ImportanceA transdiagnostic treatment, the Unified Protocol, is as effective as single diagnostic... more ImportanceA transdiagnostic treatment, the Unified Protocol, is as effective as single diagnostic protocols in comorbid emotional disorders in clinical populations. However, its effects on posttraumatic stress disorder and other emotional disorders in individuals living in war and armed conflict contexts have not been studied.ObjectiveTo evaluate the efficacy of a cultural and contextual adaptation of the Unified Protocol (CXA-UP) on posttraumatic stress disorder, anxiety, and depression compared to waitlist control in individuals exposed to armed conflict in Colombia.Design, Setting, and ParticipantsFrom April 2017 to March 2020, 200 participants 18 years and older were randomly assigned to the CXA-UP or to a waitlist condition. CXA-UP consisted of 12 to 14 twice-a-week or weekly individual 90-minute face-to-face sessions. Outcomes were assessed at baseline, posttreatment, and 3 months following treatment. Analyses were performed and compared for all randomly allocated participants...
Purpose Colombia has endured more than five decades of internal armed conflict, which led to subs... more Purpose Colombia has endured more than five decades of internal armed conflict, which led to substantial costs for human capital and mental health. There is currently little evidence about the impact of incorporating a mental health intervention within an existing public cash transfer programme to address poverty, and this project aims to develop and pilot a mental health support intervention embedded within the human capital programme to achieve better outcomes among beneficiaries, especially those displaced by conflict and the most socioeconomically vulnerable.Methods The study will consist of three phases: semi-structured one-to-one interviews, co-design and adaptations of the proposed intervention with participants and pilot of the digital intervention based on cognitive behavioural therapy and transdiagnostic techniques. to determine its feasibility, acceptability, efficacy, and usefulness in 'real settings'. Results will inform if the intervention improves clinical, ed...
The peace accord between the Revolutionary Armed Forces of Colombia (FARC) and the Colombian Gove... more The peace accord between the Revolutionary Armed Forces of Colombia (FARC) and the Colombian Government has been widely lauded by the international community, and rightly so. Yet, formidable challenges remain to its implementation. One substantial challenge is the high percentage of former guerillas as well as victims of the conflict in need of mental health care.
a Víctimas, in the Chapinero neighbourhood of Bogotá outcomes of the work that human rights advoc... more a Víctimas, in the Chapinero neighbourhood of Bogotá outcomes of the work that human rights advocates take on: work that is crucial to the advancement of rights and justice globally. We declare no competing interests.
The Journal of the Acoustical Society of America, 2017
Vowels are complex sounds with four to five spectral peaks known as formants. The frequencies of ... more Vowels are complex sounds with four to five spectral peaks known as formants. The frequencies of the two lowest formants, F1and F2, are sufficient for vowel discrimination. Behavioral studies show that many birds and mammals can discriminate vowels. However, few studies have quantified thresholds for formant-frequency discrimination. The present study examined formant-frequency discrimination in budgerigars (Melopsittacus undulatus) and humans using stimuli with one or two formants and a constant fundamental frequency of 200 Hz. Stimuli had spectral envelopes similar to natural speech and were presented with random level variation. Thresholds were estimated for frequency discrimination of F1, F2, and simultaneous F1 and F2 changes. The same two-down, one-up tracking procedure and single-interval, two-alternative task were used for both species. Formant-frequency discrimination thresholds were as sensitive in budgerigars as in humans and followed the same patterns across all conditio...
Journal of the Association for Research in Otolaryngology : JARO, Jan 20, 2016
Vowels make a strong contribution to speech perception under natural conditions. Vowels are encod... more Vowels make a strong contribution to speech perception under natural conditions. Vowels are encoded in the auditory nerve primarily through neural synchrony to temporal fine structure and to envelope fluctuations rather than through average discharge rate. Neural synchrony is thought to contribute less to vowel coding in central auditory nuclei, consistent with more limited synchronization to fine structure and the emergence of average-rate coding of envelope fluctuations. However, this hypothesis is largely unexplored, especially in background noise. The present study examined coding mechanisms at the level of the midbrain that support behavioral sensitivity to simple vowel-like sounds using neurophysiological recordings and matched behavioral experiments in the budgerigar. Stimuli were harmonic tone complexes with energy concentrated at one spectral peak, or formant frequency, presented in quiet and in noise. Behavioral thresholds for formant-frequency discrimination decreased wit...
