Chapter 6: CNS - Powerpoint

what is in the grey matter?

cell bodies and unmyelinated axons/dendrites

nuclei

mostly outer layer of brain, inner region of spinal cord

what is in the white matter?

myelinated axons

tracts

mostly inner region of brain, outer layer of spinal cord

what are neurons?

10% of CNS cells

are the excitable cells

includes multipolar (pyramidal) and axononic cells

what are microglia?

90% of CNS cells

are the support cells

what are the glial/neuroglial cells?

oligodendrocytes

astrocytes

microglia

ependymal cells

what are oligodendrocytes?

aid in CNS myelination

one neuron axon - several oligodendrocytes

one oligodendrocyte - several neuron axons

creates nodes of ranvier

what are the CNS and PNS diseases associated with demyelination?

gulliain-barre syndrom: inflammatory response (PNS)

multiple sclerosis: autoimmune disease (CNS)

heavy metal poisoning (CNS)

active herpes HHV-6: immune system (CNS)

what are astrocytes?

communication network via gap junctions

involved in blood-brain barrier

support neurons by providing nutrients

regulate ions in ISF

uptake and release of chemicals at synapse

what are microglia?

immune cells (macrophages)

phagocytosis

release reactive oxygen species (ROS): excess amounts result in degenerative neural diseases such as ALS

what are ependymal cells?

neural stem cells made up off neurons and glial cells, but are not very effective

lines ventricles and central canal with capillaries that form choroid plexus

involved in cerebrospinal fluid production and circulation

selectively permeable endothelial layer

what does the brainstem consist of?

medulla oblongata, pons, midbrain, cerebellum

cranial nerves II-XI

reticular formation

what is the reticular formation?

network between spinal cord and superior regions of the brain

involved in sleep-wake cycles, muscle tone, stretch reflex, breathing cycles, blood pressure, and pain regulation

what is the medulla?

most somatic motor pathway decussation, breathing center, heart rate center, blood pressure and swallowing

what are the pons?

coordination of breathing, relay between cerebellum and cerebrum

what is the midbrain?

auditory and visual reflexes, eye movement

what is the cerebellum?

sensory information such as proprioception, other somatic senses, and equilibrium

develop coordinated and fluid motion

what does the diencephalon consist of?

thalamus, hypothalamus, and endocrine

what is the thalamus?

integration center that can modify information

it is a relay station for eyes, ears, spinal cord, cerebellum → cerebrum

what is the hypothalamus?

involved in homeostasis

what s the endocrine?

involved in homeostasis

includes the pituitary (anterior = endocrine hormones; posterior = neurohormones from hypothalamus)

pineal gland = melatonin

what is the cerebrum?

lobes: frontal, parietal, temporal, occipital

sulci and gyri, corpus callosum

higher brain functions including basal ganglia (movement) and limbic system (cognition and emotion)

amygdala and cingulate gyrus = emotion and memories

hippocampus = memory and learning

what is the gray matter in the spinal cord?

horns

what is the white matter in the spinal cord?

ascending tracts - sensory

descending tracts - motor

propriospinal tracts - interconnect levels within spinal cord

what is the function of the dorsal root and ganglion?

involved in sensory information

what is a dermatome?

cutaneous sensory associated with a spinal nerve

what is a myotome?

muscles associated with a spinal nerve

what is the CSF?

cerebral spinal fluid flows through ventricles, subarachnoid space, villi, and cranial venous sinuses

constantly replaced and produces 500 ml/day

what are the functions of cerebral spinal fluid?

protection:

• physical: buoyancy and padding

• chemical: exchanges with interstitial fluid to remove waste solutes

how is CSF different from plasma?

increase water, decrease osmolarity

increase NaCl, decrease K+, decrease Ca2+, decrease proteins and no cells

what is the function of the blood brain barrier?

very selectively permeable: carrier mediated and receptor mediated transport

no BBB in hypothalamic-hypopseal portal system, vomiting center, pineal gland

what are the functions of the CNS?

