system. Although the ventricular system curves and folds as the brain matures, it starts out as the simple interior of the neural tube. Students often find it simpler to understand the flow of CSF in this simpler form. (pp. 29-30)

The cerebrospinal fluid (CSF) can be thought of as an ultra-filtered version of the plasma found in circulating blood. The CSF is generated by the choroid plexus primarily in the lateral ventricles, and circulates through the central canal of the spinal cord and the four ventricles of the brain. From the left and right lateral ventricles, the CSF flows into the medial third ventricle and then into the fourth ventricle, before finally reaching the central canal of the spinal cord and the surrounding subarachnoid

The Anatomy and Evolution of the Nervous System

space. Here, it is absorbed back into the blood supply. A primary function of the CSF is to protect the brain through floating the brain rather than attaching it to the skull.

*See the Lecture Enrichment section for additional information about the daily production of CSF, and see the Supplemental Teaching Strategies and Tools section for demonstrations of the effects of daily CSF turnover and CSF buoyancy.

Hydrocephalus is the condition resulting from a blockage of CSF flow through the central nervous system. The blockages usually occur at the narrow passages in the ventricle system such as the cerebral aqueduct. These blockages are commonly associated with development, tumor growth, or swelling of the brain due to trauma.

Behavioral Neuroscience Goes to Work: Treating Hydrocephalus (p. 31)

*See the Lecture Enrichment and Supplemental Reading sections for additional information about a new clinical diagnosis, normal pressure hydrocephalus (NPH), which affects the elderly and mimics Alzheimer’s disease and Parkinson’s disease but is easily alleviated.

C. The Brain's Blood Supply: The brain is supplied with blood through the carotid and vertebral arteries. (pp. 30-31)

Clicker Question #2

The neurons of the central nervous system use large amounts of energy and thus require a constant supply of oxygen and glucose among other nutrients. In fact, the average adult brain represents only 5% of the total body weight; however, the brain uses more than 20% of the body’s total cardiac output. There is no storage of oxygen or glucose within the central nervous system and so an uninterrupted supply is critical. Significant neural death occurs within three minutes of the central nervous system not receiving any new blood supply. In the event of a cardiac arrest, effective and immediate CPR first-aid helps keep oxygenated blood flowing to the central nervous system to prevent brain damage.

The carotid arteries have very large diameters whereas the upstream cerebral arteries and capillaries become very small in diameter. Debris, such as blood clots or plaque deposits, which become dislodged and pass through the carotid artery but block the smaller cerebral arteries or capillaries are common causes of strokes (discussed in detail in Chapter 15). The effect of a stroke maybe localized to particular regions of the brain depending on whether the posterior, middle, or anterior cerebral arteries are affected.

*See the Lecture Enrichment section for additional information about blood circulation within the central nervous system.

III. The Central Nervous System (pp. 33-51)

PowerPoint Slides 2-11 through 2-35

Clicker Question #3

Chapter 2

Film Clip #3: Brain-Computer Interfaces for Paralyzed Individuals

A. The Spinal Cord (pp. 34-35)

1. The spinal cord may be divided into cervical, thoracic, lumbar, and sacral segments.

The spinal cord segments are named according to vertebral bones surrounding the spinal cord. The incoming afferent sensory nerves and outgoing efferent motor nerves exit the vertebral column between each vertebral bone resulting in 31 discrete nerve segments. The 8 cervical nerves serve the head, neck, and arms; the 12 thoracic nerves serve the torso; the 5 lumbar nerves serve the lower back and legs; and the 5 sacral nerves serve the backs of the legs and the genitals. The most caudal spinal nerve is the coccygeal nerve.

2. In addition to carrying messages to and from the brain, the spinal cord provides a variety of protective and motor reflexes.

The withdrawal reflex is a commonly understood reflex that involves only three neurons. The afferent sensory neuron enters the dorsal spinal cord and forms a synapse in the gray matter of the dorsal horn with both an ascending sensory neuron that travels to the brain in the dorsal column white matter and an interneuron. In turn, the interneuron along with descending motor neurons traveling in the ventral white matter form a synapse with the outgoing ventral motor neuron to complete the reflex circuit. The level of incoming sensory signals determines activation of the interneuron with lower levels of input ascending to the somatosensory cortex without activating the reflex circuit.

*See Supplemental Teaching Strategy 1: Active Learning: Drawing Neuroanatomy.

B. Embryological Divisions of the Brain (p. 35)

In terms of evolution, the development of brain regions follows the order of hindbrain then midbrain then forebrain, with the cerebral hemispheres being the most recent brain structure to develop. Similarly, functions associated with each brain region begin with the most basic life sustaining functions and progress to more complex functions through the ascending brain regions.