Amplitude modulation (AM) is a crucial feature of many communication signals, including speech. W... more Amplitude modulation (AM) is a crucial feature of many communication signals, including speech. Whereas average discharge rates in the auditory midbrain correlate with behavioral AM sensitivity in rabbits, the neural bases of AM sensitivity in species with human-like behavioral acuity are unexplored. Here, we used parallel behavioral and neurophysiological experiments to explore the neural (midbrain) bases of AM perception in an avian speech mimic, the budgerigar ( Melopsittacus undulatus). Behavioral AM sensitivity was quantified using operant conditioning procedures. Neural AM sensitivity was studied using chronically implanted microelectrodes in awake, unrestrained birds. Average discharge rates of multiunit recording sites in the budgerigar midbrain were insufficient to explain behavioral sensitivity to modulation frequencies <100 Hz for both tone- and noise-carrier stimuli, even with optimal pooling of information across recording sites. Neural envelope synchrony, in contras...
This experiment assessed the effects of Centrophenoxine on counting behavior in rats. Intraperito... more This experiment assessed the effects of Centrophenoxine on counting behavior in rats. Intraperitoneal Centrophenoxine injections were given to rats before training on a 20-fixed-consecutive-number schedule of reinforcement. The primary measure was the number of consecutive lever presses. After Centrophenoxine injections, the number of consecutive lever presses was lower relative to baseline measures. The measures of variability indicated that although the consecutive number of responses was lower this could not be accounted for in terms of run length variability. The behavioral pattern produced by the injections was discussed in terms of possible shortterm physiological effects that affect performance.
Journal of the Association for Research in Otolaryngology, 2015
The acoustical cues and physiological processing mechanisms underlying the perception of the dist... more The acoustical cues and physiological processing mechanisms underlying the perception of the distance of sound sources are not well understood. To understand the relation between physiology and behavior, a first step is to use an animal model to study distance sensitivity. The goal of these experiments was to establish the capacity of the Dutchbelted rabbit to discriminate between sound sources at two distances. Trains of noise bursts were presented from speakers that were located either directly in front of the rabbit or at a 45°angle in azimuth. The reference speaker was positioned at distances of 20, 40, and 60 cm from the subject, and the more distant test speaker was systematically moved to determine the smallest difference in distance that could be reliably discriminated by the subject. Noise stimuli had one of three bandwidths: wideband (0.1-10 kHz), low-pass (0.1-3 kHz), or high-pass (3-10 kHz). The mean stimulus level was 60 dB sound pressure level (SPL) at the location of the rabbit's head, and the level was roved over a 12-dB range from trial to trial to reduce the availability of level cues. An operant oneinterval two-alternative non-forced choice task was used, with a blocked two-down-one-up tracking procedure to determine the distance discriminability. Rabbits were consistently able to discriminate two distances when they were sufficiently separated. Sensitivity was better when the reference distance was 60 cm at either azimuth (distance ratio=1.5) and was worse when the reference distance was 20 cm (distance ratio=2.4 at 0°and 1.75 at 45°).
The Quarterly Journal of Experimental Psychology: Section B, 2003
Experimental studies were performed using a Pavlovian-conditioned eyeblink response to measure de... more Experimental studies were performed using a Pavlovian-conditioned eyeblink response to measure detection of a variable-sound-level tone (T) in a fixed-sound-level masking noise (N) in rabbits. Results showed an increase in the asymptotic probability of conditioned responses (CRs) to the reinforced TN trials and a decrease in the asymptotic rate of eyeblink responses to the nonreinforced N presentations as a function of the sound level of the T. These observations are consistent with expected behaviour in an auditory masked detection task, but they are not consistent with predictions from a traditional application of the Rescorla-Wagner or Pearce models of associative learning. To implement these models, one typically considers only the actual stimuli and reinforcement on each trial. We found that by considering perceptual interactions and concepts from signal detection theory, these models could predict the CS dependence on the sound level of the T. In these alternative implementations, the animal's response probabilities were used as a guide in making assumptions about the "effective stimuli". In recent psychophysical studies (Early et al., 2001; Zheng et al., 2001), we used a Pavlovianconditioned eyeblink in rabbit to study detection of a tone (T) that was presented in compound with a noise masker (N). These experiments used a feature positive procedure, where TN presentations were always accompanied by the unconditioned stimulus (US), and the noise alone, N, was presented frequently and never with the US. These presentation types are designated TN + and N-, respectively. This training resulted in substantial responding to the TN compound and little responding to N.
