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Home , Arbor vitae (anatomy), Cerebral aqueduct

Sheep Brain Dissection Guide Biopsychology 230 Winter 2010

The Anatomy of Memory by Sitara Cave and Susan Schwartzenberg http://www.exploritorium.com/memory/braindissection/index.html

Unless noted otherwise, all images used with permission from Dr. Tim Cannon, University of Scranton, Behavioral Neuroscience Laboratory Note the meninges layers

• Remove dura (if still present) • You may also need to remove the arachnoid layer • It will be hard to identify the pia as it closely adheres to brain tissue External Anatomy

Now observe the major subdivisions of the brain: • Cerebral cortex • • Brain stem • Longitudinal fissure

Practice using descriptive terms below: A Closer Look

Examine the ventral underside and identify these structures: • (A) Olfactory bulbs B E F • (B) Optic chiasm C A • (C) Mammillary bodies G • (D) Hypothalamus • (E) D • (F) Medulla • (G) • (H)

There is some variance from one specimen to the next… H • Are any meninges present? • Is the pituitary gland present? • Are there any cranial nerves present that you can identify?

Return to the dorsal view, gently pull cerebellum away without detaching it. Identify these structures: • (I) I • (J) J (collectively known as the tectum, Latin for roof) K • (K) Another view

4th ventricle

I

J

• An easy way to remember the parts of the tectum: – The superior colliculus is on top of (or superior) to the inferior colliculus Begin the Dissection

Using the scalpel, make a midsagittal cut along the longitudinal fissure, dividing the brain into two halves. • Note: In order to preserve the structural integrity of the tissue, it is important not to saw. Instead, use downward pressure as you pull the blade through the tissue.

Observe the definitive gray and areas.

Observe the arborization in the cerebellum.

http://www.exploritorium.com/memory/braindissection/index.html Internal Anatomy

Did you make a true midline cut? Compare the two halves.

Test your ability to identify these structures: • (A) Corpus callosum • (B) Cingulate gyrus http://www.exploritorium.com/memory/braindissection/index.html • (C) Fornix • (D) • (E) Thalamus • (F) Hypothalamus • (G) Lateral ventricle • (H) 3rd Ventricle • (I) 4th Ventricle • (J) Optic chiasm • (K) Mammillary body • (L) • (M) Pons • (N) Medulla • (O) Spinal cord • (P) Cerebral aquaduct

See the next page for a labeled location of these areas. B C A G Q D L E O H P F I N J K M

(A) corpus callosum, (B) cingulate gyrus, (C) fornix, (D) septum pellucidum, (E) thalamus, (F) hypothalamus, (G) lateral ventricle, (H) third ventricle, (I) fourth ventricle, (J) optic chiasm, (K) mammillary body, (L) pineal gland, (M) pons, (N) medulla, (O) spinal cord, (P) Cerebral Aqueduct (Q) Arbor Vitae A closer look Coronal Sections

You may wish to use one half of the brain to make some coronal slices … A B Coronal Sections C D Try to find and identify these structures:

• (A) Corpus callosum • (B) Lateral ventricle • (C) Caudate nucleus E • (D) Putamen F • (cut like 24) G

• (E) Thalamus • (F) Third ventricle • (G) Fornix • (cut like 25/26) I

• (H) Amygdala H • (I) Body of fornix • (cut like 26/27)

J • (J) Hippocampus • (cut like 28) J Coronal Sections

Try to find and identify A B these structures:

• (A) Hippocampus • (B) Pineal gland • (cut like 29)

D C • (C) Superior colliculus • (D) Lateral ventricle E • (E) Cerebral aqueduct • (cut like 30)

• (F) Fourth ventricle

F Other Dissections

You may wish to use the other half of brain to try and dissect out some structures. For example: Hippocampus • (above) looks a bit like a clove of garlic when revealed • Just rostral to the pineal gland, cut through the caudal ½ of cerebral cortex (not too deep), then peel it back to reveal the hippocampus.

http://www.psychology.uoguelph.ca/faculty/peters/labmanual/Hippocampal.html http://www.wellesley.edu/Biology/Concepts/Html/sheepbrain.html Some Structures and Functions

Lobes: frontal - higher cognitive processing, executive function parietal - touch, proprioception, speech temporal - speech, memory, hearing occipital - vision cerebellum (not a lobe, but still...) - motor learning, balance

Ventral view: cranial nerves (if present) olfactory bulbs - smell optic chiasm - visual input crosses over to contralateral sides of brain hypothalamus - motivation and the 4 Fs (feeding, fleeing, fighting, fornicating) pons - balance, sleep medulla - heart rate, respiration spinal cord - voluntary movement, pain, sensation mammilary bodies - memory

Midsagittal view: corpus callosum - hemisphere communication cingulate gyrus - attention fornix - major axon projections from hippocampus thalamus - relay station for sensory input hypothalamus - motivation and 4 Fs lateral ventricle - full of cerebral spinal fluid (CSF), has choroid plexus choroid plexus - in ventricles, makes CSF third ventricle - CSF fourth ventricle - CSF cerebral aqueduct - connects third and 4th ventricles, allows CSF to circulate optic chiasm - visual input crosses over to contralateral sides of brain mammilary bodies - memory pons - balance, sleep medulla - heart rate, respiration spinal cord - voluntary movement, pain, sensation

Rostral to cerebellum, anterior portion of : superior colliculus - low level visual processing inferior colliculus - low level auditory and vestibular processing pineal gland - endocrine functions, production of melatonin, Descartes: seat of the soul

Rostral to pineal gland, just bellow the cortex: hippocampus – memory amygdala – emotion; memory