Lecture Quiz 2 Flashcards
Describe the diencephalon
central core of the forebrain
encloses third ventricle
deep to the basal nucle
What does the diencephalon consis of?
thalamus
hypothalamus
epithalamus
Descibe the thalamus
paired egg-shaped masses that form the superolateral walls of the third ventricle
connected at the midline by the intermediate mass
80% of diencephalon
What are the four groups of nuclei found in the thalamus?
anterior
netral
dorsal
posterior
Want do the nuclei of the thalamus do?
acts as relay center
project and receive fibers from cerebral cortex
Describe how impulses travel through the thalamus
sensual afferent impulses converge and synapse here
impulses of similar function are sorted out, edited, and relayed as a group
all inputs ascending to the cerebral cortex pass through the thalamus
What are the functions of the thalamus (aside from relay center)?
mediates sensation, motor activities, cortical arousal, learning, and memory
Where is the hypothalamus located?
below the thalamus
caps the brainstem and forms the inferolateral walls of the third ventricle
What are the mammillary bodies?
small paired nuclei bulging anteriorly from the hypothalamus
relay station for olfactory pathways
What is the infundibulum?
stalk of the hypothalamus
connects to the pituitary gland
main visceral control center of the body
What are the visceral functions of the hypothalamus?
regulates blood pressure, rate and force of heartbeat, digestive tract motility, rate and depth of breathing, and many other visceral activities
What are the emotional functions of the hypothalamus?
perception of pleasure, fear, and rage
What are the homeostatic functions of the hypothalamus?
regulates normal body temperature
What are the other functions of the hypothalamus?
regulates feelings of hunger and satiety
regulates sleep and sleep cycle
What are the endocrine functions of the hypothalamus?
releasing hormones control secretion of hormones by the anterior pituitary
supraoptic and paraventricular nuclei produce ADH and oxytocin
Where is the epithalamus located?
most dorsal portion of the diencephalon
forms roof of third ventricle
What does the pineal gland do?
extends from the posterior border of the epithalamus and secretes melatonin
What does melatonin do?
a hormone involved with sleep regulation, sleep-wake cycles, and mood
What is the choroid plexus?
a structure that secretes cerebral spinal fluid, which is then duped into the third ventricle
What does the brain stem consis of?
three regions -
midbrain
pons
medulla oblongata
Describe the brain stem in terms of gray and white matter
similar to spinal cord but contains nuclei embedded in it (grey matter)
What are the functions of the brain stem?
controls the automatic behaviors necessary for survival
provides the pathway for tracts between higher and lower brain centers
associated with 10 of the 12 cranial nerves
Where is the midbrain lcoated?
between the diencephalon and the pons
What are the cerebral peduncles?
two bulging structures of the midbrain that contain descending pyramidal motor tracts
What is the cerebral aqueduct?
hollow tube that connects the third and fourth ventricles
What cranial nerves are found in the midbrain?
III - oculomotor
IV - trochlear
What are the other nuclei found in the midbrain?
corpora quadrigemina
superior colliculi - visual reflex centers
inferior colliculi - auditory reflex centers
substantia nigra - high content of melanin, secretes dopamine
red nucleus - largest nucleus of the reticular formation; red nuclei are relay nuclei for some descending motor pathways
Where is the pons found?
bulging brainstem region between the midbrain and the medulla oblongata
forms part of the anterior wall of the fourth ventricle
What do the fibers of the pons do?
connect higher brain centers and the spinal cord
relay impulses between motor cortex and cerebellum
What cranial nerves are found in the pons?
V - trigeminal
VI - abducens
VII - facial
Where is the medulla oblongata found?
most inferior part of the brain stem
forms ventral wall of the fourth ventricle, along with pons
contains a choroid plexus of the fourth ventricle
What are the pyramids of the medulla oblongata?
two longitudinal ridges formed by corticospinal tracts
What is decussation of the pyramids?
crossover points of the corticospinal tracts
why we have lateralization of the brain
What are the cranial nerves found in the medulla oblongata?