The Journal of the Acoustical Society of America, 2002
Binaural detection with narrowband and wideband noise maskers was examined by using a Pavlovian-c... more Binaural detection with narrowband and wideband noise maskers was examined by using a Pavlovian-conditioned eyeblink response in rabbits. The target was a tone at 500 Hz, and the maskers were ten individual noise samples having one of two bandwidths, 200 Hz ͑410 Hz to 610 Hz͒ or 2900 Hz ͑100 Hz to 3 kHz͒. The narrowband noise maskers were created by filtering the wideband noise maskers such that the two sets of maskers had identical spectra in the 200-Hz frequency region surrounding the tone. The responses across the set of noise maskers were compared across bandwidths and across interaural configurations ͑N 0 S 0 and N 0 S ͒. Responses across the set of noise waveforms were not strongly correlated across bandwidths; this result is inconsistent with models for binaural detection that depend only upon the narrow band of energy centered at the frequency of the target tone. Responses were correlated across interaural configurations for the wideband masker condition, but not for the narrowband masker. All of these results were consistent with the companion study of human listeners ͓Evilsizer et al., J. Acoust. Soc. Am. 111, 336-345 ͑2002͔͒ and with the results of human studies of binaural detection that used only wideband ͓Gilkey et al.,
The Journal of the Acoustical Society of America, 2011
The use of reproducible noise maskers in studies of detection has proven useful to extend our und... more The use of reproducible noise maskers in studies of detection has proven useful to extend our understanding of coding and processing of complex sounds. In an effort to reveal potential neural mechanisms for the detection of amplitude‐modulation (AM) in the ...
The Journal of the Acoustical Society of America, 2005
The goal of this study was to estimate behavioral detection thresholds in quiet and noise for sub... more The goal of this study was to estimate behavioral detection thresholds in quiet and noise for subsequent physiological studies of responses to near‐threshold stimuli. The difficulty in measuring detection thresholds is maintaining stimulus control of behavior over schedule control. Tracking paradigms are efficient, but the large proportion of trials below threshold weakens stimulus control. The Method of Constant Stimuli controls the proportion of trials below, near, and above the SPL for a given percent correct. Here, percentages of trials at different SPLs and zero intensity catch trials were varied to determine proportions that yielded satisfactory stimulus control by a 500‐Hz tone in quiet. Trials were initiated by nose‐poke observing responses; a nose‐poke reporting response within a 3‐s window after tone onset resulted in food reinforcement. Reporting responses in the absence of tones resulted in timeouts. A metric for stimulus control was the ratio of the number of correct detections to the number ...
The characterization of ability in behavioral sound-localization tasks is an important aspect of ... more The characterization of ability in behavioral sound-localization tasks is an important aspect of understanding how the brain encodes and processes sound location information. In a few species, both physiological and behavioral results related to sound localization are available. In the Mongolian gerbil, physiological sensitivity to interaural time differences in the auditory brainstem is comparable to that reported in other species; however, the gerbil has been reported to have relatively poor behavioral localization performance as compared with several other species. In this study, the behavioral performance of the gerbil for sound localization was reexamined using a task that involved a simpler response map than in previously published studies. In the current task, the animal directly approached the speaker on each trial, thus the response map was simpler than the 90-right vs. 90-left response required in previous studies of localization and source discrimination. Although the general performance across a group of animals was more consistent in the task with the simpler response map, the sound-localization ability replicated that previously reported. These results are consistent with the previous reports that sound-localization performance in gerbil is poor with respect to other species that have comparable neural sensitivity to interaural cues.
A Pavlovian conditioned eyeblink response in rabbits (Oryctolagus cuniculus) was used to study ps... more A Pavlovian conditioned eyeblink response in rabbits (Oryctolagus cuniculus) was used to study psychoacoustical phenomena previously demonstrated in human listeners and other animals. This article contains the results of a tone-in-noise detection study to examine 2 psychoacoustical phenomena in rabbit and in human listeners: (a) the binaural masking level difference (BMLD) and (b) differential performance across reproducible noise masker waveforms. The rabbits demonstrated a BMLD comparable in size to other species. Significant differences in performance across reproducible noise masker waveforms were seen in the rabbits. This performance was compared with the performance of human listeners using the same set of waveforms.
Previous studies have shown increased life span and decreased lipofuscin deposition in brain stru... more Previous studies have shown increased life span and decreased lipofuscin deposition in brain structures when both premature and young adult animals are calorically restricted of an otherwise nutritionally adequate diet. Three-months-old C57BL/6 mice were subjected to 12 months of caloric restriction (2 g/day), and subsequently exposed to a radial maze learning paradigm. Mice in the diet restriction group showed faster learning and higher asymptotic performance on the radial maze task, as well as lower lipofuscin deposition in the neurons of hippocampus and frontal cortex relative to control mice fed ad libitum. The results suggest that dietary restriction has effects on radial maze learning, and this improved behavioral performance was associated with significant reduction in lipofuscin pigment deposition in the neurons of hippocampus and frontal cortex.
