Physiological and Behavioral Studies of Escape Responses in Calanoid Copepods

Copepods are an abundant and diverse group of crustaceans. One order of free living copepods, the calanoids, are usually < 3 mm in length, planktonic, and possess very rapid escape responses. These animals dominate planktonic communities and their escape reactions contribute to their success. Although all calanoids respond to hydrodynamic disturbances with an escape jump, minimum reaction times vary among species, ranging from 1.5 to 6 msec. To help us understand the physiological basis underlying the phenomenally short reaction times we initiated a comparative study of the internal structures by using transmission electron microscopy (TEM).Traditional chemical fixation was adequate for several species of copepods, and sensory structures were clearly shown. In these calanoids, minimum reaction times ranged from 3 msec to 6 msec and can be partially explained by giant axons, the most common way invertebrates increase the rate of conduction of nerve impulses. However, the internal structures of two copepod species, Euchaetarimana and Undinula vulgaris, were distorted (Fig. 1).

Download Full-text

Ultrastructural identification of three types of sensory setae on copepod antennae

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100141159 ◽

1995 ◽

Vol 53 ◽

pp. 956-957

Author(s):

T. M. Weatherby ◽

P.H. Lenz

Keyword(s):

Phase Locking ◽

Membrane Surface ◽

Reaction Times ◽

High Sensitivity ◽

Structural Features ◽

Calanoid Copepods ◽

Marine Food Webs ◽

Dendritic Membrane ◽

Ultrastructural Characterization

Crustaceans, as well as other arthropods, are covered with sensory setae and hairs, including mechanoand chemosensory sensillae with a ciliary origin. Calanoid copepods are small planktonic crustaceans forming a major link in marine food webs. In conjunction with behavioral and physiological studies of the antennae of calanoids, we undertook the ultrastructural characterization of sensory setae on the antennae of Pleuromamma xiphias.Distal mechanoreceptive setae exhibit exceptional behavioral and physiological performance characteristics: high sensitivity (<10 nm displacements), fast reaction times (<1 msec latency) and phase locking to high frequencies (1-2 kHz). Unusual structural features of the mechanoreceptors are likely to be related to their physiological sensitivity. These features include a large number (up to 3000) of microtubules in each sensory cell dendrite, arising from or anchored to electron dense rods associated with the ciliary basal body microtubule doublets. The microtubules are arranged in a regular array, with bridges between and within rows. These bundles of microtubules extend far into each mechanoreceptive seta and terminate in a staggered fashion along the dendritic membrane, contacting a large membrane surface area and providing a large potential site of mechanotransduction.

Download Full-text

Focusing of Visuospatial Attention

Journal of Psychophysiology ◽

10.1027//0269-8803.15.4.256 ◽

2001 ◽

Vol 15 (4) ◽

pp. 256-274 ◽

Cited By ~ 13

Author(s):

Caterina Pesce ◽

Rainer Bösel

Keyword(s):

Reaction Times ◽

Visual Space ◽

Spatial Relation ◽

Stimulus Onset ◽

Visuospatial Attention ◽

Task Demands ◽

Time Interval ◽

Behavioral Studies ◽

Task Conditions ◽

Simple Rt

Abstract In the present study we explored the focusing of visuospatial attention in subjects practicing and not practicing activities with high attentional demands. Similar to the studies of Castiello and Umiltà (e. g., 1990) , our experimental procedure was a variation of Posner's (1980) basic paradigm for exploring covert orienting of visuospatial attention. In a simple RT-task, a peripheral cue of varying size was presented unilaterally or bilaterally from a central fixation point and followed by a target at different stimulus-onset-asynchronies (SOAs). The target could occur validly inside the cue or invalidly outside the cue with varying spatial relation to its boundary. Event-related brain potentials (ERPs) and reaction times (RTs) were recorded to target stimuli under the different task conditions. RT and ERP findings showed converging aspects as well as dissociations. Electrophysiological results revealed an amplitude modulation of the ERPs in the early and late Nd time interval at both anterior and posterior scalp sites, which seems to be related to the effects of peripheral informative cues as well as to the attentional expertise. Results were: (1) shorter latency effects confirm the positive-going amplitude enhancement elicited by unilateral peripheral cues and strengthen the criticism against the neutrality of spatially nonpredictive peripheral cueing of all possible target locations which is often presumed in behavioral studies. (2) Longer latency effects show that subjects with attentional expertise modulate the distribution of the attentional resources in the visual space differently than nonexperienced subjects. Skilled practice may lead to minimizing attentional costs by automatizing the use of a span of attention that is adapted to the most frequent task demands and endogenously increases the allocation of resources to cope with less usual attending conditions.

