Lecture 19: Brain

Question 1

Define craniata:

Answer 1

Newer term for subphylum vertebrata;

Animals w/ some type of defintive head

Question 2

For each of the 5 subdivisions of the vertebrate brain, describe the changes that occur in the evolution of fishes through mammals

Answer 2

• Telencephalon: become cerebral hemispheres
• Diencephalon: epi-/hypo-/thalamus. Epithalamus: pineal gland-monitor photperiods. All have. Habenulae: smell- large in bloodhounds and sharks.
• Mesencephalon: roof=tectum. Optic lobes (superior colliculi). Well-developed in shark/amphibians. ALSO, auditory (inferior colluculi)/smell-snakes. Together these two make corpora quadrigemina
• Metencephalon: cerebellum-restiform bodies: equilibrium. Fish/shark/bird=well-developed d/t need for coordination w/ swimming/flight. Less developed in amphibian/reptile.
• Myelencephalon: well-developed in all the rest of vertebrates. Medulla oblongata. Vagal lobes.
• -tel+die= prosencephalon: divides in ray-finned fishes.
• -met+mes=rhombencephalon

Question 3

List the major evaginations from the prosencephalon

Answer 3

Telencephalic vesicles: cerebral hemispheres

Optic vesicles: retinas of the eye and asso. W/ diencephalon.

Question 4

List the major derivative from the metencephalon and describe the comparative anatomy from fishes to mammals.

Answer 4

Cerebellum, restiform bodies, floccular lobes.

Question 5

Describe the function of Vagal lobes and where theyre found

Answer 5

Vagal lobes are asso. W/ myelencephalon in teleosts.

Asso. W/ sense of taste

Question 6

Describe the comparative anatomy of the cerebellum and r/t types of activity

Answer 6

Agnathans: cerebellum doesnt bulge. Cell bodies on surface..

Chondrichthyes (restiform bodies) and teleosts: well-developed for swimming.

Amphibians: poorly developed cerebellum.

Reptiles: poorly developed metencephalon. Floccular lobes

Birds: very large cerebellum. Well-developed Floccular lobes

Mammals: well-developed cerebellum.

Question 7

List the major derivatives from the mesencephalon and describe

the transition from the medulla to the spinal cord

Answer 7

Optic lobes [superior colliculi]

Auditory tubes [inferior coliculli]
=collectively make the corpora quadrigemina

Roof of mesencephalon is tectum. Displays a prominent pair of optic lobes in all craniates. Gray matter masses. Serve as reflex and relay centers for impulses from retina. Especially in large birds.

***Need more

Question 8

List the major derivatives from the diencephalon

Answer 8

Epithalamus

Thalamus

Hypothalamus

Question 9

Describe the comparative anatomy of the epithalamus, including the habenulae.

Answer 9

.Epithalamus:

• pineal body-photosensitive
• parapineal body (organ)
• choroid plexus
• habenulae-asso. W/ olfaction. Reflexes to odor. Largest in shark and bloodhound.

Gnathostomes had median eye (prob. Pineal gland) agnathans and gnathostomes have pineal gland.

Question 10

Describe the location and function of the thalamus, including the various groups of thalamic nuclei

Answer 10

Thalamus: relay nuclei for both motor and sensory pathways. 80% of diencephalon. Interprets pain, temp. Light touch, arousal,etc.
Relays:
Sensory:
-Medial geniculate body: auditory
-Lateral gen inculcate body: visual
-Ventral posterior nucleus: sensation/pain

Motor(voluntary):

• ventral lateral and subthalmic: motor
• ventral anterior: motor and arousal

Reticular: alertness
Anterior: memory-hippocampus

Question 11

Describe the development of the cerebral cortex from pallium to neocortex and r.t the comparative anatomy

Answer 11

Telencephalon: cerebrum, olfactory tract/bulbs, striatum(thickening in floor of cerebrum), lamina terminalis

-Agnathans, fishes, and amphibians do not have cortex.
-reptiles: major development-dorsal ventricular ridge. Receives visual, auditory, sensory stimuli from thalamus to striatum. Additional increase in size, then crocodillians pallium is asso. W/ neurons [beginning of cerebral cortex]
-birds:retain basic reptilian pattern. [reptiles w/ feather] add another layer of neurons on top of dorsal ventricular ridge (avian ridge)
MAMMALS: addition of neocortex.

Question 12

List the lobes and functions of the mammalian cerebral cortex

Answer 12

Occipital lobe: eye focusing, visual images/memory,visual perception.

Parietal: somatesthetic interpretation, speech comprehension, speech formulation connecting thought/emotion- Wenicke’s area

Frontal: voluntary motor control-precentral gyrus. Motivation. Mood, aggression, verbal communication-Broca’s area

Temporal: olfactory and auditory sensations /memories

Insula: involved in memory. Highest levels of brain function (abstract thought, judgement). Cant be seen from surface.

Question 13

Describe the comparative anatomy of the striatum and list the nuclei and their functions that make up the striatum in higher vertebrates

Answer 13

Striatum: forms floor of the telencephalon. Made of telencephalonic basal nuclei.

Fishes: globus pallidus: primitive
Amphibians: additional nuclei for extensive motor activities in limb muscles
Birds: well developed striatum.
Mammals: additional nuclei added to striatum-basal ganglia (nuclei)-amygdaloid nucleus

Question 14

Large subconscious movements of skeletal muscles

Answer 14

Putamen

Question 15

Regulates muscle tone

Answer 15

Globes pallidus