During early embryonic development, the brain is divided into three parts: the hindbrain, the midbrain, and the forebrain. The midbrain and the hindbrain collectively comprise the brainstem. The midbrain does not divide further, but the hindbrain divides into the metencephalon (pons and cerebellum) and the myencephalon (medulla). The forebrain further divides into the diencephalon and telencephalon. The telencephalon contains the basal ganglia, limbic system, and cerebral cortex.

C. The Hindbrain (pp. 35-38)

The Anatomy and Evolution of the Nervous System

Film Clip #4: Human Brain Tutorial on Brainstem and Diencephalon

1. The hindbrain consists of the medulla, pons, and cerebellum. The medulla is also known as the myelencephalon, and together, the pons and cerebellum make up the metencephalon.

In addition to containing nuclei representing the first central nervous system synaptic processing of incoming somatosensory, vestibular, auditory, and taste neural signals, the medulla and pons also contain several nuclei that control life sustaining functions such as heart rate, respiration, and the vomiting reflex.

*See the Lecture Enrichment section for additional information about the hindbrain nuclei.

In addition to its known role in coordinating neural signals from the sensory and motor systems, the cerebellum also likely plays a role in cognitive functions such as attention, learning, and memory. The specific role of the cerebellum in advanced cognitive functioning has yet to be fully characterized.

Abnormal development of the cerebellum is often observed in individuals with autism spectrum disorder who have deficits in language, cognition, and social awareness.

The dentate nucleus is enlarged in monkeys and humans, and a portion of this – the neodentate – is only present in humans.

*See the Supplemental Reading section for additional information about the well-documented role of the lateral interpositus nucleus of the cerebellum in the ability of rabbits to learn the classical conditioning of an eye blink in response to an auditory tone (see Chapter 12).

2. Running through the medulla and pons at the midline is the reticular formation, which helps control arousal.

3. Due to the associated life sustaining functions, damage to hindbrain - and the reticular formation in particular – is likely to cause coma or death. Trauma to the brain often produces a swelling response that can apply pressure on the hindbrain inducing a transient coma until the pressure is relieved.

D. The Midbrain (pp. 38-39)

Clicker Question #4

The midbrain, also known as the mesencephalon, contains the remaining section of the reticular formation, the periaqueductal gray, the red nucleus, the superior colliculi, the inferior colliculi, and the substantia nigra. The dorsal and ventral regions are referred to as the tectum and tegmentum, respectively.

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The periaqueductal gray is involved in gate control theory of natural pain management as part of the descending pathway responsible for the release of opioid peptides in response to incoming pain signals in the spinal cord.

The red nucleus is involved in the motor output pathway and is the efferent nucleus receiving information from the lateral interpositus nucleus of the cerebellum to produce the conditioned eyelid response to an auditory tone in the example of classical conditioning learning discussed in the Supplemental Reading section.

The substantia nigra is a midbrain nucleus specifically targeted during the neural degeneration of Parkinson’s disease. The loss of the pathway from the substantia nigra to the basal ganglia produces the primary motor symptoms of Parkinson’s disease.

The superior and inferior colliculi are respectively involved in the ability to orientate the body toward visual and auditory stimuli. Animals that rely on visual and auditory tracking to detect prey have proportionally larger superior or inferior colliculi.

E. The Forebrain (pp. 39-50)

The forebrain includes the diencephalon and the telenencephalon.

PowerPoint Slides 2-22 through 2-35

Clicker Questions #5 and 6

Film Clip #5: Horizontal Section of Human Brain at the Roof of the Third Ventricle

Film Clip #6: The Basal Ganglia

Film Clip #7: Sagittal Section at the Hippocampus

Film Clip #8: Sagittal Section at the Amygdala

1. The diencephalon contains the thalamus and hypothalamus.

A common misconception is that the thalamus serves as a “relay” nucleus with little or no processing of incoming sensory information. The thalamus receives sensory and regulatory input, and participates in states of consciousness and arousal (see Chapter 11) and learning and memory (see Chapter 12).

*See the Lecture Enrichment section for additional information regarding the role of the processing in the thalamus.

The hypothalamus is best described as the central regulator of the internal physiological state of our body, including the homeostatic functions of circadian rhythms, thermoregulation, reproduction, and ingestive behavior. The hypothalamus also controls the release of hormones from the pituitary gland and regulates the activation of the autonomic nervous system. The hypothalamus is a collection of nuclei, including the ventromedial and suprachiasmatic nuclei.

