exam 4 slides

first order neurons

the first carriers of the message, recieves the signal, upper motor neurons

second order neurons

next in line, order goes on until signal reaches destination, lower motor neurons

motor output

• the command to move a muscle of the body comes directly from the motor cortex

• the axon of these upper motor neurons crosses to the contralateral side of the spinal cord at the level of the medulla

• the signal then makes its way down the ventral spinal cord to the next neuron in line, the lower motor neuron

• the lower motor neuron has its cell body in the ventral side of the spinal cord and it then sends its axon to the muscle that needs to move.

motor output is specific

homunculus: map of body laid across the brains primary motor cortex in precentral gyrus, represents amount fo cortical tissue dedicated to moving specific body parts

primary motor cortex

executes voluntary movements by organizing the activity of unspecialized cells, adds force and direction control

primary somatosensory cortex

supplies motor areas w/ info about the body like limb position, sends info from posterior to parietal

posterior parietal cortex

supplies motor areas w/ info about location of body parts in relation to objects in space

cerebellum

contributes order and timing to intended movements, sends info back to motor cortex, maintains balance, refines movements, controls composetory eye movements, involved in learning movement sequences

premotor cortex

combines info needed for movement, begins programming, target being reached for and its location, which arm to use and its location

prefrontal cortex

holds in memory info about the world and body while selecting appropriate movement and target

supplementary motor area

assembles sequences of movements, coordinates movements between 2 sides of body

basal ganglia

use info from secondary areas and somatosensory cortex to integrate and smooth movements

ALS

amyotrophic lateral sclerosis, neurodegenerative disease, begins in adulthhod and rapidly advances, deterioration and loss of upper and lower motor neurons, motor neurons stop sending signals to muscles and they weaken and leads to paralysis, no cure, cause unknown or its inherited, nucleo-cytoplasmic transport defects, impaired DNA repair, transport defects

executing movements

• sensory info comes into somatosensory cortex

• relayed to posterior parietal cortex (ppc) and and ppc relays info to prefrontal cortex

• pfc is conscious decision making, working memory, wwhats going on right now

• premotor cortex is programming an action plan

• supplemental motor area is assembles sequences (step 1, step 2, etc), sequence of muscle movements

• primary motor cortex is executes signal to move, signal gets muscles to move

movement results as…

the dinal command sent to the primary motor cortex, there are LOTS of things that need to be considered before executing the movement, this happens VERY FAST and includes integration from sensory info and info about our position in space

movements need to be smooth

subconcious info must be considered, need to integrate proprioceptive info and other sneses (sight, sound) to coordinate movements

cerebellum

• starting and stopping the movement, lots of cross talk and integration

• cerebellum recieves info from spinal cord

• spinal cord - location of limbs in space, muscle postion, length, and force

• spinal cord talks to the thalamus

• thalamus - fine tunes info going to sensory cortex, also talks to motor cortex to coordinate movements

• thalamus talks to motor cortex

• motor cortex - regulates output of motor commands

cerebellum has a different job then basal ganglia

• cerebellum recieves the sensory info from msucles to make us aware of where our limbs are in space and plays a role in balance

• IT DOES NOT PRODUCE MOTOR MOVEMENTS, it modifies how the primary motor cortex sends the signal to the muscle to tell it to actually move

basal ganglia

• recieves info from primary and secondary motor areas and somatosnesory cortex

• functions - smooth movements through thalamus, learn movement sequences performed as a unit, main NT are GABA and dopamine

  • the basal ganglia are a GROUP of brain structures located under the cortex, they form a curcuit that regulates motor output, this helps us start and stop motor movement in a smooth way

tourette’s syndrome

• involuntary, sudden movements or vocalizations called tics

• tics can vary from small movements and grunting sounds to large movemenst and repetitve vocalizations

• exact cause is unknown

• abnormalities in basal ganglia, frontal lobes, cortex in general have been found

• simple tics - eye blinking/darting, swallowing, coughing, shoulder shrugging, head jerking, nose/lip twitches, and throat clearing

Dopamine is…

main NT produced in substantia nigra in the basal ganglia, it helps to regulate motor movement (not reward), GABA is main NT in brain, NT wouwld inhibit certain aspects of muscle activation to smooth movements, BASAL GANGLIA ITSELF DOES NOT PRODUCE MOTOR MOVEMENTS, it simple modifies how primary motor cortex sneds the signal to muscle to actually move

attention is…

vital to survival, the attention system allows us to focus on what is important and to ignore irrelevant things going on both internally and externally, paying attention takes energy, attention can be consious or subconsous

acetylcholine

• released by basal forebrain to the cortex and mediates consious attention and learning

• released by brain stem nucluei to the cerebellum, brain stem, and spinal cord

• mediates attention related to reflexes and survival

norepinephrine

• focuses “neuronal” attention to stimuli, decreases “background” noise to be able to more clearly detect signals

