Brains n stuff Flashcards
1
Q
What is a neural system?
A
- distributed ensemble of peripheral and central neurons + circuits
- involved in transducing, encoding, relaying, processing specific types of information
2
Q
What are the 5 things a sensory system can do?
A
- Transduce external stimuli (at periphery)
- Encode distinct information about stimuli (in neurons of dorsal root ganglion)
- Relay information about distinct attributes of stimuli (PNS to CNS)
- Represent periphery in an orderly fashion in the brain (cortex)
- Process info to generate sensory perception (at post-central gyrus, etc.)
3
Q
What is transduction?
A
neural event –> physical/chemical stimulus detected via molecular signaling –> causes a change in the electrical activity of specialized receptors
4
Q
How do sensory systems encode?
A
- specify info about stimuli by transforming receptor response into patterns of electrical activity (esp APs)
- also encode spatial information about stimuli via receptive field (region of sensory space –> local receptor transduction leads to maximal change in patterns of afferent electrical activity; ie small fields w/better 2 pt resolution - finger tips, lips; lg fields w/worse 2 pt resolution - back, calves)
5
Q
What is adaptation?
A
- necessary to encode distinct types of information
- receptor adjustment to different levels of stimulus intensity (reflected in pattern of APs encoded by afferents)
- slowly adapting: APs gradually become less frequent (all pain receptors)
- rapidly adapting
6
Q
How can information be relayed in sensory systems?
A
- parallel pathways: distinct ppn of cell bodies, axons, targets in a sensory system that carry information about a specific stimulus
- referred pain: relay of visceral discomfort via cutaneous (skin/surface) afferents
7
Q
How do sensory systems represent information?
A
- representation: systematic distribution of specific response ax ppns of nrns in the brain (corresponds to topography/computational fcns of stimuli sensory periphery transduced from the sensory periphery)
- primary mode of representation is topographic maps –> systematic distribution of specific responses ax ppns of nrns w/ pt-pt relationship w/ lcn of stimuli sensory periphery transduced from sensory periphery
8
Q
How do sensory systems process information?
A
neural processing: sum of electrical activity ax multiple neural circuits in a broad range of anatomical locations in the brain
- leads to: interpretation of ID, quality of stimuli, planning of behavioral response (motor activity), internal representation/abstraction/memory
9
Q
What is parallel processing of pain discrimination?
A
Processing by location + intensity
- sensory: discriminative (somatosensory cortex)
- affective: motivational (anterior cingulated cortex, insular cortex)
10
Q
What is somatosensation?
A
- physical force (painful) messes up skin –> transduced by specialized sensory rec
- lots of specialization
- classes of peripheral rec (superficial to deep): free nerve endings (pain), meissner’s corpuscle (discriminative, light touch - fast), merkel cells (skin distention - slow), Ruffini endings (sustained P - slow), Pacinian corpuscle (vibratory touch - rapid)
11
Q
What is mechanosensation?
A
- sense of touch, pressure, proprioception
- channels detect physical deformation of membrane –> channel open –> Na/Ca influx –> AP
- dynamic range (light vs hard P)
- threshold for AP activity
12
Q
What is proprioception?
A
- sense of position of limbs/jts in space
- -> muscles (muscle spindles)
- -> jts (golgi tendon organs)
13
Q
What is nociception?
A
- detection of painful stimuli (including heat, chemicals)
- capsaicin rec/channel (capsaicin binds to TRP1 channel –> mediator for pain)
- intensity sets threshold for encoding painful nature of stimulus
- pain transduction also d/t endogenous signals (bradykinin, prostaglandins, histamine, H+, ATP), inflammation
14
Q
What are the parallel pathways and how are they discriminated?
A
From fastest to slowest transduction:
- Dorsal Column/Medial Lemniscus: proprioception, touch, pressure (large, myelinated)
- Anterolateral/Spinothalamic: pain, temp + pain, temp, itch (unmyelinated) (small)
15
Q
How do opioids work on pain?
A
descending brainstem inputs activate local dorsal horn interneurons –> inhibit pain transduction (dorsal horn)
16
Q
What is neural plasticity?
