Cerebral Hemispheres Flashcards
What do the cerebral hemispheres develop from?
Telencephalon
What are the types of cortex?
Neocortex - 6 layers, 90%
Allocortex - 3 layers, made up of paleocortex (olfactory) and archicortex (hippocampal)
How is the neocortex organized?
Six layers each that acts as its own functional unit, but also work together
What are columnopathies?
Disorders of the modular arrangement of cortical columns
E.g. Autism Spectrum Disorder
What are unimodal association cortices?
Modality-specific association cortex that is located proximal to primary sensory cortices of the same modality
What are heteromodal association cortices?
Receives inputs from multiple sensory modalities
Higher order functions
Recently evolved
What is false localization?
Focal lesions cause specific defects, but redundancies and overlaps may lead to misinterpreting exam results
What does pure alexia commonly result from?
Occlusion of the left PCA - suppplies occipital love and splenium of corpus callosum
Right occipital lobe could process visual input but cannot send information to language ares in the left brain
What causes Acalculia?
Lesion in the dominant parietal lobe
Why is visual spatial disorientation common in early Alzheimer’s?
Damage to neurons in the association cortices - specifically in the parietal lobe
What would cause memory impairment?
Lesion in the hippocampus of the temporal lobe
What would cause a behavioral or personality change?
Frontal cortex/lobe damage
What causes destructive eye deviation?
Damage in the frontal eye field (area 8)
Causes deviation toward the side of the lesion
What causes irratative eye deviation?
Seizure, causes deviation away from the side of the lesion
What is apraxia?
Lack of ability to perform voluntary movements when asked
What are frontal release signs?
Reflexes that infants are born with, that are later inhibited with further development of the frontal lobe
What is agnosia?
Deficits in sensory information
Results in normal perception stripped of meaning
typically arises from damage to the ventral stream of sensory perception
What is visual agnosia?
inability to recognize visual objects
Associated with left occiptial/temporal lobe lesions
Can be apperceptive or associative
What is prosopagnosia?
Inability to recognize familiar faces
Typically results from bilateral damage to fusiform gyrus
What is auditory agnosia?
Inability to recognize sounds
Associated with auditory cortex/temporal lobe lesions
What is construction apraxia?
Losing the ability to focus on anything in one half of their visual field
Non-dominant parietal lobe damage
type of contralateral neglect
What is the centrum semiovale?
Deep white matter that consists of bundles of myelinated axons
What is the arcuate fasciculus?
Part of the longitudinal fasciculus; connects Broca’s and Wernicke’s
Results in conduction aphasia
What is the uncinate fasciculus?
Connects temporal with the frontal cortex
Plays a role in empathy and recognition
lesion can also cause changes in hearing and olfaction
What is the cingulate gyrus?
Conntects emotion centers and memory structures such as the hippocampus as part of the limbic system
What is the default mode network?
Internal cognition, thought, dialogue
What does the corpus callosum connect?
Connects homotypical regions on both sides of the brain
What does the anterior commisure connect?
Connects temporal lobes, olfactory cortices, and olfactory bulbs
What does the posterior commisure connect?
Connects pretectal structures
How do axons travel up to and down from the cortex?
Through capsules that expand out into the corona radiata that traverses the whole of the cortex
What does the external capsule connect?
Calustrum and insular cortex
Broca’s and Wernicke’s area
“Corticalcortical” tract
What is the insula?
Lies deep within the lateral sulcus
Involved in consciousness, emotion, empathy, self-awareness, and managing interpersonal relationships
What two structures make up the lentiform nucleus?
Putamen and Globus Pallidus
Physically connected
What two structures make up the Neostriatum?
Caudate and Putamen
Embryonically linked
What structures make up the corpus striatum?
Caudate
Putamen
Globus Pallidus
What structures make up the limbic cortex?
Cingulate gyrus and Parahippocampal gyrus
Corticoid areas, like the amygdala
What are the functions of the limbic system?
Homeostasis
Olfaction
Memory
Emotion
What is the internal medullary lamina?
Y -shaped white matter tract that divides the thalamus into 3 primary regions
What is the only thalamic nucleus that does not project to the cortex?
Reticular nucleus
What are the functional divisions of the thalamus?
Sensory
Motor
Limbic
Multi-modal
Intralaminar
What nuclei make up the sensory division of the thalamus?
Ventral Posterior lateral nucleus (VPL)
Ventral posteriomedial nucleus (VPM)
Lateral geniculate nucleus (LGN)
Medial geniculate nucleus (MGN)
What nuclei make up the motor division of the thalamus?
Ventral anterior nucleus (VA)
Ventral Lateral nucleus (VL)
What nuclei make up the limbic division of the thalamus?
Anterior nucleus
Mediodorsal nucleus
What nuclei make up the multi-modal division of the thalamus?
Pulvinar
Lateral posterior
Lateral dorsal
What nuclei make up the intra-laminar division of the nucleus?
Reticular
Centre-median
Intra-laminar
What is Dejerine-Roussy Syndrome?
Thalamic pain syndrome
Contralateral lack of sensation and tingling that progresses to severe pain; typically follows thalamic stroke
