Which cerebral lobe is the auditory area in

The next topic is the phonological network at Superior temporal sulcus. What subcortical connections does it receive? How does it fit into the big picture? How does it work? The left hemisphere prefers the smaller, higher frequency window, while the right hemisphere prefers the larger, lower frequency window: Fig. Identifying cases of cortical deafness has proved to be difficult for several reasons: patients rarely suffer bilateral lesions in auditory cortex; some patients believed to suffer from cortical deafness may, in fact, suffer from auditory inattention or neglect; cortical deafness is often transient, resolving to a less severe, or more specific, auditory processing disorder such as pure word deafness or auditory agnosia.

The right-ear advantage for certain speech sounds Two windows of temporal integration Some data Prosody in the right hemisphere Emotional prosody Tones versus noise Planum temporale Disorders of auditory cortex: cortical deafness Powerpoint and podcast The next topic Quick search. Powered by Sphinx 1. The primary visual cortex , also known as V1, receives visual information from the eyes.

This information is relayed to several secondary visual processing areas, which interpret depth, distance, location and the identity of seen objects. Help QBI research Give now.

Skip to menu Skip to content Skip to footer. Site search Search. Site search Search Menu. Lobes of the brain. Home The Brain Brain anatomy. Wikimedia Although we now know that most brain functions rely on many different regions across the entire brain working in conjunction, it is still true that each lobe carries out the bulk of certain functions. QBI Bumps and grooves of the brain In humans, the lobes of the brain are divided by a number of bumps and grooves.

Temporal lobe Separated from the frontal lobe by the lateral fissure, the temporal lobe also contains regions dedicated to processing sensory information, particularly important for hearing, recognising language, and forming memories. These neighboring areas are mostly buried within the lateral sulcus as well, but may extend out to the superior temporal gyrus. The demarcations of the auditory cortex in general, however, are imprecise. The auditory cortex plays a critical role in our ability to perceive sound.

It is thought to be integral to our perception of the fundamental aspects of an auditory stimulus, like the pitch of the sound. But it is also important in various other aspects of sound processing, like determining where in space a sound originates from as well as identifying what might be producing the sound.

The auditory cortex is also thought to be involved in higher-level auditory processing, such as recognizing aspects of sound that are specific to speech. Damage to the auditory cortex can disrupt various facets of auditory perception. For example, damage e.

The auditory cortex primarily receives auditory information from a nucleus in the thalamus called the medial geniculate nucleus , which is where all incoming information about hearing is sent before it is processed by the cerebral cortex.

Cells in the primary region of the auditory cortex and in some parts of the non-primary regions as well are arranged so they form what is known as a tonotopic map. What this means is that different areas of the auditory cortex are involved in processing different sound frequencies. Frequency , when referring to sound waves, is related to pitch. While this is apparent in the non-human primate and in some neuroimaging studies, most research in humans indicates that specific task conditions, stimuli or previous experience may bias the recruitment of specific prefrontal regions, suggesting a more flexible role for the frontal lobe during auditory cognition.

Connections from the auditory cortex to the frontal lobes mediate a number of functions including language, object recognition and spatial localization. Discerning what types of auditory information reaches the frontal cortex, where that auditory input originates, and how information is utilized by the frontal lobes for complex behaviors, such as communication, is a fundamental question of neuroscience.

The frontal cortex is a heterogeneous region with multiple functional subdivisions, including the prefrontal cortex, which lies in the anterior frontal lobe and consists of medial, lateral, and orbital subdivisions.

Possible auditory functions and connections of frontal pole, medial and orbital areas of the frontal lobe are described elsewhere including Medalla and Barbas Figure 1. Top panel are schematics of the lateral and frontal surfaces of the monkey A and human B brain from Petrides and Pandya Inset diagram is the lower part of arcuate sulcus to show cytoarchitectonic areas within the banks of the sulcus.

The frontal lobe is well-known for its role in speech and language processes and executive functions that include working memory, planning, and decision making Fuster, Early lesion studies indicated that lesions of prefrontal cortex caused impairments in delay response, delay spatial alternation, and delay object alternation tasks Pribram et al.

In the last two decades there have been a wealth of neuroimaging studies in human subject and single-unit recording studies in non-human primates, which confirm a role in working memory for the prefrontal cortex Funahashi et al.

Unfortunately most neurophysiology studies utilize visual working memory paradigms. Therefore, while these studies have shed light on the neuronal mechanisms underlying prefrontal visual information processing and visual memory, there is much less known about prefrontal processing of auditory information. Fortunately, the past decade has seen several advances in our understanding of the organization of the primate auditory cortical system and how this system, is critical for speech, auditory attention, and multisensory integration.

