Diencephalon Flashcards
The ______________ is the largest portion of the diencephalon. It is a complex group of nuclei interposed between the _________ and lower centers of the ______________.
thalamus
cortex
brain stem
The thalamus receives ______________________ information from sensory pathways, processes this information and relays it to the ____________. It is also intimately associated with the motor systems - in particular with the _______________________________.
ascending sensory
cortex
basal ganglia, cerebellum and motor cortex
Is the thalamus a part of the reticular activating system?
yes
The brain has two thalami which are egg shaped nuclear masses, one on each side of the _____________________. They function with respect to reciprocal connections with the ________________ cortex.
third ventricle
ipsilateral
What are the two gross subdivisions of the thalamus?
A. Fiber layers
B. Nuclear subdivisions
What are the 6 nuclear subdivisions of the thalamus (part of the gross subdivisions of the thalamus)?
- anterior group
- medial group
- lateral group
- metathalamic group
- intralaminar group
- reticular coat
The anterior group nuclear subdivision =
related to the limbic system
The media group nuclear subdivision =
related to a number of systems, but the primary access to prefrontal cortex
The lateral group nuclear subdivision =
relay nuclei for somatosensory and motor cortical areas
The metathalamic group nuclear subdivision =
Lateral and Medial Geniculate nuclei
The intralaminar group nuclear subdivision =
Centromedian nucleus that is related to the reticular formation
The reticular coat nuclear subdivision =
outer most shell of the thalamus (not a part of the reticular formation)
What are the 6 SPECIFIC nuclear groups?
- Anterior thalamic group
- Medial group
- Lateral group
- Metathalamus
- Intralaminar
- Thalamic reticular coat
Describe the anterior thalamic group SPECIAL nuclear group:
limbic
Describe the media group SPECIAL nuclear group:
- limbic, association cortex, basal ganglia
* Dorsomedial nuc. - major one
Describe the lateral group SPECIAL nuclear group:
•Lateral group - divided into dorsal and ventral tier
- Dorsal tier - pulvinar
- Ventral tier - VPM, VPL, VL,VA (nuclei relaying sensory and motor information)
Describe the metathalamus SPECIAL nuclear group:
Lateral and medial geniculate nuclei
Describe the intralaminar SPECIAL nuclear group:
associated with reticular formation, almost everything else; Centromedian nucleus
Describe the thalamic reticular coat SPECIAL nuclear group:
not reticular formation, acts in gating efferent thalamic information
What are the subcortical afferents to thalamic nuclei? (We have already done a lot of these)
- sensory pathways
- basal ganglia
- cerebellum
- reticular formation
Name the 4 functions of the thalamic nuclei:
- Gated relay for transmission of all sensations (except olfaction) for conscious perception
- Chief integrating center of all sensory information
- Plays dominant role in maintenance and regulation of the state of consciousness, alertness and attention = Awareness; area of affect-deals with emotion, pain, agreeableness; highly subjective
- Integrative center for motor activity - basal ganglia and cerebellum
The cortical relay nuclei receive:
highly ordered SENSORY and MOTOR information and then relay it in an accurate manner (maintaining topographic, tonotopic, visuotopic organization) to specific sensory and motor cortices, i.e. VPM, VPL, VA, VL, LGN, MGN
Association nuclei receive:
little or no direct afferents from sensory/motor pathways, but have extensive interthalamic connections and receive afferents from other subcortical nuclei (limbic, etc.). These project back to association cortices (mostly frontal, parietal and temporal lobes); includes pulvinar, dorsomedial
Nonsepcefic nuclei; intralaminar nuclei (CM) associated with ___________________________________________. Reticular thalamic nucleus functions as an ______________________________________.
behavioral arousal and sensory/motor integration, sleep.
inhibitory feedback regulator of thalamic neuronal activity-gating of sensory information.
Thalamic pain syndrome - usually ____________ in origin; thalamogeniculate artery (by loss of connections at the thalamic level or cortical level, pain sensations cannot be interpreted accurately.) The ability to discriminate between an ____________________ vs. a painful one becomes blurred.
vascular
irritating stimulus
In thalamic pain syndrome, studies on the pathways and sensitization of the central pathways reveal a very broad scope of regions involved in the “increased” perception of pain. This can be as a result of either:
irritative stimuli such as an intervertebral disc or radiculopathy to more centrally mediated changes to circuitry as a result of stroke, TBI, SCI.
In thalamic pain syndrome, central sensitization of pain has shown __________________________________________. This heightened response begins at _____________________________________________________.
heightened cortical responses in the thalamus, cingulated gyrus (limbic or emotion), parietal lobe and prefrontal cortex.
the synapse in the dorsal horn and can involve more than just the transfer of noxious sensations to ultimately affect non-noxious stimuli such as touch.
Clinically this is seen as hyperalgesia or allodynia.
In thalamic pathologies, changes in stimulus thresholds:
- elevated for tactile and position sense
2. lowered for nociorecptive stimuli
In thalamic pathologies, at threshold, sensations are exaggerated, exceptionally unpleasant =
- pin prick leads to severe burning pain
2. muscle leads to unpleasant responses
In thalamic pathologies, _______________ pain is experienced.
spontaneuos
In thalamic pathologies, emotional instability =
inappropriate laughing or crying; altered gating of emotion to cortex
In thalamic pathologies, pseudobulbar affect =
stroke patients with brainstem and thalamic lesions
The hypothalamus is responsible for:
homeostatic influences necessary for life; i.e., cardiorespiratory, thermoregulation, metabolic, water resorption, digestive activity.
Activites, by the hypothalamus, are manifested by ____________________________________________________________________________. This area acts in a reflexive manner receiving _________________________________.
control or influence over the pituitary gland, autonomic nervous system at the level of the brainstem and the spinal cord.
afferent visceral information.
It is also influenced by higher centers, primarily _________________________________.
limbic system and prefrontal cortex.
The limbic system, responsible for _____________________________, influences the hypothalamus and thus the autonomic nervous system effecting cardiovascular, respiratory and emotional reactions to ___________________________________________.
emotion, moods and motivation,
ongoing situations; embarrassment, fear, anxiety.
List 3 autonomic control areas of the hypothalamus:
- anterior hypothalamus
- lateral hypothalamus
- ventromedial hypothalamus
What is the anterior hypothalamus related to?
related to septal region of limbic system
What are the autonomic control areas of the hypothalamus looked as?
“upper motor neurons” of the ANS