The Anatomy and Evolution of the Nervous System

2. The telencephalon contains the basal ganglia, the limbic system structures, and the cerebral cortex.

a) The basal ganglia

The basal ganglia consist of the anterior and medially located caudate nucleus, the putamen and globus pallidus located anterior and lateral to the thalamus, and the subthalamic nucleus located below the thalamus. The basal ganglia border the lateral ventricles and degeneration of the basal ganglia, such as that occurring in Huntington’s disease, is often identified through brain scans revealing enlarged lateral ventricles. Pressure on the basal ganglion from CSF in the lateral ventricles produces the shuffling gait symptom of normal pressure hydrocephalus.

b) The limbic system

The limbic system consists of medial subcortical structures collectively involved in memory or the interpretation and expression of emotion. Some limbic structures such as the amygdala and septal area appear to have specific emotional functions (fear, rage, attack, and aggression), while other areas such as the cingulate cortex have broader functional roles. The anterior cingulate cortex (ACC) also participates in decision-making, error-detection, anticipation of reward, and empathy. The posterior cingulate cortex (PCC) participates in eye movements, spatial orientation, and memory, and is one of the first structures affected by Alzheimer’s disease. The hippocampus, parahippocampal gyrus, mammillary bodies, and fornix form tightly connects circuits involved in the formation of declarative memories (see Chapter 12). Emotion, the sense of smell, and the formation and recall of memories have strong associations between one another, thus the olfactory bulbs are often associated as limbic system structures.

c) The cerebral cortex

The “hills” of the cortex are referred to as gyri (plural of gyrus), and the “valleys” are referred to as sulci (plural of sulcus) or fissures. The extent of the convolution of the cerebral cortex into gyri and sulci is directly related to the amount of cortical surface area contained within the skull. As the skull restricts the available volume for brain matter, the “wrinkling” of the cortex allows a greater surface area and thus more cortical neurons.

Most cognitive functions are associated with the cerebral cortex and there is a positive correlation between the degree of cortical convolution and the cognitive abilities of various species.

*See the Supplemental Teaching Strategies and Tools section for a demonstration of the ability of convolutions to increase surface area.

The cerebral cortex is made up of six layers that cover the outer surface of the cerebral hemispheres. Layer I is composed of nerve fibers. Layers II and IV

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contain granule cells, while layers III and V contain pyramidal cells. Layer VI has many types of neurons.

Brodmann divided the cerebral cortex into 52 areas based on the distribution of the cell bodies in the six layers of the cortex. More simply, the cerebral cortex is divided into four lobes: the frontal lobe, which is associated with motivation, personality, emotion, cognitive tasks such as executive function and judgment, and the motor system; the parietal lobe, which is associated with somatosensation, association cortex, and advanced visual processing, such as how to correctly respond to a visual stimulus; the temporal lobe, which is associated with the auditory system, language comprehension, and association cortex involved with memory storage; and the occipital lobe, which is almost exclusively reserved for processing visual stimuli.

The cerebral cortex also can be divided into sensory (somatosensation in the anterior parietal lobe, audition in the superior temporal lobe, vision in the occipital lobe, olfaction in the ventral frontal lobe, and gestation in the insular cortex at the junction of the temporal and parietal lobes), motor (posterior frontal lobe), or association cortex based on function. Most of the sensory areas of the brain are located towards the back (caudal areas), whereas most of the motor areas of the brain are located rostrally.

The two cerebral hemispheres are connected by the corpus callosum and the anterior commissure.

*See the Lecture Enrichment Section for additional information about correlations between corpus callosum size and handedness.

d. Localization of function in the cortex (pp. 46-49)

Details of the functions of specific brain regions are revealed when the area of interest is damaged. For example, the case of Phineas Gage, who survived an impalement of the frontal lobe, demonstrated the association between frontal lobe damage and personality changes.

Connecting to Research: The Connectome and Phineas Gage (p. 48)

Thinking ethically: Can we Localize Intelligence in the Brain? (p. 49)

Some functions, such as language, appear to be localized on one hemisphere or the other.

While there is good evidence of the lateralization of function for some specific tasks, such as language comprehension in Wernicke’s area of the left temporal lobe and language production in Broca’s area of the left frontal lobe, the lateralization of other more intricate cognitive functions is much less clear (see Chapter 13). In general, the right hemisphere reacts more to negative emotional

The Anatomy and Evolution of the Nervous System

stimuli (avoidance), whereas the left hemisphere reacts more to positive stimuli (approach; see Chapter 14).

e. Brain Circuits and the Connectome (pp. 49-50)

Neurons function within circuits. The Human Connectome Project seeks to map the neural connections within a healthy, adult human brain, using methods (e.g., diffuse tensor imaging) for investigating connections at the cellular and more macro levels.