These advances have made it possible and necessary to investigate the pathways that bring auditory information to the prefrontal cortex and the neural mechanisms which underlie auditory cognition. Historically, anatomical tract tracing and lesion degeneration studies provided evidence that presumptive auditory cortical regions send projections to prefrontal cortex.

One general principal observed in these studies of prefrontal-auditory connections is the rostro-caudal topography Pandya and Kuypers, ; Chavis and Pandya, ; Petrides and Pandya, ; Seltzer and Pandya, ; Barbas, ; Romanski et al. Reciprocal connections are apparent between the caudal STG and caudal PFC, including caudal dorsal area 46, periarcuate area 8a and the inferior convexity, or ventral prefrontal cortex—areas 12 and 45 Petrides and Pandya, ; Barbas, In addition, middle and rostral STG are reciprocally connected with rostral 46 and area 10 and orbito-frontal areas 11 and 12 Pandya and Kuypers, ; Pandya et al.

Furthermore, studies noted projections from the anterior temporal lobe to orbital and medial prefrontal cortex and the frontal pole Petrides and Pandya, ; Barbas, ; Carmichael and Price, ; Hackett et al.

While these studies inform us of the existence of temporal prefrontal connectivity they do not indicate which of these connections carries acoustic information. To understand the flow of auditory information to the prefrontal cortex, it is necessary to know what parts of the temporal lobe are, in fact auditory responsive. Progress in defining the connections and areal organization of the auditory cortex was greatly accelerated by advancements in auditory cortical neurophysiology and neuroanatomy.

First, Rauschecker and colleagues delineated the physiological boundaries of auditory cortical core and belt regions Rauschecker et al. These studies provided the first electrophysiological evidence for three separate tonotopic regions in the non-primary lateral belt cortex AL, ML, and CL antero-lateral belt, middle-lateral belt, caudal-lateral belt cortex respectively with frequency reversals separating them. Compared with primary auditory cortical neurons, which readily respond to relatively simple acoustic elements, such as pure tones, neurons of the lateral belt association cortex prefer complex stimuli including band-passed noise and vocalizations Rauschecker et al.

Simultaneous advances in anatomical organization confirmed and extended these findings. Several groups showed that primary and non-primary auditory cortex could be distinguished on the basis of differential staining for the calcium binding protein parvalbumin along with cytoarchitectonic changes Morel et al.

These combined physiological and anatomical studies made it possible to recognize individual boundaries of the auditory cortical system and showed its organization to consist of a primary, or core, region composed of potentially two areas, AI and R, surrounded by and connected to, a medial and lateral belt of secondary auditory association cortex with a lower density of parvalbumin staining Morel et al.

A third zone lying adjacent to the lateral belt is the parabelt auditory cortex. Further distinctions between the core and belt, and the belt and parabelt have been based on myeloarchitectonic, and connectional differences. Recent neurophysiological studies have examined the more complex auditory and multisensory responses of the belt Ghazanfar et al.

Two relevant studies followed on the heels of this revised characterization of auditory core and belt regions and described prefrontal-auditory connections in the context of these defined core, belt and parabelt regions Hackett et al.

Importantly, projections to the PFC from higher order cortical auditory regions such as parabelt and STS were more robust than the early auditory cortical regions such as the lateral belt, suggesting a cascade of lighter to stronger projections to the prefrontal cortex from early to late auditory processing regions Figure 2 , Hackett et al. Figure 2. Coronal sections through the temporal lobe are shown in A—C with black dots illustrating the location of retrogradely labeled cells.

Labeling is heaviest in the superior temporal sulcus regions TPO and TAa, moderate in the parabelt and lighter in the lateral belt. D A photomicrograph from a temporal lobe section adjacent to that shown in B.

Adapted from Romanski et al. Figure 3. A circuit diagram summary of auditory inputs from temporal lobe areas to the PFC, from anatomical studies including: Petrides and Pandya, ; Seltzer and Pandya, ; Hackett et al. Thicker lines represents stronger connections. While these anatomical studies suggest that the PFC receives auditory information, since afferents from the auditory belt and parabelt terminate in PFC, more direct evidence that projections are carrying acoustic information is obtained when anatomical and physiological methods are combined.

