recap

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46.3 recap

Complex functions of the nervous system can be understood in terms of the properties of neurons and neural networks. Language functions are lateralized to the left cerebral hemisphere. So, since information about objects seen in the left visual field is processed in the right visual cortex, cannot be described in words, but they can be drawn. Imaging shows the integration of different brain areas in the hearing, reading, and speaking of words. REM and non-REM sleep and awake states involve very different activities in many areas of the brain. Sleep states have a regular organization of expression during the daily rest phase. At the cellular level, learning and memory involve changes in synaptic strength, and memory processes involve interactions of neural networks from different brain areas. Declarative memories are acquired through the hippocampus. Consciousness may involve creation of a perception of the self in the insular cortex.

learning outcomes

You should be able to:

  • Recognize the characteristic EEGs associated with wakefulness, non-REM sleep, and REM sleep, and infer which brain areas are active during these distinct phases of the sleep–wake cycle.

  • Describe the flow of information when speaking a written or a heard word, and specify which areas of the brain are involved in speech processing.

  • Connect the modification of synaptic strength in place cells to the development of a spatial map in the hippocampus.

  • Connect evolutionary changes in brain structures to the development of self-awareness.

Question 1

What is the significance of paralysis of skeletal muscles during REM sleep?

Paralysis of skeletal muscles during REM sleep prevents the possibility that an individual would act out his or her dreams while in the dreaming state.

Question 2

If a person with a severed corpus callosum is shown an object in his left visual field, how will he be able to communicate to an observer what that object is?

A person with a severed corpus callosum would not be able to describe in words an object in his left visual field, but he could draw it or point to a similar object in a picture.

Question 3

What does the case of H.M. tell us about the brain mechanisms underlying the acquisition of declarative memories?

Since H.M. was capable of immediate memory but could not retain longer-term declarative memories, we can conclude that the hippocampus is necessary for acquiring new declarative experiences and consolidating them into long-term memory.

Question 4

What is unique about the insular lobes of higher mammals that may explain the evolution of consciousness?

Humans, great apes, elephants, and some marine mammals have an expanded insular lobe, which is involved in integrating physiological information from throughout the body, as well as social and emotional information, and may therefore generate a sense of self-awareness.