Start studying Gross Anatomy of the Brain and Cranial Nerves 6. Learn vocabulary When comparing human and sheep brains, you observe some profound differences between them. Record your Pons/Medulla Relationship. Human: More. Human vs Sheep Brain. There are a few differences between the human and sheep brain. The human brain is larger in size and shape when. between the sheep and human brain, so that this dissection will give you valuable insight into How do we determine what the different regions of the brain do?.
Though the sheep has generally been regarded as an unintelligent animal, it is increasingly recognized that sheep are able to perform some advanced tasks, such as remembering the faces of other sheep and humans for two years or longer. Olfactory Bulb The sheep, like many mammals, has a more developed sense of smell, or olfaction, than humans do. The olfactory bulb is the part of the brain located underneath the frontal lobe that is responsible for relaying sensory information from the nose to the rest of the brain.BIO201 class 17
The olfactory bulb in sheep is two to three times the size of the human olfactory bulb, despite the sheep brain being much smaller overall. This reflects the importance of the sense of smell to the sheep. In addition to helping it understand its surroundings and avoid danger, sense of smell also plays a crucial role in establishing the bond between mother and infant, known as imprinting. Optic Chiasm The optic chiasm is a cross-shaped structure centrally located on the underside of the brain where the optic nerve fibers from each eye partially cross over to the corresponding optical tract on the other side of the brain.
It is more pronounced in the sheep brain because sheep, like many prey animals, have eyes toward the sides of the head that operate more independently, giving the sheep a much wider field of vision.
When comparing human and sheep brains, you observe some profound differences between them.?
Therefore most of the visual information from each eye crosses over. Humans have more frontal eyes, and share information from each eye more evenly between the brain hemispheres to enable complex visual processing tasks, such as depth perception. Other motor systems are concerned with gross motor movements, such as, dancing, walking, or waving goodbye. This may be a good time to restate conventions concerning names of tracts in the CNS.
If you keep the rule 'from-to' in mind, you will always be able to tell the site of origin and destination for a given tract. The first name in the title indicates the site of origin of the tract, while the second name indicates the tract's destination.
The tract known as the corticospinal tract, according to the rule, originates from neurons whose cell bodies reside in the cortex and project their axons to the spinal cord.
The trapezoid body consists of fibers carrying information from the right ear to left auditory cortex and information from the left ear to right auditory cortex. The trapezoid body is to the auditory system what the optic chiasm is to the visual system. Unlike somatosensory cortex, the auditory and visual cortices receive bilateral input, that is, each projection site receives information from both ears or both eyes, respectively. If it has not been stripped away, you will find the VIII cranial nerve, the vestibulo-cochlear or auditory nerve at the most lateral extent of the trapezoid body.
On the ventral surface of your sheep brain, locate the very prominent swelling between the trapezoid body and the cerebral peduncles, the pons. Its name is derived from the Latin word, pons, which means 'bridge.
Difference Between Human and Sheep Brain | Difference Between | Human vs Sheep Brain
Pyramidal tract fibers descending from motor cortex to their destination in the spinal cord are one example of these fibers of passage. Immediately posterior to the the cerebral hemispheres, you find the cerebellum, a large, complex structure concerned with all levels of motor coordination.
The cerebellar surface is characterized by intricate, extremely fine convolutions called folia. The folia are analogous to the gyri of the cerebral hemispheres. Like the cerebral hemispheres, the cerebellum has an inner core of white matter. In the cerebellum this inner core of white matter is called the arbor vitae.
Click on the image below for a larger view. The white-matter core consists of axons projecting to and from the cerebellar hemispheres, the spinal cord, sensory and motor cortices, and other regions of the brain. The cerebellum sends information to the brain and spinal cord via axons that exit from the cerebellum. In this way, we have information coming into the cerebellum that helps guide cerebellar control of our motor behavior.