In one such study, Romanski et al. These highly specific rostrocaudal topographical frontal-temporal connections suggest the existence of separate streams of auditory information that targeted previously identified visual domains in the prefrontal cortex. Previous studies have designated these regions in the frontal lobe as being involved in visuo-spatial DLPFC and visual object VLPFC processing based on physiological responses to visual stimuli Wilson et al. Previous examination of responses in area 45 and the gradation of visual responses from the frontal eye fields located just dorsal to it argue in favor of stronger visual inputs to area 45 Webster et al.

Mulatta differ with the recent studies cited by Gerbella et al. Furthermore, we maintain that characterization of VLPFC must be accomplished with both anatomical and physiological data as stated above. Cytoarchitectonic boundaries vary across the different the studies we have referenced. Preuss and Goldman-Rakic show a much smaller boundary for area 45 while Saleem et al.

Gerbella et al. These differences confirm that additional studies combining neurophysiology and anatomical methods are needed to understand the organization of the frontal lobe in general, and VLPFC specifically.

This is in agreement with the notion that our association cortical regions receive highly processed information about a sensory stimulus after it has undergone transformations through earlier sensory cortical regions. Figure 4. Thick and dark gray arrows illustrate dense projections from STS, with less dense projections arriving from parabelt and lateral belt regions.

Prior to , responses to acoustic stimuli of a non-spatial nature were sporadically noted across a widespread region of the frontal lobe in Old and New World primates Newman and Lindsley, ; Benevento et al.

Several of these studies used auditory stimuli in combination with visual stimuli as task elements but did not systematically explore the selectivity of auditory responsive cells Ito, ; Vaadia et al. Despite reports of responses to complex stimuli including clicks, environmental sounds and vocalizations, the prior neurophysiological recordings in the frontal lobe of non-human primates failed to demonstrate a discrete clustering of auditory cells indicative of an auditory responsive domain Newman and Lindsley, ; Tanila et al.

Romanski and Goldman-Rakic , described a discrete auditory responsive region in the macaque prefrontal cortex in which a region of VLPFC had neurons which responded to a variety of complex acoustic stimuli including species-specific vocalizations.

Further analysis showed that prefrontal neurons typically responded to stimuli that were acoustically similar Romanski et al. Specifically neurons responded to species-specific vocalizations that had a similar acoustic morphology and not a similar behavioral referent, Romanski et al.

Furthermore the complex responses of prefrontal neurons to these sounds could be predicted as linear functions of the probabilistic output of the HMM Averbeck and Romanski, The auditory responsive region in VLPFC lies adjacent to a region where visually responsive neurons, face cells and face-responsive patches have been localized O'Scalaidhe et al. Thus, the idea that VLPFC neurons might be responsive to both vocalization and faces is hardly surprising.

VLPFC, as mentioned previously, receives afferents from both auditory and visual portions of the temporal lobe as well as a robust innervation from the multisensory area TPO in the dorsal bank of the STS Barbas, ; Romanski et al.

A study by Benevento et al. Using species-specific vocalizations and their accompanying facial gestures, Romanski and colleagues demonstrated multisensory responses to simultaneously presented faces and vocalizations in VLPFC neurons Sugihara et al.

Sugihara et al. Since the region of VLPFC where multisensory neurons are located overlaps extensively with the location of previously characterized auditory responses, it is probable that previous studies which examined either unimodal auditory or unimodal visual functions included multisensory cells in their populations.

It is possible that the specific pattern of afferent input may dictate the types of neurophysiological responses found in VLPFC. The fact that neurons in VLPFC exhibit a wide range of response latencies to auditory stimuli 30— ms also supports this concept of heterogeneous afferents Romanski and Hwang, For example, a small number of auditory responsive neurons have extremely fast latency responses, these cells could be receiving inputs from early auditory cortical areas Romanski et al.

It is possible that these feature-sensitive, rapid onset responses could arise from early auditory cortex such as the anterior belt region AL which is known to project sparsely to this region and would arrive first.

In contrast, neurons which respond to combinations of complex acoustic features, or more generally to task variables may be more likely to receive afferents from parabelt and rostral STG which would be several synapses away from VLPFC and would presumably take longer and provide more highly processed information about an auditory object.

Multisensory responses in VLPFC have longer latencies than unimodal auditory response latencies measured in the same cells multisensory response range 50— ms; Romanski and Hwang, As reviewed above the frontal cortex receives afferents from early and late auditory cortical processing stations allowing frontal lobe neurons to detect and discriminate auditory stimuli Ito, ; Watanabe, ; Romanski and Goldman-Rakic, ; Poremba et al.

DLPFC receives information from caudal auditory regions, which have been shown to preferentially process auditory location information and VLPFC receives input from rostral auditory regions that show a greater preference for type of stimuli Romanski et al.