XIII, IX, X, XI, and XII
What are the nuclear complexes found in the medulla oblongata?
vestibular nuclear complex - equilibrium cardiovascular control center respiratory control center vasomotor center - blood pressure addition centers for - vomiting, hiccuping, swallowing, coughing, sneezing
Where is the cerebellum located?
dorsal to the pons and medulla
protrudes under the occipital lobe of the cerebrum
makes up 11% of brain’s mass
What does the cerebellum do?
provides precise timing and appropriate patterns of skeletal muscle contraction
cerebellar activity occurs subconsciously
Describe the exterior of the cerebellum
two bilaterally symmetrical hemispheres connected medially by the vermis
each hemisphere has three lobes - anterior, posterior, and flocculonodular
has folia - transversely oriented gyri
Describe the interior of the cerebellum
neural arrangement - gray matter cortex, internal white matter, scattered nuclei
arbor vitae - distinctive treelike pattern of the cerebellar white matter
What are the cerebellar peduncles?
three paired fiber tracts that connect the cerebellum to the brain stem
How do cerebellar fibers differ from cortical fibers?
they are ipsilateral
from and to the same side of the body
What does the superior peduncle connect to?
cerebellum to the midbrain
what do the middle peduncles connect?
pons to the cerebellum
What do the inferior peduncles connect to?
medulla to the cerebellum
What happens during cerebellar processing?
Cerebellum receives impulses of the intent to initiate voluntary muscle contraction
proprioceptors and visual signals “inform” cerebellum of body’s condition
cerebellar cortex calculates the best way to perform a movement
a “blueprint” of coordinated movement is sent to the cerebral motor cortex
What is the cerebellum’s role in cognitive function?
plays a role in language and problem solving
recognizes and predicts sequences of events
What are the two functional brain systems that are widespread across the brain?
Limbic
Reticular
Where is the limbic system located?
structures are located on the medial aspects of cerebral hemispheres and diencephalon
amygdala
hypothalamus
anterior nucleus of the thalamus
What does the amygdala do?
deals with anger, danger, and fear response
What does the cingulate gyrus do?
Plays a role in expressing emotions via gestures
resolves mental conflict
puts emotional responses to odors
What can be deduced from the fact that the limbic system interacts with the prefrontal lobes?
one can react emotionally to conscious understandings
one is consciously aware of emotion in one’s life
What do hippocampal structures of the limbic system do?
convert new information into long-term memories
Describe the reticular formation of the brain
composed of three broad columns along the length of the brain stem - raphe nuclei, medial group, lateral group
has far-flung axonal connections with hypothalamus, thalamus, cerebellum, and spinal cord
What does the reticular activating system do?
sends impulses to the cerebral cortex to keep it conscious and alert
filters out repetitive and weak stimuli (~99%)
What can affect RAS?
inhibited by sleep centers, alcohol, drugs
severe injury results in permanent unconsciousness
How does the RAS apply to motor function?
helps control coarse motor movements
autonomic centers regulate visceral motor functions
What does an EEG do?
reflects the electrical activity on which higher mental functions re based
records electrical activity that accompanies brain function
measures electrical potential differences b/w various cortical areas
Describe brain waves
patterns of neuronal electric activity
each person’s are unique
continuous train of peaks and troughs
wave frequency expressed in Hz
Describe alpha waves
regular and rhythmic low-amplitude slow synchronous waves inficating an "idling" brain 8-13 Hz
Describe beta waves
rhythmic
more irregular waves occuring during the awake and mentalls alert state
14-30 Hz
Describe theta waves
more irregular than alpha waves
common in children but abnormal in adults
4-7 Hz
Describe delta waves
high-amplitude waves seen in deep sleep and when RAS is damped
4 Hz or less
What is consciousness?
