Lab 3- Using the brain atlas PDF

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PHYSIOLOGICAL PSYCHOLOGY I – PSYC 2900/3 Lab # 3 – September 24 & 26, 2019

The Virtual Brain – navigation in brain space using atlases.

Part 1: Histological atlases Two of the earliest methods of investigating brain function are stimulating the brain with electrical current, and recording the electrical activity produced by neurons, either as action potentials produced by individual neurons and axons, or slow (graded) potential s produced by populations of neurons. However in order to accomplish this, the electrodes need to be introduced through small holes in the skull, which means that it is not possible to visually guide the electrode. So how do neuroscientists proceed? A classical technique is to remove the brain of an experimental animal or deceased patient who donated their brain, harden it in formaldehyde so it retains its shape, and then cut it up into very fine sections, which are then mounted on glass slides. The instrument used to do the slicing is referred to as a microtome. The mounted slides can then be stained with tissue dyes to produce visual contrast between different types of tissue. Different stains will produce different contrast depending on what cellular materials absorb the stain – for example some dyes are taken up more by protein in the nucleus and cell body, and so tend to stain grey matter, while others are absorbed by lipid and tend to stain white matter. Brains can be sliced through any axis – coronal, axial or sagittal, but the important point is that the set of slides covering the whole brain can be inspected to visualize the internal structures of the brain at each slice. A complete set of such slides makes up a brain atlas. A fine example of such an atlas is the Human Brain Atlas that has been created by the Michigan State University. Fortunately for students of neuroscience, MSU has created and posted a digital version of this atlas. The URL for this website is: https://www.msu.edu/~brains/brains/human/ Open it now and take a look at the main page. Note that you can use it to view slices in the coronal, horizontal (axial) or sagittal planes. Clicking on a particular slice in the montage will open that slice for viewing. Note that you can choose between a grey matter and a white matter stain. Study question: - What is the difference between these stains, and why are the differences useful?

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Let’s see if we can find the following brain structures: The cerebral ventricles, including the lateral ventricles, the third ventricle, the cerebral aqueduct and the fourth ventricle – Study questions: - Try looking through the brain using each of the slice orientations (coronal, sagittal, axial). Scroll through the views in each section so that you can examine the whole brain. Note how different the shape of the ventricles looks in each of the views, and in each of the slices. This will help you go understand how to look at brain parts from different viewpoints. - Where are each of the ventricles these located in relation to the brain’s “primary vesicles” – the hindbrain, midbrain and forebrain? Which ventricle is associated with which brain region? The cerebellum and pons Study questions: - How is the cerebellum connected to the rest of the brain? Does it appear to have different parts? What does the cerebellum contribute to behavior? Do the different parts make different contributions? What cranial nerves arise in the hindbrain? What do they control? The midbrain Study questions: - Which part of the ventricular system is associated with the midbrain? - Where are the tectum and tegmentum in relation to the above structure? What does each of these parts of the midbrain contribute to the control of behavior? The thalamus and hypothalamus Study questions: - Can you find different nuclei in the thalamus? Are they connected to the cortex? Is there a plan in terms of what is connected to where? - Does the hypothalamus have distinct nuclei? What might these contribute to the control of behavior? -What endocrine gland is connected to the hypothalamus? Why is this important for instinctive behavior?

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The Limbic system: The hippocampus, amygdala and cingulate cortex Study questions: - What does the amygdala do? What is it connected to? How is it related to mind and behaviour? - How did the hippocampus get its name? What is it connected to? How is it related to cognitive function? The basal ganglia Study questions: - What are the primary components of this system? - Are there inputs and outputs to these circuits? Where do they come from and go to? The cerebral cortex Study questions: - Can you locate the prominent fissures including the median longitudinal, sylvian, rhinal and calcarine fissures? How about the central sulcus? How do these relate to the lobes of the cerebral hemispheres? - Can you identify some prominent white matter structures, including the corona radiata, corpus callosum, anterior and posterior commissures? What are these and what do they do? - Can you find the fornix? What system is it associated with? How about the cingulum? - Where is the pyramidal tract and what does it do

-----------------------------------------------------------------------------------------------------------Note: You can check locations by toggling labels on and off in the section views.

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