Cytoarchitecture of the superior olivary complex of three neotropical species of bats (Noctilio leporinus, Phyllostomus hastatus and Carollia perspicillata) with different foraging behavior

Abstract

<jats:p>Abstract The understanding of the echolocation by studying different auditory nuclei of echolocating bats can be an important link in elucidating questions arising in relation to their foraging behavior. The superior olivary complex (SOC) is the primary center for processing the binaural cues used in sound localization since echo locating bats rely on acoustic cues to navigate and capture prey while in flight. The present study was taken to test the hypothesis that the SOC of echolocating neotropical bats with different foraging behavior will exhibit morphological variations in relative size, degree of complexity and spatial distribution. The brains were collected from six male adult bats of each species: Noctilio leporinus (fish eating), Phyllostomus hastatus (carnivorous/omnivorous) and Carollia perspicillata (fruit eating). They were double-embedded and transverse serial sections were cut and stained with cresyl fast violet. The SOC measured as 640 ± 70 µm in the N. leporinus bat, 480 ± 50 µm in the P. hastatus and 240 ± 30 µm in the C. perspicillata bat. The principal nuclei of the SOC of in all three bats were the LSO, MSO and MNTB. The MSO and LSO were very well developed in N. leporinus bats. The MSO of N. leporinus bat subdivided into DMSO and VMSO. The main cell type of cells present in MSO and LSO are dark staining multipolar cells in all the bats studied. The well-developed MSO and LSO of N. leporinus bats indicate that these bats are highly sensitive to low frequency sounds and interaural intensity differences, which help these bats to forage over water by using various types of echolocation signals. The average size of SOC in P. hastatus and C. perspicillata bats can be attributed to the fact that these bats use vision and smell along with echolocation to forage the food.</jats:p>

Cytoarchitecture of the medial nucleus of trapezoid body of three neotropical species of bats (Noctilio leporinus, Phyllostomus hastatus, and Carollia perspicillata) with different foraging behavior

“…The MNTB appeared large in size, extending medially to the raphe and penetrated by most of the fibres of passage in all the bats studied. The auditory nuclei are relatively larger in echolocating animals like the marmoset (Prado Reis and Abrantes Erhart, 1979), dolphins (Thomas et al, 2004;DeLong et al, 2007) and bats (Zook and Casseday, 1982;Gibbons et al, 2013aGibbons et al, , b, 2019Adogwa et al, 2014;Gibbons et al, 2019) than the human and non-human primates (Neuweiler and Covey, 2000) which is similar in the present study. The very well developed MNTB in N. leporinus (1160 ± 124 μm in length) indicated that this bat heavily depends on the echolocation than the two other bats studied.…”

“…Since the different bats forage different environment, it is assumed that different foraging strategies reflect on morphology of the MNTB, an important nucleus in sound localization pathway. Though few studies were done on comparative cytoarchitecture of the various auditory nuclei of echolocating bats with different foraging strategies (Gibbons et al, 2013a(Gibbons et al, , b, 2019Adogwa et al, 2014), the MNTB was not studied.…”

Morphology and unbiased stereology of the lateral superior olive in the short‐beaked common dolphin, Delphinus delphis (Cetacea, Delphinidae)

“…However, these bats possess a well‐developed MSO that is homolog to the MSO in non‐echolocating mammals with some differences in connectivity pattern and function in acoustic contrasting (Casseday & Pollak, 1988; Grothe et al, 1994; Pollak & Casseday, 1988). Anatomical differences in the SOC among echolocating bat species are thought to be linked to differences in feeding strategy and echolocation strategies (Gibbons et al, 2019; Zook & Casseday, 1982).…”

“…The size of the LSO was proposed to be correlated to the hearing range exploited by an animal (Moore, 2000; Schwartz, 1992). Generally, LSO and MNTB are well developed in mammals with good high frequency hearing and are especially prominent in echolocating bats and odontocetes (Gibbons et al, 2019; Grothe et al, 2010). The volume of the LSO in D. delphis (average 150 mm 3 ) is the largest for any mammal measured so far and could reflect the dolphins' adaptation to high frequencies.…”

“…These nuclei are surrounded by the medial nucleus of the trapezoid body (MNTB), and several periolivary cell groups (Heffner & Masterton, 1990; Moore & Moore, 1971; Schwartz, 1992; Stotler, 1953; Strominger & Hurwitz, 1976). LSO and MSO are present in most mammals, however they vary in morphology and most prominently in size, depending on the hearing ability of the species (Gibbons et al, 2019; Irving & Harrison, 1967; Schwartz, 1992). Mammals with good high‐frequency hearing (e.g., mice, rats, and echolocating bats) usually possess a well‐developed LSO and MNTB (Glendenning & Masterton, 1983; Harrison & Irving, 1966; Hofmann, 1908; Irving & Harrison, 1967; Moore & Moore, 1971).…”