A
change in electrical activity of individual nrns, neural circuits, sensory/motor/cognitive maps d/t differences in stimulation, experience or injury
17
Q
What is somatosensory plasticity?
A
altered peripheral use + activity can change central respresentation
18
Q
When is plasticity bad?
A
phantom limbs/pain following amputation/trauma –> mismatch between central representation + periphery
19
Q
What neural structures are in the visual system?
A
- retina (transducing/encoding –> neural events only happen in retina)
- relay: optic nerve, optic chiasm, optic tract, LGN
- primary visual cortex (representation/procession): motion processing (parietal lobe) + form processing (temporal lobe)
20
Q
What are the two types of photoreceptors?
A
- Rods (opsin, rhodopsin)
2. Cones (ospins, encode for color)
21
Q
Explain the pathway of phototransduction.
A
Visual field –> cone cell –> retina –> photoreceptor –> bipolar cell –> ganglion cell (produce APs, begin to selectively process info)
22
Q
Explain the polarization of photoreceptors (light vs dark).
A
- depolarized in the dark (high [cGMP] = Ca/Na channel constantly open)
- hyperpolarized when illuminated/light (low [cGMP] = Ca/Na closes = K+ hyperpolarizes cell)
23
Q
What are the classes of information encoded by the visual system?
A
- topography: where is it; fovea (nrns matched to pts in visual field)
- luminance: how much light (proportional to how many photons available)
- contrast/color: what is it (perceptual quality; discriminating form)
- depth: how near/far is it
- motion sensitivity: is it moving yo
24
Q
What are the parallel pathways for form and motion in visual information?
A
- parallel pathways separate (retina to LGN)
- P cells (form)
- M cells (motion)
25
What is critical period plasticity?
- restricted times during which experience can significantly + permanently alter behavior/brain circuits
- ie changes made (ie one eye sewn shut) --> compensation (other eye adds axonal terminals that expand into area normally taken up by shut eye)
26
What is auditory function?
- identifies pressure-created waves generated by vibrating air
- localization + identification of stimuli
- topography (spatial rep) by quantitative aspects of stimuli
27
What is vestibular sensation?
- detecting + representing CHANGES in head + body position
- acceleration + direction of body movement relative to space/gravity
- provides info that regulates ongoing movements of eyes, head, posture adjustment
28
What is the information pathway for auditory/vestibular sensation?
- information relayed via brainstem
| - info transduced in inner ear (time differences represent location of sound)
29
What are the two sensory organs in the inner ear?
vestibular labyrinth + cochlea
30
What does the vestibular labyrinth do?
- physical orientation specialized to detect movement + acceleration horizlly + vertically
- vestibular hair cells: encode info about acceleration, velocity, head position
- semi-circular (fluid-filled) canals
- vestibulo-ocular reflex: used to localize brainstem lesions (fast/slow eye movements in response to water)
31
What does the cochlea do?
- surface vibrates in response to diff freq to represent different tones (pitches) --> vibrations displace distinct regions of cochlear surface
- cochlear hair cells transduce stimuli (physical displacement of hair cells) + encode frequency based on cochlear position
- frequency encoded in cochlea but is represented/processed in primary auditory cortex
32
What are the chemosensory cells and what do they do?
- id'y + abundance of stimuli --> little topography or spatial representation
- detection of noxious/hazardous stimuli, edible + nutritious food; recognition of pheromonal signals
- reles on GPCR to transduce airborne/water soluble chemical stim
- molecular diversity --> specificity
-
33
How is olfaction transduced?
- olfactory epithelium --> direct production of AP
- id'g airborne chemical stimuli
- lg gene family --> multiple variable AAs --> diversity
34
How is gustation transduced?
- id'g ingested water-soluble stimuli
- transduction via taste ells
- distinct molecular rec for ea taste class
- parallel lines transduce/encode ea category separately
35
What are olfactory deficits early signs of?
- Alzheimers
- Parkinsons
- Huntingtons
- Schizophrenia
36
What is a motor unit?
all muscle fibers innervated by one alpha motor neuron
37
What is an alpha motor neuron?
