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Anatomical pathways for auditory memory in primates.

Munoz-Lopez MM, Mohedano-Moriano A, Insausti R - Front Neuroanat (2010)

Bottom Line: However, whether auditory memory is organized similarly is still unclear.Alternatively, the anatomical organization of memory could be different in audition.This alternative "indirect stream" hypothesis posits that, unlike the visual association cortex, the majority of auditory information makes one or more synapses in intermediate, polymodal areas, where they may integrate information from other sensory modalities, before reaching the medial temporal memory system.

View Article: PubMed Central - PubMed

Affiliation: Human Neuroanatomy Laboratory, Department of Health Sciences, School of Medicine, University of Castilla-La Mancha Albacete, Spain.

ABSTRACT
Episodic memory or the ability to store context-rich information about everyday events depends on the hippocampal formation (entorhinal cortex, subiculum, presubiculum, parasubiculum, hippocampus proper, and dentate gyrus). A substantial amount of behavioral-lesion and anatomical studies have contributed to our understanding of the organization of how visual stimuli are retained in episodic memory. However, whether auditory memory is organized similarly is still unclear. One hypothesis is that, like the "visual ventral stream" for which the connections of the inferior temporal gyrus with the perirhinal cortex are necessary for visual recognition in monkeys, direct connections between the auditory association areas of the superior temporal gyrus and the hippocampal formation and with the parahippocampal region (temporal pole, perhirinal, and posterior parahippocampal cortices) might also underlie recognition memory for sounds. Alternatively, the anatomical organization of memory could be different in audition. This alternative "indirect stream" hypothesis posits that, unlike the visual association cortex, the majority of auditory information makes one or more synapses in intermediate, polymodal areas, where they may integrate information from other sensory modalities, before reaching the medial temporal memory system. This review considers anatomical studies that can support either one or both hypotheses - focusing on anatomical studies on the primate brain, primarily in macaque monkeys, that have reported not only direct auditory association connections with medial temporal areas, but, importantly, also possible indirect pathways for auditory information to reach the medial temporal lobe memory system.

No MeSH data available.


Direct auditory pathway to the medial temporal cortex. (A) Core and belt areas of the auditory cortex, shown in the lateral view of the primate brain, have dense and reciprocal connections. Belt areas have dense connections with parabelt areas, where the projection to the parahippocampal region originates, i.e. the direct pathway (B) The architectonic areas that comprise the parahippocampal region are shown in a medial view of the primate brain. Additional cortical areas that receive auditory input and project to the parahippocampal region are shown in gray, but they form part of the indirect pathway (see Figure 3 for further details). Connections between the parahippocampal region and the hippocampal formation are summarized on the right-hand side. See list of abbreviations.
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Figure 2: Direct auditory pathway to the medial temporal cortex. (A) Core and belt areas of the auditory cortex, shown in the lateral view of the primate brain, have dense and reciprocal connections. Belt areas have dense connections with parabelt areas, where the projection to the parahippocampal region originates, i.e. the direct pathway (B) The architectonic areas that comprise the parahippocampal region are shown in a medial view of the primate brain. Additional cortical areas that receive auditory input and project to the parahippocampal region are shown in gray, but they form part of the indirect pathway (see Figure 3 for further details). Connections between the parahippocampal region and the hippocampal formation are summarized on the right-hand side. See list of abbreviations.

Mentions: In sum, the cortex of the rostral part of the STG, including the dorsal part of TP and, to a lesser extent, areas Ts1–3 of the auditory parabelt project directly to EC, the rostral part of areas 35 and 36 of the perirhinal cortex, and areas TH and TF of the posterior parahippocampal cortex. There is an additional projection from the caudal STG to area TH. The auditory projections to EC are, however, very meager in comparison with its polymodal input (Mohedano-Moriano et al., 2008). Similarly, auditory afferents to the perirhinal and posterior parahippocampal cortices are very meager compared to visual input. This is in line with the second hypothesis that the major route, by which the auditory information reaches the medial temporal cortex is via indirect connections, the dorsal TP possibly being one of the major indirect pathway (Figure 2).


