Cortex, Learning, Memory (2) Flashcards
What is the function of the cerebral cortex?
Processes information associated
with each modalities of sensation, language, skilled movements, emotional makeup and
sensitivity to societal norms; cognitive functions information processing
What are the phylogenic divisions of the cortex?
archicortex (hippocampus) and
paleocortex (olfactory cortex] and neo
(90% of the total cortex) cortex (6 layers only mammals)
What are the characteristics of projection neurons? What percent of cortex?
are pyramidal in shape, use Glu as NT, carry information from one stage to the next for processing or command, 70%
What are the characteristics of interneurons? What percent of cortex?
usually inhibitory, using GABA as NT, layer IV are excitatory and use Glu as NT, 25%
Sensory cortices, such as primary visual cortex, which layer is prominent?
internal granule layer(layer IV) where incoming information terminates.
Motor cortices, such as the primary motor cortex, involved with outputs, have a well
developed what layer?
internal pyramidal layer (layer V) and a meager layer IV
The neural stem cells (NSCs) are oriented how? divide where? What do these cells do initially?
radially oriented in the wall of the
neural tube, near the ventricular surface, thus forming a ventricular zone (VZ), divide symmetrically to increase stem cell pool
NSC’s eventually divide how?
asymmetrically to generate stem cells that remain in VZ and daughter cells that migrate out towards the pial surface
How does laminar organization develop?
first wave radially migrating neuroblasts settle in cortical plate (CP), splits into
superficial marginal zone (MZ) & underlying sub plate (SP) layer. SP cells generate layer VI neurons. layer V cells migrate
thru layer VI neurons to reach CP and differentiate; process repeated; projection neurons in dorsal telencephalon
GABAergic interneurons are born where? How do they migrate?
ventral telencephalon (MGE and LGE); tangentially to the neocortex
What signal molecule takes a cortical progenitor to a neuronal precursor?
Ngn
What causes differentiation to an astrocyte?
Id+Hes; cortical progenitor lacking a signal molecule or just Hes?
What is the function of signal molecule Mash 1?
ventral progenitor to neuronal precursor
What is the function of signal molecule Neuro D?
neuronal precursor to GABAergic interneuron or pyramidal neuron; location/progenitor dependent
What is the function of signal molecule ID and Hes?
maintainence of progenitor cells ventral and cortical
What causes differentiation of an oligodendrocytes?
signal molecule Olig
What are the 2 kinds of neocortex organization?
laminar and columnar
A cortical column corresponds to what?
cylindrical area, extending from ventricular surface towards the pial surface
What is the significance of columnar organization?
fundamental computational modules; similar response properties within column
What are the brodman’s areas of the primary sensory cortex and their associated sense?
1,2,3- sensory cortex, 17- vision, 41,42- auditory
What are the brodman’s areas of the Higher order sensory cortex (unimodal) and their associated sense?
5, 7(vision) =2° sensory cortex, 18-21 =vision, 22 =auditory
What are the brodman’s areas of the Primary motor cortex?
4 =primary motor cortex (execution)
What are the brodman’s areas of the Higher order motor cortex and their function?
6 (medial) =supplementary cortex (complex motor sequences, bi-mannual coordination)
8 =frontal eye field, 44-45 =motor speech area
What are the brodman’s areas of the Association cortex (multimodal) and their function?
39,40,19,21,22,37= Posterior (sensory+language), Rostral of 6 = Anterior
(cognition+motor planning), 23,24,38,28,11 =limbic (emotion+memory)
PET scan identifies different cerebral
cortical regions involved in a particular
function by what?
Measurement of the regional blood flow
Visual stimuli evoked activities in what?
primary and secondary visual cortex.
Auditory stimuli evoked activities in what?
primary and secondary auditory cortex.
Speaking words evoked activities in what?
primary motor cortex and the Broca’s area near the sylvian fissure.
Word association that requires attention and
thoughts evoked activities in what?
left inferior frontal area, anterior cingulate gyrus, and posterior temporal lobe.
Mirror neurons are premotor neurons
that fire when what?
performs object directed actions and when observing some one else performing the same class of actions
Two major areas containing mirror neurons have been identified as?
ventral premotor area (inferior frontal cortex) and inferior parietal cortex.
The premotor neurons areas are not only involved in action recognition but also in what?
understanding the intention of the action; critical component of establishing social behavior and norms.
What is the function of the association cortex?
integrate sensory inputs to motor , interpret sensory information in the backdrop of
experience and emotion, focusing attention while exploring the environment for goal-directed movement
What is the flow of processing in the association cortexes?
peripheral receptors (retina) through primary
cortex (17) and unimodal cortex (area 20) to multimodal assoc.areas (21; PrCo) for integration with other senses, Post. assoc. area (21) project to ant. assoc. area (46,
25, 35) for planning motor action in
response to sensory inputs.
