Attention from a neurological viewpoint

Attention is a very complex phenomenon and the notes here are meant to give a general idea of how it works!
As with any other part of this website, the notes I have made are based on Cognitive Neuroscience, 4th ed., Banich & Comption, 2018.

Let's start with the basics and try to build from there. I'm sure you already have an intuitive sense of what attention is. But we need to be a bit more technical than that, so here is a quick definition of attention:

Attention is the ability to focus on a specific stimulus/task while ignoring other stimuli that are irrelevant to your task.

(maybe talk about how complicated this process rly is by breaking it down to steps?)

Attention at its very core consists of alertness and arousal. Without these functions we wouldn't be aware of our surroundings and we wouldn't be able to pay attention to anything!
In other words, the first thing we need to do to pay attention is be awake and aware.
Alertness and arousal are controlled by the reticular activating system (RAS) depicted below:

Figure referenced from Cognitive Neuroscience, 4th ed., Banich & Comption, 2018, pg.298

The RAS keeps our nervous system active and it has two routes to do so:

1. The dorsal route which relies on acetycholine (ACh) and projects to the thalamus helps us stay awake and alert by modulating the amount of glutamate (an excitatory neurotransmitter) in the brain.
2. The ventral route which relies on noradrenergic (NA) and serotonergic systems (5-HT).

The NA system is responsible for alertness and arousal. This subsystem is implicated in psychiatric disorders characterized by hyperaroused states, such as PTSD!
The 5-HT system helps us stay awake and suppresses REM sleep.