Sensory gating
Encyclopedia
Sensory gating describes neurological processes of filtering out redundant or unnecessary stimuli in the brain
from all possible environmental stimuli. Also referred to as filtering, or sensorimotor gating, sensory gating prevents an overload of irrelevant information in the higher cortical centers of the brain. The pulvinar nuclei of the thalamus
plays a major role in attention, and filters out unnecessary information. Although sensory gating is largely automatic, it also occurs within the context of attentional processes.
The cocktail party effect
illustrates how the brain inhibits input from environmental stimuli, while still processing sensory input from the attended stimulus. The cocktail party effect demonstrates sensory gating in hearing, but the other senses also go through the same process protecting primary cortical areas from being overwhelmed.
and synapse at the thalamus. Within the thalamus, the pulvinar nuclei functions as the gatekeeper, deciding which information should be inhibited, and which should be sent to further cortical areas. Sensory gating is mediated by a network in the brain which involves the auditory cortex (AC), prefrontal cortex and hippocampus. [5] Furthermore, the hippocampus, amygdala, striatum, medial prefrontal cortex, and midbrain dopamine cell region as other areas involved in sensory gating (GABAergic neurons only).
Research of sensory gating primarily occurs in cortical areas where the stimulus is consciously identified because it is a less invasive means of studying sensory gating, while the hippocampus and rhinal regions are not studied as often. Studies on rats have shown the brain stem, thalamus, and primary auditory cortex play a role in sensory gating for auditory stimuli.
. For normal sensory gating, if a person hears a pair of clicks within 50ms of one another, the person will gate out the second click because it is perceived as being redundant. Evidence of the gating can be seen in the P50 wave, occurring in the brain 50 ms after the click. Low values of the P50 wave indicate that sensory gating has occurred. High values of the P50 wave indicate a lack of sensory gating. Individuals with schizophrenia
only reduce the amplitude of S2 by 10-20%, whereas individuals without schizophrenia reduce the amplitude of S2 by 80-90%.
is a measure of inhibition of a latter stimuli when two stimuli are presented. It is a non-invasive technique used to understand sensory gating within individuals presenting with neuropsychiatric disorders including, but not limited to, Autism
.
(EEG), a technique used to measure an event-related potential
(ERP), and Magnetoencephalography
(MEG) are used to show sensory gating starts almost immediately after the receiving the stimulus. Positron emission tomography
(PET) studies have shown that an increased need to gate information is accompanied by increased engagement of the thalamus. P50 wave testing is one of many auditory event-related potential studies.
The P50 Auditory Gating deficit is one of the best established biological traits associated with schizophrenia.
(ASD) show patterns of restrictive and repetitive behaviors, in turn reflecting difficulties with inhibitory mechanisms in the brain. This information leads to the belief that sensory gating may be effecting some of the visible symptoms of ASD.
Nicotine can correct sensory gating deficits for individuals with Schizophrenia and their families, but the effects only last about thirty minutes after nicotine intake. The same effect is present among those self-medicating for attention-deficit/hyperactivity disorder.
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
from all possible environmental stimuli. Also referred to as filtering, or sensorimotor gating, sensory gating prevents an overload of irrelevant information in the higher cortical centers of the brain. The pulvinar nuclei of the thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
plays a major role in attention, and filters out unnecessary information. Although sensory gating is largely automatic, it also occurs within the context of attentional processes.
The cocktail party effect
Cocktail party effect
The cocktail party effect describes the ability to focus one's listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations. The effect enables most people to talk in a noisy place...
illustrates how the brain inhibits input from environmental stimuli, while still processing sensory input from the attended stimulus. The cocktail party effect demonstrates sensory gating in hearing, but the other senses also go through the same process protecting primary cortical areas from being overwhelmed.
Neural regions involved in sensory gating
Most information from sensory receptors make their way to the brain through neuronsNeuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
and synapse at the thalamus. Within the thalamus, the pulvinar nuclei functions as the gatekeeper, deciding which information should be inhibited, and which should be sent to further cortical areas. Sensory gating is mediated by a network in the brain which involves the auditory cortex (AC), prefrontal cortex and hippocampus. [5] Furthermore, the hippocampus, amygdala, striatum, medial prefrontal cortex, and midbrain dopamine cell region as other areas involved in sensory gating (GABAergic neurons only).