1. communication between PNS and CNS: integration of information

2. communication within brain

function of the CNS: communication between PNS and CNS

involves cranial nerves and spinal nerves

reflexes

what are the different types of reflexes?

autonomic, somatic, reflex arc

what are autonomic reflexes?

glands, smooth muscle, cardiac muscles

what are somatic reflexes?

skeletal muscles

what are reflex arcs?

spinal cord integration is the simplest reflex

monosynaptic and polysynaptic

what are monosynaptic reflexes?

sensory neuron → motor neuron

what are polysynaptic reflexes?

sensory neuron → interneuron → motor neuron

function of the CNS: communication within brain

neural plasticity: creation of new synapses and pathways

complex brain reflexes: originate in the brain and integrates multiple brain regions

how does the brain integrate and communicate?

sensory area information → association area information → motor area information

what is does the parietal lobe consist of?

primary somatic sensory cortex or somatosensory cortex

sensory association area

homunculus

what does the occipital lobe consist of?

primary visual cortex

visual association

what does the temporal lobe consist of?

primary auditory cortex

association area

what does the insula consist of?

gustatory cortex

what does the frontal lobe consist of?

primary motor cortex

motor association area

prefrontal association area

what is cerebral lateralization or cerebral dominance?

right brain DOES NOT EQUAL left brain

what is the left hemisphere associated with?

language, verbal, math

what is the right brain associated with?

spatial

what is motor dominance?

right or left handedness

somatic motor control

how is sensations perceived?

1. transduction in the the PNS

2. transmission to the CNS

3. interpretation in the CNS

how do we we get motor output

4. skeletal movement (somatic motor system with cerebellum and basal ganglia)

5. neuroendocrine signals (hypothalamus and autonomic system via adrenal gland)

   1. visceral response (medulla, hypothalamus, autonomic system)

what is the behavioral state system?

involved with consciousness

regulated by the reticular activating system (RAS) and hypothalamus

what are consicous experiences?

something you are aware of

awake or asleep, thoughts or ideas, feelings or perceptions

how can we measure consciousness?

electroencephalogram (EEG) and magnetic resonance imaging (MRI)

how do electroencephalograms work?

looks at graded potentials: EPSPs and IPSPs

specifically looking at pyramidal cell functions

what are EGG waveform characteristics?

amplitude (microVolts)

frequency (Hz)

what does high/low amplitudes in EEG waveforms mean?

high: synchronous firing and many neurons active

low: asynchronous firing or few neurons active

what does high frequency in EEG waveforms means?

increased frequency typically means increased state of alertness

how can EEGs be used a diagnostic tool?

abnormal patterns may be indicators of disease or damage

ex: epilepsy

what are the EEG waveform characteristics when awake?

awake = active interactions with the environment

beta and alpha rhythm

what do beta rhythms indicate?

active, calm, eyes open, attentive to an external stimulus

desynchronized waveforms: 16-31 Hz

what are gamma waves?

32+ Hz

cross-modal sensory processing

short-term memory matching of recognized objects, sounds, tactile sensations

what do alpha rhythms indicate?

awake, relaxed, eyes closed

synchronized waveform: 8-15 Hz

how can EEGs be used to help us learn about sleep?

brain is still active

theta and delta rhythms

what do theta waves indicate?

usually drosy, sleepy, relaxed and idling

synchronized waveforms: 4-7 Hz

what do delta waves indicate?

slow wave sleep, some continuous attention tasks

synchronized waveforms:

what are the stages of nonrapid eye movement?

N1, N2, N3

what are characteristics of N1 NREM?

drowsiness and light sleep

alpha waves and some theta waves

what are characteristics of N2 NREM?

decreased sensitivity to stimuli

theta waves + spindles and K-complexes

what are characteristics of N3 NREM?

deep or slow wave sleep

predominantly delta rhythms

essential for rest and release of growth hormones

what stage is associated with rapid eye movement?

