3- cerebral cortex Flashcards
fractionation
the ability to move body parts independently and to localize motor actions to a limited set of muscles
cerebral cortex contributes to this
what structure is involved with goal-directed movemnt
cerebral cortex
I want to do this movement
- It is part of the progress in refining motor learning
primary motor cortex mapping
‘Dynamically mapped’: as for skilled hand movements
The mapping is not for a specific muscle but for movements
primary motor cortex - Mutable
greatest change with skilled use;
rewarded behavior;
(this is all goal-oriented movement)
Motor cortex neurons - force
Force encoded by single neurons
Motor cortex neurons - direction
Direction coding occurs by an ensemble of neurons,
results in 99% accuracy for direction
is the cortex interest more in isolated movement or collective movement
isolated movement
diagram:Coding the proximal and distal movements together
Supplemental motor area (SMA) role
role in plan and program movement
internally triggered motor acts
What is a internally triggered motor acts
creating a motor behavior - I want to do this – this internally triggers an action
Motor set
premovement associated with planning andprogramming
motor set and SMA
50-70% of the neurons are for motor set in SMA
Cortico-cortico connections
extensive with prefrontal and parietal association areas; and connections to basal ganglia, limbic areas, and cerebellum
SMA neurons selectivity
neurons in the SMA are very selective
- Push turn pull > pull push turn
Lateral premotor (PM) responds to
externally-triggered /guided motor programs and plans object cues
External cue
There is a target and I want to get to it
Visually-guided reaching what area
premotor dorsal (PMd)
Visually-informed grasping what area
premotor ventral (PMv)
Visually-guided reaching - what is happening
Translates visual info of object location to reaching direction
Visually-guided reaching - pathway
Extrastriate to dorsal premotor (PMd) via medial dorsal- and medial intra-parietal areas
Visually-informed grasping from what area
premotor ventral (PMv)
Visually-informed grasping - what is happening
Translates visual info about object properties into successful grasping
Visually-informed grasping - pathway
Dorsal extrastriate cortex to premotor ventral (PMv) via anterior intra-parietal area
what are Mirror neurons
special neurons in PMv active when a monkey watches another perform a task; and when the monkey actually performs
where are mirror neurons found
premotor ventral (PMv) area
Cingulate motor areas (CMA) function
integrates multiple behavioral factors to weight movement decisions
prefrontal - cing
temporal organization of motor behavior; movement decisions based on experience
limbic - cing
flavor’ to movement; weighting; accounting for reward; appropriate - ‘urge to move’
Cingulate motor areas (CMA) is part of what
Part of anterior cingulate cortex: Area 23, 24 dorsal
CMA to spinal cord centers
Direct CMA to spinal cord centers to carry out motor plan
Posterior parietal cortex (PPC) role
role in identification of self relative to world
our actions vs. their actions distinction
Internal representation of body image (right > left PPC)
neurons of the PPC
Neurons have complex receptive fields: multimodal and context dependent (somatosensory, visual, auditory, vestibular)
Lesions associated with PPC result in
issue with movements that involve special temporal patterns
PPC lesions - Gaze disorders
mis-reaching, right-left disorientation
Does a lot of visual spatial relationship: where is your body in relationship to where the target is
What is Gnosis
whose hand?
Where are you in space and your hand
seen with PPC lesion
what is Constructional apraxia and what issue is it seen with
the inability of patients to copy accurately drawings or three-dimensional constructions
draw a clock; put on a sweater (not a novel task – something people have done before …)
what part of the cortex is involved when we are learning something new
a lot of areas - most
lots of activity, neurally insufficient
Prefrontal cortex (PFC) overall role
Role: Motor planning, judgement
EX: when to cross the street, how to study
organizes events, selects appropriate motor acts
PFC contributor to overall role
Select appropriate - suppress inappropriate behavior for current conditions
Modeling behavior – based on internal representations of reality
Temporal organization of motor events
Provides control and flexibility in behavior
change our mind
Dorsolateral prefrontal cortex DLPFC
(areas 8 ,9 & 46) provides cognitive control for the dorsal pathway; ‘how’
visual guided reaching
Ventral prefrontal cortex, VLPFC
(areas 44, 45, 47 & 12) provides cognitive control for ventral pathway; ‘what’
Guides selection and retrieval of semantic memory - Recall information that you need to understand your situation
Actively maintains stimulus information; drives retrieval in posterior cortex
anterior of the Ventral prefrontal cortex
Abstract thinking
Abstract thinking
using the things that have not been put together before
posterior part of the Ventral prefrontal cortex
concrete thinking
concrete thinking
things that you know well about
Medial aspect of the brain general characteristic
higher intensity of action/ meaning is medial
lateral aspect of the brain general characteristic
practical aspect of how to solve issues
low intensity is lateral
what is Learning
a change in behavior that results from acquiring knowledge about the world
what is Memory
process by which knowledge is encoded, stored and retrieved.
