Neuropsychology Psychology 162, Fall 2008

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Final Laboratory Project

Description of the Laboratory

One of the goals for the LADRs is to introduce students to some of the varied research methods associated with different disciplines of inquiry.  In the Natural World LADR it is a requirement to design and conduct your own research project.  It is not possible to actually do many acctual studies in Neuropsychology at the undergraduate level, so we will be again using a simulation to examine the brain.  As in the second laboratory, we will be looking at the visual cortex.  You will have access to a region of cortex and your goal will be to design a set of procedures to allow you to discover how the visual cortex is organized.

Goals for the Laboratory

1. To develop further  your skills in systematic observation, the hallmark of science
2. To give you some experience in conducting your own scientific investigation
3. To develop skills in communicating your findings and conclusions
4. To learn more about using single cell recording as a method for uncovering the organization of the brain.

Background

Go back to the chapter in the text on the visual system and reread it.  Briefly, Hubel and Wiesel (e.g., 1959, 1962, 1968) in several brilliant studies began the uncovering of the organization of the brain.  As you recall, anatomy precedes physiology.  To understand the functioning of the visual cortex, We need to start with the organization of the brain to build.  In this case, the study of the physiology (behavior) of the neurons of the visual cortex was instrumental in uncovering this anatomy.

Hubel and Wiesel (1959) started with the discovery of simple and complex cells.  We covered that in the second laboratory.  But that is only the beginning.  These cells are not arranged randomly in the brain.  They and the other researchers that followed them found the brain arranged into groups of columns Hubel and Wiesel (1962, 1968) called hypercolumns.  In each column, all the cells were all of the same orientation and eye preference.  In one direction, the columns change orientation, by about 10 deg steps, and in the other direction, the columns alternated eye preference.  The locations of the receptive fields in each column overlapped and each hypercolumn responded to adjacent areas of the retina. 

Directions for the Laboratory

In this project, your goal is to determine the layout of the cortex.  The simulated cortex is organized similarly to the cortex, but not identical.  It can vary in certain ways.  Moreover, different groups will have different organizations of their visual cortex. 

First, load this PowerPoint to review how the program works and the structure of the interface that you will be dealing with.

The brain region you are studying is the right striate cortex.  The fovea is on the extreme left side of the striate cortex but in the middle vertically just like the actual brain.  For your study, both eyes are always being stimulate so you will not be able to determine if a cell prefers one eye or the other.

So you are to first develop a research plan in conjunction with the instructor to investigate and identify the structure of your brain.  Note some important limitations, similar to actual research, that are embedded in the program.

• Once you leave a cell to record from another cell, that cell is dead and cannot be studied again.
• Once you leave a column to record from another column, that column has been destroyed and cannot be recorded from again.
• Once you leave a brain region, it cannot be reentered.
• When you close the program, you lose that anima.  The next time you open the program, it will have the same general characteristics you are studying, but it the equivalent of a new animal and so will differ in some ways.
• These limitations do no related to stimulating a region of the retina.  it can be stimulated any number of times.

Laboratory Write-up

Introduction

The issue in the introduction is what can the organization of the visual cortex tell us about both seeing and the brain in general?

Method

This is a simulation, pretend it is a real animal.  Take your pick of the mammals from about a cat/dog level to more complex. You will need to write a participant section about the handling and care of the animals.  The references below and many other in the library will be good guides.

In the equipment, you are doing single cell recording.  The reports below can give you an idea of the equipment you will need.

Same goes for the procedure, at least as far as how the recording was done.

Results

If you take this at all seriously you will have more data than you can report in a lifetime.  Pick your cells carefully and your procedure systematically.  Then try to use your data to tell a story about how these simple and complex cells are organized in the region of the cortex you are studying.

Discussion

Now that you have your ideas about how the striate cortex is organized in your organism, what does it mean about how our brains see?  What do you need to know more?  What is missing?  Any ideas about next steps to study?

You will be emailed the link to your brain.

References:

Hubel, D. L., & Wiesel, T. N. (1959).  Receptive fields of single neurones in the cat's striate cortex.  Journal of Physiology, 148, 574-591.

Hubel, D. L. & Wiesel, T. N. (1962). Receptive fields, binocular interaction and functional architecture in the cat's visual cortex.  Journal of Physiology, 160, 106-154.

Hubel, D. L. & Wiesel, T. N. (1968). Receptive fields and functional architecture of monkey striate cortex.  Journal of Physiology, 195, 215-243.

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