olfactory and limbic systems Flashcards
olfactory sensory neurons
- no circuitry or synapses in the epithelium
- receptors have axons (thin, unmyelinated, slow) that project directly to the olfactory bulb
how often do receptors die and be replaced
every 60 days
can sensory cells regenerate
yes
where are first order neurons located
between receptors and olfactory bulbs
second order neurons synapse with ? in ?
tuftal and mitral cells; olfactory glomerulus
bipolar neurons
second order neurons
olfactory nerve components
bipolar nerves with unmyelinated axons
principal neurons of the olfactory bulb
mitral and tuftal cells
aromatic compounds recognize ?
particular receptors
aromatic compounds travel where ?
particular glomerulus
glomerulus
basic processing component of the olfactory bulb
polysynaptic structure of olfactory bulb function
ensuring conversion of specific olfactory impulses to the mitral and tuft cells
periglomerular and granular cell function
mediate local and lateral inhibition
where is the olfactory tract located
in the olfactory sulcus
what does the olfactory tract contain
the axons of mitral and tufted cells
where does the olfactory tract run
to olfactory trigone
second order olfactory nerves transmit info to ? via ?
olfactory stria; olfactory tract
olfactory tract projects via ? to ? on the base of the frontal/medial temporal lobe
stria; olfactory cortex
largest olfactory stria
lateral olfactory stria
lateral olfactory stria
- to primary olfactory cortex (piriform cortex)/parahippocampal gyrus on temporal lobe
- conscious awareness (recognition) of odor
uncinate fit
- temporal lobe epilepsy
- seizures with elaborate and multiple sensory, motor, and/or psychic components
what precedes uncinate fits
hallucinations of disagreeable odors
types of olfactory strias
- lateral olfactory stra
- medial olfactory stria
- intermediate olfactory stria
medial olfactory stria
- to septal area/lower, posterior part of the medial surface of the frontal lobe
- olfactovisceral reflexes
intermediate olfactory stria
- olfactory tubercle
- reward behavior
anterior commissure function
connects two halves of the olfactory system (anterior to the columns of the fornix)
what does the insula recieve
taste input from the medial part of vpm of thalamus (flavor)
orbitofrontal cortex function
furthers conscious smell olfactory perception
olfactory pathway
how does the limbic system operate
influencing endocrine system and autonomic nervous system
limbic system functions
- control emotions and emotional responses
- mood
- motivation
- pain and pleasure sensations
limbic system links complex goal directed behavior to …
primitive, instinctive behavior, important for survival
cortical areas of limbic system
- septal area
- cingulate gyrus
- parahippocampal gyrus
deeper structures of limbic system
- hippocampal formation and fornix
- amygdala
- mammillary bodies
- anterior nuclei of the thalamus
hypothalamus
- maintain homeostasis
- stimulation produces behaviors seen in other limbic areas (rage, aggression, docile behaviors)
thalamus
- relays sensory information to limbic system
- connects brainstem to cerebrum/relay center
amygdala
- emotion, reproduction, fear, aggression
- modulation of autonomic and neuroendocrine systems
- stimulation can produce rage
hippocampus
- memory conversion
- associative learning and memory (memory acquisition and short term memory)
limbic structures are interconnected by …
- fornix
- mammillothalamic tract
- stria terminalis
- cingulum
hippocampus damage results in
amnesia
amygdala lesion result
docile behavior
kluver-bucy syndrome
- ignore social conventions
- bilateral lesions of the anterior temporal lobe
how is the amygdala connected to the hypothalamus
stria terminalis
what is the amygdala directly connected to
thalamus and neocortex
septal area components
- septal nucleus
- septum pellucidum
- small portion of neocortex
- relief of fear, docile behavior, stress
septum pellucim
thin membrane between 2 lateral ventricles
septal area lesion result
rage and aggressive behavior
what is the septal area connected to
hypothalamus and hippocampus (fornix)
cingulate gyrus
- overlies corpus callosum
- control of emotional and visceral responses, aggressive behavior
how does the cingulate gyrus connected with the hypothalamus
mammillothalamic tract
what is the cingulate gyrus connected to
anterior nuclear group of the thalamus through thalamic radiations
papez circuit
how are papez circuit functions mediated
through hypothalamus and autonomic nervous system
diseases related to the limbic system
- acquired disorders
- dementia
- neuropsychiatric disorders
acquired disorders (limbic system)
- violence
- suicidal behavior
- agitation
- mood swings
dementia
degeneration of limbic system structures (may be genesis of other neurodegenerative disorders)
neuropsychiatric disorders
- anxiety
- schizophrenia
- psychopathic disorders
olfactory nerve versus olfactory tract
- olfactory bulb is a relay station for the transmission of the impulse coming from the olfactory nerve
- from the olfactory bulb, impulses then travel through the olfactory tract
- olfactory tract divides into the medial and lateral olfactory striae, then connects to the olfactory cortex