Without an intact cerebellum, you would find it difficult to walk, maintain a sense of balance, or to perform a complex behavior, such as, hit a tennis ball with a tennis racket, an action that requires hand-eye coordination and timing. The cerebellum has other important functions; it is important for establishing skill memories and for the occurrence of classically conditioned responses.
Nestled between the cerebellum and the cerebral hemispheres are two prominent elevations sitting symmetrically on either side of the midline. You may have to pull your cerebellum gently and caudally to reveal them. Collectively, these four structures are called the corpora quadrigemina 'bodies of four twins'but it is easier to remember them in their pairwise configurations: This region of the midbrain is also called the tectum 'roof'because the colliculi 'little hills' form the roof, or upper boundary of the Aqueduct of Sylvius.
Look at the figure connected to this link to see the relationship between the colliculi tectum and the aqueduct of sylvius.
Difference Between Human and Sheep Brain
The figure will clarify the location of the colliculi. If you are unable to see any of the structures named in this paragraph clearly and easily, seek help from the instructor, or lab assistant.
- Differences Between Human and Sheep Brains
On the ventral surface of the brain, at the midline just anterior to the oculomotor nerve, locate the small, but distinct, tissue that looks like the tip of a tongue. Cells in the mammillary bodies are particularly vulnerable to alcohol. Autopsies have shown significant destruction of the mammillary bodies in chronic alcoholics suffering from a severe memory disorder known as Korsakoff's syndrome.
Some neurologists believe that the mammillary bodies are involved in memory processes. While the mammillary bodies form the caudal limit of the hypothalamusits anterior border is marked by the optic chiasm.
The general outline of the hypothalamus from the ventral aspect, thus, assumes a diamond-like configuration. Although the hypothalamus is not a very large structure, it is quite complex. The hypothalamus contains many different nuclei that are concerned with regulation of temperature, hunger and satiety, sexual behavior, and, perhaps, even sexual preference. The last structures to concern us are evolutionarily older, archi-cortex. On the ventral aspect of the brain, notice the moderately large, relatively smooth masses of cortical tissue just lateral to the cerebral peduncles.
Follow the tissue from its most caudal limit near the lateral-most partof the pons to its most anterior limit near the olfactory bulbs. This mass of tissue, the rhinencephalon or 'smell brain,' is easily visible in the sheep brain, but it is hidden from external view by the temporal lobe in human brain.
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One important structure located in the rhinencephalon is the hippocampal gyrusa structure that is exremely important for development and maintenance of memories. It should not surprise you to learn that loss of cells in the hippocampus is one of the characteristics of Alzheimer's patients, individuals who suffer severe memory impairments.
The hippocampus is critical to the functioning of our declarative memory processes, among other behaviors. Declarative memory processes are those processes concerned with our memory for facts, for example, the capital of the state of California, or the name of the structure that is intimately involved in the development of memory hippocampus.
Recent research has shown that the amygdala is important for emotional learning. Our emotional memory system is distinct from our declarative memory system. For example, you may have been in a terrible car accident that was immediately preceded by the blaring of a car horn. Later, you may find that you become tense and anxious when you hear car horns. Your memory for the details of the accident, for example, when and where the accident occurred, who else was in the car, or what kind of car struck you are declarative memories that are dependent upon the hippocampus.
The emotional memories, fear and anxiety associated with the accident, are activated via the amygdala, which plays an essential role in modulating conditioned emotional responses. The amygdala was recently found to play a role in psychological drug dependence. More about that in lecture. This completes the second section of the dissection. Now would be a good time to review the structures you observed in the first dissection.
Once again, it would be helpful to make an index card for each term, or structure that appears in the list of important terms and structures. You will find that it is not very effective to study only the figures, because the practicum will require you to be able to identify structures on actual tissue.
Use your brain specimen as you study. I encourage you to study in groups. Point out the structures listed in the dissection guides for one another, can you name them without resorting to the guide? Can you specify what functions the structures support, etc?