neurology Flashcards
Lisencephalies and heterotopia
disorders of incomplete neuron migration, the latter more focal. Underlie seizure disorders, autism and other.
Somatosensory pathway of pain, temperature, coarse touch, deep pressure
spinothalamic tract, VPL, VPI, intralaminar nuclei of thalamus, somatosensory cortex, prefrontal cortex, anterior cingulate gyrus, striatum S-11
Somatosensory pathway of 2 point discriminitaion, tactile , vibratory, kinesthetic, muscle tension, joint position
fasciuli gracillis and cuneatus, vpl of thalamus, somatosensory cortex
inferior temporal lobe
shape, form, and color of the object—the what questions
the posterior parietal lobe
location, motion, and distance—the where questions
responses to complex shapes
the right ITC.
prosopagnosia
disconnection of the left ITC from the visual association area in the left parietal lobe.
overall contour, perspective, gestalt
right hemisphere
adds internal detail and complexity
left hemisphere
Apperceptive visual agnosia
inability to identify and draw items using visual cues. bilateral lesions in the visual association areas.
Associative visual agnosia
inability to name or use objects despite the ability to draw them. bilateral medial occipitotemporal lesions
Color agnosia
the inability to recognize a color despite being able to match it.
Color anomia
is the inability to name a color despite being able to point to it.
Anton
bilateral occipital lobe lesions.
Etiologies for anton’s disorder
hypoxic injury, stroke, metabolic encephalopathy, migraine, herniation resulting from mass lesions, trauma, and leukodystrophy.
Balint’s syndrome
1 .optic ataxia (the inability to direct optically guided movements), 2. oculomotor apraxia (inability to direct gaze rapidly). 3. simultanagnosia (inability to integrate a visual scene to perceive it as a whole). bilateral parietooccipital lesions.
Gerstmann’s syndrome
agraphia, calculation difficulties (acalculia), right-left disorientation, and finger agnosia. dominant parietal lobe.
Color perception
lesions of the dominant occipital lobe that include the splenium of the corpus callosum.
Auditary system
brainstem cochlear nuclei, lateral lemniscus ,inferior colliculi, medial geniculate nucleus (MGN) of the thalamus. primary auditory cortex in the posterior temporal lobe.
auditory processing
left hemisphere tends to be dominant for it.
lexical processing
the extraction of vowels, consonants, and words from auditory input. occurs in higher language association areas, especially in the left temporal lobe
word deafnes
an inability to recognize speech, disconnection of the auditory cortex from Wernicke’s area- lesion in left parietal cortex.
auditory sound agnosia
inability to recognize nonverbal sounds, such as a horn or a cat’s meow. right hemisphere correlate of pure word deafness.
Olfactory system
1 or 2 of 3,000 processing units called glomeruli. Each neuron in the epithelium displays a unique odorant receptor- 10,000 different odors. Odorant binding- impulses to sensory nerves through the cribriform plate to the olfactory bulb.
Olfactory pathway
olfactory signals do not pass through the thalamus but project directly to the frontal lobe and the limbic system, especially the pyriform cortex. The connections to the limbic system (amygdala, hippocampus, and pyriform cortex) are significant. Olfactory cues stimulate strong emotional responses and can evoke powerful memories.
vomeronasal organ
is thought to detect pheromones
higher olfactory processing
in phylogenetically more primitive animals have evolved in humans into the limbic system.
Taste
gustatory nerves nucleus solitarius in the brainstem. only broad classes of stimuli: sweet, sour, bitter, and salty. Taste fibers activate the medial temporal lobe. higher cortical localization poorly understood.
Under a state of hypnosis
gross distortions of perception in any sensory modality and changes in the ANS can be achieved instantaneously. involves both sensory and association areas of the brain. shifts in attention in an environmental setting determine changes in the regions of the brain that are activated, on an instantaneous time scale. attention-mediated variations in synaptic utilization.
Activation of the rubrospinal tract
stimulates flexion of all limbs( primitive- newborns and anencephlic)
activation of the vestibulospinal tract
causes all limbs to extend.
corticospinal tract
controls fine movements, eventually dominates the brainstem system during the first years of life. in strokes- spasticity returns as the cortical influence is ablated and the actions of the brainstem motor systems are released from cortical modulation.
The basal ganglia
a subcortical group of gray matter nuclei. mediate postural tone. striatum, the pallidum, the substantia nigra, and the subthalamic nucleus
bradykinesia
Overactivity of the striatum owing to lack of dopaminergic inhibition (e.g., in parkinsonian conditions) results in, an inability to initiate movements.
corpus striatum
the caudate and putamen and globus alllidus: harbor components of both motor and association systems. caudate nucleus plays an important role in the modulation of motor acts. The caudate is also thought to influence associative, or cognitive, processes.
Huntington
caudate shrinks dramatically in Huntington’s disease. This disorder is characterized by rigidity, on which is gradually superimposed choreiform, or “dancing,” movements.