Neurobiology, Class 2

Front 1

What are the pre-central and post-central gryi? Where are they located? How can I remember this?

Back 1

The pre-central gyrus is the primary motor cortex, and it is in the frontal lobe. The post-central gyrus is the primary somatosensory cortex, and it is in the parietal lobe.

You can remember that the pre-central gyrus is rostral to the central sulcus by remembering that "pre" is like prefrontal cortex, the most rostral part of the brain.

Front 2

What view is this? Identify the cingulate gyrus.

Back 2

Front 3

What forms the roof and floor of the third ventricle?

Back 3

The thalamus forms the roof and the hypothalamus forms the floor of the third ventricle

Front 4

What forms the roof and floor of the cerebral aqueduct?

Back 4

The tectum (& inferior and superior colliculi) form the roof. The tegmentum forms the floor.

Front 5

Where is the fornix in a mid-saggital view? What structures does it connect? What process has it been implicated in?

Back 5

The fornix is a hook-shaped fiber tract below the corpus callosum. It connects the hippocampus to the mammillary bodies. This pathway has been implicated in emotional regulation.

Front 6

Identify the lateral ventricles, the third ventricle, the cerebral aqueduct, the fourth ventricle, and the spinal canal.

Back 6

Front 7

What is the septum pellucida?

Back 7

The septum pellucida is a thin membrane that separates the left and right lateral ventricles.

Front 8

Recite the pathways through which CSF flows, using all the correct terms.

Back 8

The CSF is produced in the lateral ventricles. Via the Foramen of Monro, it flows into the Third Ventricle. It then flows from the Third Ventricle into the cerebral aqueduct. From here it flows into the fourth ventricle. From here it flows either into the spinal canal or the meninges.

Front 9

What is the choroid plexus? Where is in found?

Back 9

The choroid plexus is a layer of epithelial cells on the surface of the lateral ventricles that secrete CSF.

Front 10

What is hydrocephalus? What is the cause? Why is it dangerous? How is it treated?

Back 10

Hydrocephalus is a condition caused by an obstruction of the ventricular system. Fluid builds up downstream of the blockage, and impinges on surrounding tissue, damaging it. It is treated by inserting a shunt that shuttles excess CSF into the abdomen.

Front 11

Basically, what is the function of the thalamus? Where is the thalamus located?

Back 11

The thalamus is a gateway for incoming sensory info, where the information gets modified along the way. The thalamus is located on the roof of the third ventricle, but bulges outward.

Front 12

How does the human thalamus compare to the thalamus in other organisms?

Back 12

The human thalamus is proportionally larger than the thalamus in other species.

Front 13

What are the 3 divisions of the thalamus? How do you remember this mnemonically? What are their general functions? Where do they project to? What holds them together?

Back 13

1. Lateral thalamic nuclei- sensory/motor functions.
2. Anterior thalamic nuclei- memory; projects to mammillary bodies
3. Mediodorsal thalamic nuclei- memory & emotion; projects to PFC.

Remember this as LAMDA (Lateral, Anterior, MedioDorsal)

They are held together by a tissue called intermedullary lamina.

Front 14

What surrounds the thalamus?

Back 14

The thalamus is surrounded by the nRt: the nucleus reticularis of the thalamus.

Front 15

Identify the thalamus in this picture. Identify the structures immediately caudal to the thalamus

Back 15

The caudal structures are the superior colliculi.

Front 16

What is the lateral geniculate nucleus? Given its function, why does it make sense that it is in the location that it is?

Back 16

The lateral geniculate nucleus is a nucleus of the thalamus that receives sensory projections from the retina. It makes sense that it is a lateral nucleus because the lateral region of the thalamus has sensory/motor functions.

Front 17

Recite the thalamic circuit pathway, including all the appropriate areas and details.

Back 17

Front 18

Why is the thalamic circuit a feedback loop?

Back 18

There is feed-forward from relay/thalamocortical cells to cortex. There is then feedback from cortex to thalamus.

Front 19

Where is the relevant thalamic structure in this picture? What is it?

Back 19

The structure is the pulvinar nucleus of the thalamus.

Front 20

What is the relevant midbrain area we need to know about?

Back 20

The substantia nigra produces dopamine. Disorder in this structure causes Parkinson's disease.

Front 21

What is the basic functional organization of the spinal cord? What is the exception?

Back 21

The spinal cord is divisible into two halves:

1. Dorsal half- sensory
2. Ventral half-motor (except for spinothalamic tract, which is sensory)

Front 22

What are the two different parts of the dorsal half of the spinal cord? How are they different? What functions do each of them mediate?

Back 22

1. Dorsal horn- gray matter, pain/temperature.
2. Column- white matter (because it consists of axons projected from the dorsal root ganglion), discriminative touch

Front 23

What is unusual about the spinothalamic tract?

Back 23

Although it is an ascending sensory pathway, it is found on the ventral half of the spinal cord, on the LATERAL HORN of the gray matter.

Front 24

What section is this? How can you tell?

Back 24

CERVICAL- two distinct dorsal columns, bulging lateral horns that look pointy; bottom part of gray matter has kidney-shaped appearance.

Front 25

What section is this? How can you tell?

Back 25

THORACIC- long thin dorsal horns, small lateral (i.e. intermediolateral) horns in ventral half because of few efferent motor projections.

Front 26

What section is this? How can you tell?

Back 26

LUMBAR- bottom parts of gray matter are bulbous like testicles, which makes sense since lumbar is lower than cervical. There are no distinct ventral horns jutting out like at cervical level.

Front 27

What section is this? How can you tell?

Back 27

SACRAL- there is so much more gray matter than white matter.

Front 28

Why does the sacral spinal cord have proportionally more gray matter than the other levels?

Back 28

Because there's not much ascending info coming from the lower back muscles, and most of the descending pathways already exited at the lumbar level. Thus, high proportion of gray to white matter.

Front 29

Describe the differences between the somatosensory and pain pathways in the spinal cord.

Back 29

Information from both pathways eventually reaches the contralateral side of the brain. However,they differ in where the decussation occurs:

1. somatosensory pathway- info goes up the ipsilateral side, and decussates in the pons.

2. Pain pathway- info decussates at the level of the dorsal root ganglion from which it entered, and then simply ascends up the contralateral side of the spinal cord.