- generates F in muscles when they fire AP
- in SC (in distinct places) and brainstem --> innervates skeletal muscles directly
- generation of F encoded in patterns of electrical signals
38
What are the 6 basic things that motor systems?
1. Regulate contraction/elongation of skeletal + smooth muscles (synaptic terminals at NMJ w/ACh)
2. Regulate glandular secretion (S - NE; PS - ACh)
3. Organize concerted contraction + complimentary relaxation of muscle groups (reflexes)
4. Command skilled movement + mntn posture + balance (primary motor cortex)
5. Correct ongoing movements based on sensory info (cerebellum)
6. Initiate complex goal-directed actions (basal ganglia)
39
Where is the autonomic/visceral nervous system located?
```
medulla oblongata (give me scoliosis)
brainstem
```
40
What are the four steps of the reflex arc?
1. Hammer tap stretches tendon (--> sensory receptor in leg extensor muscle)
2. Sensory nrn synapses w/excit. motor neuron in SC (--> spinal internrn --> inhibits motor neuron to flexor muscles)
3. Motor neuron conducts AP to synapses on extensor muscle fibers --> CONTRACTION
4. Leg extends
41
What are the functions of the upper motor neurons?
- activity correlates w/specific muscle contraction in distinct body parts; represent direction of movement
- segregation of cortical + bs upper motor neuron inputs (parallel motor pathways)
- anticipatory motor control of posture + balance
- distinct consequences of upper vs lower motor neuron damage (Babinski sign)
42
How does the cerebellum regulate movement?
- receives input from somatosensory, motor, association regions of cortex (+ vestibular sys, SC, BS)
- neurons send info back to motor cortex via thalamus
- purkinje cells are tonically active --> correct signals by slowing their AP output
43
How does the basal ganglia regulate movement?
- receives input from entire cortex (except primary visual + auditory cortex)
- relies on balance of inhibitory + excitatory inputs + outputs
44
What does Parkinson's do to the basal ganglia?
disrupts balance --> inc inhib of motor cortex --> dec movement
1. Dopaminergic nrns in substantia nigra degenerate
2. Difficulty initiating complex movements
3. Paucity of movement (lack of facial expression)
45
What does Huntington's do to the basal ganglia?
disrupts balance --> dec inhibition of motor cortex --> inc movement
1. Nrns in caudate + putamen degenerate
2. Inapprop complex motor behavior (including speech)
3. Constant writhing movements as ds progresses
46
What is the definition of language?
arbitrary association of symbols w/objects, circumstances, actions, intentions, emotions, concepts (independent of modality)
47
What are the fundamental properties of language?
- distinctly human
- represented in specific brain regions + circuits
- dmg to specific brain regions results in distinct language deficits
- distinct aspects of language are lateralized
48
What are the two general features of language?
- symbolic representation: matching of symbols to objects, etc. (lexical aspect)
- stereotypic performance: order + context (syntactic + semantic aspects)
49
What is the association cortex?
neural circuits that represent cognitive info is frontal lobe (what do I want to do about it?), parietal lobe (is it interesting?), temporal lobe (what is it?)
50
What is Broca's Area?
- prefrontal; planning
| - damage = productive aphasia
51
What is Wernicke's Area?
- temporal; auditory association, visual association
| - damage = receptive aphasia
52
What are the language fcns of the L hemisphere?
- analysis of R visual field
- stereognosis
- lexical + syntactic language
- writing
- speech
53
What are the language fcns of the R hemisphere?
- analysis of L visual field
- stereognosis
- emotional coloring of language (damage --> inability to perceive or impart emotional + affective content of language)
- spatial abilities
- rudimentary speech
54
What is Broca's aphasia?
- halting speech
- perseveration: tendency to repeat words/phrases
- disordered syntax, grammar, structure of individual words
- comprehension intact
55
What is Wernicke's aphasia?
- fluent speech
- little spontaneous repetition
- adequate syntax + grammar
- contrived/inappropriate words
- comprehension not intact
56
What are the critical periods for language development?
1. Early "pre-language" behavior modality dependent in infants
2. Decline in acquisition of second language (critical period occurs before 3rd-7th birthday)
