The Half Decent Pharmaceutical Chemistry Blog

No video has ever deserved to be in a post, here, although this is a rather common habit among bloggers. 

I came across this video, however, last week: it reminded me of a nice lecture during the course of neuroscience.

The director is Italian, as well as the website where the band, the Whitest Boy Alive, held the contest: in a nutshell, they asked users to create a clip for their latest single.

Here's the winner and, in my opinion, it's a pretty wonderful and smart video. And, besides, the song is cool.

Check it out.

When I found this picture on my neuroscience book, I thought it looked like it had been taken from some American comic...doesn't it? However, I like it and decided to put it on my blog.

Well, studies on monkeys are certainly of paramount importance for neuroscientists, considering the many similarities between our brain and that of, say, rhesus monkey.

Many studies are carried out on this animal. Chemoarchitecture, for example, is based on the different distribution of receptors. Neuroanatomy is performed on dead monkeys: basically, you inject a dye and track the path. Obviously, both require the so-called animal sacrifice.
Single cell recording needs the animal to be alive and awake: as the picture above shows, electrods are inserted in the brain in order to register the activity of particular neurons according to the kind of stimulation. It has to be said that a certain (high) level of comfort for the monkey is always guaranteed: juice is released every time it completes its task, the chair where it sits must be very comfortable, etc.

Sure, studies are performed on human beings too. First of all, there is ablation: when there is a (rare) damage to only one specific area of the brain, this gives the opportunity to determine the function(s) of that part, comparing with normal patients. This technique was the only one the pioneers of neuroscience (such as Broca) could use to map the brain.
Moreover, nowadays, instrumental techniques such as EEG, fMRI and PET help us to study directly on human beings.

Imagine you are packing gunpowder into a huge rock with a hammer. Imagine that, suddenly, something goes awry and the tamping iron you're using ignites the powder, hits your face and goes through your brain, landing behind you. Imagine to be conscious while all this happens....

This dreadful accident took place in Vermont on September 13, 1848 and Phineas Gage was the name of the protagonist of this tale. A tale who became a legend and a milestone in the history of neuroscience.

Surprisingly, Gage perfectly recovered from the accident from a physical point of view. However, the huge damage to his frontal lobe caused an enormous change in Gage's behaviour: in a nutshell, he became rude, violent, unable to organize his life and work. A violent child.
When I was told this story, I said to myself that this change was likely to be a consequence of the shock the whole accident certainly generated in Gage.
Although this interpretation could be correct, the shock wasn't the only cause, as many other studies proved.

The frontal association cortex has been studied on human beings quite a lot and certainly more than any other association area. In fact, psycosurgery was, sadly, a common practice until the 1960s: it was the easiest way to treat many mental disorders (have you seen "One Flew Over the Cuckoo's Nest"?).

Studies on monkeys have proved the importance of this association area for planning actions. A part of this area, the prefrontal cortex, shows great electric activity every time the aforementioned action is some sort of movement. This is possible due to the connection between prefrontal and premotor cortices.

Interestingly, here is where the difference between human being and monkey is remarkable: our frontal association cortex is (predictably) more developed in the former. In fact, the greater ability to interpret situations and plan a particular behaviour is one of our distinguishing features.

Not only does this cortex interpret a large spectrum of inputs, but it also works out a response, which we generally call 'behaviour' (a series of responses which differ according to the context).

In 1941, W.R. Brain published an article (Brain.1941; 64: 244-272), where he described a phenomenon he studied on people with injuries of the parietal association cortex, people who suffered from what would have been later called spatial neglect. They were completely unaware of anything that was on their left: either objects on the left field of view or the whole left part of their body.

Two weeks ago, I talked about the relationship between the temporal association area and the ability to recognise things.
What the parietal association cortex does, instead, is processing inner and outer inputs, which results in our ability to recognise, localize and pay attention to whatever is around us. In other words, this part of the brain plays a key role in all the visuospatial tasks we normally perform.

Interestingly, there is a partial hemispheric specialization for what concerns attention: the right hemisphere shows increasing activity with inputs coming either from the right or left, while the left one with those from the right side only.
Consistently, any damage to the left parietal cortex doesn't lead to spatial neglet, since the right hemisphere neutralizes the effect of the injury.

Now, check out how someone, suffering from neglet, draws a clock or cuts a line "in the middle".

Far from being a surprise, spatial neglect makes impossible to do simple actions such as dressing yourself or moving in your own house (as Brain wrote, patients always turned right, opened doors on the right, etc.).

Last night I drove after three months of cycling. I took some relatives to a small restaurant on the hills surrounding Bologna. I ate quite a lot, as usuall, and we had a nice time together.
By the way, the journey from home to the place wasn't that nice, since, although I like driving VERY much, a small, dark, hill road is not what you would call the easiest one for reviewing your driving skills. Nevertheless, I didn't have any trouble: I was just a little bit worried in the beginning.

It's hard to define what memory actually is: maybe the faculty of recalling facts or recognizing episodes of the past is the clearest.
Certainly, finding out all the cerebral pathaways that deal with this faculty is one of the toughest tasks of today's neuroscientists.
However, nowadays we know something.

First of all, we can define three (but there are different classifications) memories: short-term, long-term implicit and explicit memory.

Short-term memory can be called working memory as well. This second, more modern name is used to underline the functions of this kind of memory. A short-term memory, in fact, helps us every time a particular task needs a quick storage and manipulation of information/data (i.e. remembering addends for a sum and calculating the result).
Studies on monkeys and patients with brain injuries have revealed that some areas of the premotor cortex show an increases activity during processes which require the use of working memory.

When it comes to long-term memories, things get more complicated and unknown. There are five regions certainly involved: one is subcortical ( the amygdala) and the others are in the temporal cortex (namely, enthorinal, perirhinal and parahippocampal cortex, hippocampus).
Explicit memory is also called declarative memory: basically, it's when we are aware of knowing something (i.e. where we live).

Amygdala has a central role in linking memories and emotions together.

Hippocampus is nicknamed "teacher", because of its paramount importance for declarative memory. Its bidirectional connections with all the cortices explain why it plays a key role in explicit memory.
Interestingly, in the hippocampus there are staminal neurons.

Perirhinal cortex makes us remember, in a nutshell, objects, while parahippocampal cortex is linked to visuospatial memory. Both have the same bidirectional links to all the cortices we described for the hippocampus.
These two regions send information to the enthorinal cortex, which processes the inputs. Enthorinal cortex is linked to the hippocampus too and provides a huge number of inputs for it.

Implicit memory is also known as procedural memory: we know how to do something, but we are just not aware of it. And that's the link between yesterday's driving after a long time and memory. Implicit memory is what  helps us doing many things without, literally, thinking about what we are doing. For example, if we constantly had to think about how to move our legs while cycling, we would be probably fall down very quickly.
The scheme is quite simple: all cortices have connections with basal ganglia but not the way back. Hence, we can't be aware of the process.
Basal nuclei (another name for basal ganglia) receive stimuli also from the substantia nigra.
Inputs travels from basal nuclei to ventral thalmus and, finally, reach the premotor and motor cortex.