This traditional division of labor between dorsal and ventral prefrontal regions is supported by some neurophysiology studies. Early studies demonstrated that DLPFC neurons were preferentially responsive when acoustic stimuli were presented from specific directions Azuma and Suzuki, or when animal subjects localized auditory or visual stimuli Vaadia et al. In latter studies which focused on working memory processes, neurons in DLPFC were active during the mnemonic processing of auditory and visual location Kikuchi-Yorioka and Sawaguchi, ; Artchakov et al.

In both studies, a portion of DLPFC neurons were spatially selective during the delay for both auditory and visual cues. However, other neurophysiological studies demonstrated that DLPFC neurons were active during non-spatial tasks. Studies by Watanabe showed that prefrontal neurons responded when tones were predictive of juice reward and Bodner et al. More recently, recordings during a non-spatial auditory delayed match-to-sample task demonstrated task related activity in neurons in both dorsal and ventral PFC Plakke et al.

During this task, cells in this region appeared to be responsive to tracking when a relative stimulus is needed to be remembered or responded too.

The general task responses of these neurons suggests that the role of the DLPFC in auditory working memory may be for rule representation or response control, as previously suggested in studies of visual working memory Fuster et al. Together these studies suggest that the role of DLPFC in auditory memory may relate more to task and cognitive requirements than to acoustic stimulus encoding. Figure 5. A An example cell with increased activity during the auditory cues, wait time and response periods for correct trials.

B An example cell with increased firing rated during auditory cue and wait time periods for correct trials. As described above, VLPFC contains neurons that are responsive to complex sounds including, species-specific vocalizations and human vocalizations Romanski and Goldman-Rakic, ; Romanski et al. VLPFC involvement in auditory feature processing is supported by studies showing single-units that encode categories of vocalization call types Averbeck and Romanski, , ; Plakke et al.

Moreover, evidence that VLPFC cells are multisensory and respond to the simultaneous presentation of faces and their corresponding vocalizations strongly suggests a role in recognition and identity processing, a ventral stream function Sugihara et al. Several studies from Cohen and colleagues have examined neuronal responses in VLPFC during non-spatial auditory performance tasks Cohen et al.

For example, VLPFC neurons were modulated during non-spatial auditory discrimination but showed no modulation during spatial auditory discrimination Cohen et al. Nonetheless, inactivation studies are needed to determine whether VLPFC is essential in the performance of working memory or decision making tasks. Toward this end, a recent study by Plakke et al. Thus, processing of auditory information in DLPFC may relate more to the task demands, while processing of auditory information in VLPFC is clearly related to auditory features and task demands.

The anatomical and neurophysiological studies performed in nonhuman primates delineate somewhat separable roles for dorsal and ventral frontal lobe regions. How these functional streams in nonhuman primates map onto auditory function in the human brain is, as yet, not completely clear.

Although it is well known that speech and language functions rely on the cortex within the inferior frontal gyrus IFG neuroimaging studies have provided evidence that the human frontal lobe is also active during auditory discrimination Zatorre et al.

For example, several imaging studies have described activations in DLPFC superior frontal gyrus, superior frontal sulcus during auditory spatial localization Griffiths et al. For instance there were increases in activity in DLPFC when participants listened to numbers and made self-ordered choices Petrides et al. Dorsolateral activity is also increased during studies of divided auditory attention Benedict et al.

Taken together these studies suggest DLPFC may be recruited more frequently based on cognitive demands including the type of process that is necessary such as monitoring information in memory, encoding auditory information, as well as manipulation of spatial information.

Interestingly, there has also been activation within the IFG during nonverbal auditory stimulus detection Linden et al. The activation of the more anterior regions of the IFG areas 47 and 45 during nonverbal auditory sound detection, discrimination and auditory feature detection Zatorre et al. The role of VLPFC in general sound discrimination is also supported by its activation when listening to rhymes Burton et al.

Localization of auditory cognition to discrete networks in the human brain is complicated by the potential activation of language networks when verbal stimuli are used as memoranda in cognitive tasks. This suggests that the prefrontal cortex is not simply dividing the processing of auditory information based solely on verbal information Figure 6. Figure 6. For a list of the studies plotted see Supplemental Table 1. In order to examine auditory function independent of language circuits, noise bursts were used for both a spatial localization and non-spatial pitch discrimination auditory task Alain et al.

The use of identical auditory stimuli under different demands, which led to diverse activation patterns, indicates cognitive load can recruit specialized areas within the frontal cortex Alain et al. A similar pattern of results emerged in Du et al.