Thalamus Flashcards
what are the 4 parts of the diencephalon?
- thalamus
- epithalamus
- subthalamus
- hypothalamus
what does the thalamus include?
- metathalamus
- medial + lateral geniculate bodies
what is the thalamus referred to as (functionally)?
the gateway to the cortex
what are the 3 Cs of the thalamus’s function?
Consciousness
Control
Cognition
The is the main structure of the thalamus?
internal medullary lamina
what are the 3 major nuclear groups as divided by the internal medullary lamina?
- medial group
- lateral group
- anterior group
what does the Posterior group of the thalamus contain?
- pulvinar
- medial
- later gniculate body
what does the anterior nuclear group do?
- has heavily reciprocal connections with hypothalamus
- specifically mammillary bodies
where does the anterior nuclear group receive input from?
-hippocampus via Fornix
what does the anterior nuclear group connect to?
Cingulate gyrus
what is the function of the anterior nuclear group?
- limbic/emotional
- also memory (fornix heavily linked to hippocampus)
what do bilateral lesions of the anterior nuclear group lead to?
-memory iimpairments
what is anterograde amnesia?
poor forming of new memories
what is retrograde amnesia?
poor recall of information from past years
what is the main nucleus of the medial nuclear group?
-mediodorsal nucleus
what is the medial nuclear group connected to?
reciprocally connected with the prefrontal cortex
where does the medial nuclear group receive input from?
- subcortical structures that are involved in:
1. the processing of signals related to emotional/affective behaviors (amygdala)
2. the expression of motor behaviors (substantia nigra)
what is the function of the medial nuclear group?
control of emotion + complex behaviors (decision making + judgement)
what are 3 symptoms/results of bilateral Mediodorsal nucleus lesions?
- syndrome characterized by indifference, poor motivation
- lack of insight (unaware they have a problem
- apathy: indifference + incapacity to keep an ongoing activity
what used to be performed to relieve certain psychiatric conditions?
- prefrontal lobotomy
- surgical interruption of the reciprocal connections between the MD and prefrontal cortex
what are the 3 most functionally significant groups of the lateral nuclear group?
- ventral posterior nucleus (VP)
- ventral lateral nucleus (VL)-cerebellum
- ventral anterior nucleus (VA) - basal ganglia
what is the ventral posterior nucleus inferior for?
-for spinothalamic and medial meniscal systems
what is the ventral posterior medial for?
-for trigeminal sensory
what do unilateral lesions of the VP lead to?
-contralateral loss of sensation on both the body and the face
where does the Ventral lateral nucleus receive input from?
-the cerebellum
what does the VL connect to?
-motor cortex
what is the function of the VL?
-motor
what are clinical signs of lesions to the VL?
-signs after stroke resemble cerebellar signs
where does the ventral anterior nucleus receive input from?
basal ganglia
what does the VA connect to?
premotor cortex
what is the function of the VA?
-motor function
what are clinical signs/symptoms of VA lesions?
-basal ganglia movement disorders
what are the 3 components of the posterior nuclear group?
- the pulvinar
- the lateral geniculate bodies
- the medial geniculate bodies
where does the pulvinar receive input from?
superior colliculus and pretectum
what is the pulvinar connected to?
- lateral geniculate body
- connects reciprocally to extensive areas of parietal, occipital, and temporal cortices
what is the function of the pulvinar?
- visual functions
- related to eye movements in visual attention
what is an example an effect of damage from the pulvinar?
-visual neglect
what are 2 other things the pulvinar is involved in?
- speech mechanisms + language
- pain mechanisms
where does the lateral geniculate body receive input from?
optic tract
what does the lateral geniculate body connect to?
the visual cortex
what is the function of the lateral geniculate body?
vision
where does the medial geniculate body receive input from?
-inferior colliculus
what does the medial geniculate body connnect to?
the auditory cortex
what is the function of the medial geniculate body?
hearing
what can occur if the thalamic relay nuclei of the somatosensory auditory or visual pathways are damaged?
- contralateral hemianethesia
- hemihypoacusis
- contralateral hemianopsia
do voluntary or involuntary movements occur with thalamic pathology?
both
what other kind of impairments can occur with thalamic pathology?