Download Full-text

Seasonal diving and foraging behaviour of Eastern Canada-West Greenland bowhead whales

Marine Ecology Progress Series ◽

10.3354/meps13356 ◽

2020 ◽

Vol 643 ◽

pp. 197-217 ◽

Cited By ~ 4

Author(s):

SME Fortune ◽

SH Ferguson ◽

AW Trites ◽

B LeBlanc ◽

V LeMay ◽

...

Keyword(s):

Climate Change ◽

Late Summer ◽

Calanoid Copepods ◽

Eastern Canada ◽

West Greenland ◽

Bowhead Whales ◽

Seasonal Movement ◽

Dive Behaviour ◽

Calanus Glacialis ◽

Canada West

Climate change may affect the foraging success of bowhead whales Balaena mysticetus by altering the diversity and abundance of zooplankton species available as food. However, assessing climate-induced impacts first requires documenting feeding conditions under current environmental conditions. We collected seasonal movement and dive-behaviour data from 25 Eastern Canada-West Greenland bowheads instrumented with time-depth telemetry tags and used state-space models to examine whale movements and dive behaviours. Zooplankton samples were also collected in Cumberland Sound (CS) to determine species composition and biomass. We found that CS was used seasonally by 14 of the 25 tagged whales. Area-restricted movement was the dominant behaviour in CS, suggesting that the tagged whales allocated considerable time to feeding. Prey sampling data suggested that bowheads were exploiting energy-rich Arctic copepods such as Calanus glacialis and C. hyperboreus during summer. Dive behaviour changed seasonally in CS. Most notably, probable feeding dives were substantially shallower during spring and summer compared to fall and winter. These seasonal changes in dive depths likely reflect changes in the vertical distribution of calanoid copepods, which are known to suspend development and overwinter at depth during fall and winter when availability of their phytoplankton prey is presumed to be lower. Overall, CS appears to be an important year-round foraging habitat for bowheads, but is particularly important during the late summer and fall. Whether CS will remain a reliable feeding area for bowhead whales under climate change is not yet known.

Download Full-text

People represent their own mental states more distinctly than others’

10.31234/osf.io/qyu69 ◽

2018 ◽

Cited By ~ 1

Author(s):

Mark Allen Thornton ◽

Miriam E. Weaverdyck ◽

Judith Mildner ◽

Diana Tamir

Keyword(s):

Mental State ◽

Social Distance ◽

Activity Patterns ◽

Mental States ◽

Direct Access ◽

Social Brain ◽

Privileged Access ◽

Behavioral Studies ◽

The Social ◽

External Cues

One can never know the internal workings of another person – one can only infer others’ mental states based on external cues. In contrast, each person has direct access to the contents of their own mind. Here we test the hypothesis that this privileged access shapes the way people represent internal mental experiences, such that they represent their own mental states more distinctly than the states of others. Across four studies, participants considered their own and others’ mental states; analyses measured the distinctiveness of mental state representations. Two neuroimaging studies used representational similarity analyses to demonstrate that the social brain manifests more distinct activity patterns when thinking about one’s own states versus others’. Two behavioral studies support these findings. Further, they demonstrate that people differentiate between states less as social distance increases. Together these results suggest that we represent our own mind with greater granularity than the minds of others.

Download Full-text

Ecological and behavioral studies of the western bean cutworm (Lepidoptera: Noctuidae) in corn

10.31274/rtd-180813-15943 ◽

2007 ◽

Author(s):

David Lee Dorhout

Keyword(s):

Behavioral Studies ◽

Western Bean Cutworm ◽

Lepidoptera Noctuidae

Download Full-text

Chromosomal and Behavioral Studies of Mexican Drosophila. V. Frequencies of Multiple Insemination in Three Natural Populations

The American Naturalist ◽

10.1086/284650 ◽

1987 ◽

Vol 129 (3) ◽

pp. 458-462 ◽

Cited By ~ 5

Author(s):

L. Levine ◽

O. Olvera ◽

R. F. Rockwell ◽

M. E. de la Rosa ◽

E. Akin ◽

...

