2-Minute Neuroscience: Direct Pathway of the Basal Ganglia

The direct pathway is a circuit in the basal ganglia best-known for its hypothesized role in movement. In this video, I discuss the structures that are considered part of the direct pathway, and explain how they are thought to work together to facilitate movement.

TRANSCRIPT:

The basal ganglia are a group of structures that are generally considered to include the caudate and putamen (which are collectively known as the striatum), the globus pallidus, subthalamic nucleus, and substantia nigra. The globus pallidus is further divided into internal and external segments, and the substantia nigra is divided into the substantia nigra pars compacta and substantia nigra pars reticulata. The direct pathway is a circuit in the basal ganglia best-known for its hypothesized role in movement.

The direct pathway model involves glutamate neurons that project from the thalamus to motor regions of the cerebral cortex. These excitatory projections are thought to be involved with stimulating movement. Neurons from the globus pallidus internal and substantia nigra pars reticulata, however, project to the thalamus and maintain a steady release of the neurotransmitter GABA which acts to inhibit the thalamic neurons and suppress movement. This mechanism is thought to be important in keeping unwanted movements from occurring. When we want to make a movement, however, information about the movement is sent from the cortex to the striatum via the corticostriatal pathway. Glutamate neurons in this pathway excite neurons in the striatum, and the activated striatal neurons release GABA in the globus pallidus internal and substantia nigra pars reticulata, inhibiting the activity of these regions and stopping the inhibition of neurons in the thalamus that are involved with movement. This effectively opens a gate for movement to occur. Activity along this pathway tends to occur just prior to a movement, and thus has been linked to the facilitation of movement.

The substantia nigra pars compacta is thought to modulate the activity of the direct pathway. Neurons from the substantia nigra pars compacta travel to the striatum via the nigrostriatal pathway, and release dopamine in the striatum. One effect of this seems to be the facilitation of activity in the direct pathway.

References:

Lanciego JL, Luquin N, Obeso JA. Functional neuroanatomy of the basal ganglia. Cold Spring Harb Perspect Med. 2012 Dec 1;2(12):a009621. doi: 10.1101/cshperspect.a009621.

Purves D, Augustine GJ, Fitzpatrick D, Hall WC, Lamantia AS, Mooney RD, Platt ML, White LE, eds. Neuroscience. 6th ed. New York. Sinauer Associates; 2018.

Special thanks to Nicole Lookfong for help with fact-checking the script for this video.

[MD-]

good video !today i officially give up understanding and or memorizing this pathway and it shall forever remain vague and grey in my brain. i have made peace with that fact.

[IBassGaming]

I will never get why random ass youtube videos (that's meant in a good way) are easier to understand and better illustrated than my neuroscience lectures.
Nowadays I don't even start reading the chapter of the books before checking out a video. Look how easy it is to comprehend this! Insane. Kudos and thanks for carrying me through my Uni ^^

[manasidevakumar]

This is the most straightforward and easy to understand explanation for the direct pathway. Thank you so much!

[aaronsweeney]

I am a psychology/biology double-major, and I was a research assistant in the laboratory of behavioral and neural plasticity for most of the duration of my undergraduate program. We were researching neural mechanisms that lead to substance use disorders, focusing on how long-term exposure to stimulant drugs of abuse negatively affect the mechanisms in the brain that regulate the release of dopamine. At any rate, this video reminded me of how much I enjoy learning about the circuit!

[alstroemeria]

Thanks man, I'm already lost with all this CNS shenanigans just now until I found your channel.

[blancateresapachecosoto]

ALWAYS WILL BE GRATEFULL WITH YOU, YOUR EXPLANATION IS INCREDIBLE! THANK YOU

[melisaaltnyelek]

It has been so helpful just before my Advanced Physiological Psychology final. :D Thank you!

[imannoyed]

I was looking for a video on this the other day on your channel and was disappointed to not have found it. Really happy to see this since you make the topic much easier to understand. Thank you for this :-)

[anuishkananty]

I love your videos; they are very simple and easy to understand. Thank you and keep it up. God bless you

[helios]

Great as always! Thank you for all the help!

[ssingh]

Thankyou so much for explaining it in such an easy way to understand

[khadijah]

Amazing videos and so well explained!! :) I can definitely tell that these videos are going to save me in neuroanatomy lol

[jankithakkar]

Thank you so much it is very helpful to understand in way you are teaching keep doing this

[medicoshealth]

wow.. you kinda inspired me to make youtube videos so that I could help others..

[randomcontent]

good explanation, nice and short, helpful

[patrickl.]

How timely, midterm next week on this. Good review video.

[triskeliongames]

Do the dopamine receptors have an excitatory or inhibitory effect? Because it your video it is stated that in the direct pathway the substantia nigra pars compacta has an excitatory effect on the striatum, but I have an image here that says otherwise. I am just checking, could you maybe explain why the substantia nigra pars compacta does have an excitatory effect here and not an inhibitory one?

[TheToxicMegacolon]

This was fucking amazing man. Thank you.

[MarioNOOOO]

So the motorcortex recieve information from the thalamus, but how the thalamus get its signals? Is there a loop from motorcortex - thalamus - motorcortex?

[shitbag.]

Take care of yourself. Ya hear?

Videos are fun and helpful but stay healthy.