In this unit, we cover the visual scene in 3D - the many clues to depth. We then turn to body senses (position and touch) and how our brains detect the configuration of our own bodies. Along the way, we cover the resting membrane potential, the action potential, and how they arise. Finally, we bring vision and the body together, and throw some beanbags at a visual target while wearing prisms! This material is covered in Making Space, chapters 2 and 3.

In this unit, we turn to the brain and how it uses the spatial position of neurons within the brain to organize information about the spatial position of stimuli in the world (Making Space chapter 4). You'll learn about how we identify where one object ends and another begins, what a receptive field is, and how some neurons are sensitive to edges and the boundaries of objects. Maps occur in both visual cortex and body (somatosensory) cortex, and these maps may be responsible for various "phantom" sensations (examples from normal vision, patients with body part amputations, and electrical stimulation experiments).

In module 4, we turn to the fascinating puzzle of how we deduce sound location--a process that requires quite a bit of detective work. Our brains piece together multiple types of clues, including subtle differences in timing, loudness, frequency content, and how sounds appear to change as we turn our heads. Because our ears don't form images of sounds, our brains don't have to use maps to encode sound location. The second half of the videos this module concern alternative forms of brain representation, how the brain translates between different types of representation, and what we know about brain representations for sound location. The material is covered in chapter 5, "Sherlock Ears" and chapter 6, "Moving with Maps and Meters", in Making Space. Be forewarned, there are about 70 minutes of video this module, as compared to previous modules' 50-60 minutes. After watching the full set, you'll see why these videos are grouped together as a unit. To make things more manageable, we've broken the quiz into two parts; that way, you can get feedback on one part before moving on to the next, if you like.

This module we turn to how spatial locations are defined, and discuss the concept of a reference frame. Initially, reference frames are quite different for visual, auditory, and somatosensory information. Visual location is defined with respect to the eyes, whereas sound locations are detected with respect to the head and ears, and tactile locations are detected based on body surface position. As you'll see, the brain transforms these signals into new reference frames to facilitate interactions between these sensory systems. We then consider space on a larger scale, and ask how we know where we are and how we navigate from one place to another. Knowledge of self-motion relies in part on the vestibular system, our sense of balance. The vestibular system works in concert with vision and motor systems to update our sense of position and keep us from getting lost. This module's material is covered in chapters 7, "Your Sunglasses Are in the Milky Way", and 8, "Going Places" of Making Space.

In this final module of the course, we build several important links between the sense of space and other kinds of cognition. Videos 6.1-6.5 concern the relationship between space and memory. Memory is reflected in multiple different kinds of neural mechanisms and involves multiple brain regions. The memory and spatial functions of these mechanisms and brain regions overlap. Video 6.5 in particular features work by John O'Keefe concerning response patterns known as "place fields" in the hippocampus, and work by May-Britt and Edvard Moser concerning grid cells. This seminal work was recognized by the 2014 Nobel Prize in Medicine and Physiology. Videos 6.6-6.9 turn to thought more generally, and present a series of theories and experiments that suggest that the brain is actually using sensory and motor structures to think and reason. Thus, our brain systems for space may be engaged in a wide set of mental functions, which are shaped by the multiple purposes of this neural infrastructure. This module's material is covered in chapters 9, "Space and Memory", and 10, "Thinking about Thinking" of Making Space. I hope you enjoy this synthesis of all you have learned and what it means!