Anatomical pathways for auditory memory in primates.

Munoz-Lopez MM, Mohedano-Moriano A, Insausti R - Front Neuroanat (2010)

Direct auditory pathway to the medial temporal cortex. (A) Core and belt areas of the auditory cortex, shown in the lateral view of the primate brain, have dense and reciprocal connections. Belt areas have dense connections with parabelt areas, where the projection to the parahippocampal region originates, i.e. the direct pathway (B) The architectonic areas that comprise the parahippocampal region are shown in a medial view of the primate brain. Additional cortical areas that receive auditory input and project to the parahippocampal region are shown in gray, but they form part of the indirect pathway (see Figure 3 for further details). Connections between the parahippocampal region and the hippocampal formation are summarized on the right-hand side. See list of abbreviations.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 2: Direct auditory pathway to the medial temporal cortex. (A) Core and belt areas of the auditory cortex, shown in the lateral view of the primate brain, have dense and reciprocal connections. Belt areas have dense connections with parabelt areas, where the projection to the parahippocampal region originates, i.e. the direct pathway (B) The architectonic areas that comprise the parahippocampal region are shown in a medial view of the primate brain. Additional cortical areas that receive auditory input and project to the parahippocampal region are shown in gray, but they form part of the indirect pathway (see Figure 3 for further details). Connections between the parahippocampal region and the hippocampal formation are summarized on the right-hand side. See list of abbreviations.
Mentions: In sum, the cortex of the rostral part of the STG, including the dorsal part of TP and, to a lesser extent, areas Ts1–3 of the auditory parabelt project directly to EC, the rostral part of areas 35 and 36 of the perirhinal cortex, and areas TH and TF of the posterior parahippocampal cortex. There is an additional projection from the caudal STG to area TH. The auditory projections to EC are, however, very meager in comparison with its polymodal input (Mohedano-Moriano et al., 2008). Similarly, auditory afferents to the perirhinal and posterior parahippocampal cortices are very meager compared to visual input. This is in line with the second hypothesis that the major route, by which the auditory information reaches the medial temporal cortex is via indirect connections, the dorsal TP possibly being one of the major indirect pathway (Figure 2).

Bottom Line: However, whether auditory memory is organized similarly is still unclear.Alternatively, the anatomical organization of memory could be different in audition.This alternative "indirect stream" hypothesis posits that, unlike the visual association cortex, the majority of auditory information makes one or more synapses in intermediate, polymodal areas, where they may integrate information from other sensory modalities, before reaching the medial temporal memory system.

View Article: PubMed Central - PubMed

Affiliation: Human Neuroanatomy Laboratory, Department of Health Sciences, School of Medicine, University of Castilla-La Mancha Albacete, Spain.

ABSTRACT
Episodic memory or the ability to store context-rich information about everyday events depends on the hippocampal formation (entorhinal cortex, subiculum, presubiculum, parasubiculum, hippocampus proper, and dentate gyrus). A substantial amount of behavioral-lesion and anatomical studies have contributed to our understanding of the organization of how visual stimuli are retained in episodic memory. However, whether auditory memory is organized similarly is still unclear. One hypothesis is that, like the "visual ventral stream" for which the connections of the inferior temporal gyrus with the perirhinal cortex are necessary for visual recognition in monkeys, direct connections between the auditory association areas of the superior temporal gyrus and the hippocampal formation and with the parahippocampal region (temporal pole, perhirinal, and posterior parahippocampal cortices) might also underlie recognition memory for sounds. Alternatively, the anatomical organization of memory could be different in audition. This alternative "indirect stream" hypothesis posits that, unlike the visual association cortex, the majority of auditory information makes one or more synapses in intermediate, polymodal areas, where they may integrate information from other sensory modalities, before reaching the medial temporal memory system. This review considers anatomical studies that can support either one or both hypotheses - focusing on anatomical studies on the primate brain, primarily in macaque monkeys, that have reported not only direct auditory association connections with medial temporal areas, but, importantly, also possible indirect pathways for auditory information to reach the medial temporal lobe memory system.

No MeSH data available.