🍱
1.1 introductie perceptie tot
bewustzijn
1. Inleiding: gewaarwording en waarneming
2. Verwerking van sensorische informatie in sensorische systemen
3. Is alles wat je waarneemt ook waar?
4. Informatieverwerking in het brein
5. Codering van informatie
6. Hoe kun je perceptie bestuderen en meten?
PWP
H17 Kandel
Algemeen principe van sensorische systemen
1. Prikkel of stimulus
2. Sensorische receptoren - foto-, chemo-, mechanoreceptoren
3. Transductie -
4. Transmissie - Perifere zenuwstelsel naar centrale zenuwstelsel - (afferente neuron
zit met synaptische spleet en neurotransmitters verbonden aan receptor of afferente
neuron heeft aan het uiteinde een specialisatie (pacini) waardoor directe
depolarisatie; actiepotentiaal afhankelijk van drempel) - vind decussatie plaats
(kruisende banen) - informatie gaat via actiepotentialen naar de cortex
5. Perceptie: verwerking van gewaarwording tot waarneming in de hersenen.
Functionele map van cortices - tonotopie/somatotopie/retinotopie. verwerking (alle
informatie behalve ruik gaat via thalamus naar primaire cortex. Daarna naar
secundaire cortex en dan naar de association cortex. )
6. Actie
1.1 introductie perceptie tot bewustzijn 1
, 1. Inleiding: gewaarwording en waarneming
Sensorische systemen vormen een deel van het zenuwstelsel en zorgen voor een link
tussen ons lichaam en de omgeving en verwerken de sensorische informatie om een
reactie op de stimuli uit de omgeving op te wekken.
'gewaarwording' (sensation) - informatie
uit de omgeving vekrijgden dmv perifere
sensorische systemen (zintuigen)
'Waarneming' (perception): gebruiken en
interpreteren van de informatie door
middel van (centrale) processen in het
zenuwstelsel
2. Verwerking van sensorische informatie in sensorische
systemen
Kandel H17'Stimuli Are Represented in the Nervous System by the Firing Patterns of
Neurons' p388
stimuli—modality, location, intensity and duration
The neural coding of sensory information is better understood at the early stages of
processing than at later stages in the brain. Pioneered by Vernon Mountcastle. A neural
code describes the relationship between the activity in a specified neural population and
its functional consequences for perception or action. Sensory systems are ideal for the
study of neural coding because both the physical properties of the stimulus input and
the neural or behavioral output of these systems can be precisely defined and quantified
in a controlled setting. Neuroscientists can also modify activity within sensory circuits by
direct stimulation with electrical pulses, chemical neurotransmitters, and modulators, or
can use genetically encoded light-activated ion channels (optogenetics) to depolarize or
1.1 introductie perceptie tot bewustzijn 2
, hyperpolarize sensory neurons. To understand the brain we must understand how the
different task per neuron is organized in networks of neurons.
Functional differences between sensory systems:
different stimulus energies that drive them
different discrete pathways that compose each system
Conscious sensations are different from the stimuli as our brain extracts certain features
and interprets it within the constrains of the brain's intrinsic features.
Sensory receptors in sense organs: eye, nose, ear, tongue and skin - only respond to a
specific kind of energy (receptor specificity) at specific locations and sometimes only
with a particular temporal or spatial pattern. Receptors transform the stimulus energy
into electricl energy. The amplitude and duration of the electrical signal produced by the
receptor, termed the receptor potential, are related to the intensity and time course of
stimulation of the receptor. The process by which a specific stimulus energy is
converted into an electrical signal is called stimulus transduction.
sensorische receptorcellen - energie omzetten in elektrochemische boodschappen.
In mammals:
Mechanoreceptors
Chemoreceptors
photoreceptors
thermoreceptors
Each major sensory system has several submodalities. (I.E. sweet, sour, salty etc).
Some submodalities are mediated by subclasses of receptors of that modality and
others are derived by combinding information from different receptor types. For example
cones are tuned to a preferred stimulus (green to ..nm), you can plot a tuning curve.
1.1 introductie perceptie tot bewustzijn 3
, The existence of submodalities points to an important principle of sensory coding,
namely that the range of stimulus energies—such as the wavelength of light—is
deconstructed into smaller, simpler components. The brain eventually integrates these
diverse components of the stimulus to convey an ensemble representation of the
sensory event.
The receptor potential produced by the stimulus must be transformed into sequences of
action potentials that can be propagated along axons to eventually reach the brain. in
which the frequency of action potentials is proportional to the intensity of the stimulus,
spike train encoding. the intensity of a stimulus is represented in the brain by all active
neurons in the receptor population: population code, as receptors have different
thresholds.
Changes in frequency of action potential - intensity of stimulus
Sequences of Action Potentials Signal the Temporal Dynamics of Stimuli. The
patterning of spike trains plays an important role in encoding temporal fluctuations of the
stimulus, such as the frequency of vibration or auditory tones, or changes in rate of
movement. The temporal properties of a changing stimulus are encoded as changes in
the firing pattern, including the interspike intervals, of sensory neurons.
Changes in the firing pattern - temporal information of stimulus
If a stimulus persists unchanged for several minutes without a change in position or
amplitude, the neural response and corresponding sensation diminishes, a condition
called receptor adaptation. slowly adapting receptors generate action potentials
throughout the period of stimulation, whereas rapidly adapting receptors only generate
action potentials at the beginning and end of a stimulus.
The area a receptor receives information from is the receptive field. Receptive fields of
the receptors in the hands are smaller than those on the arm - providing a more detailed
scene as there are more receptors concentrated in the hand.
