Thalamus

Abstract

The thalamus is an almond-shaped structure sitting atop the brainstem and nestled at the center of the cerebrum. It is often referred to as the doorway to the cortex as everything, except olfaction, traveling up to the cortex goes through the thalamus. Think of the thalamus as acting like a flashlight which allows you to focus on important things while ignoring non-important things. Imagine sitting in a coffee shop reading this book, and there are all sorts of sensory inputs coming into your thalamus competing for the book’s attention. There is the sound of people ordering, maybe there is a cold breeze that comes and goes as someone opens the door, there is the smell of the coffee and other odors in the air, and there are all types of interesting people coming and going in your visual fields. All this information is flooding your thalamus, but, presumably, you want to pay attention to what you are reading. Your thalamus, like a flashlight, focuses on the page in front of you and tries to ignore all the other sensory inputs. If someone comes rushing into the front door yelling, then your thalamus, or flashlight, is going to change its focus and shift to the person in the door.