Thalamus

Anatomy of Thalamus Thalamus has two sides connected by ______ _____________*

Anatomy of Thalamus Thalamus has two sides connected by Massa intermedia*

Anterior Nuclear Group Anterior tubercle Anteroventral (AV) Anterodorsal (AD) Anteromedial (AM) Input: ______________________ tract; Output: ___________ ________. via ? Function: _______ ________ with __________ formation and ____________ _________ (_____ circuit)

Anterior Nuclear Group Anterior tubercle Anteroventral (AV) Anterodorsal (AD) Anteromedial (AM) Input: mammillothalamic tract; Output: cingulate gyrus. via ant. limb of internal capsule Function: memory function with hippocampal formation and cingulate gyrus (Papez circuit)

Central Pain Damage to the thalamus most often occurs as a result of vascular accidents, typically involving the ____________________________ or ____________ arteries. The damage frequently involves other structures in addition to the thalamus (?). Damage more or less restricted to the ______________ thalamus can cause a characteristic type of _______________ that is somewhat similar to _____________ ____________, in that paroxysms of intense _____ may be triggered by _______________________ stimuli. The pain may spread to involve one entire ______of the body and is usually resistant to ___________ drugs. Similar syndromes of __________ ________ __________ in some patients after damage almost anywhere along the __________________ pathway (ALS). This particular variety, because of the site of damage, is called ____________ pain.

Central Pain Damage to the thalamus most often occurs as a result of vascular accidents, typically involving the thalamogeniculate or paramedian arteries. The damage frequently involves other structures in addition to the thalamus (e.g., the adjacent internal capsule). Damage more or less restricted to the posterior thalamus can cause a characteristic type of dysesthesia that is somewhat similar to trigeminal neuralgia, in that paroxysms of intense pain may be triggered by somatosensory stimuli. The pain may spread to involve one entire half of the body and is usually resistant to analgesic drugs. Similar syndromes of central pain develop in some patients after damage almost anywhere along the anterolateral pathway (ALS). This particular variety, because of the site of damage, is called thalamic pain.

Clinical Correlation Thalamic (Dejerine-Roussy) Syndrome The combination of (3), all contralateral to a posterior thalamic lesion, is called the thalamic syndrome (Dejerine-Roussy syndrome). It is often accompanied by mild and transient ____________ (a result of damage to _______________ fibers in the adjacent __________ __________) and by various types of residual ____________ movements (a result of damage to nearby ________ ________).

Clinical Correlation Thalamic (Dejerine-Roussy) Syndrome The combination of thalamic pain, hemianesthesia, and sensory ataxia, all contralateral to a posterior thalamic lesion, is called the thalamic syndrome (Dejerine-Roussy syndrome). It is often accompanied by mild and transient paralysis (a result of damage to corticospinal fibers in the adjacent internal capsule) and by various types of residual involuntary movements (a result of damage to nearby basal ganglia).

Dorsomedial Nucleus Input (5) Output: (2) Function: mediation of _________ ____________ and ____________ behavior; ____?

Dorsomedial Nucleus Input Amygdaloid Temporal neocortex Caudal obitofrontal ctx Frontal eye field (area 8) SNr Output: Prefrontal cortex Hypothalamus Function: mediation of affective process and emotional behavior; pain?

Intralaminar Thalamic Nucleus Centromedian nucleus (CM); Parafascicular nucleus; Rostral intralaminar nucleus. Imput ? Output ?. Function: ?

Intralaminar Thalamic Nucleus Centromedian nucleus (CM); Parafascicular nucleus; Rostral intralaminar nucleus. Imput Cerebral cortex and reticular formation; Nonciceptive stimuli from spinal cord; MGP. Output Putamen; Other specific thalamic nuclei. Function: influence the transmission of sensory information to the cortex.

Lateral Dorsal Nucleus Input: _________ Output ___________ _________ (posterior) and __________________ cortex of the ___________ ________ Function: _____________ of the _________ ___________ nuclei.

