Functional Anatomy of the Cerebrum

Question 1

Identify the location and general functions of all the major lobes of the cerebrum.
Relate the primary sensory cortices to the lobes in which they are located

Answer 1

Occipital lobes: visual cortex
Temporal lobes: auditory cortex
Piriform lobe: aka rhinencephalon, “small brain”, olfactory cortex (anosmia)
Fronto-parietal region: somatosensory cortex, aka somaesthetic cortex. The motor cortex is sometimes also lumped here: overlaps with the primary cortex (sensorimotor cortex)

Question 2

hypothalamus functions

Answer 2

1. appetite and satiety
2. osmoregulatory/ thirst center
3. temperature regulation
4. circadian rhythms
5. rage and pleasure

remember is endocrine functions as well as visceral motor system

Question 3

consciousness =

Answer 3

cerebral cortex and ARAS

Question 4

parts of the limbic system

Answer 4

Fornix (axons that came out of hippocampus and goes into synapse down into hypothalamus)
Hippocampus (interface between neocortex and limbic structures
Cingulate gyrus (neocortical)
Amygdala (wont be able to see grossly, emotional memory)
Hypothalamus (cortical influences, limbic influences, physiologic changes)

Question 5

the limbic system

Answer 5

Both cortical and subcortical structures
“Anatomical substrate for drive-related and emotional behavior”
Creates complex behaviors with Neocortex (consciousness, perceptions) and Hypothalamus (drives, physiologic changes)

not true that we only use 10% of our brain

Generates emotional memory (amygdala), different from factual memory. Hard to convince the brain everything is okay especially if you’re a dog

Question 6

signs of midbrain compression

Answer 6

tentorial herniation
early compression: reduces autonomic influences of hypothalamus on parasympathetic nuclei of cranian n iii - miosis
increased compression: mydriasis, poor prognosis in head trauma patients

Question 7

Levels of consciousness:

Answer 7

Alert - normally responsive to environment
Obtunded - withdrawn, but still responsive (avoid the word depressed, client would think you are referring to their emtional state)
Stuporous - unresponsive except to painful stimuli
Comatose - non-responsive to all stimuli (except by reflex)
Delirious (demented, but not insane) - responds abnormally

Question 8

Signs of abnormal consciousness (delirium)

Answer 8

Compulsive wandering/pacing
Head-pressing
Somnolence
Abnormal vocaliztion
Circling (not a good localizer, big circles, usually > lesion [adversive syndrome]), when you damage a part of the cerebra, cna cause circling.

Question 9

define a seizure

Answer 9

A seizure is a cortical event
characterized by abnormal neuronal discharge which is both excessive and
hypersynchronized.

Question 10

three stages of a seizure

Answer 10

Aura
Altered behavior at start of abnormal electrical activity
Usually brief (min’s)
Often w/ alterations in sensation or emotion
Ictus (letal period)
Period of maximal neuronal activity
Behavior depends on the region affected
One or more
As in consciousness
Hallucinations
ANS activity
Psychic manifestations (rage, fear)
Alterations in mm. activity
<5 min (usually 1-2 min)
Post ictus (post-ictal period)
Confusion, disorientation
Often cortical blindness
wondering/restlessness
Minutes to hours

Question 11

big picture type seizures

Answer 11

May involve all of cerebrum: generalized seizure
May involve only oart of the cerebrum: partial (or focal) seizure - possibility for it to spread
May start in one focus and spread throughout cerebrum: partial seizure w/ secondoary generalization

Question 12

types of partial and generalized seizures

Answer 12

**Partial seizure: **
(common) Simple partial, no loss of consciousness, e.g. focal motor seizure

(not so common) Complex partial: altered consciousness focus usually limbic > behavioral/emotional seizure aka psychomotor seizure

Generalized seizure:
(most common) Convulsive: consciousness altered/lost bilateral motor activity aka: grand mal (aka tonic-clonic seizure, major motor seizure)

(uncommon, would need ECG running to diagnose) Non-compulsive: consciousness altered no collapse/ convulsions aka: petit mal (aka absence seizure) RARELY documented in animals

Question 13

Grand mal seizure

Answer 13

ICTUS:
Collapse
Extensor rigidity (=”tonic phase”)
Opisthotonous and apnea
Clonic limb movements (=”clonic phase”)
paddling / chewing
ANS activity (often urination)
Vocalizations

Question 14

Seizure pharmacology

Answer 14

Rx > decrease effect of glutamate or increase effect of GABA
Eg. phenoarbitol augments Cl- current of GABA receptor

Question 15

seizure like disorders

Answer 15

**Narcolepsy: **episodic and sudden onset of REM sleep
Intrinsic inhibitory pathways that paralyzes you when you are asleep
Cataplexy = one aspect of narcolepsy sudden loss of tone in nearly all striated mm. (Extraocular and respiratory mm. spared)
An element of narcolepsy but cataplexy can happen on its own.

Question 16

types of epilepsy

Answer 16

Epilepsy = (common in dogs) non-progressive, recurrent seizures w/o active disease process
Primary epilepsy: aka idiopathic, inherited, cryptogenic
Acquired epilepsy: results from prior trauma, damage (= change in neuronal excitability)
Car accident, head trauma