Classic cognitive neuroscience studies that highlight conclusions that could not be drawn from behavioral experiments Background: I studied psychology prior to going into cognitive neuroscience for my PhD. While I know my own area in depth, I lack the kind of broad overview that people who have done their Masters in cognitive neuroscience tend to have. I was recently asked to give a general talk on cognitive neuroscience, in a country where it pretty much doesn't exist yet as a field. The talk is for highly talented high school kids who are at a summer school for scientific research in psychology. We have all afternoon for this.

My idea was to first talk about neuroimaging techniques: what do the machines look like, what do they measure, what kind of conclusions can we draw using them. I then wanted to go on to some examples where neuroscience was used to draw conclusions about cognitive functions, such that the conclusions couldn't have been drawn using just behavioural experiments. 

For example, for memory, I thought I could talk about HM and how we learned about the distinction between short-term and long-term memory when his hippocampi were removed. For language, I could talk about the effect of cloze probability on the N400 evoked potential. For consciousness, I could talk about the role of feedback connections and how selectively knocking out early areas with TMS before the feedback signal comes back can abolish conscious perception. I'm still not sure what examples to use for:


Attention
Motor control
Executive functions
Emotions
Clinical applications
Sleep
Perception of space or time
Social behaviour
Other


I would love to hear your thoughts on the most classical Cognitive Neuroscience findings you can think of. What would your list look like? It can be anything really, as long as it's not just behavioural. Rats, monkeys and zebrafish are also welcome to the list :)
For introductory cognitive neuroscience, I think it is often best to start with interesting neuropsychological cases -- I think such cases provide an intriguing and intuitive way to get into the relationship between mind and brain. You already plan to talk about HM (and you can mention the movie Memento if you think students might be familiar or interested in it), I would suggest following that approach in the other domains. A few suggestions:


Executive functions/social behavior: Phineas Gage (frontal lobe damage produced impulsivity, rudeness, etc.)
Language: pure anomia (patients can report lots of information about an object but can't name it), jargon aphasia (patients produce nonsense words without realizing they are nonsense)
Conceptual knowledge: semantic dementia (progressive degeneration of semantic knowledge)
Spatial attention: hemispatial neglect (patients don't notice things on one side of visual field, usually the left side following right parietal lesions)
Motor control: ideational apraxia (impairment of action planning), ideomotor apraxia (impairment of object use), optic ataxia (impairment of visually-guided reaching)
Face perception / visual expertise: prosopagnosia (typically described as impairment of face perception, though it affects other versions of visual expertise)


More generally, there is a good two-volume set called Classic Cases in Neuropsychology (Vol. 1, Vol. 2) edited by Chris Code et al. that describes lots of interesting and influential cases.