Lateral Dorsal Nucleus Input: Unknown Output Cingulate gyrus (posterior) and supralimbic cortex of the parietal lobe Function: extension of the anterior thalamic nuclei.

Lateral Posterior Nucleus Input: ___________ ______ Output: _________ ___________ _________ (area __ and __) Function: ?

Lateral Posterior Nucleus Input: Parietal lobe Output: Superior parietal lobule (area 5 and 7) Function: integration of different modalities of sensory inputs and cognitive functions associated with them.

Layer VI pyramidal cells >> ? Thalamus >> Layer III ___________ _________ Thalamus >> Layer IV ___________________ Nonspecific Thalamus >> more superficial layers including Layer __?

Layer VI pyramidal cells >> Thalamus Specific Thalamus >> Layer III pyramidal cells; Thalamus >> Layer IV interneurons; Non-specific Thalamus >> more superficial layers including Layer I.

Pulvinar Nucleus Input (3) Output (2) Function: ?

Pulvinar Nucleus Input Superior colliculus and visual cortex (visual); Temporal neocortex (auditory) Output Inferior parietal lobule; Adjoining regions of temporal lobe. Function: integrates auditory and visual inputs to perform complex sensory discrimination learning and cognitive tasks.

REM and non-REM Sleep EEG Non-REM sleep is associated with _________________ _______ ______ waves as a result of: __________ in ______________ neuronal activity; Decrease in (3) activity; Mediated by the _________ and __________. More syncronous firing >> higher _____________ Thalamus (reticular nuc.) cortex.

REM and non-REM Sleep EEG Non-REM sleep is associated with high-voltage slow EEG waves as a result of: Increase in GABAergic neuronal activity; Decrease in NE, 5-HT and Ach activity; Mediated by the thalamus and cortex. More syncronous firing >> higher amplitude; Thalamus (reticular nuc.) cortex.

Reticular Nucleus Input (2) Output: (1) Function: ?

Reticular Nucleus Input Corticothalamic collateral fibers; Thalamocortical collateral fibers Output: GABAergic inhibition to specific thalamic nuclei. Function: disconnect the cerebral cortex from the thalamus for periods of time when reticular neurons display bursting or tonic discharges during sleep.

Thalamus and REM Sleep Control circuitry for REM sleep. ______________ (probably glutamate) projections from the __________ ___________ __________; Activated ______________ neurons in the midbrain reticular formation (MRF) in turn ___________ ____________ neurons ___________; Other midbrain structures received input from MRF ____________ activate ___________ neurons; project to ____ ___________ control centers; ____________ ________________ neurons.

Thalamus and REM Sleep Control circuitry for REM sleep. Excitatory (probably glutamate) projections from the pontine reticular formation; Activated cholinergic neurons in the midbrain reticular formation (MRF) in turn depolarize thalamic neurons directly; Other midbrain structures received input from MRF indirectly activate thalamic neurons; project to eye movement control centers; inhibitory reticulospinal neurons.

The Gateway to the Cerebral Cortex Portions of the dorsal thalamus serve as primary relay nuclei to send _________ information to specific regions of the ___________ ___________; Specific parts of the thalamus play a dominant role in the maintenance and regulation of the state of _________________, ___________ and _____________; Some of the nuclei may serve as ______________ centers for _________________ functions; Since the __________ _____________ connects with _____________, so it also involves in the process related to __________; Physiologically the thalamus and related neuronal subsystems are concerned with __________________ and __________________ of _________ activities.

The Gateway to the Cerebral Cortex Portions of the dorsal thalamus serve as primary relay nuclei to send sensory information to specific regions of the cerebral cortex; Specific parts of the thalamus play a dominant role in the maintenance and regulation of the state of consciousness, alertness and attention; Some of the nuclei may serve as integrative centers for sensorimotor functions; Since the anterior nucleus connects with hippocampus, so it also involves in the process related to memory; Physiologically the thalamus and related neuronal subsystems are concerned with synchronization and desynchronization of cortical activities.

