neurophysiology ii
Terms
undefined, object
copy deck
- contents of the membranous labrynth
- hair cells (communicates head position), organ of Corti (audition), vestibular apparatus (semicircular canals for angular displacement, utricle & saccule for forward, backward, & verticle movements)
- Describe the ionic composition of endolymph.
- similar to intracellular fluid, high K+
- Describe the mechanism of hair cell depolarization.
- movement of stereocilia toward kinocilium depolarizes the hair cell (K+ in), while movement away from the kinocilium hyperpolarizes the hair cell.
- effect & mechanism of vestibular nerve when head turns left.
- hyperpolarization of the hair cells in the right horizontal canal, and depolarization of hair cells in the left horizontal canal. This will cause a decrease in firing rate in the right vestibular nerve fibers, and an increase in firing rate on the left.
- lesions of the upper midbrain or above (for example in the cortex or internal capsule) produce what posture?
- decorticate posture (arm flexion, leg extension)
- Lesions in the lower midbrain or pons result in what type of posture?
- decerebrate (all limbs extended)
- what does a progression in a patient from decorticate posture to decerebrate posture indicate?
- rostral to caudal deterioration of the brainstem (dangerous for respiratory center)
- begins in medial vestibular nucleus, terminates at cervical levels, and controls neck movements that position the head.
- medial vestibulospinal tract
- Uses vestibular input to hold images stable on retina, during fast head movements
- VOR
- Uses visual input to hold images stable on retina during slow head movements
- optokinetic reflex
- Bring objects of interest into the fovea
- saccade
- Holds moving targets in the fovea
- smooth pursuit
- Adjusts eyes so that both can foveate the object at any depth
- vergence
- Horizontal saccades are generated where?
- in the pontine reticular formation
- vertical saccades are generated where?
- in the mesencephalic reticular formation.
-
Damage to any of
the structures involved in vestibulo-ocular or optokinetic reflexes, including the cerebellum, and the vestibular apparati, vestibular nuclei or damage to other parts of the brainstem, results in what? - pathological nystagmus
- a lesion of the MLF (often resulting from multiple sclerosis) results in what?
- Internuclear ophthalmoplegia (weak conjugated adduction on the affected side)
- caused by the dislodging of an otolith crystal
- benign positional vertigo (no hearing loss)
-
caused by the overproduction (or insufficient drainage) of endolymph,
which can rupture the membranous labyrinth and cause mixing of endolymph and perilymph. - vertigo (Meniére’s Disease: sustained firing of CN VIII, deafness, N/V
- What does an EEG measure?
-
Real-time electrical potentials that are generated in the cortex and volume
conducted through the meninges, cranium and skin. - created by ann EPSP, which draws current from areas farther away, creating a current source.
- local current sink
- Adjacent positive and negative regions are called a(n):
- dipole
- the change in EEG that occurs in response to a sensory stimulus, such as a flash of light or shock to the skin. This technique is used to assess the function of an ascending sensory system, from the periphery all the way to cortex.
- evoked potential
- EEG characteristics of sleep & wakefulness:
- awake state--high frequency, low amplitude, desynchronized EEG. Slow wave sleep--low frequency, high amplitude, synchronized EEG.
- sleep stage characterized by slight slowing of the EEG
- 1
- sleep stage characterized by high-amplitude k complexes and low-amplitude sleep spindles
- 2
- sleep stages characterized by slow high-amplitude delta waves
- 3 and 4
- reticular formation structure located in the tegmentum of the caudal midbrain and rostral pons; stimulation there causes wakefulness, and lesions cause sleep.
- ascending reticular activating system (ARAS)
- a set of medial forebrain structures that are interposed between the hypothalamus and lateral forebrain (sensorymotor)structures.
- limbic system
- Functions in identification of appropriate object for drives
- amygdala
- Functions in identification of appropriate context for drive
- hippocampus
- paths that connect the amygdala to the hypothalamus
- stria terminalis, ventral amydalofugal path
- path that connects the hippocampus to the hypothalamus
- fornix
-
Functions in assigning affective (emotional) significance to sensory
stimuli, and initiate appropriate emotional responses. - amygdala
-
a constellation of behavioral problems
in monkeys, after bilateral damage to the temporal lobes, specifically the amygdala. These include attempting to eat non-food objects, lack of fear of predators, attempting to copulate with animals from a diffe - Kluver-Bucy Syndrome
- allocortical structure that receives processed sensory input from the entorhinal cortex
- hippocampus
- Limbic structures in the medial temporal lobe include:
- hippocampus, entorhinal cortex, amygdala, parahippocampal cortex.
- lesion producing anterograde amnesia:
- medial temporal lobe
- critical structures involved in memory consolidation:
- the hippocampus,entorhinal cortex, and perirhinal cortex. Amygdala is not involved
- type of memory affected by ECT
- memory consolidation (hippocampus; may take as long as two years)
- areas of the brain that function in recollection of episodic (events) & semantic (facts) memory
- Hippocampus, nearby cortical areas, diencephalon
- area of the brain that functions in recollection of skilled memory
- striatum, motor areas of the cortex, cerebellum
- area of the brain that functions in emotional associations
- amygdala
- area of the brain that functions in conditioned reflexes
- cerebellum
- what is the physical basis for memory formation (what is a memory)?
- new dendritic spine formation
- hippocampal neurons that fire to mark a particular location (formation of a cognitive map)
- place cells
- first cells to die in the brain during hypoxia
- CA1 in the hippocampus (Sommer's area)
- subcortical area of the telencephalon that provides a major cholinergic input to the hippocampus
- septum
- adjacent structures to the septum that provide cholinergic input to the neocortex
- nucleus basalis of Meynert, diagonal band of Broca
- lesion that produces misdirected aggression (site and name of lesion):
- septum; septal rage
- Pathways from the septum, hippocampus and amygdala, traveling through the lateral hypothalamus and ending in the midbrain tegmentum
- medial forebrain bundle
- location of "reward center" affected during self-stimulation
- medial forebrain bundle
- dopaminergic pathway from the ventral tegmental area (VTA) to the nuc. accumbens.
- mesolimbic pathway
- pathway affected in drug abuse (reward center):
- mesolimbic dopamine pathway
- damage to the mediodorsal nucleus of the thalamus, MD, and the mammillary bodies of the hypothalamus; patient has problems forming new memories and often confabulates
- Korsakoff's psychosis
- two main systems affected in Alzheimer's patients:
- hippocampus (anterograde), basal forebrain (projects to forebrain w/ ACh; retrograde)
- toxin that produces Alzheimer's disease; directly related to cholesterol levels:
- Beta amyloid
- first neurons to degenerate in Alzheimer's patients
- perirhinal/entorhinal areas
- method of diagnosis of Alzheimer's
- amyloid plaques & neurofibrillary tangles