Thread by @MedinaRiojaMD

Frontal lobe: anatomy, history, Edgar Allan Poe and beyond, why not?
🧠📝✍️🕵️

Part 2: Areas and connections

"For the moon never beams, without bringing me dreams of the beautiful Annabel Lee." E. A. Poe.

#Neurology #Anatomy #Teaching #EndNeurophobia #Neurotwitter

1/🧵

⚠️Disclaimer:
Due to the complexity of this structure, this tweetorial is composed of three main parts.

1️⃣ Gross anatomy and microscopic anatomy (sort of)
2️⃣ Areas and connections
3️⃣ Clinical Syndromes and curiosities

Hope you enjoy!

2/🧵

Do you remember last Tweetorial's question?

Exner's area 🧠📝🥸

Described in 1881, the area located close to the superior frontal sulcus in BA6, anterior to the hand primary motor area, has been involved in the handwritten production of words.
📜

3/🧵

“No subject in neurology has attracted more attention or excited more discussion than agraphia” Hermon Gordinier (1903).

More recent evidence shows that Exner's area is more like a "bridge" than the only center involved in handwritting. 🤔

4/🧵

Back to the topic (we can discuss more about areas involved in language later).

The history of the Frontal Lobe and it's areas is long and interesting. Phineas Gage and his accident changed the way we see the prefrontal cortex. ❓

5/🧵

In order to make it easier for us to understand it. Three main regions are to be studied:

🥇Primary motor area
🥈 Premotor and Supplementary Motor Area (SMA)
🥉Prefrontal Cortex
And...last but not least Broca's area (complex) 🗣🔈️

6/🧵

We will return to the prefrontal cortex when we speak about "prefrontal syndromes", after all, the first mention of a "prefrontal syndrome" was after Phineas Gage accident's, right? 🤔🕊️
Right? 🤪

Right? 😜

7/🧵

🧠 Primary motor cortex

📜Penfield's map of the human body (the homunculus).

🚗Based on novel data, some authors proposed a dual-systems model of behavioral control, in which effector isolating and whole-organism action implementation regions alternate.

8/🧵

Premotor cortex 🧠
- Huge interactions with parietal lobe.

🔽Ventral: motor responses according visual information.

⬆️Dorsal: precise hand movements, object properties.

9/🧵

SMA 🧠

💃Involved in production of complex movements and motor programming
🥅Connections with MANY regions (cortical and subcortical)

Lesions cause apraxias (yep, even though this is not parietal lobe, interesting discussion could arise) 😖

10/🧵

Bereitschaftspotential, have you heard of it?
🤔🕵️

11/🧵

Bereitschaftspotential ⚡

Negative potential originated from the SMA that precedes voluntary movement.

From German, "readiness potential" 💬

12/🧵

Lesions in this region can cause curiosis symptoms, such as Alien 👽hand 🤚 syndrome
⬇️

13/🧵

https://twitter.com/1138982294633537536/status/1575928497239130112

Broca's area (complex) 🗣️

As I said previously, our understanding in language has evolved dramatically since the first localizationist models.

14/🧵

Broca's area (complex) 🗣️

We now know that Broca's area is not one isolated area involved in speech production, but part of a complex network.

15/🧵

The connection between Broca's area (complex) and the SMA mediates speech production and speech inhibition. Aslant's tract (my favorite white matter tract) is in charge of that union. 🛣️

💬

16/🧵

Prefrontal cortex🧠
Three main parts (nomenclature may change between authors)

🥇Dorsomedial
🥈Lateral
🥉 Ventromedial/orbitofrontal

Main function: Executive function.

17/🧵

What is executive function? 🤔

Mental processes that help us reach goals, plan, regulate inhibition and social knowledge. 🧑‍🏫

It's more complex than that, but I like to see it as the mental processes that help us behave and reach our own personal goals.

18/🧵

Disclaimer⚠️🚨

Executive function.

MANY components.

Much more complex than what I said above.

Extensive definition and description is not the main goal of this tweetorial.

19/🧵

Ventromedial/orbitofrontal 🧠

Highly involved in inhibition and behavioural control. 🤖

20/🧵

Do you know what is "schadenfreude"?

Answer in next tweetorial.

21/🧵

Lateral/dorsolateral prefrontal cortex 🧠

In charge of managing information📄

Word retrieval 🗣️

22/🧵

Medial and dorsomedial prefrontal cortex 🧠

1️⃣ Action monitoring
2️⃣ Self knowledge
3️⃣ Mentalizing (understand others)
4️⃣ Outcomes

23/🧵

🔁The prefrontal cortex does not work alone, networks between cortical and subcortical structures regulate and help it's function.

Basal ganglia are one of the main protagonists here, as some Loops described by Alexander, et al (1986) demonstrate it. ➿

24/🧵

Frontal lobe connections: some basics 🥇

3️⃣ main types of white matter fibers

🥇Commissural: communicate both hemispheres
🥈Association: communicate between same hemisphere
🥉Projection: cortical with subcortical structures

25/🧵

The brain is what it is, not because of the individual parts that conform it, but by the connections within itself.

(This also applies in many other scenarios, not only the 🧠)

26/🧵

Thalamus has MANY projections to the prefrontal cortex, most of them come from the anterior, medial and ventral parts of it.

27/🧵

So far we have covered most of the functional areas of the frontal lobe, next and final tweetorial will be focused on clinical syndromes and clinical pearls that happen when there is a problem with the frontal lobes (Poe will be mentioned as well) 🕵

Hope you liked it!

28/28🕵️

Sources:
1.- Cortex. 2010 Oct;46(9):1204-10.
doi: 10.1016/j.cortex
2.- Psychopathology. 2015;48(4):222-9.
doi: 10.1159/000381986
3.- Schoenberg M, Scott J. The Little Black Book of Neuropsychology, 2011

More sources
4.- A mind-body interface alternates with effector-specific regions in motor cortex. 10.1101/2022.10.26.513940
5.- Neuroscientist. 2006 Apr;12(2):143-52.
doi: 10.1177/1073858405284255
6.-Nat Rev Neurosci. 2008 Nov;9(11):856-69.
doi: 10.1038/nrn2478

More more sources:
7.- Surg Radiol Anat. 2017 Apr;39(4):357-365.
doi: 10.1007/s00276-016-1748-0
8.- Brain Lang. 2016 Nov;162:60-71.
doi: 10.1016/j.bandl.2016.08.004
9.- Front Hum Neurosci. 2016 Jun 1;10:249.
doi: 10.3389/fnhum.2016.00249

Sources 2.0
10.- Cortex. 2019 Feb;111:148-163.
doi: 10.1016/j.cortex.2018.10.015
11.- Brazis P, Masdeu J, Biller J. Localization in Clinical Neurology Seventh ed. 2. 2017
12.- Handb Clin Neurol. 2019;163:197-219.
doi: 10.1016/B978-0-12-804281-6.00011-2

Sources 2.01
13.- Continuum (Minneap Minn). 2018 Jun;24(3, BEHAVIORAL NEUROLOGY AND PSYCHIATRY):704-726. doi: 10.1212/CON.0000000000000609
14.- Handb Clin Neurol. 2019;163:19-34.
doi: 10.1016/B978-0-12-804281-6.00002-1

Sources 2.10
15.- Nat Rev Neurosci. 2005 Sep;6(9):691-702.
doi: 10.1038/nrn1747
16.- Nat Rev Neurosci. 2006 Apr;7(4):268-77.
doi: 10.1038/nrn1884
17.- Handb Clin Neurol. 2019;163:95-122.
doi: 10.1016/B978-0-12-804281-6.00006-9