-memory (alcoholic-Korsakoff, Wernicke Korsakoff Syndrome)
what result from damage to the posterior and ventral thalamus?
-somatosensory changes
what are the 5 symptoms/clinical signs of Thalamic Pain syndrome (damage to VPL and VPM)
- hemiansthesis
- astereognosis
- paroxysmal pain
- dysethesia
- hyperpathia
what are 3 reasons that clinical signs of thalamic pain syndrome could take 2-3 weeks to develop
- few surviving/damaged neurons in injured left thalamus sending abnormal messages to cortex
- may be pathways not knkown about carrying info that bypasses somatosensory thalamus (VPL + VPM)
- peripheral stimuli to tissue receptors may trigger dual somatosensory messages
7 main functions of the thalamus?
- regulating states of sleep + wake
- sensation + pain
- vision
- hearing
- support of motor systems
- learning + memory
- language + speech
thalamic nuclei have storng reciprocal connections with ______
the cerebral cortex
what can extensive bilateral damge tot he thalamus lead to?
-permanent coma
what is they hypothalamus?
-ventral component of diencephalon surrounding 3rd ventricle
is the hypothalamus often affected by stroke?
-rarely (rich in blood supply)
what is the hypothalamus often affected by?
- tumors
- developmental disorders
- infections
- alcoholism
- head trauma
what is the hypothalamus’s key function?
-homeostasis (regulating + maintaining normal body function)
what are 6 factors of homeostasis?
- body weight + body temp
- food, salt + water intake
- sexual cycles, orientation, onset of puberty
- circadian rhythms
- body growth
- stress response
what are 6 areas of change that indicate alterations in endocrine and automic functions by the hypothalamus?
- appetite, weight + temp
- metabolism
- sexual behavior
- sleep cycles
- body growth
- mood
what are the two function systems of the hypothalamus/pituitary gland?
- the hypothalamo-hypophysial tract (magnocellular neuroendocrine system) - Hypothalamus-Posterior Pituitary
- tubero-hypophysial tract (Parvocellular neuroendocrine system - Hypothalams-anterior pituitary
what does the hypothalamohypophysial tract/Magnocellular neuroendocrine system connect?
-connects hypothalamus with neurohypophysis (posterior pituitary)
what does the magnocellular neuroendocrine system constitute?
-nuceli of the hypothalamus that contain: vasopressin (ADH) and oxytocin producing cells
what does vasopressin/ADH do?
- controls water balance
- retains water by distal tububles of the kidney
what is the release of vasopressin/ADH controlled by?
-osmotic changes in blood
where are osmoreceptors located?
-anterior periventricular region
what does oxytocin act on?
- uterine smooth muscles (uterine contractions during birth)
- myoepithelial cells of mammary gland (milk)
what is oxytocin controlled by?
afferents from nipples to magnocellular nuclei
What does interruption of the magnocellular neuroendocrine system?
- diabetes insipidus
1. polyuria
2. low specific gravity
3. no alteration in blood and urine glucose
what does the parvocellular neuroendocrine system do?
connects hypothalmus with anterior pituitary
what does GnRF and LHRF do?
controls release of LH and FSH
what 2 hormones are essential for development of bones, connective tissue, viscera + reproductive organs
GH
prolactin
result of too much GH (children)
gigantism
result of too little GH (children)
dwarfism
result of too much GH (adults)
Acromegaly
what controls the release of prolactin?
PIF and dopamine
what is TSH?
controls body’s metabolic rate, tempt, level of general activity
too little TSH
hypothyroidism
too much TSH
hyperthyroidism
what does ACTH do?
release cortisol + corticosterone from adrenal cortex of kidney
what is the result of too much cortisol
cushing’s disease
symptoms of cushing’s disease
- hypertension
- truncal obesity
- diabetes
what is the result of too little ACTH
addisoin’s disease
symptoms of addison’s disease
- weakness
- weight loss
- increased skin pigmentation
- hypotension
- hypoglycemia
pituitary tumor signs are:
- oversecretion of pituitary hormones
2. inadequate secretion of hormones
