auditory information is processed in the medial geniculate nucleus of the thalamus.
auditory information is processed in the medial geniculate nucleus of the thalamus.
where is auditory information processed in the thalamus?
medial geniculate nucleus
thalamocortical (tc) fibers have been referred to as one of the two constituents of the isothalamus, the other being micro neurons. thalamocortical fibers have a bush or tree-like appearance as they extend into the internal capsule and project to the layers of the cortex. the main thalamocortical fibers extend from different nuclei of the thalamus and project to the visual cortex, somatosensory (and associated sensori-motor) cortex, and the auditory cortex in the brain. thalamocortical radiations also innervate gustatory and olfactory pathways, as well as pre-frontal motor areas. visual input from the optic tract is processed by the lateral geniculate nucleus of the thalamus, auditory input in the medial geniculate nucleus, and somatosensory input in the ventral posterior nucleus of the thalamus. thalamic nuclei project to cortical areas of distinct architectural organization and relay the processed information back to the area of original activity in the thalamus via corticothalamic (ct) fibers. the thalamic reticular nucleus (trn) receives incoming signals via corticothalamic pathways and regulates activity within the thalamus accordingly. cortico-thalamic feedback neurons are mostly found in layer vi of the cortex. reciprocal ct projections to the thalamus are of a higher order than, and synapse with, the trn in much greater number than do thalamocortical projections to cortex. this suggests that the cortex has a much bigger role in top down processing and regulation of thalamic activity than do the processes originating in thalamic interneurons. large-scale frequency oscillations and electrical rhythms have also been shown to regulate tc activity for long periods of time, as is evident during the sleep cycle. other evidence suggests ct modulation of tc rhythms can occur over different time scales, adding even more complexity to their function.
thalamocortical radiations
the amount of time between when an individual hears incriminatory information or the voice of their perpetrator, for instance, and the time they are required to recall the auditory information as an earwitness can affect their recall accuracy rate. memory for auditory information including voice recognition appears to decline over time; studies have found that participants can recall more correct auditory information immediately after the initial presentation than after a four-day time interval, supporting several other studies finding similar results. furthermore, the extent to which the time-interval affects memory recall for auditory information depends upon whether the witness just heard the auditory information of whether it was accompanied by visual information too, such as the face of the perpetrator. one study has found that recall is enhanced when both auditory information is heard and visual information is seen, as opposed to just hearing auditory information. still, when individuals are asked to remember the voice and the speech content, they are only likely to have remembered the gist of what has been said as opposed to remembering verbatim. this clearly has implications for the amount of weight that is placed upon earwitness testimony in court. earwitnesses are not typically required to give statements or recall a voice or auditory information immediately after an event has occurred, but instead are required to recall information after a time-delay. this could significantly impair the accuracy of their recall. the testimonies of those who have only heard the voice of a suspect compared to a witness who has both seen the face and heard the voice of a suspect should also be treated with extreme caution in court.
eyewitness memory