Chapter 2 The Biology of Mind © 2013 Worth Publishers

The Inner and Outer Parts of the Nervous System The peripheral nervous system [PNS] consists of ‘the rest’ of the nervous system. The PNS gathers and sends information to and from the rest of the body. The central nervous system [CNS] consists of the brain and spinal cord. The CNS makes decisions for the body. No animation. The descriptive text is color-coded to go with the part of the nervous system referred to in the diagram. The image is from a previous version of the text.

More Parts of the Nervous System No animation. Note that the autonomic, somatic, sympathetic, and parasympathetic branches of the nervous system are all part of the PNS. Nerves consist of neural “cables” containing many axons. Nerves consist of neural “cables” containing many axons. Nerves are part of the peripheral nervous system and connect muscles, glands, and sense organs to the central nervous system.

The Autonomic Nervous System: The sympathetic NS arouses (fight-or-flight) The parasympathetic NS calms (rest and digest) No animation. 1. Question to ask students: Why not just stay aroused all the time?...to allow the body to repair itself and regain energy from food. 2. Comment to students: note the sympathetic nervous system’s effect on the stomach and bladder., This helps us understand why “I was so upset that I wet my pants” or “I was so upset I threw up.” Now you can take these reports as a sign of strong activation of the sympathetic part of the autonomic nervous system.

Studying cases of brain damage When a stroke or injury damages part of the brain, we have a chance to see the impact on the mind. No animation. Instructor: Some examples of brain areas we learned about thanks to patients with brain damage: the frontal lobes (as with Phineas Gage, pictured here), Broca’s area, and Wernicke’s area. Broca’s area is named after French physician Pierre Paul Broca (1824-1880) . Wernicke’s area was named after German physician Carl Wernicke (1848-1905).

We can stimulate parts of the brain to see what happens Parts of the brain, and even neurons, can be stimulated electrically, chemically, or magnetically. This can result in behaviors such as giggling, head turning, or simulated vivid recall. Researchers can see which neurons or neural networks fire in conjunction with certain mental experiences, and even specific concepts. Click to reveal bullets. Hopefully students will understand that brain stimulation is less dramatic than the use of a bolt of lighting; it involves only small electrodes. Although people feel like the stimulation of certain brain locations produces vivid memories, research has proven that this impression is false; the memories feel vivid, but are inaccurate.

EEG: electroencephalogram PET: positron emission tomography An EEG (electroencephalogram) is a recording of the electrical waves sweeping across the brain’s surface. It is useful in studying seizures and sleep. The PET scan allows us to see what part of the brain is active by tracing where a radioactive form of glucose goes while the brain performs a given task. No animation. EEGs use electrodes placed on the scalp.

MRI: magnetic resonance imaging fMRI: functional MRI MRI (magnetic resonance imaging) makes images from signals produced by brain tissue after magnets align the spin of atoms. The arrows below show ventricular enlargement in a schizophrenic patient (right). Functional MRI reveals brain activity and function rather than structures. Functional MRI compares successive MRI images taken a split second apart, and shows changes in the level of oxygen in bloodflow in the brain. Click to reveal Functional MRI information.

Phineas Gage (1823-1860) Case study: In a work accident, a metal rod shot up through Phineas Gage’s skull, destroying his eye and part of his frontal lobes. After healing, he was able to function in many ways, but his personality changed; he was rude, odd, irritable, and unpredictable. Possible explanation: Damage to the frontal lobes could result in loss of the ability to suppress impulses and to modulate emotions. The possible explanation appears with a click. See if students can guess at an explanation for Gage’s symptoms based on the area of brain damage.

Plasticity: The Brain is Flexible This 6-year-old had a hemispherectomy to end life-threatening seizures; her remaining hemisphere compensated for the damage. If the brain is damaged, especially in the general association areas of the cortex: the brain does not repair damaged neurons, BUT it can restore some functions it can form new connections, reassign existing networks, and insert new neurons, some grown from stem cells Click to reveal bullets and example. Despite lists of lateralized functions, there are many areas of overlap and duplication in the hemispheres. This is part of the reason that the girl with only one hemisphere was able to adapt.

Our Two Hemispheres Lateralization (“going to one side”) The two hemispheres serve some different functions. How do we know about these differences? Brain damage studies revealed many functions of the left hemisphere. Brain scans and split brain studies show more about the functions of the two hemispheres, and how they coordinate with each other. Click to reveal bullets. Brain scan studies show normal individuals engage their right brain when completing a perceptual task and their left brain when carrying out a linguistic task. However, many functions of the two hemispheres overlap.

Split-Brain Patients “Split” = surgery in which the connection between the brain hemispheres is cut in order to end severe full-brain seizures Study of split-brain patients has yielded insights discussed at the end of the chapter Click to reveal bullets.

Split- Brain Studies To end severe whole-brain seizures, some people have had surgery to cut the corpus callosum, a band of axons connecting the hemispheres. Click to reveal two sentences. Researchers have studied the impact of this surgery on patients’ functioning.

Divided Awareness in the Split Brain Try to explain the following result: No animation. See if the students can piece it together: the left hemisphere is the one that does verbal language, and that hemisphere is processing the right visual field, so what it can verbally report is “Art.”

The divided brain in action Talent: people are able to follow two instructions and draw two different shapes simultaneously Drawback: people can be frustrated that the right and left sides do different things Click to reveal second bullet. People with ‘divided brains’ may be more likely to report frustration with what the LEFT hand is doing; see if students can figure out why that is (the left hemisphere is the one talking to you and doesn’t know what input or purposes the right hemisphere is acting on). The Future of Brain Research: Can these questions be answered? Is every part of the mind’s functioning going to be found someday on some brain scan? If so, have we found the mind, or is that still something separate from the brain?

Whole-brain Association Activity Whole-brain association activity involves complex activities which require communication among association areas across the brain such as: memory language attention meditation and spirituality consciousness Click to reveal list.