IV. The Peripheral Nervous System (pp. 51-57)

PowerPoint Slides 2-36 through 2-40

A. The Cranial Nerves: Twelve pairs of cranial nerves exit the brain and provide sensory and motor functions to the head and neck. (pp. 51-52)

A simple summary of the nerves is as follows: CNI, olfactory nerve, smells; CNII, optic nerve, sees; CNIII, oculomotor nerve, moves eyes, constricts pupils, accommodates; CNIV, trochlear nerve, moves eyes; CNV, trigeminal nerve, chews and provides facial sensations; CNVI, abducens nerve, moves eyes; CNVII, facial nerve, tastes and produces facial expressions; CNVIII, auditory-vestibular nerve, hears and provides balance / posture sensations; CNIX, glossopharyngeal nerve, tastes and provides sensory / motor functions of throat; CNX, vagus nerve, provides input to and sensations from the chest (heart, liver, digestive tract); CNXI, spinal accessory nerve, moves the head, neck, and shoulders; CNXII, hypoglossal, moves the tongue. It is often helpful for students to employ a mnemonic device to remember the order and names of the twelve cranial nerves. To remember these in order: On Old Olympus Towering Tops, a Finn and German Viewed Some Hops.

B. The Spinal Nerves (pp. 52-53)

1. Spinal nerves contain dorsal afferent nerve roots and ventral efferent nerve roots of the somatic nervous system that merge outside the cord to form mixed nerves. A common pitfall is confusing the afferent and efferent terms. An easy association is that “a” comes before “e” in the alphabet and often we think of incoming “afferent” sensory information arriving before an outgoing “efferent” motor response to that sensation. Another mnemonic is to think of “a” for “access” and “e” for “exit.”

2. Efferent nerves are myelinated, whereas afferent nerves may or may not be myelinated (see Chapters 7 and 8).

C. The Autonomic Nervous System provides sensory and motor innervation to glands, organs, and smooth muscle. (pp. 49-52)

Two subcomponents of the autonomic nervous system, the sympathetic and parasympathetic nervous system, act in opposition to one another with three primary

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differentiations: action on target organs, anatomical pathway, and type of neurotransmitter released.

1. The sympathetic nervous system operates during times of arousal and prepares the body for fight-or-flight reactions. The sympathetic nervous system is connected at the level of the ganglion producing a system known as the sympathetic chain. This connectivity results in the sympathetic nervous system being activated simultaneously as a whole unit allowing fast and complete reactions to an emergency. Norepinephrine is the primary neurotransmitter released by the sympathetic nervous system to its target organs.

Film Clip #9: Fight or Flight

2. The parasympathetic nervous system operates during times of rest and restoration. Unlike the sympathetic nervous system, the parasympathetic neurons are not connected with individual neural pathways to each target organ. This allows for differential activation of specific targets in response to particular needs, such as activation of the digestive system in response to the ingestion of food. Acetylcholine is the primary neurotransmitter released by the parasympathetic nervous system to its target organs.

3. The enteric nervous system controls conscious sensations, including pain, hunger, and satiety. This control is exerted by communication with endocrine cells that release hormones necessary for digestion. In particular, 95% of the serotonin present in the body is released by actions of the enteric nervous system. Here, serotonin controls reflexes that moves food through the digestive tract. An excess of serotonin can lead to nausea and vomiting.

Building Better Health: Do Gluten-Free Diets Have Benefits for People with Autism Spectrum Disorder? (p. 57)

4. The actions of the endocrine system are largely controlled by the hypothalamus. The hypothalamus controls the autonomic nervous system by way of connections in the midbrain tegmentum. The pituitary gland (known as the "master gland") controls hormone secretions from many other glands.

V. Evolution of the Human Brain and Nervous System (pp. 57-61)

PowerPoint Slides 2-41 through 2-45

A. Natural Selection and Evolution (pp. 58)

1. Natural selection is the process by which favorable traits become more common in subsequent generations due to organisms’ varying reproductive success.

2. Fitness is a dynamic characteristic defined as the likelihood that an organism will reproduce successfully compared to other members of the same species.

B. Evolution of the Nervous System (pp. 57-61)

The Anatomy and Evolution of the Nervous System

Film Clip #10: Oldest Fossil Brain

Film Clip #11: Reverse Evolution

1. The nervous system has been a relatively recent development in the course of evolution.

2. Single-cell organisms originated 3.5 billion years ago. Organisms developed neural nets approximately 700 million years ago, followed by organisms with ganglia located in a head region approximately 250 million years ago. Human brains appeared approximately 7 million years ago.

