Section 1.4 of the textbook describes circadian rhythms. You may have noticed that you have natural highs and lows throughout the day. Thinking about your own 90-minute cycle and how it may relate to yourself and learning, how would you prepare yourself for taking a big test in your course/class at the end of the day? If you need more information, consider reviewing the Circadian Rhythms Fact Sheet from the National Institutes of Health or the open-access Journal of Circadian Rhythms.
Willis, J., & Mitchell, G. (2014). The neuroscience of learning: Principles and applications for educators. San Diego, CA: Bridgepoint Education.
o Chapter 1: section 1.4 Structures and Functions of the Brain
The Diencephalon: Taking Care of the Bodyâ€™s Business
The diencephalon is located directly above the midbrain. Information from the midbrain must pass through the diencephalon in order toreach the higher parts of the forebrain. While the lobes of the brain play a critical role in such aspects of our lives as voluntary control,thinking, perception, and memory storage, the diencephalon is a processing center for things that go on without our conscious awareness orvolition. The structures in the diencephalon take care of business that supports the body without our conscious supervision.
The diencephalon is composed of two components, the hypothalamus and the thalamus. The hypothalamus is a control center that is incharge of maintaining the overall metabolic state of the body. To do this, the hypothalamus maintains body temperature, signals for therelease of hormones from the pituitary gland, activates hunger and thirst responses, and maintains the biological clockâ€”our circadianrhythm. Acircadian rhythm controls ourcircadian cycle, which is a change in biological and behavioral functioning over a 24-hour period. Forexample, we have different levels of alertness throughout the day. Typically, levels of alertness increase until about midday, and then decrease.After a period of rest, alertness levels increase again until evening and then begin to drop again. Ourcircadian rhythm responds to externalcues such as the setting and rising of the sun or changes in the seasons.
The sensory processing component of the diencephalon, the thalamus, receives all sensory information before it goes to the specific lobe ofthe brain where it is analyzed. In the case of smell this process is a little different. When sensory information comes in from the nose, it is firstprocessed by the primary olfactory cortex in the base of the temporal lobe. Next, it is passed to the thalamus, which relays the information tothe orbitofrontal cortex (located in the frontal lobe) for further processing of smell information. In other senses, the information would passthrough the thalamus en route to the primary cortical area. It should be noted that sensory pathways in the brain also project to otherstructures. For example, there is a branch of the taste pathway that travels to the limbic system. However, as sensory information istransmitted to higher cortical areas (i.e., the visual cortex in the occipital lobe or the orbitofrontal cortex for smell), it passes through thethalamus. It is in the thalamus that sensory information is evaluated for its characteristics (is it sound, a visual image, a report of pain comingfrom the left foot?) and directed on to the lobe of the brain where it is more specifically identified (What sound is it? What is this a visualpicture of? Is the foot pain sharp, burning, or a numbness?). The thalamus is composed of a large number of nuclei, or clusters of neurons,that relay information to and from structures in the forebrain, especially the largest structure, which is called the cerebrum. It is the functionof the nuclei in the thalamus to process incoming information and pass it on to the cerebrum. Thus, the thalamus acts like a switchboardoperator relaying information between the cerebrum and other parts of the brain. There is evidence that the thalamus also receivesinformation from the cerebrum and plays an important role in attention (Haber & Calzavara, 2009; McAlonan, Cavanaugh, & Wurtz, 2006;Sillito, Jones, Gerstein, & West, 1994; Zikopoulos & Barbas, 2006).
The diencephalon, together with the midbrain and hindbrain, makes up the brain stem. In terms of evolutionary development, the brain stemis considered to be the oldest part of the brain.