12 DIENCEPHALON 12.1. Thalamic Anatomy and Interconnections with the Cerebral Cortex 12.2. Hypothalamus and Pituitary Gland 12.3. Schematic of Hypothalamic Nuclei 12.1 THALAMIC ANATOMY AND INTERCONNECTIONS WITH THE CEREBRAL CORTEX The thalamus, the gateway to the cerebral cortex, conveys extensive sensory, motor, and autonomic information from the brain stem and spinal cord to the cortex. All sensory projections to the cortex except olfaction are processed through thalamic nuclei. Thalamic nuclei are reciprocally interconnected with regions of cortex. Specific thalamic nuclei project to circumscribed regions of cortex. These nuclei include (1) sensory projection nuclei (VPL: somatosensory; VPM: trigeminal; LGB: visual; MGB: auditory; pulvinar: sensory); (2) motor-related nuclei (VL and VI: cerebellum; VA and VL: basal ganglia); (3) autonomic- and limbic-related nuclei (anterior and LD: cingulate cortex; MD: frontal and cingulate cortex); and (4) nuclei related to association areas (pulvinar and LP: parietal cortex). Nonspecific thalamic nuclei (intralaminar nuclei, such as CM, parafascicular, and medial VA) send diffuse connections to widespread regions of cerebral cortex and to other thalamic nuclei. The reticular nucleus of the thalamus helps to regulate the excitability of thalamic projection nuclei. Specific lesions of the thalamus can result in diminished sensory, motor, or autonomic activity related to loss of the specific modalities processed. Some thalamic lesions can lead to excruciating paroxysms of neuropathic pain, which is referred to as thalamic syndrome. CLINICAL POINT The thalamus has a complex blood supply that is derived extensively from the penetrating posterior cerebral, posterior communicating, and other nearby arteries. Thalamic nuclei are seldom individually affected by infarcts and lesions but are damaged along with nearby regions. Lesions that affect one side of the thalamus seldom produce permanent deficits unless sensory nuclei are involved. Thalamic lesions can result in changes in consciousness and alertness (intralaminar, reticular nuclei); affective behavior (medial dorsal, ventral anterior, intralaminar nuclei); memory functions (midline, medial, mammillary, and possibly anterior nuclei); motor activity (ventrolateral, ventral anterior, posterior, other nuclei); somatic sensation (ventral posterolateral and posteromedial nuclei); vision (lateral geniculate nuclei); and perceptions and hallucinations (dorsomedial, intralaminar nuclei). Medial dorsal lesions may produce a reciprocal disconnect with the prefrontal cortex and bring about a deficit in frontal functions. 12.2 HYPOTHALAMUS AND PITUITARY GLAND Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: VENTRICLES AND THE CEREBROSPINAL FLUID SPINAL CORD MOTOR SYSTEMS VASCULATURE DEVELOPMENTAL NEUROSCIENCE SENSORY SYSTEMS Stay updated, free articles. Join our Telegram channel Join Tags: Netters Atlas of Neuroscience with STUDENT CONSULT Online Access Jun 4, 2016 | Posted by admin in NEUROLOGY | Comments Off on DIENCEPHALON Full access? Get Clinical Tree
12 DIENCEPHALON 12.1. Thalamic Anatomy and Interconnections with the Cerebral Cortex 12.2. Hypothalamus and Pituitary Gland 12.3. Schematic of Hypothalamic Nuclei 12.1 THALAMIC ANATOMY AND INTERCONNECTIONS WITH THE CEREBRAL CORTEX The thalamus, the gateway to the cerebral cortex, conveys extensive sensory, motor, and autonomic information from the brain stem and spinal cord to the cortex. All sensory projections to the cortex except olfaction are processed through thalamic nuclei. Thalamic nuclei are reciprocally interconnected with regions of cortex. Specific thalamic nuclei project to circumscribed regions of cortex. These nuclei include (1) sensory projection nuclei (VPL: somatosensory; VPM: trigeminal; LGB: visual; MGB: auditory; pulvinar: sensory); (2) motor-related nuclei (VL and VI: cerebellum; VA and VL: basal ganglia); (3) autonomic- and limbic-related nuclei (anterior and LD: cingulate cortex; MD: frontal and cingulate cortex); and (4) nuclei related to association areas (pulvinar and LP: parietal cortex). Nonspecific thalamic nuclei (intralaminar nuclei, such as CM, parafascicular, and medial VA) send diffuse connections to widespread regions of cerebral cortex and to other thalamic nuclei. The reticular nucleus of the thalamus helps to regulate the excitability of thalamic projection nuclei. Specific lesions of the thalamus can result in diminished sensory, motor, or autonomic activity related to loss of the specific modalities processed. Some thalamic lesions can lead to excruciating paroxysms of neuropathic pain, which is referred to as thalamic syndrome. CLINICAL POINT The thalamus has a complex blood supply that is derived extensively from the penetrating posterior cerebral, posterior communicating, and other nearby arteries. Thalamic nuclei are seldom individually affected by infarcts and lesions but are damaged along with nearby regions. Lesions that affect one side of the thalamus seldom produce permanent deficits unless sensory nuclei are involved. Thalamic lesions can result in changes in consciousness and alertness (intralaminar, reticular nuclei); affective behavior (medial dorsal, ventral anterior, intralaminar nuclei); memory functions (midline, medial, mammillary, and possibly anterior nuclei); motor activity (ventrolateral, ventral anterior, posterior, other nuclei); somatic sensation (ventral posterolateral and posteromedial nuclei); vision (lateral geniculate nuclei); and perceptions and hallucinations (dorsomedial, intralaminar nuclei). Medial dorsal lesions may produce a reciprocal disconnect with the prefrontal cortex and bring about a deficit in frontal functions. 12.2 HYPOTHALAMUS AND PITUITARY GLAND Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: VENTRICLES AND THE CEREBROSPINAL FLUID SPINAL CORD MOTOR SYSTEMS VASCULATURE DEVELOPMENTAL NEUROSCIENCE SENSORY SYSTEMS Stay updated, free articles. Join our Telegram channel Join Tags: Netters Atlas of Neuroscience with STUDENT CONSULT Online Access Jun 4, 2016 | Posted by admin in NEUROLOGY | Comments Off on DIENCEPHALON Full access? Get Clinical Tree