3. Early neural networks consist of ventrally located ganglia, which are vulnerable to attack or damage. Such animals without a spinal cord are called invertebrates.

4. Chordates (also known as vertebrates) are the only animals possessing a true spinal cord and brain. The location of the brain in the head is close to major sensory systems. The brain and spinal cord are protected by bone, and the dorsal location is easier to defend.

5. As the brain evolved, it became larger. In particular, the encephalon or cerebral cortex expanded and due to the capacity limit of the skull, the cerebral cortex became more convoluted.

*See the Supplemental Reading section for additional information on comparative neuroanatomy across species.

C. Evolution of the Human Brain (pp. 59-61)

Clicker Questions #7 and #8

Film Clip #12: Human Evolution

Film Clip #13: Hominid Development

Film Clip #14: Neanderthal DNA Sequenced

Film Clip #15: Brain Evolution

1. Human beings have experienced very rapid brain development over the last seven million years, possibly in response to the challenges of using tools, language, social behavior, body size, the need to adapt to changing climates, and the long dependency of children.

2. It is unclear is why such major cultural changes over the last 200,000 years, such as agriculture, urbanization, and literacy, have not produced additional changes in brain size. One explanation of the late of recent changes in brain size is that a ceiling effect may have been reached where the advantages of further increases in brain size may be offset by childbirth difficulties and the large amount of resources required by the nervous system.

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LECTURE ENRICHMENT

II. B. – Daily CSF ProductionThe total CSF volume in an adult is approximately 120 ml and the average daily production of CSF ranges between 300 to 500 ml resulting in approximately three turnovers per day. The passages between the lateral ventricles and the third ventricle as well as the cerebral aqueduct are narrow and have the potential to be restricted by either the growth of a tumor or general swelling of the brain in response to a traumatic event. Since the CSF is continuously produced, restricting its flow results in an increase of ventricle pressure that can produce brain damage if the pressure is not relieved by insertion of a shunt to drain the excess CSF. Hydrocephalus is a condition, typically occurring during development in newborn infants, in which the CSF flow is restricted and must be relieved through shunt insertion.

II. B. – Normal Pressure HydrocephalusNormal pressure hydrocephalus (NPH) is a relatively new clinical diagnosis that typically occurs in elderly patients and is believed to be related to a decrease in the absorption of CSF by the arachnoid villi. The symptoms of NPH, dementia, a shuffling gait, and urinary incontinence, are often misdiagnosed as either Alzheimer’s disease or Parkinson’s disease.

Typically, NPH is diagnosed using a neuroimaging scan of the brain to identify enlarged ventricles due to the CSF pressure. Insertion of a shunt to relive the CSF pressure immediately alleviates all three debilitating symptoms. *See the Supplemental Reading List for additional information.

II. C. – Blood Circulation in the Central Nervous SystemBlood containing oxygen and nutrients is supplied to the brain through arteries and capillaries found in the subarachnoid space found between the arachnoid and pia mater layers. Blood containing waste products pools in the venous sinus cavities between the arachnoid space and dura before exiting the brain through the veins. A leak in the blood system may produce a pocket of fluid that depending on its location may be described as a subdural or subarachnoid hematoma.

III. B. 1. – Hindbrain NucleiIt is important to note that the hindbrain sensory nuclei are not merely “relay” synapses, but, rather, there is significant processing of the incoming sensory signals in these hindbrain nuclei. Several of the hindbrain nuclei that control life sustaining functions utilize common neurotransmitters, such as dopamine, permitting serious side-effects of dopaminergic drugs that are intended to activate higher cortical centers such as the nucleus accumbens.

III. D. 1. – Processing in the ThalamusIt is well documented that the thalamus plays a critical role in filtering incoming sensory information based on the amount of attention paid to particular sensations. Furthermore, using the vision system as an example, there is a divergence of neural signals within the complex

The Anatomy and Evolution of the Nervous System

retinotopic organization of neurons in the lateral geniculate nucleus of the thalamus. This provides both the first central nervous system consolidation of visual fields from both the left and right retinas, as well as a separation of the magnocellular and parvocellular pathways with approximately 1 million incoming ganglion axons to each ipsilateral thalamus and 1.5 million projection neurons to the visual cortex in the occipital lobe.

III. D. 3. d) – Corpus Callosum and HandednessThe corpus callosum of individuals who are left-handed appears to be approximately 10% larger than the corpus callosum of individuals who are right-handed. It is speculated that an increase in neural transmission from the language areas of the left hemisphere to the motor output of the right hemisphere may be related to this increase in connectivity.

