Physiology of
nervous sytem
Reflexes
Reflexes
• Definition of reflex arc
– nervous /reflex/ circuit, which starts
from peripheral receptor, continues to
spinal chord (cerebral cortex) and leads
back to periphery (effector)
Parts of reflex arc
•
•
•
•
•
Receptor
Ascendent nervous tract
Spinal cord (Cerebral cortex)
Descendent nervous tract
Effector
Reflex arc classification
By the reflex tract
• spinal reflex
• axonal reflex
• ganglionic reflex
Reflex arc classification
1. Spinal reflex
• By the receptor origin
and terminal effector
– Somatosomatic
reflex – reflex starts
and ends in soma, not
in visceral organs.
Reflex arc classification
1. Spinal reflex
• By the receptor origin and terminal
effector
– somatovisceral reflex - reflex starts in
soma and ends in visceral effector
Reflex arc classification
1. Spinal reflex
• By the receptor origin and terminal
effector
– viscerovisceral reflex – reflex starts
and ends in visceral organs
Reflex arc classification
2. Axonal reflex
• By the receptor
origin and terminal
effector
– axonal reflex – senzoric
activity travels by one
fiber of peripheral nerve
to bifurcation, and then
back to the same tissue,
resulting in neuroeffector
response. E.g.
vasodilatation leads to
vasocontriction.
Reflex arc classification
3. ganglionic reflex
• By the receptor origin
and terminal effector
– ganglionic reflex – does
not take into account the
spinal chord. Reflex starts
in peripherym synapses
are within autonomic
ganglion, ending in
peripheral effector.
Reflex arc classification
• By the interneuron target in spinal
chord.
– Intrasegmental reflex – all central
reflex activities are located in one spinal
segment. E.g. posterior radices enter
the segment C7, synapses are in C7
and motoric neuron leaves from C7
segment
– Intersegmental reflex- more than one
spinal segment
Reflex arc classification
• By the interneuron target in spinal
chord.
– Ipsilateral reflex – central reflex
activity stays on the same side of the
spinal chord
– Contralateral reflex – afferent stimulus
enters on one side, and efferent motoric
exit on the other
Reflex arc classification
• By number of synapses
– Monosynaptic reflex – reflex
contains only one central
synapse. There is only minimal
delay in response and effector
answer is rapid to stimulus
– Di (bi)-synaptic reflex – two
synapses are within spinal cord
Reciprocal inhibition
Reflex arc classification
• By the number
of synapses
– Polysynaptic
reflex – more
than two
synapses in
spinal cord
Extension
reflex
Think F.A.S.T.
act FAST
Physiology of
central nervous
system
Higher nervous
functions
Cognition and association centers
• Cognition
– various function of association centers
– processes leading to environment acknowledgement
– the ability to respond to outer or inner stimulus, to
identify its significance and ability to plan the adequate
response
– enter – mainly from primary and secondary senzoric
and motoric cortex, thalamus and brainstem
– exit - hippocampus, basal ganglia, cerebellum,
thalamus, and other asociation centers
Structure of brain cortex
•
Cytoarchitectonics
– Brodmann
•
Characteristics
1. primary source of input
and output
2. vertical and horizont axis
of connections
3. similar cells are along
the all layers
4. Interneurons in layers
send long axon into cells
with similar function
Parietal lesions
• Brain, 1941
• Unilateral lesion of right parietal lobe
– ignorance of left parts of environment
– topography is maintained
– contralateral neglect syndrome
• Inability to percieve objects on one side, in spite of
evidence that senzoric and motoric abilities are intact
– Loss of paying attention and concetration
Temporal lesions
• Defects of learning
– agnosias
– integrative aperceptive agnosia – inability of object
recognition
• dorsal simultanagnosia – inability to recognise more objects,
bumping into objects that are near together
• ventral simultanagnosia – inability to recognise complex pictures
– integrative association agnosia
• color agnosia – inability to recognize colors
• topographic agnosia
• prosopagnosia – inability to recognise faces
– ability to recognise familiar person by the help of other signs
– lower temporal lobe is responsible for recognition
Frontal lesions
• Most processed data
– largest part in humans and primates
– wide range of symptoms when damaged
– interconnections to senzoric and motoric part
and other associative areas
• perception of yourself in environment
• Ability to plan and realise
– „personality“ impairmnet
– Phine porucha as Gage , 1848
• Lesion of frontal lobe when building
railroad
Psychosurgery
• Egas Moniz
Joe A, 1920-1930
• frontal lobotomy
because of massive
tumour
• gaining of new abilities
• loss of „appropriate“
behavior and planning
Memory & learning
• Qualitatively 2 types of memory
– declarative
• material which is avaliable to
consciousness and can be expressed by
words
• eg. sing a song,...
– procedural
• can not be expressed by words, not
available to consciousness, includes
experience
• Thinking about how to do it, will impair
procedure itself
• eg. dial-up the number, to return tennis
ball,...
Phylogenetic memory
• developed in individual species on the
basis of their experience /instincts/
• several generations needed to develop
• vertical distribution
Memory
• From the view of time, when memory is
mostly effective
– immediate memory
– short-termed memory
• working memory – to procede with movement sequence,
eg. when looking up for keys
– long-termed memory
Long-termed memory
• engram
– physical meaning of long-term memory
in neuronal net
• depends on longtermed changes and
effectiveness of signal transmission
in relevant synaptic connections
• inaccuracy
Memory capacity
• unlimited
– However, memorizing of absurdity is not large...up to
7-9 digits
– association will significantly improve memory
– training is meaningful
• up to 80 digits, when there is a meaningfull context
• Arturo Toscanini - conductor who remembered more than
250 orchestral works and music to more than 100 operas
• Alexander Aitken – remembered π to 1000 digits
• Indic mnemonist – π to 31 811 digits and Japanese
menmonist knew π to 40 000!!!
– what the info means to individual and how it can
enrich the knowledge he already has
• Scholar sy
– Christopher
•
•
•
•
anoxia during delivery
lived in hospital from the begining
overall IQ between 55-65
without attending the school, just reading
books
• He could speak fluently in puberty:
– dannish, finish, dutch, french, german, greece,
hindi, italian, norwegian, polish, portugase,
russian, spanish, swedish, turkish and welshs
Forgeting
(Forgiving?)
Human brain is very
good at forgeting
– defense mechanism?
– forgeting stuff, that is
not important to
person
Pathologic forgeting
–
Alzheimers disease
Amnesia
• Forgeting the
circumstances because of
accident
– anterograde
• inability to recall new
memory after the accident
– Retrograde
• inability to recall the memory
before the accident
Structures responsible for new
memory – shortterm memory
• Limbic system
• Hippocampus
– CA1 area
• Hypothalamus &
thalamus
– corpora
mammaria
• Basal ganglia
– amygdala
Structures responsible for new
memory– longterm memory
• Coincidently found out, when performing
electroconvulsive therapy of depression, when
electrocity is send only into one hemisphere
– Pacients after procedure developed
retrograd amnesia for up to 3 years before
– hemispheres are the source of longterm
memories
– Different cortex = different cognition –>
different memory
Mental test rotation (MR)
A
B
C
D
?
A
E
Spatial visualisation (SV)
A
B
C
D
D
?
Mazes
Central plate
arms
(1 – 8)
ending
Morris water maze
• 5 consecutive days
• 1 day = 4 runs
• 1 run = 1 min
1,35m
• orientation = signs
• detecting:
– latency times
– travelled distance, etc
Hello, I would like to
order about 50
individuals of Homo
sapiens species, for
the experiment