Keyword(s):

Natural Populations ◽

Behavioral Studies

Download Full-text

Critical Examination of the Parametric Approaches to Analysis of the Non-Verbal Human Behavior: A Case Study in Facial Pre-Touch Interaction

Applied Sciences ◽

10.3390/app10113817 ◽

2020 ◽

Vol 10 (11) ◽

pp. 3817

Author(s):

Soheil Keshmiri ◽

Masahiro Shiomi ◽

Kodai Shatani ◽

Takashi Minato ◽

Hiroshi Ishiguro

Keyword(s):

Normal Distribution ◽

Human Subjects ◽

Critical Examination ◽

Reliable Estimate ◽

Support Vector ◽

Face Area ◽

Behavioral Studies ◽

Touch Interaction ◽

Ordinary Regression ◽

Simplifying Assumptions

A prevailing assumption in many behavioral studies is the underlying normal distribution of the data under investigation. In this regard, although it appears plausible to presume a certain degree of similarity among individuals, this presumption does not necessarily warrant such simplifying assumptions as average or normally distributed human behavioral responses. In the present study, we examine the extent of such assumptions by considering the case of human–human touch interaction in which individuals signal their face area pre-touch distance boundaries. We then use these pre-touch distances along with their respective azimuth and elevation angles around the face area and perform three types of regression-based analyses to estimate a generalized facial pre-touch distance boundary. First, we use a Gaussian processes regression to evaluate whether assumption of normal distribution in participants’ reactions warrants a reliable estimate of this boundary. Second, we apply a support vector regression (SVR) to determine whether estimating this space by minimizing the orthogonal distance between participants’ pre-touch data and its corresponding pre-touch boundary can yield a better result. Third, we use ordinary regression to validate the utility of a non-parametric regressor with a simple regularization criterion in estimating such a pre-touch space. In addition, we compare these models with the scenarios in which a fixed boundary distance (i.e., a spherical boundary) is adopted. We show that within the context of facial pre-touch interaction, normal distribution does not capture the variability that is exhibited by human subjects during such non-verbal interaction. We also provide evidence that such interactions can be more adequately estimated by considering the individuals’ variable behavior and preferences through such estimation strategies as ordinary regression that solely relies on the distribution of their observed behavior which may not necessarily follow a parametric distribution.

Download Full-text

Defining the Role of Attention in Hierarchical Auditory Processing

Audiology Research ◽

10.3390/audiolres11010012 ◽

2021 ◽

Vol 11 (1) ◽

pp. 112-128

Author(s):

Caitlin N. Price ◽

Deborah Moncrieff

Keyword(s):

Auditory Processing ◽

Auditory Pathway ◽

Simultaneous Recording ◽

Neural Encoding ◽

Top Down ◽

Attentional Processes ◽

Clinical Interventions ◽

Speech In Noise ◽

Behavioral Studies ◽

Electrophysiological Studies

Communication in noise is a complex process requiring efficient neural encoding throughout the entire auditory pathway as well as contributions from higher-order cognitive processes (i.e., attention) to extract speech cues for perception. Thus, identifying effective clinical interventions for individuals with speech-in-noise deficits relies on the disentanglement of bottom-up (sensory) and top-down (cognitive) factors to appropriately determine the area of deficit; yet, how attention may interact with early encoding of sensory inputs remains unclear. For decades, attentional theorists have attempted to address this question with cleverly designed behavioral studies, but the neural processes and interactions underlying attention’s role in speech perception remain unresolved. While anatomical and electrophysiological studies have investigated the neurological structures contributing to attentional processes and revealed relevant brain–behavior relationships, recent electrophysiological techniques (i.e., simultaneous recording of brainstem and cortical responses) may provide novel insight regarding the relationship between early sensory processing and top-down attentional influences. In this article, we review relevant theories that guide our present understanding of attentional processes, discuss current electrophysiological evidence of attentional involvement in auditory processing across subcortical and cortical levels, and propose areas for future study that will inform the development of more targeted and effective clinical interventions for individuals with speech-in-noise deficits.

Download Full-text