SUPPLEMENTAL READING LIST

Genes to CognitionCold Spring Harbor Laboratory in New York maintains a multimedia-rich site covering neuroanatomy, genetics, cognition, and clinical disorders. Especially useful for teaching this chapter is the 3-D interactive brain. The brain can be fully rotated, and underlying structures can be selected. http://www.g2conline.org/

The Cerebellum’s Role in CognitionEvidence is emerging to support a role of the cerebellum in cognitive functioning. In particular, the cerebellum has been shown to play a critical role in the ability of rabbits to learn an association between an eyelid response and an auditory tone through a classical conditioning paradigm. More information on the role of the cerebellum in this learning process can be found in the following publications:

Learning- and cerebellum-dependent neuronal activity in the lateral pontine nucleus. Bao S, Chen L, Thompson RF. Behav Neurosci. 2000 Apr;114(2):254-61.

Neuronal activity in the cerebellar interpositus and lateral pontine nuclei during inhibitory classical conditioning of the eyeblink response. Freeman JH Jr., Nicholson DA. Brain Res. 1999 Jul 3;833(2):225-33.

Reversible lesions of the red nucleus during acquisition and retention of a classically conditioned behavior in rabbits. Clark RE, Lavond DG. Behav Neurosci. 1993 Apr;107(2):264-70.

Normal Pressure Hydrocephalus (NPH) eMedicine Reference Entry for Normal Pressure Hydrocephalus. Author: Arif Davli. Contains background, pathophysiology, symptoms, and treatment information for the relatively new

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clinical diagnosis of normal pressure hydrocephalus in the elderly. http://www.emedicine.com/neuro/topic277.htm

Saved from Senility. 60 Minutes Broadcast on October 7, 2004 featuring case studies of NPH. Videotape Information 1-800-848-3256. http://www.cbsnews.com/stories/2004/10/04/60II/main647205.shtml

The Visible Human Project®

The National Library of Medicine’s Visible Human Project® provides serial sections through not only the nervous system but the entire body of a man and woman allowing visualization of the central and peripheral nervous system components in relation to non-neural physiological structures. http://www.nlm.nih.gov/research/visible/visible_human.html

The Human Brain: An Introduction to Its Functional AnatomyThe Human Brain describes the structure and function of the brain and nervous system focusing on neurobiology and neurophysiology. The latest edition includes clinical content, many images depicting neurological disorders, and expanded sections on higher cortical functions such as learning and memory. Publication information: John Nolte, The Human Brain: An Introduction to Its Functional Anatomy. 6th edition, C.V. Mosby, Print Book ISBN: 9780323041317, eBook ISBN: 9780323064750.

Other useful references include:

Haines, D.E. (2011). Neuroanatomy: An Atlas of Structures, Sections, and Systems, 8th edition, Lippincott. ISBN: 9781605476537

Nolte, J. (2013). The Human Brain in Photographs and Diagrams 4th edition, Mosby. ISBN: 978-8184735789

Neuroanatomy Through Clinical CasesNeuroanatomy through Clinical Cases uses over 100 actual clinical case studies and high-quality radiological images as the basis for teaching functional neuroanatomy. The clinical cases and images in this text would provide excellent examples in the classroom instruction of neuroanatomy. Each chapter is separated into a section of background neuroanatomical information followed by related clinical cases. The clinical cases are presented as a narrative of the patient’s symptom development and subsequent neurological examination. Publication information:

Blumenfeld, H. Neuroanatomy through Clinical Cases, 2nd edition, Sinauer Associates, ISBN: 9780878936137

Comparative Neuroanatomy Across SpeciesThis website provides good visual and descriptive information about comparative neuroanatomy across multiple species. http://serendip.brynmawr.edu/bb/kinser/Home1.html

The Anatomy and Evolution of the Nervous System

SUPPLEMENTAL TEACHING STRATEGIES AND TOOLS

Active Learning: Drawing NeuroanatomyEncouraging students to physically draw the components of the nervous system engages the students in an active learning process that will produce longer lasting memories than mere observation of text or lecture diagrams. A common stumbling block is the students’ belief that they cannot draw very well. This anxiety can be alleviated by the instructor producing their own drawings during the lecture, encouraging the students to do likewise, and demonstrating that even crude or unrefined drawings are still very beneficial in understanding the anatomical terms and the locations of central nervous system structures. Good opportunities to use active learning through drawing are presented during instruction of the anatomical directions (especially the difference between four-legged animals and humans, draw an example for each and label the anatomical directions in both the head and spine of the human), the lobes of the brain, and the spinal cord anatomy (draw a cross-section of the spinal cord including the white versus gray matter and dorsal versus ventral nerves; in addition, it can also be beneficial to then draw a spinal reflex circuit to aid in understanding the relationship between afferent and efferent pathways in the spinal cord).

