Thalamus Flashcards
Motor specific nuclei of thalamus (2)
Ventral lateral (VL) Ventral anterior (VA)
Sensory specific nuclei of thalamus (4)
Ventral posterolateral (VPL) Ventral posteromedial (VPM) Lateral geniculate (LGN) Medial geniculate
Association nuclei function: (3)
- Connect w/ association cortical areas
- Receive input from many other thalamic nuclei
- Connections w/ cortex that are not directly reciprocal
Association specific thalamic nuclei (2)
Mediodorsal nucleus
Pulvinar
Limbic specific nuclei
Anterior group (AN) Laterodorsal nucleus (LD)
Non-specific thalamic nuclei
Midline nuclear group Intralaminar group (centromedian nucleus)
Ventral posterolateral nucleus
Input:
Output:
Input: Spinothalamic = pain/temp, DCML = discriminative touch
Output: Reciprocally connected w/ postcentral gyrus (limb and trunk of somatosensory cortex)
Ventral posteromedial nucleus (VPM)
Input:
Output:
Input:
Trigeminothalamic system: sensory from face
Taste from NTS via dorsal longitudinal fasciculus –>Medial, parvicellular portion of VPM (VPMpc)
Output:
VPM: Face portions of somatosensory cortex (postcentral gyrus)
VPMpc: anterior part of insula (primary gustatory cortex)
Lateral geniculate nucleus (LGN)
Input:
Output:
Input: Visual (optic tract) of contralateral visual field
Output: Primary visual cortex (V1) in occipital lobe (cuneus and lingual gyrus) via optic radiation
Lateral geniculate nucleus
Magnocellular projections from layers ___ and ___ convey info about ____ from ____
Layers 1 and 2
Movement, depth and small differences in brightness
Retinal rods
Lateral geniculate nucleus
Parvocellular projections from layers ___ to ___ convey ____ from ____
Layers 3-6
Fine details about form and color
Retinal cones
Inputs from temporal retina end (ipsilateral) end in layers ___
2, 3, 5
Inputs from nasal retina end (contralateral) end in layers ___
1, 4, 6
Medial geniculate nucleus
Input:
Output:
Input:
Auditory input from inferior colliculus
Output:
Auditory cortex in Heschl’s gyrus of temporal lobe via auditory radiations
Ventral lateral nucleus (VL)
Input:
Output:
Input:
Crossed output of cerebellar deep nuclei via thalamic fasciculus
Output:
Primary motor cortex in precentral gyrus
Ventral anterior nucleus (VA)
Input:
Output:
Input:
Inhibitory input from ipsilateral basal ganglia via thalamic fasciculus
Output:
Lateral part: trunk and limb regions of premotor cortex
Medial part: premotor, frontal eye fields, cingulate and parietal cortices
Lateral part of ventral anterior nucleus (VA) receives input from:
globus pallidus internal segment (GPi)
Medial part of ventral anterior nucleus (VA) receives input from:
Sustantia nigra pars reticulata (SNr)
Thalamc fasciculus is a composite bundle containing _____ fibers that is insinuated between ____ and ___.
Cerebellothalamic (Crossed)
Pallidothalamic (Uncrossed)
Thalamus, zona incerta
Basal ganglia disease on motor function are expressed (ipsilaterally/contralaterally)
Contralaterally
Cerebellar disease are expressed (ipsilaterally/contralaterally)
Ipsilaterally
Mediodorsal nucleus (MD)
Input:
Output:
Function:
Input:
Amygdala, olfactory cortex, ventral pallidum (basal forebrain)
Output:
Prefrontal cortex and limbic system
Function:
Attention, planning, organization, abstract thinking, multitasking, active memory
Lesions affecting mediodorsal nucleus results in ____
apathy
memory changes
difficulty in switching tasks
Pulvinar
Input:
Output:
Function:
Input:
Retina, superior colliculus, spinothalmic tract (indirectly)
Output:
Parietal, temporal, occipital lobes
Function:
Language processing, visual perception, pain perception
Anterior group (AN)
Input:
Output:
Function:
Input:
Para-hippocampal region via fornix and mammillary bodies (mammillothalamic tract)
Cholinergic input from midbrain
Output: Cortex of cingulate gyrus
Laterodorsal nucleus (LD)
Input:
Output:
Function:
Input: Parahippocampal region via fornix Output: Parietal cortex, retrosplenial cortex Function: Spatial learning and memory
Korsakoff’s syndrome caused by:
Severe degenerative changes in anterior group
Changes in mammillary bodies
Spatial and context-dependent memory formed from distributed neural system made from: (6)
anterior group, laterodorsal nucleus, mammillary bodies, fornix, mammillothalamic tract, cingulate and retrosplenial cortices
Midline nuclear group
Input:
Output:
Function:
Input:
Pain-related info from midbrain PAG
Cholinergic elements of Ascending Reticular Activating System
Locus ceruleus (NE) and midbrain raphe (5-HT)
Output:
Diffusely to cortex and striatum
Thalamic paraventricular nucleus connected w/ suprachiasmatic nucleus
Function: General cortical arousal
Intralaminar group (centromedian nucleus)
Input:
Output:
Function:
Input: non-reciprocal input from motor cortex Cholinergic input from ARAS Output: Reciprocally connected w/ striatum and basal ganglia Function: Attention to motor tasks
Lesions of centromedian nucleus lead to ____
Unilateral motor neglect
Thalamic relay neurons on burst mode are ____
Function:
Hyperpolarized, “de-inactivated”
Less able to pass incoming signal to cortex BUT maximized initial stimulus detection
Thalamic relay neurons in tonic mode are ____
Function:
Depolarized
Better linear summation (pass signal to cortex) BUT poorer detectability for new stimuli
Function of intralaminar thalamic cells
Hyperpolarize thalamic relay neurons via GABAb receptors –> primed for bursting activity
Switch between burst mode and tonic mode is controlled by ___
Modulatory afferents to these cells = thalamic reticular nuclei (TRN) + feedback pathway from cortex
Thalamic reticular nuclei (TRN) are innervated by ____
Involved in:
Cholinergic fibers of ARAS from midbrain
Coordinating information traffic from relevant sensory channels
During slow-wave sleep, TRN keeps all thalamocortical neurons in ____ mode
burst –> can’t pass signals
During wakefulness, TRN _____
selectively switches populations of relay neurons from burst to tonic mode
Blood supply to thalamus is mostly from ____
Posterior cerebellar artery
Infarct in inferolateral a. (branch of PCA) will cause (4):
Ataxia
Hemiparesis
Hemianesthesia
Hemihyperesthesia
Infarct in the paramedian a. will cause (3):
Hemiparesis (motor neglect)
Memory/learning problems
Apathy
Infarct in anterior (tuberothalmic) a. will cause (3):
Amnesia
Language difficulty
Euphoria/mood
Contralateral hemianesthesia caused by:
VPL/VPM damages
Contralateral hemianopsia (blindness) caused by:
Lateral geniculate nucleus (LGN) damage
Contralateral hemichorea caused by:
VA/VL damage
Contralateral hemitremor and hemiataxia caused by:
VL damage
Retrograde/anterograde amnesia caused by:
MD, midline nuclei
Dejerine-Roussy Syndrome characterized by: (5)
Hemi-ataxia Hemi-tremor Hemi-chorea Hemi-anesthesia 2 pt touch Hyperesthesia: exaggerated pain and temp.
