There are two broad types of cellular systems that perform sensory transduction. In one, a neuron works with a sensory receptor, a cell, or cell process that is specialized to engage with and detect a specific stimulus. Stimulation of the sensory receptor activates the associated afferent neuron, which carries information about the stimulus to the central nervous system.
In the second type of sensory transduction, a sensory nerve ending responds to a stimulus in the internal or external environment; this neuron constitutes the sensory receptor. Free nerve endings can be stimulated by several different stimuli, thus showing little receptor specificity.
For example, pain receptors in your gums and teeth may be stimulated by temperature changes, chemical stimulation, or pressure. The first step in sensation is reception: the activation of sensory receptors by stimuli such as mechanical stimuli being bent or squished, for example , chemicals, or temperature.
The receptor can then respond to the stimuli. Think for a moment about the differences in receptive fields for the different senses. For the sense of touch, a stimulus must come into contact with body. For the sense of hearing, a stimulus can be a moderate distance away. For vision, a stimulus can be very far away; for example, the visual system perceives light from stars at enormous distances. Visual sensory system : This scheme shows the flow of information from the eyes to the central connections of the optic nerves and optic tracts, to the visual cortex.
Area V1 is the region of the brain which is engaged in vision. Transduction is the process that converts a sensory signal to an electrical signal to be processed in a specialized area in the brain. The most fundamental function of a sensory system is the translation of a sensory signal to an electrical signal in the nervous system.
This takes place at the sensory receptor. The change in electrical potential that is produced is called the receptor potential. How is sensory input, such as pressure on the skin, changed to a receptor potential?
As an example, a type of receptor called a mechanoreceptor possesses specialized membranes that respond to pressure. Disturbance of these dendrites by compressing them or bending them opens gated ion channels in the plasma membrane of the sensory neuron, changing its electrical potential. Receptor potentials are graded potentials: the magnitude of these graded receptor potentials varies with the strength of the stimulus.
If the magnitude of depolarization is sufficient that is, if membrane potential reaches a threshold , the neuron will fire an action potential. In most cases, the correct stimulus impinging on a sensory receptor will drive membrane potential in a positive direction, although for some receptors, such as those in the visual system, this is not always the case.
Mechanoreceptor activation : a Mechanosensitive ion channels are gated ion channels that respond to mechanical deformation of the plasma membrane. A mechanosensitive channel is connected to the plasma membrane and the cytoskeleton by hair-like tethers. This in turns aids the social development of the child. All the sensory systems need to work together for effective sensory processing.
It is important to recognise that there are in fact 7 senses that make up the sensory system and it is these sensory systems that process information as the building blocks to many other skills. If left untreated, what can difficulties with sensory processing lead to? Kid Sense provides Occupational Therapy and Speech Therapy services to children with developmental challenges in their movement, play, speech, language, learning and behaviour.
We are the longest continually owned private provider of paediatric Occupational Therapy in Adelaide, South Australia. We're not around right now. But you can send us an email and we'll get back to you, asap. Visual sense: is the ability to understand and interpret what is seen. The visual system uses the eyes to receive information about contrast of light and dark, colour and movement. It detects visual input from the environment through light waves stimulating the retina.
Auditory Sense: is the ability to interpret information that is heard. The auditory system uses the outer and middle ear to receive noise and sound information. They receive information about volume, pitch and rhythm. It is important for the refinement of sounds into meaningful syllables and words.
Gustatory Sense: is the ability to interpret information regarding taste in the mouth. It uses the tongue to receive taste sensations, and detects the chemical makeup through the tongue to determine if the sensation is safe or harmful. Olfactory Sense: is the ability to interpret smells. It uses the nose to receive information about the chemical makeup of particles in the air to determine if the smell is safe or harmful. Tactile sense: is the ability to interpret information coming into the body by the skin.
It uses receptors in the skin to receive touch sensations like pressure, vibration, movement, temperature and pain. It is the first sense to develop in the womb , and as such is very important for overall neural organisation. Proprioceptive Sense: is the ability to interpret where your body parts are in relation to each other. It uses information from nerves and sheaths on the muscles and bones to inform about the position and movement of body through muscles contracting, stretching, bending, straightening, pulling and compressing.
Vestibular sense: is the ability to interpret information relating to movement and balance. The vestibular system uses the semi-circular canals in the inner ear to receive information about movement, change of direction, change of head position and gravitational pull. It receives information about how fast or slow we are moving, balance, movement from the neck, eyes and body, body position, and orientation in space. Researchers from Bielefeld University, Oxford University Great Britain , and Aix-Marseille University France investigated this phenomenon of flexibility in perception, and have now published a study on their findings that appears in the scientific journal Neuron 29 April In their publication, the researchers reveal where sensory stimuli are integrated in the brain, and in which area of the brain this flexibility can be located.
From Bielefeld University, Professor Dr. Christoph Kayser and Dr. In his work, Kayser deals with multi-sensory integration -- the combination of various sensory data. This happens, for instance, when watching a movie: you hear what the characters are saying to each other while at the same time watching the movements of their lips.
It is not always useful, however, for auditory and visual information to be automatically integrated in the brain: one example of this would be watching a foreign-language film that is dubbed and the movements of the actors' lips do not match the spoken sounds. The researchers' study was looking to identify the areas of the brain in which flexible sensory integration takes place.
For this, they tested out three potential models. While different sensory stimuli were processed completely apart from each other in the first model, they were automatically integrated in the second model.
The third variant was the model of "causal inference" in which different sensory stimuli are only integrated if they are not distant from each other in spatial or chronological terms. For example, if you always hear a sound and see an image at the same time, the brain integrates this information. However, if the sound and image appear together, they will not be integrated -- even though they were previously separate from each other. Sensory stimuli are therefore not automatically integrated -- this is only the case if they do originate from the same source," says Kayser.
To test these three models, study participants were exposed to visual and auditory stimuli.
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