In addition, students can be encouraged to use the coloring book feature of the Student Study Guide. Illustrations from the textbook appear with keys and label lines.

Demonstrating Daily CSF TurnoverFor this demonstration you will need the following items: 6 pack of 500 ml bottles of water, 150 ml beaker, 2 L beaker, and 1 tennis ball. At the front of the class, set up the 150 ml beaker inside of a 2 L glass beaker and remove 3 of the bottles of water from the 6 pack leaving the other 3 bottles of water intact in the 6 pack ring binder.

Demonstrate the total volume of the CSF by pouring enough water to fill the 150 ml beaker. Next, demonstrate the total amount of CSF produced each day by continuing to empty the 500 ml water bottle into the 150 ml beaker inside of the 2 L beaker. Finally, demonstrate the effects of hydrocephalus by adding another 1 or 2 500 ml bottles of water to show the amount of CSF and corresponding pressure produced per day in the event of a blockage of the ventricle system.

Demonstrating Daily CSF BuoyancySimilar to the reduction in your body weight when you float in a pool, the buoyancy effect of the CSF reduces the weight of the brain 97% from 1500 grams to 50 grams, the difference between the weight of four cans of soda versus a tennis ball. For this demonstration you will need the following items: three 500 ml bottles of water and one tennis ball. During this demonstration, you can pass the additional 3 bottles of 500 ml water leftover from the above CSF turnover demonstration (approximate weight 1500 g) and the tennis ball (approximate weight 50 g) around the class as a demonstration of the reduction in adult brain weight due to the buoyancy effect of CSF.

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Demonstrating the Ability of Convolutions to Increase Surface AreaFor this demonstration you will need a bowl, several large sheets of paper, and scissors or a marker pen. To demonstrate the difference in surface area for smooth and convoluted structures such as the cerebral cortex of various species, first fit a piece of paper to the inside of the bowl in as smooth a manner as possible. Then, cut off the excess paper or trace the rim of the bowl on the paper with the marker. The bowl represents the fixed volume of the skull and the paper represents the amount of cortex for a species with a relatively smooth cerebral cortex. Now, crumble a sheet of paper to produce small convolutions in the surface and fit as much of the paper around the inside of the bowl as possible. Then, cut off any excess paper or trace the rim of the bowl on the paper with the marker. Finally, flatten the convoluted paper and compare to the original surface area of the smooth paper. This demonstration works best if rehearsed with various size bowls and pieces of paper prior to use in the classroom.

Sheep Brain DissectionsMany online demonstration is especially useful to faculty who have limited lab facilities. A simple version can be found here: http://www.hometrainingtools.com/articles/brain-dissection-project.html. This version includes downloadable pdfs for printing and labeling.

This Exploratorium version has some excellent images: http://www.exploratorium.edu/memory/braindissection/index.html

A nice handout with photographs and clear directions is here: http://psych.hanover.edu/classes/neuropsychology/Syllabus/Labs/DISSECTION.pdf

Human Brain TutorialThis nice little site compares MRI images and models of the human brain. You click on a structure, and a name appears along with a multiple choice question to test your learning. http://www.gwc.maricopa.edu/class/bio201/brain/BrainModelMap.htm

FILM CLIP SUGGESTIONS1) The Ventricles (5:12)http://www.youtube.com/watch?v=9hI1j4xQ-n8&feature=related

2) Insertion of a CSF Shunt (1:04)http://www.youtube.com/watch?v=Qmym2iFVNw8&feature=related

3) Brain-Computer Interfaces (Stanford University) (14:11)Krishna Shenoy is creating "brain-computer interfaces" that will enable paralyzed patients to control prosthetic arms and computer cursors. In this short talk, Shenoy describes how his team of Stanford researchers has built a system that achieves typing at 15 words-per-minute, just by "thinking about it".http://www.youtube.com/watch?v=I7lmJe_EXEU&feature=PlayList&p=373EE4E8CFAA2B19&index=0&playnext=1

The Anatomy and Evolution of the Nervous System

4) A tutorial on the brainstem and diencephalon using a real human brain (4:40)http://www.dailymotion.com/video/x5ugwe_neuroanatomy-neuroanatomia_school

5) Horizontal Section of Human Brain at the Roof of the Third Ventricle (4:31)Various structures in a human brain horizontal slice at the level of the roof of the third ventricle. Structures include thalamus, caduate, lateral ventricles, fornix, internal capsules and more.http://www.youtube.com/watch?v=hSOK2_SZLW8&feature=related