1.1 introductie perceptie tot bewustzijn 4
1.1 introductie perceptie tot
bewustzijn
1. Inleiding: gewaarwording en waarneming
2. Verwerking van sensorische informatie in sensorische systemen
3. Is alles wat je waarneemt ook waar?
4. Informatieverwerking in het brein
5. Codering van informatie
6. Hoe kun je perceptie bestuderen en meten?
PWP
H17 Kandel
Algemeen principe van sensorische systemen
1. Prikkel of stimulus
2. Sensorische receptoren - foto-, chemo-, mechanoreceptoren
3. Transductie -
4. Transmissie - Perifere zenuwstelsel naar centrale zenuwstelsel - (afferente neuron
zit met synaptische spleet en neurotransmitters verbonden aan receptor of afferente
neuron heeft aan het uiteinde een specialisatie (pacini) waardoor directe
depolarisatie; actiepotentiaal afhankelijk van drempel) - vind decussatie plaats
(kruisende banen) - informatie gaat via actiepotentialen naar de cortex
5. Perceptie: verwerking van gewaarwording tot waarneming in de hersenen.
Functionele map van cortices - tonotopie/somatotopie/retinotopie. verwerking (alle
informatie behalve ruik gaat via thalamus naar primaire cortex. Daarna naar
secundaire cortex en dan naar de association cortex. )
6. Actie
1.1 introductie perceptie tot bewustzijn 1
, 1. Inleiding: gewaarwording en waarneming
Sensorische systemen vormen een deel van het zenuwstelsel en zorgen voor een link
tussen ons lichaam en de omgeving en verwerken de sensorische informatie om een
reactie op de stimuli uit de omgeving op te wekken.
'gewaarwording' (sensation) - informatie
uit de omgeving vekrijgden dmv perifere
sensorische systemen (zintuigen)
'Waarneming' (perception): gebruiken en
interpreteren van de informatie door
middel van (centrale) processen in het
zenuwstelsel
2. Verwerking van sensorische informatie in sensorische
systemen
Kandel H17'Stimuli Are Represented in the Nervous System by the Firing Patterns of
Neurons' p388
stimuli—modality, location, intensity and duration
The neural coding of sensory information is better understood at the early stages of
processing than at later stages in the brain. Pioneered by Vernon Mountcastle. A neural
code describes the relationship between the activity in a specified neural population and
its functional consequences for perception or action. Sensory systems are ideal for the
study of neural coding because both the physical properties of the stimulus input and
the neural or behavioral output of these systems can be precisely defined and quantified
in a controlled setting. Neuroscientists can also modify activity within sensory circuits by
direct stimulation with electrical pulses, chemical neurotransmitters, and modulators, or
can use genetically encoded light-activated ion channels (optogenetics) to depolarize or
1.1 introductie perceptie tot bewustzijn 2
, hyperpolarize sensory neurons. To understand the brain we must understand how the
different task per neuron is organized in networks of neurons.
Functional differences between sensory systems:
different stimulus energies that drive them
different discrete pathways that compose each system
Conscious sensations are different from the stimuli as our brain extracts certain features
and interprets it within the constrains of the brain's intrinsic features.
Sensory receptors in sense organs: eye, nose, ear, tongue and skin - only respond to a
specific kind of energy (receptor specificity) at specific locations and sometimes only
with a particular temporal or spatial pattern. Receptors transform the stimulus energy
into electricl energy. The amplitude and duration of the electrical signal produced by the
receptor, termed the receptor potential, are related to the intensity and time course of
stimulation of the receptor. The process by which a specific stimulus energy is
converted into an electrical signal is called stimulus transduction.
sensorische receptorcellen - energie omzetten in elektrochemische boodschappen.
In mammals:
Mechanoreceptors
Chemoreceptors
photoreceptors
thermoreceptors
Each major sensory system has several submodalities. (I.E. sweet, sour, salty etc).
Some submodalities are mediated by subclasses of receptors of that modality and
others are derived by combinding information from different receptor types. For example
cones are tuned to a preferred stimulus (green to ..nm), you can plot a tuning curve.
1.1 introductie perceptie tot bewustzijn 3
, The existence of submodalities points to an important principle of sensory coding,
namely that the range of stimulus energies—such as the wavelength of light—is
deconstructed into smaller, simpler components. The brain eventually integrates these
diverse components of the stimulus to convey an ensemble representation of the
sensory event.
The receptor potential produced by the stimulus must be transformed into sequences of
action potentials that can be propagated along axons to eventually reach the brain. in
which the frequency of action potentials is proportional to the intensity of the stimulus,
spike train encoding. the intensity of a stimulus is represented in the brain by all active
neurons in the receptor population: population code, as receptors have different
thresholds.
Changes in frequency of action potential - intensity of stimulus
Sequences of Action Potentials Signal the Temporal Dynamics of Stimuli. The
patterning of spike trains plays an important role in encoding temporal fluctuations of the
stimulus, such as the frequency of vibration or auditory tones, or changes in rate of
movement. The temporal properties of a changing stimulus are encoded as changes in
the firing pattern, including the interspike intervals, of sensory neurons.
Changes in the firing pattern - temporal information of stimulus
If a stimulus persists unchanged for several minutes without a change in position or
amplitude, the neural response and corresponding sensation diminishes, a condition
called receptor adaptation. slowly adapting receptors generate action potentials
throughout the period of stimulation, whereas rapidly adapting receptors only generate
action potentials at the beginning and end of a stimulus.
The area a receptor receives information from is the receptive field. Receptive fields of
the receptors in the hands are smaller than those on the arm - providing a more detailed
scene as there are more receptors concentrated in the hand.
1.1 introductie perceptie tot bewustzijn 4