R

what are characteristics of R in REM?

overall decreased muscle tone and activity, except for eye movement, increased respiration, heart rate, blood pressure, and muscle twitches in face and limbs

dreaming, stimulate areas of the brain used for learning, thinking and organizing information

what is sleep apnea?

relaxation of airway muscles that obstructs breathing

what are the cycles of NREM and REM sleep?

N1 → N2 → N3 → N2 → R

typically 4-6 cycles per night, shifts from NREM sleep to more REM

how are the sleep-wake cycles controlled?

reticular activating system

hypothalamus

pineal gland

how does the reticular activating system control sleep-wake cycle?

norepinephrine and serotonin neurons are active in wake periods

cholinergic neurons are active in REM sleep periods

how does the hypothalamus control sleep-wake cycle?

preoptic area involves GABA neurons which are active inNREM sleep

histamine neurons are active in wake periods

how does the pineal gland control sleep-wake cycle?

darkness will increase melatonin released

induces lower body temperature

how does caffeine affect the sleep-wake cycle?

• adenosine: ATP → ADP → AMP → adenosine

  • adenosine receptors in reticular activating system

  • adenosine accumulation triggers sleep

• caffeine mimics adenosine by being an adenosine receptor competitor

  • activity activates the pituitary which released epinephrine from adrenal gland

  • also a release of dopamine which makes you feel better

what is emotion?

perception of and predisposition towards the environment

friendly and happy vs threatening and fearful

what is the physiological response to emotional behavior?

hypothalamus, limbic amygdala, and cerebral cortex are involved

heart rate, blood pressure, pupil dilation, sweating, blushing, etc.

what are the internal responses to emotional behavior?

limbic system and integrating areas such as the cerebral cortex are involved

what is the primary motivated behavior or drive?

behavior to promote homeostasis

ex: hungry → eat

what is the secondary motivated behavior?

behavior to reflect preferences or involves choices

ex: what to eat or drink

how does reward and punishment affect motivation?

positive and negative reinforcement affect how dopamine diffuses in the modulatory system

ex: amphetamines and caffeine increase the release of dopamine = positive

ex: antipsychotic drugs blocks the release of dopamine = negative

what are persistent inner emotions or perceived state of being?

longer lasting, more consistent or stable than moods

1. depression

2. seasonal affective depressive disorder

3. bipolar disorders

what is depression?

depressed activity in the limbic system and prefrontal cortex

primary depression/endogenous depression

secondary depression/exogenous or reactive depression

treatment: antidepressents alter activity at the synapses and duration of presence of neurotransmitters

treatment: electroconvulsive therapy (ECT)

what is a treatment for season affective depressive disorder?

phototherapy

what is bipolar disorder?

manic depression: mood swings

treatments: lithium and anti-convulsant drugs reduce extreme mood swings

how is lithium an effective treatment for bipolar disorder?

lithium inhibits dopamine neurotransmission and promotes GABAergic neurotransmission

presynaptic: facilitates GABA release

postsynaptic: upregulates GABA_B receptors

what are the different types of learning?

associative learning

non-associative learning

orienting response

what is associative learning?

2 things are associate with each other

ex: desired behavior → reward

what is nonassociative learning?

repetition of a single stimulus

habituation → decreases response

sensitization → amplification of response

habituation and sensitization are examples of ____________________

selective attention

what is orienting response?

responding to a novel stimulus

what is memory?

ability to store and retriieve learned material

what is neural encoding?

development of memory traces

‘commit to memory’ - memory formation - memory traces

parallel processing

what is parallel processing?

alternate pathways allows branching and converging of information

what is amnesia?

loss of memory

retrograde and anterograde amnesia

what is retrograde amnesia?

loss of memory for information acquired before the onset of amnesia