6) The Basal Ganglia (5:35)http://www.youtube.com/watch?v=EluAk9NWOJI

7) Sagittal Section at the Hippocampus (1:56)Various structures in a human brain sagittal slice at the level of the hippocampus. Structures include amygdala, caduate, lateral ventricles, hippocampus, internal capsules and more.http://www.youtube.com/watch?v=MD0XHzsRhLo&feature=related

8) Sagittal Section at the Amygdala (2:11)Various structures in a human brain sagittal slice at the level of the amygdala. Structures include amygdala, caduate, lateral ventricles, hippocampus, internal capsules and more.http://www.youtube.com/watch?v=wQJ1nAY9jxY&feature=related

9) Fight or Flight (3:45)The role of the amygdala, hypothalamus, and cortex in responding to danger.http://www.youtube.com/watch?v=RyP8L3qTW9Q&feature=related

10) Oldest Fossil Brain (0:41) http://www.newscientist.com/articlevideo/dn16699/14612708001-bugeyed-fish-reveals-oldest-fossil-brain.html

11) Reverse Evolution (1:40)Scientists have reversed evolution, reconstructing a gene that existed more than 500 million years ago. The gene controls our ability to smile or frown.http://www.youtube.com/watch?v=qyJGA_1_v8A&feature=channel

12) Human Evolution (2:14)http://www.youtube.com/watch?v=ahloeBhlcYk&feature=related

13) Hominid DevelopmentDikika Research ProjectThe DiscoveryApe or Human?What Can We Conclude?http://www.nature.com/nature/focus/hominiddevelopment/video/index.html

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14) Neanderthal DNA SequencedIntroductionNew TechniquesAnalysisConclusionshttp://www.nature.com/nature/videoarchive/neanderthaldna/

15) Evolving Brain (1:17)Battles over teaching evolution may be playing out near you. Meanwhile, scientists have new evidence that our most important organ - the brain- is still evolving.http://www.youtube.com/watch?v=o5_COfNSu5k&feature=channel**Note: Lahn’s work is undeniably controversial given its racial implications, so instructors should research this topic prior to presenting the film. See an interview with Lahn at SEED, from http://seedmagazine.com/content/article/seed_interview_bruce_lahn/His original paper is here: http://www.sciencemag.org/cgi/content/abstract/309/5741/1720

CLICKER QUESTIONS FOR AUDIENCE RESPONSE SYSTEMS1. I have had a vaccination for bacterial meningitis.

A. YesB. No

Question type: React

2. John’s grandfather had a serious stroke involving his left middle cerebral artery. Which behavior are likely to be the most challenging for him now?

A. seeing the right visual fieldB. planning behavior and making decisionsC. interpreting the facial expressions of other peopleD. speaking and understanding language

Question type: Check your learning

3. Daniel damaged his spinal cord at the cervical level in an automobile accident. What will be the most likely result of his accident?

A. Daniel’s damage will heal over the course of about six months to a year.B. Daniel will be a quadriplegic, meaning he will lose the use of arms and legs.C. Daniel will probably be paralyzed on the right side of his body.D. Daniel will be a paraplegic, meaning that he will lose the use of his legs, but not his arms.

Question type: Check your learning

4. The substantia nigra can be found in which division of the brain?A. The myelencephalonB. The metencephalonC. The mesencephalonD. The diencephalon

The Anatomy and Evolution of the Nervous System

E. The telencephalonQuestion type: Check your learning

5. If you were a physician treating a patient with a tumor pressing on his or her amygdala, which action would you take?

A. Inform the patient that in rare similar cases, irrational violence has occurred.B. Simply treat the medical condition without discussing the possible behavioral outcomes.C. Alert authorities that the patient has a definite risk of irrational violence.D. Discuss the possibility of irrational violence with the patient’s immediate family

members.Question type: React

6. Which statement is correct?A. Sensory and motor areas are evenly distributed among the four lobes of the brain.B. Sensory processing takes place in the right hemisphere, whereas motor processing takes

place in the left.C. Sensory processing takes place toward the front of the brain, and motor processing occurs

towards the back of the brain.D. Sensory processing takes place toward the back of the brain, and motor processing

occurs towards the front of the brain.Question type: Check your learning

7. Human beings, as we know them, developed from earlier species of animals.A. TrueB. False

Question type: ReactNote: This is the classic question used in Miller et al.’s work on public opinion world-wide about evolution: Miller, J.D., Scott, E.C., & Okamoto, S. (2006). Science communication. Public acceptance of evolution. Science, 313, 765-766. Figure 2.3 compares rates of agreement in many different countries.

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8. Evolution is still occurring among contemporary humans.A. TrueB. False

Question type: React

The Anatomy and Evolution of the Nervous System