encompasses perception of sensation, voluntary initiation, control of movement, and capabilities associated with higher mental processing
Where is consciousness expressed in the brain
involves simultaneous activity of large areas of the cerebral cortex
superimposed on other types of neural activity
holistic and totally interconnected
What is the graded scale of consciousness?
alertness
drowsiness or lethargy
stupor
coma
What are the two types of sleep?
non-rapid eye movement (NREM)
rapid eye movement (REM)
When does NREM occur in sleep?
the first 30-45 minutes of sleep
four stages
When does REM occur?
after the fourth NREM stage has been achieved
What is stage 1 of NREM?
eyes are closed and relaxation begins
alpha waves
one can be easily aroused
What is stage 2 of NREM?
EEG pattern is irregular with sleep spindles (high-voltage wave bursts)
What is stage 3 of NREM?
sleep deepends
theta and delta waves appear
vital signs decline
dreaming is common
What is stage 4 of NREM?
EEG pattern is dominated by delta waves
skeletal muscles are relaxed
arousal is difficult
What happens during REM sleep?
EEG pattern reverts through the NREM stages to the stage 1 pattern vital signs increase skeletal muscles are inhibited most dreaming takes place here rapid pulse/resp rate erection mental activity increase
What do sleep patterns tell us?
alternating cycles of sleep and wakefulness reflect a natural circadian rhythm
the brain is actively guided into sleep
typical sleep pattern alternates between REM and NREM
What regulates the sleep cycle (specific)?
suprachiasmatic and preoptic nuclei of the hypothalamus
What happens when someone is deprived of sleep?
slow-wave sleep is presumed to be the restorative stage
those deprived of REM sleep become moody and depressed
What happens with sleep as you age?
daily sleep requirements decline with age
What is speculated about the importance of sleep and information?
REM sleep may be a reverse learning process where superfluous information is purged from the brain
What is narcolepsy?
lapsing abruptly into sleep from awake state
What is insomnia?
chronic inability to obtain the amount or quality of sleep needed
What is sleep apnea?
temporary cessation of breathing during sleep
What is the locus coeruleus
cluster of neurons in RAS
active when we are awake, they produce norepinephrine for fight or flight response
inactive when we are sleeping
no motor activity results from cortical stimuli because they are prevented from reaching the spinal cord
What are the three principles of memory?
storage - occurs in stages and is continually changing
processing - accomplished by the hippocampus and surrounding structures
memory traces - chemical or structural changes that encode memory
What is short term memory?
a fleeting memory of the events that continually happen
lasts seconds to hours and is limited to 7 or 8 pieces of information
What is long term memory?
has limitless capacity
What are the factors that affect transfer of memory from short term to long term?
emotional state - alert motivated and aroused = good
rehearsal
association - new info with old memories
automatic memory - subconscious info stored in LTM
What is fact memory?
entails learning explicit information
is related to our conscious thoughts and our language ability
is stored with the context in which it was learned
What areas are involved in fact memory?
hippocampus and amygdala
specific areas of the thalamus and hypothalamus
ventromedial prefrontal cortex and the basal forebrain
What is skill memory?
less conscious than fact memory and involves motor activity
is id acquired through practice
do not retain the context in which they were learned
difficult to unlearn
What areas of the brain are involved in skill memory?
corpus striatum - mediates the automatic connections between a stimulus and a motor response
portion of the brain receiving the stimulus
premotor and motor cortex
Describe the mechanisms of memory (9 points)
neuronal RNA content is altered
dendritic spines change shape
extracellular proteins are deposited at synapses involved in LTM
number and size of presynaptic terminals may increase
more neurotransmitted is released by presynaptic neuron
new hippocampal neurons appear
long-term potentiation is involved and is mediated by NMDA receptors
synaptic events involve the binding of brain-derived neurotropic factor
BDNF is involved with NA, CA, and MG influence at synapses