VPL/VPM is Responsible for Central Pain also Responsible for other Sensory Functions The cause of thalamic pain is still not understood, but lesions that cause it almost always involve ______________ Extensive damage to the posterior thalamus also causes total (or near total) loss of _______ ________ in the _______________ ______ and ______. After a period of time, some appreciation of _________, __________, and ________ __________ stimuli usually returns. Functions customarily associated with the _______ __________ tend to be more ___________ and _____________ impaired. Discriminative tactile sensibility may be ______________, ____________ sense may be greatly impaired, and a sensory type of ataxia (resulting from the loss of _________________) may persist. Romberg test: test of position sense in which the patient is asked to stand with feet together and eyes closed. ____________, _______ and ___________________ inputs are combined to produce the sense of ____________ and ___________. If one of the three systems is defective, the remaining two are ___________ for most functions. Loss of two of the three systems is _________________.

VPL/VPM is Responsible for Central Pain also Responsible for other Sensory Functions The cause of thalamic pain is still not understood, but lesions that cause it almost always involve VPL/VPM. Extensive damage to the posterior thalamus also causes total (or near total) loss of somatic sensation in the contralateral head and body. After a period of time, some appreciation of painful, thermal, and gross tactile stimuli usually returns. Functions customarily associated with the medial lemniscus tend to be more severely and permanently impaired. Discriminative tactile sensibility may be abolished, position sense may be greatly impaired, and a sensory type of ataxia (resulting from the loss of proprioception) may persist. Romberg test: test of position sense in which the patient is asked to stand with feet together and eyes closed. Vestibular, visual and somatosensory inputs are combined to produce the sense of orientation and movement. If one of the three systems is defective, the remaining two are adequate for most functions. Loss of two of the three systems is disabling.

Ventral Anterior Nucleus Imput Medial segment of ________ ________ >> _____; _____ ___________ of the substantia nigra >> _____ Output _____________ and ___________ areas (area __) Function: provide ____________ to motor ctx; produce widespread ____________ changes of ____ neurons

Ventral Anterior Nucleus Imput Medial segment of globus pallidus >> VApc; Pars reticulata of the substantia nigra >> VAmc Output Suplementary and premotor areas (area 6) Function: provide feedback to motor ctx; produce widespread excitability changes of ctx neurons

Ventral Lateral Nucleus Input: _________ __________ of cerebellum >> VLc (posterior); _____ and ___ >> VLo (anterior). Output: _______ _________ cortex (area 4) and _____________ areas (area 6) Function: provide feedback to _________ __________.

Ventral Lateral Nucleus Input: Dentate nucleus of cerebellum >> VLc (posterior); MGP and SN >> VLo (anterior). Output: Primary motor cortex (area 4) and premotor areas (area 6) Function: provide feedback to motor cortex.

Ventral Posterior Lateral Nucleus Input: Somatosensory information from _____ by __ and ______ ____________________ tract. Output ___________ _________ cortex Function: _________________ and _____ _______ for the whole body.

Ventral Posterior Lateral Nucleus Input: Somatosensory information from body by ML and direct spinothalamic tract. Output Primary sensory cortex Function: somatosensory and pain relay for the whole body.

Ventral Posterior Lateral Nucleus pars oralis (VPLo) VPLo constitutes a distinctive part of the "______ __________" zone of the ________ __________ __________ region which receives inputs from the _____________ deep cerebellar nuclei and projects to the ___________ _________ ___________ (area 4).

Ventral Posterior Lateral Nucleus pars oralis (VPLo) VPLo constitutes a distinctive part of the "cell sparse" zone of the ventral lateral thalamic region which receives inputs from the contralateral deep cerebellar nuclei and projects to the primary motor cortex (area 4).

Ventral Posterior Medial Nucleus Input Somatosensory information from head by ________________ __________ Output: Primary sensory cortex for _______ region Function: ?

Ventral Posterior Medial Nucleus Input Somatosensory information from head by trigeminal pathway. Output: Primary sensory cortex for head region Function: somatosensory and pain relay for head.