18 – Thalamus/Hypothalamus

Question 1

What does the forebrain consist of?

Answer 1

-cerebral cortex (cerebrum)
-diencephalon

Question 2

Diencephalon location:

Answer 2

-stays in midline as during development the cerebral hemispheres grow out from it

Question 3

What structures are in the diencephalon?

Answer 3

-thalamus
-epithalamus (pineal gland)
-hypothalamus
*anything with “thalamus”

Question 4

Thalamus contains:

Answer 4

-large number of nuclei (grey matter)

Question 5

Thalamus role:

Answer 5

-relay and processing centre for info going in/out of the cerebral cortex
*ALL info except the olfactory nerve
-central role in maintaining consciousness
-sleep

Question 6

Thalamus role and sleep:

Answer 6

-coordinates neuronal firing
>bursting patterns of brain activation are blocked by the thalamus

Question 7

What are some signs of a lesion in the thalamus?

Answer 7

-altered level of consciousness (ex. more sleepy)
-seizures
-proprioceptive deficits
-UMN signs
-maybe LMN signs for CN II and III
*can press on other structures and getting different issues/signs

Question 8

Hypothalamus location:

Answer 8

-ventral aspect of the diencephalon
>surrounds the ventral aspect of the 3rd ventricle

Question 9

What are some physiological, behavioral and hormonal responses to maintain homeostasis that the hypothalamus does?

Answer 9

-thermoregulation
-osmoregulation
-appetite/thirst
-sleep/wake cycles
-endocrine regulation

Question 9

Hypothalamus role:

Answer 9

-control internal stimuli (increased CO2 and micturition)
>regulation of internal body environment
-coordinates physiological, behavioral, and hormonal responses to maintain HOMEOSTASIS

Question 10

Hypothalamus lesion consequence to neuroendocrine regulation (oxytocin+ADH):

Answer 10

-abnormal endocrine production=multi-system malfunction
>diabetes insipidus
>Cushing’s (hyperadrenocorticism)

Question 11

Hypothalamus lesion consequence to regulation for ANS:

Answer 11

-organ dysfunction
-inability to maintain BP
-inability to thermoregulate

Question 12

Hypothalamus lesion consequences to coordination and production of defensive behaviour: (b/c it’s part of limbic system)

Answer 12

-increase aggression (rage behaviour)
-increase fear
-star-gazing behavior
Ex. rabies causes this so they bite another animal

Question 13

Hypothalamus lesion consequences to thermoregulation:

Answer 13

*various regions
-heat loss center (hypothermia)
-heat retention center (hyperthermic)
*animals can change their set point

Question 14

Hypothalamus lesion consequences to osmoregulation and water intake:

Answer 14

-abnormal water consumption
>polydipsia
>adypsia

Question 15

Hypothalamus lesion consequences to food intake and metabolism:

Answer 15

-abnormal feeding behaviours
>polyphagia
>aphagia

Question 16

Hypothalamus lesion consequences to circadian rhythm:

Answer 16

-in animals: we do not appreciate abnormalities in sleep-wake cycles
-reported in humans

Question 17

Other related abnormalities with the hypothalamus:

Answer 17

-space occupying masses
-fevers: abnormal increase to ‘normal’ body temperature
-general anesthesia can alter various aspects (not totally sure of effects)

Question 18

Space occupying masses in hypothalamus may result in:

Answer 18

-abnormal vision: close proximity to optic chiasm
-abnormal consciousness: close proximity to thalamus and brainstem (reticular formation)

Question 19

General anesthesia some changes to the ‘body’:

Answer 19

-alter level of consciousness
-colder