Research of sensory gating primarily occurs in cortical areas where the stimulus is consciously identified because it is a less invasive means of studying sensory gating, while the hippocampus and rhinal regions are not studied as often. Studies on rats have shown the brain stem, thalamus, and primary auditory cortex play a role in sensory gating for auditory stimuli.
Paired-click paradigm
The paired-click paradigm is a common non-invasive technique used to measure sensory gating, a type of event-related potentialEvent-related potential
An event-related potential is any measured brain response that is directly the result of a thought or perception. More formally, it is any stereotyped electrophysiological response to an internal or external stimulus....
. For normal sensory gating, if a person hears a pair of clicks within 50ms of one another, the person will gate out the second click because it is perceived as being redundant. Evidence of the gating can be seen in the P50 wave, occurring in the brain 50 ms after the click. Low values of the P50 wave indicate that sensory gating has occurred. High values of the P50 wave indicate a lack of sensory gating. Individuals with schizophrenia
Schizophrenia
Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...
only reduce the amplitude of S2 by 10-20%, whereas individuals without schizophrenia reduce the amplitude of S2 by 80-90%.
Prepluse Inhibition (PPI)
PPIPrepulse inhibition
Prepulse Inhibition is a neurological phenomenon in which a weaker prestimulus inhibits the reaction of an organism to a subsequent strong startling stimulus . The stimuli are usually acoustic, but tactile stimuli Prepulse Inhibition (PPI) is a neurological phenomenon in which a weaker...
is a measure of inhibition of a latter stimuli when two stimuli are presented. It is a non-invasive technique used to understand sensory gating within individuals presenting with neuropsychiatric disorders including, but not limited to, Autism
Autism
Autism is a disorder of neural development characterized by impaired social interaction and communication, and by restricted and repetitive behavior. These signs all begin before a child is three years old. Autism affects information processing in the brain by altering how nerve cells and their...
.
Other techniques
ElectroencephalographyElectroencephalography
Electroencephalography is the recording of electrical activity along the scalp. EEG measures voltage fluctuations resulting from ionic current flows within the neurons of the brain...
(EEG), a technique used to measure an event-related potential
Event-related potential
An event-related potential is any measured brain response that is directly the result of a thought or perception. More formally, it is any stereotyped electrophysiological response to an internal or external stimulus....
(ERP), and Magnetoencephalography
Magnetoencephalography
Magnetoencephalography is a technique for mapping brain activity by recording magnetic fields produced by electrical currents occurring naturally in the brain, using arrays of SQUIDs...
(MEG) are used to show sensory gating starts almost immediately after the receiving the stimulus. Positron emission tomography
Positron emission tomography
Positron emission tomography is nuclear medicine imaging technique that produces a three-dimensional image or picture of functional processes in the body. The system detects pairs of gamma rays emitted indirectly by a positron-emitting radionuclide , which is introduced into the body on a...
(PET) studies have shown that an increased need to gate information is accompanied by increased engagement of the thalamus. P50 wave testing is one of many auditory event-related potential studies.
Schizophrenia
A large interest in sensory gating research is directed at improving deficits among people diagnosed with Schizophrenia. People with schizophrenia often have deficits in gating the neuronal response of the P50 wave. Since people with schizophrenia can often have an overload of attended stimuli, the P50 wave may serve a critical role in illuminating sensory gating at a neurological level.The P50 Auditory Gating deficit is one of the best established biological traits associated with schizophrenia.
Autism Disorders
Adults diagnosed with Autism spectrum disordersAutism spectrum
The term "autism spectrum" is often used to describe disorders that are currently classified as pervasive developmental disorders. Pervasive developmental disorders include autism, Asperger syndrome, Childhood disintegrative disorder, Rett syndrome and Pervasive Developmental Disorder Not Otherwise...
(ASD) show patterns of restrictive and repetitive behaviors, in turn reflecting difficulties with inhibitory mechanisms in the brain. This information leads to the belief that sensory gating may be effecting some of the visible symptoms of ASD.
Nicotine and sensory gating
One reason people report they like smoking cigarettes is Nicotine’s ability to aid their selective attention.Nicotine can correct sensory gating deficits for individuals with Schizophrenia and their families, but the effects only last about thirty minutes after nicotine intake. The same effect is present among those self-medicating for attention-deficit/hyperactivity disorder.