• locus coeruleus, in pons area

• innattentive, non alert —> task engaged —> distracted

brain waves reflect..

levels of consoiusness

neurons can fire in synchrony

can measure electricity on surface of skull

beta waves

alert, engaged in work, busy thinking

alpha waves

relaxed imaged and visuals, self-introspection, day dreaming

theta waves

between awake/sleep, deep meditation, flow of ideas/creativity, altered states

delta waves

unconsious, very deep sleep

change blindess

brain fails to notice significant, unexpected changes in a visual scene, caused by limited attention

EEG

electroencephalogram, records the brain electrical activity using electrodes attached scalp

endogenous cues

internal, top-down signals that voluntaryily direct attention based on knowledge, intention, or memory

exogenous cues

external, involuntary stimulus, like a flash of light or loud noise or sudden movement that automatically drawws attention to a specific location, bottom up processing

locus coeruleus

small nucleus in the dorseolateral pons of brain stem, primary site for synthesizing norepinephrine

the hippocampus

• memories are NOT all stored in one place, memories are circuits of neuronsn that are activated

• memories are a series of associations and connections, you can think of the hippocampus as the ringleader

• memories are made by new connections between neuronsm these neurons connect to other neurons to create a circuir, when you remeber something the entre circuit is activated

hippocampus anatomy

part of limbic system, located right next to the amygdala, associates emotions with memories, help us remeber fearful experiences

making associations

• spatial navigation

  • place cells increase firing when individual is in a specific location in an environment, collectively form a spatial map, dependent on environemtnal cues and landmarks, also found in humans and primates

spatial memory

encoding, storing, retrieval info about environment including object locations and navugations

basics of memory

external events ———> Sensory memory

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| encoding

. ⌄

. working/ST memory

^ |

retrieval | | encoding

. | ⌄

. LT memory storage

types of memory

• working memory - consious, active processing of incoming auditory and visiospatial info and info retrieved from LTM

• explicit memory - memory of facts and experiences that one can consiously know and declar

  • semantic - facts not associated with a particular context

  • episodic - events associated with spatial temporal contect in which we experienced them -

  • ---

    implicit memory - memory involving the integration of many skills including motor leanring, conditioning, visual discrimination and priming, usually involves overlapping brain circuits

basic memory processes

encoding - acoustic, visual, semantic

storage - episodic, procedural, semantic

retrieval - recall, recognition

declaritive/explicit memory

requires hippocampus, recalling specific memories into wm or consiousness, rat with hippocampus lesion could NOT remeber which arms it had visited no

non declaritive / explicit memory

requires basal ganglia, has motor component, automatic, requires little to no thought

brain regions involved in memory

• amygdala - emotional components to memory

• hippocampus - constructing memorues and associtaions

• where pathway - dorsal, spatial processing, location, movement, spatial transformations and relations

  • what pathway - ventral, object processing, color, texture, details, shape, and size

brain regions involved in implicit memory

• basal ganglia - input from other brain regions help regulate movement

  • cerebellum - controls balance and whwen to start/stop movements, relays sensory info from the musclrs and about the lovation of limbs in space

brain regions involeved in explicit memory

• MTL - medial temporal lobe, recognition memeory, encodes diff features into episodic representations, aids w associative memories, during retrieval of memoires the MTL compares encoded memories to new sensory info to send known memories to ther brain regions for further processug, MTL as filign cabinet

memory is not just encoding

• retrieval

  • prefrontal cortex - organizes info an keeps aspects of info distint in MTL during encoding, durinc retrieval the PFC montiors what is being pulled from the MTL and holds retrieved info in WM

alzheimers disease

• progressive neurodegenerative disease

• causes dmentia - loss of memory, difficulty maintaining convos, cognitive decline

• 5.1 million adults over 65 have it

• cause not clear, genes have been linked or environemnt can play a factor

  • no cure or medication, onlu supportive treatments

10 warning signs of demntia

1. memory loss

2. difficulty performing familiar tasks

3. problems with language

4. disorientation about time and place

5. poor/decreased judgement

6. problems keeping track of things

7. misplacing things

8. changes in mood and behavior

9. trouble with images and spatial relationships

   1. withdrawal from work and social activities

mild cognitive impairment

7 years, disease being in MTL, short term memory loss

mild alzheimers

2 years, disease spreads to lateral temporal and parietal lobes, reading problems, poor obect recognition, poor sense of direction

moderate alzheimers

2 years, disease spreads to frontal lobe, poor judgement, impulseivity, short attention span

severe alzheimers

3 years, disease spreads to occiptial love, visual problems

brain shrinks with AD

neuronal cell death especially in hippocampus, loss of supportive cells like glia, cortex shrinks, ventricles enlarge

things go wrong in and around neurons

• around - proteins aggregate in extracellular space around neurons, beta-amyloid plaques, disrupt communications between enurons

• in - neurofibrillary tangles disrupt structure and function