What is the function of the Anterior Association Area?
judgment and restraint, long-term planning, order and organization
A dorsolateral convexity lesion results in what?
apathetic, lifeless abulic state
An orbitofrontal lesion results in what?
impulsive and disinhibited state with poor judgment
What is the function of the posterior association cortex?
integrates somatic sensory information with other sensory modalities (i.e.,vision) towards
perception, planned manipulation of objects and sense of body with respect to space.
A lesion to the posterior association cortex results in what?
agnosia, which is complex such as defects in spatial perception, visuomotor integration and selective attention.
What is Balint’s syndrome?
inability to make sense of a complex visual
scene as a whole and reach objects of interest
What are neglect syndromes?
could be personal (self-image), spatial
(extra personal space), or representational (Remembered extra personal space) neglect
Language processing, speech and skilled
motor formulation are primarily where?
left hemispheres (=dominant hemisphere); rt hand 4% on rt side, lt hand- 15% bilateral and 15% rt side
The non dominant hemisphere is
specialized for what?
non verbal functions, processes information for complex visual spatial skills, provide, emotional overtone to language and events, sense of direction and music perception
What is learning?
Modification of behavior as a result of experience
what is memory?
Storage and retrieval of information.
What are the two kinds of non-associative learning?
habituation and sensitization
What is habituation?
Decrease in response to repeated presentation of a stimulus. Ex: ticking of a new clock.
What is sensitization?
Increase in response to a weak stimulus when it follows a strong stimulus. Ex: drug addiction
What are the different forms of associative learning?
Classical conditioning, Operant (instrumental) conditioning
What is Operant (instrumental) conditioning?
involves association of a stimulus with a
response. Consequences to behavior can involve reward or punishment and will
cause the behavior to either increase (reinforcement) or decrease (punishment). (Gambling or salary)
What is classic conditioning?
involves reflexive behavior. Pairing of unconditioned stimulus with a conditioned stimulus. Example: meat with a bell for Pavlov’s dog.
What is the molecular basis for associative learning?
Long term potentiation (LTP) and long term depression (LTD) in the hippocampus and neocortex.
Where does motor learning occur? What molecular process?
Occurs in the cerebellum and is thought to involve LTD
What is mental retardation?
many disabilities, most notable is general difficulty in learning. genetic or environ. causes. neocortex is often involved although other areas of the brain may be affected
Brain damage after traumatic injury results in what?
Problems in learning may occur depending on which areas of the brain are damaged.
What are the different kinds of memory?
declarative- semantic or episodic and procedural
What is sematic memory? Damage to where results in impairment?
Knowledge of facts. Not hippocampal formation, but parahippocampal gyrus
What is episodic memory? Damage to where results in impairment?
Recollection of specific events. Specifically to the hippocampal formation.
What is procedural memory? What areas of the brain may be involved?
Learning how to complete tasks efficiently. cerebellum and basal ganglia.
What are the stages of memory? What is the capacity of each?
sensory (200-500) limited capacity, short-term (working sec-min) capacity 4-7 items, long term (decades) capacity unlimited
Transferrring information from short term to long term memory appears to require what?
hippocampus
Long term memories are thought to be stored where?
neocortex
What are the stages of processing of memory?
encoding, storage, and retrieval
what is Anterograde amnesia? What area is involved?
An inability to form new memories; hippocampal formation
What is retrograde amnesia? brain area involved?
An inability to retrieve old memories, neocortex
What are the characteristics of early Alzheimer’s?
May involve dysfunction of neurons affecting LTP and LTD prior to obvious degeneration. Memory loss primarly of recent events
Some of the memory deficits that occur in Late stage Alzheimer’s disease may be
due to degeneration of what?
degeneration of the entorhinal cortex and hippocampus, although widespread
degeneration of neocortex also occurs
In Alzheimer’s the pyramidal neurons in layer II of the entorhinal cortex exhibit what? when else does this occur in a lesser extent?
neurofibrillary tangles; normal aging
What is the amount of pyramidal neurons effected in the different stages of Alzheimer’s?
mild- 50%, severe- 90%; memory loss is recent and older
What combination of APOE alleles reulsts in what level of Alvheimers risk?
2 APOE4 67% late-onset Alzheimer’s, APOE3 and APOE4 18%, 2 APOE3 (most common, baseline) 5%, APOE2 and APOE4 5%, APOE2 and APOE3 3%, 2 APOE2 0.1%
What is the cause of Korsakoff’s syndrome? What is damaged? Symptoms?
thiamin deficiency following chronic alcoholism, Damages several structures including mammillary bodies, Impairs acquistion of new memories
Bilateral damage to the hippocampal formation results in what?
no acquisition of new memories, unable to encode new information about events that
happened to him (anterograde amnesia), declarative but not procedural
