Thalamus
Describe the function both generally and in terms of specific nuclei
-Thalamus is more than a relay station, it appears to modulate the flow of information to the cerebral cortex 1. Sensory - Lateral Posterior, Pulvinar, Ventral Posterior Lateral, Ventral Posterior Medial, Medial Geniculate, Lateral Geniculate 2. Motor - Ventral Anterior, Ventral Lateral, Centromedian 3. Limbic - Anterior, Medialdorsal, Pulvinar 4. Consciousness - Reticular and Centromedian
Describe the organization of the thalamus and identify the major nuclei
1. Anterior division (Anterior nucleus) - Projections from Mamillothalamic tract 2. Medial division (mediodorsal nucleus) - Projections from limbic system 3. Lateral division -Dorsal nuclei (lateral dorsal, lateral posterior, pulvinar) -Ventral nuclei (ventral anterior, ventral lateral, ventral posterior lateral, ventral posterior medial, medial geniculate, lateral geniculate) 4. Intralaminar nuclei (centromedian and reticular)
Thalamic Syndrome (Dejerine-Roussy)
1. Damage to the thalamus after a stroke 2. Can result in: loss of fine touch and ataxia followed (perhaps much later) by pain that may become worse with many different stimuli. An example of neuropathic, central pain not caused by damage to body tissues
Describe the major inputs to thalamic nuclei and outputs of thalamic nuclei
1. Superior colliculus and pretectal nucleus > Pulvinar & LP > Posterior parietal cortex 2. Retina > LGN > Striate Cortex 3. Inferior Colliculus > MGN > Heschel's Gyrus 4. Gracilis & Cuneatus Nuclei, Spinal Cord > VPL > Post-central gyrus 5. Sensory/Spinal of CN V, Solitary Nucleus > VPM > Post-central Gyrus 6. Cerebellum > VL > Motor & Premotor Cortex 7. Basal Ganglia > VA > Supplementary Cortex 8. Amgydala, Septal nuclei > MD > Prefrontal Cortex 9. Mammillary Bodies > Anterior Nucleus > Cingulate gyrus
Identify the location of the thalamus in the brain
1. The thalamus is found in the dorsal diencephalon 2. Located dorsal to the hypothalamus. It is separated from hypothalamus by the hypothalamic sulcus. The thalamus is ventral to the epithalamus (habenula and pineal gland) 3. The right and left thalami are separated by the dorsal portion of the third ventricle 4. The thalamus can be identified in sagittal views by the intrathalamic adhesion 5. The thalamus is medial to the posterior limb of the internal capsule and lentiform nuclei
What happens with lesion at VPL?
Loss fine touch, proprioception, pain, temperature of body
What happens with lesion to VL?
Loss of coordination and balance
What happens with lesion at Anterior nucleus?
Loss of emotional correlates of pain, sadness, learning from error detection and reward-based decision making, memory
What happens with lesion at VA?
Loss of executive order, cognitive, motor, limbic, oculomotor functions
What happens with lesion at VPM?
Loss of fine touch, proprioception, pain, temperature of face and taste
What happens with lesion at MGN?
Loss of hearing
What happens with lesion at MD?
Loss of limbic functions: emotions, memory, learning, smell, reward system,
What happens from lesion at pulvinar & LP?
Loss of pupillary response and visual reflexes
What happens with lesion at LGN?
Loss of vision