Sem 4 Week 6 Lecture 3

Front 1

Nervous system is adaptable

Back 1

Throughout life!

Front 2

Plasticity

Back 2

Used to describe diff types of change associated with the neuron and its connections--> implies an adaptable structure

Front 3

What provides the major shaping stimulus in nervous system development?

Back 3

Experience

Front 4

Dev of organs & their force or power of actions are always

Back 4

In direct relation to the employment of those organs.

Front 5

Connections between a neuron and its target are

Back 5

neither specified nor fixed.

Front 6

Dev of neural connections in many regions of the brain is characterized by an

Back 6

Initial overproduction of neurons,axons and synapses--> selective elimination or pruning of excess no. of these structures at certain periods.

Front 7

Development leads to

Back 7

Primary connections formation(cell division + process extension)

Front 8

Experience leads to

Back 8

Dev. of maps with changes in synaptic strength.

Front 9

Neuronal activity determines the

Back 9

Morphological dev. of nervous system.

Front 10

Selective innervation of homonymous spinal motorneurons by

Back 10

Primary muscle afferents

Front 11

Neuronal activity appears to regulate

Back 11

-Expression of cell adhesion molecules
-synthesis & secretion of neurotrophins
-expression of glutamate & GABA receptors at individual synapses.

Front 12

Neurons are fixed in cortex but

Back 12

connectivity happens via growing dendritic tree.

Front 13

Spines

Back 13

Sites of excitatory contacts with other neurons.

Front 14

Survival of neurons is dependent on

Back 14

Functional synaptic contacts with their targets(in vertebrates,it occurs due to competition between neurons at level of target they innervate)

Front 15

What appears to be a common denominator of early neuron survival and later modulation of neruonal connections ?

Back 15

Competitive acquisition of trophic factors.

Front 16

Synaptic rearrangements

Back 16

Dev of ocular dominance columns.

Front 17

Experience EXPECTANT processes

Back 17

experiences obtained from normal environment that shape developing sensory and motor systems of a species

Front 18

Experience-Dependent processes

Back 18

Involve experiences which differ in both timing and character and that are UNIQUE to the individual.

Front 19

Maturation of CST takes place

Back 19

Post natally

Front 20

What ensures correct connections with target neurons in the CTS?

Back 20

Specific axon guidance molecules.

Front 21

What increase in complexity during a protracted postnatal period ?

Back 21

Terminal and preterminal corticospinal axon branches.

Front 22

Unilateral lesion of CST during early postnatal life or interference with neural activity in sensorimotor cortex results in

Back 22

-Aberrant corticospinal org.
-maintenance of exuberant projections from non-damaged side
-disrupts dev. of alpha motorneurons & their afferent segmental control.

Front 23

Kittens deprived of visual info abt their limb mvts fail to demonstrate

Back 23

Normal visually guided behaviours in maturity.

Front 24

Roles of functional activity:-

Back 24

-Dev of spinal motorneurons
-Dev. of dendritic morphology
-Dev. of synaptic inputs

Front 25

Lack of activity in target muscles affect

Back 25

the way CST develops.

Front 26

What is the basis of learning ?

Back 26

-although new neurons cant be generated,each neuron retains the ability to form new processes & new synaptic connections
-although nerve cell body is fixed component within each centre of adult nervous system,synaptic circuits it forms with processes of other neurons are subject to ongoing modifications.

Front 27

Neurons can proliferate new processes to

Back 27

Replace those that have been lost or damaged.

Front 28

Loss of a particular type of synaptic terminal stimulates

Back 28

Production of axonal sprouts-->mobility to move to vacated sites + necessary chemoaffinity to establish new synaptic connections

Front 29

Perinatal damage to one hemisphere

Back 29

-Disrupts normal competition between contralateral & ipsilateral projections
-Abnormal preservations of ipsilateral projections
-impairment of motor skill learning
-secondary disruption of the dev. of motorneurons and their afferent segmental control.,m

Front 30

In blind individuals,Braille reading and auditory localizaton tasks activate

Back 30

Areas of cortex normally involved in VISUAL PROCESSING.

Front 31

Mechanisms underlying remodelling in nervous system in response to experience

Back 31

-Dendritic branching
-Dendritic spine density
-Perforated synapses
-Multiple synaptic boutons

Front 32

Topographic maps in CNS are

Back 32

Dynamic and continually modified by experience.

Front 33

What happens to cortical sensory maps following variety of pertubations that affected relevant AFFERENT signals?

Back 33

Became reorganized

Front 34

Major perturbation ?

Back 34

Transection of peripheral nerve or surgical correction of syndactyly

Front 35

Minor perturbation ?

Back 35

Differential stimulation of restricted areas of skin.

Front 36

Peripheral denervation in adult mammals not only produces reorganization in somatotopy in SI and thalamus BUT

Back 36

Also alters the expression of INHIBITORY NT & levels of metabolic activity.

Front 37

What happens following sectioning of motor nerve to muscle groups ?

Back 37

-Immediate effect of such lesion is that cortical stimulation of sites that formerly activated the denervated muscles no longer produced mvts
-within hrs of lesion,stimulation of these sites result in activation of new sets of muscles.

Front 38

What induces alterations in the representational features of the SI cutaneous map of the stimulated limb?

Back 38

Tactile experience promoted by environmental enrichment.

Front 39

What are the 2 mechanisms that explain observed changes in cortex?

Back 39

-Collateral sprouting
-Alterations in effectiveness of previously existing connections by formation of new synaptic contacts or potentiation of existing synapses.

Front 40

Following focal cortical lesions,recovery of skilled motor performances is assoc. with

Back 40

Functional cortical reorganization.

Front 41

What happens following brain injury?

Back 41

-Spontaneous recovery-->reparative processes occuring immediately following a lesion.
-Recovery is accompanied by significant structural brain reorganization.

Front 42

After stroke,

Back 42

Substantial functional reorganization occurs in motor cortex.

Front 43

Retaining of skille hand use i nthe baove case resulted in

Back 43

Prevention of the loss of the hand territory adjacent to the infarct + functional reorganization in undamaged motor cortex surrounding infarct was accompanied by behavioural reocvery of skilled hand fucntion

Front 44

Where does reorganization occurs after infarct?

Back 44

At the rim of infarct(penumbra) with extension into neighbouring representations.(region surrounding injury may be vulnerable to behavioural pressure during early post-lesion period)

Front 45

What other changes occur?-

Back 45

-Changes in vasculature to support the increased metabolic load assoc. with higher levels of neural activity
-alterations in pattern of synaptic connections only occur in response to demand for skilled mvts.

Front 46

Mechanisms underlying recovery :-

Back 46

1. Multiple parallel corticospinal projections provide substrate for recovery
2.Adult brain capable of significant reorg. in response to peripheral perturbations or to cortical lesions.

Front 47

During recovery,adaptive changes occur in

Back 47

Both ipsilateral and contralateral hemispheres.

Front 48

Surviving penumbra has

Back 48

Propensity for long term potentiation that can be exploited with training.

Front 49

Drivers to recovery include :

Back 49

-Repeated motor practice
-Goal-directed training.