Declarative memory
a type of long-term memory that involves consciousrecollectionof particular facts and events.
implicit memory
does not require the conscious or explicit recollection of past events or information, and the individual is unaware that remembering has occurred
EX: singing a familiar song, typing on your computer keyboard, and brushing your teeth
Short term (STM) type
primary and working
LTM types
procedural
episodic
sematic
age related factors and LTM
LTM can be impacted by aging
Executive function
combining visual and spatial info – trail making (connect the letters), more the one activity going (EF)
Association as seen in MOCA - testing and example
semantic memory
name the animals, watch - time
procedural memory
skills, tasks
learning by doing
LTM - implict
episodic
events experiences
what did you do on summer break
LTM - explict
semantic
facts and concepts
LTM - explicit
two forms of LTM
explict and impilct
types of implicit LTM
priming
procedural
associated learning
non-associated learning
types of explicit memory
sematic
episodic
priming brain
neocortex
saying number over and over again, we might learn them without trying
Word used during instruction are important, walk the curve (not given different part of the gait different phases)
procedural brain
striatum
skills and habitu
associated learning two types
emotional response
skeletal musculature
emotional response - brains
amy
chemotherapy and walking into that room again
skeletal musculature - brains
cere
what patterns of muscle activation go together, synergies, learn without our conscious attention
nonassociative learning
habituation
Sensitization
habituation - brains
reflex pathways
repeated exposure something over time , eventually you have remembered it
Sensitization - brains
reflex pathway
procedural learning without intent/learning without repetitions , exposed to something that scared you – something that has a large impact on you
Lion and dog
what is the role of Working memory
Maintains current, transient goal relevant knowledge
Two subsystems of wokring memeory
verbal information
visuospatial information
verbal information - working memory
self-talk, ask you SSN you are tell it back to yourself, phone numbers
keeping speech-based information in awareness
visuospatial information - working memory
retains mental images of visual objects and locations of objects in space
Prefrontal cortexand vision
Prefrontal cortex– heavily connected with parietal lobe/ visual inputs
Prefrontal cortex and wokring memory
through the hIppo PFC is highly involved
the PFC keep the stimulus that you are working with available at the time
maintains information is the working memory
making a LTM step s
encoding
consolidation
storage
retrieval
encoding - LTM
new information is attended to and linked with existing information in memory (this linked to association)
consolidation -LTM
makes temporarily stored information more stable, processes of LTP
Have to keep on using it to get to LTP
stroage - LTM
neural mechanisms by which memory is retained over time
Retrieval - LTM
when stored information is recalled
explicit memory - brains
medial temporal lobe
where is episodic information stored
stored in prefrontal cortex
Entorhinal cortex and Parahippocampal and perirhinal cortex role togethere
these are pathways between hippo and association cortices
Parahippocampal and perirhinal cortex
cortical areas that surround hippocampus
Perirhinal cortex particularly important encoding
object recognition
Parahippocampal cortex important for encoding
spatial context .
what is stored in the Association cortices
semantic knowledge distributed throughout association cortices (prefrontal cortex, limbic, parieto-occipital-temporal) in bits and pieces
Entorhinal cortex role
main input and output path to hippocampus
Hippocampus role
converts declarative STM to LTM
Hippocampus and parahippocampal and perirhinal cortex
Bind together spatial and object information from perirhinal and parahippocampus forming a unified memory.
perirhinal -lateral entorhinal stream
“what’ – object characteristics derived from
unimodal sensory information from association cortices
parahippocampal medial entorhinal stream
“where’ - spatial context derived from polymodal sensory information from association cortices
semantic memory flexablity
highly flexible
Not a static repository of information – it shifts and is integrates
It grows and changes as we continuously acquire, integrate, and reinforce rich representations of the relations between words
Semantic richness
Refers to the amount of information contained within or associated with a word or concept, and it influences the speed and accuracy of behavioral responses.
Words and concepts that are richer, or associated with more information, are better remembered
semantic memory hippocampus
the hippocampus is critical to encoding and consolidation of semantic memories
hippo damage and sematic memory
Following hippocampal damage, patients fail to show normal acquisition of new semantic information
still have procedural memory
Neural substrates of procedural memory
BG
SMA
Cbm
Amygdala
Classical conditioning
associated learning - implicit , LTM
Stimulus/Response; cause and effect presumed between events, Pavlov
Operant conditioning
associated learning - implicit , LTM
a form of learning in which new behaviors develop in terms of their consequences, behavior appears >reward
specific consequences are associated with specific behavior
Enduring plasticity
relation of pre- and post-synaptic elements, strengthens the connection
Patterned activity at a synapse
Temporal and spatial summation
if there is repeated stimulation at the synapse then the post synaptic membrane will react differently due to the high stimulus > greater than normal amount of transmitter released
Showing that the experience of the synapse can change the response –. Mech of memory at the cellularly
Changes in synaptic physiology
Presynaptic facilitation/axoaxonic synapses
Convergent inputs
Postsynaptic intracellular events
Second messenger systems – changing the neuron both functionally and structurally for the future
Structural changes in the synapse - memory
New synapse, enlarged; specialization of receptors, dendrites, endplates
Involves protein synthesis, even gene activation
Long-term changes in synaptic strength
Biochemical
Anatomical
Declarative memory failure
Retrograde
Anterograde
Traumatic brain injury (TBI)
Retrograde amnesia
loss of memories for events that occurred before trauma or disease that caused the condition
Anterograde amnesia
loss of memory for events following the trauma or disease
Now I can do but I cannot create a memory - HM
Traumatic brain injury (TBI)
may have severe declarative memory deficits, but often retain procedural memory
Alzheimers disease due to what
part of dementia
plaques and neurofibrillary tangles
Tau/amyloid deposits
Alzheimers disease location
Starts in entorhinal and hippocampus, spreads to other temporal areas, then parietal then frontal
Early AD what do we lose
Declarative memory loss is episodic and semantic
Early AD and frontal lobe
deficits in short term memory and attention, executive function, have a hard time learning new things