ImportanceA transdiagnostic treatment, the Unified Protocol, is as effective as single diagnostic... more ImportanceA transdiagnostic treatment, the Unified Protocol, is as effective as single diagnostic protocols in comorbid emotional disorders in clinical populations. However, its effects on posttraumatic stress disorder and other emotional disorders in individuals living in war and armed conflict contexts have not been studied.ObjectiveTo evaluate the efficacy of a cultural and contextual adaptation of the Unified Protocol (CXA-UP) on posttraumatic stress disorder, anxiety, and depression compared to waitlist control in individuals exposed to armed conflict in Colombia.Design, Setting, and ParticipantsFrom April 2017 to March 2020, 200 participants 18 years and older were randomly assigned to the CXA-UP or to a waitlist condition. CXA-UP consisted of 12 to 14 twice-a-week or weekly individual 90-minute face-to-face sessions. Outcomes were assessed at baseline, posttreatment, and 3 months following treatment. Analyses were performed and compared for all randomly allocated participants...
Purpose Colombia has endured more than five decades of internal armed conflict, which led to subs... more Purpose Colombia has endured more than five decades of internal armed conflict, which led to substantial costs for human capital and mental health. There is currently little evidence about the impact of incorporating a mental health intervention within an existing public cash transfer programme to address poverty, and this project aims to develop and pilot a mental health support intervention embedded within the human capital programme to achieve better outcomes among beneficiaries, especially those displaced by conflict and the most socioeconomically vulnerable.Methods The study will consist of three phases: semi-structured one-to-one interviews, co-design and adaptations of the proposed intervention with participants and pilot of the digital intervention based on cognitive behavioural therapy and transdiagnostic techniques. to determine its feasibility, acceptability, efficacy, and usefulness in 'real settings'. Results will inform if the intervention improves clinical, ed...
The peace accord between the Revolutionary Armed Forces of Colombia (FARC) and the Colombian Gove... more The peace accord between the Revolutionary Armed Forces of Colombia (FARC) and the Colombian Government has been widely lauded by the international community, and rightly so. Yet, formidable challenges remain to its implementation. One substantial challenge is the high percentage of former guerillas as well as victims of the conflict in need of mental health care.
a Víctimas, in the Chapinero neighbourhood of Bogotá outcomes of the work that human rights advoc... more a Víctimas, in the Chapinero neighbourhood of Bogotá outcomes of the work that human rights advocates take on: work that is crucial to the advancement of rights and justice globally. We declare no competing interests.
The Journal of the Acoustical Society of America, 2017
Vowels are complex sounds with four to five spectral peaks known as formants. The frequencies of ... more Vowels are complex sounds with four to five spectral peaks known as formants. The frequencies of the two lowest formants, F1and F2, are sufficient for vowel discrimination. Behavioral studies show that many birds and mammals can discriminate vowels. However, few studies have quantified thresholds for formant-frequency discrimination. The present study examined formant-frequency discrimination in budgerigars (Melopsittacus undulatus) and humans using stimuli with one or two formants and a constant fundamental frequency of 200 Hz. Stimuli had spectral envelopes similar to natural speech and were presented with random level variation. Thresholds were estimated for frequency discrimination of F1, F2, and simultaneous F1 and F2 changes. The same two-down, one-up tracking procedure and single-interval, two-alternative task were used for both species. Formant-frequency discrimination thresholds were as sensitive in budgerigars as in humans and followed the same patterns across all conditio...
Journal of the Association for Research in Otolaryngology : JARO, Jan 20, 2016
Vowels make a strong contribution to speech perception under natural conditions. Vowels are encod... more Vowels make a strong contribution to speech perception under natural conditions. Vowels are encoded in the auditory nerve primarily through neural synchrony to temporal fine structure and to envelope fluctuations rather than through average discharge rate. Neural synchrony is thought to contribute less to vowel coding in central auditory nuclei, consistent with more limited synchronization to fine structure and the emergence of average-rate coding of envelope fluctuations. However, this hypothesis is largely unexplored, especially in background noise. The present study examined coding mechanisms at the level of the midbrain that support behavioral sensitivity to simple vowel-like sounds using neurophysiological recordings and matched behavioral experiments in the budgerigar. Stimuli were harmonic tone complexes with energy concentrated at one spectral peak, or formant frequency, presented in quiet and in noise. Behavioral thresholds for formant-frequency discrimination decreased wit...
Amplitude modulation (AM) is a crucial feature of many communication signals, including speech. W... more Amplitude modulation (AM) is a crucial feature of many communication signals, including speech. Whereas average discharge rates in the auditory midbrain correlate with behavioral AM sensitivity in rabbits, the neural bases of AM sensitivity in species with human-like behavioral acuity are unexplored. Here, we used parallel behavioral and neurophysiological experiments to explore the neural (midbrain) bases of AM perception in an avian speech mimic, the budgerigar ( Melopsittacus undulatus). Behavioral AM sensitivity was quantified using operant conditioning procedures. Neural AM sensitivity was studied using chronically implanted microelectrodes in awake, unrestrained birds. Average discharge rates of multiunit recording sites in the budgerigar midbrain were insufficient to explain behavioral sensitivity to modulation frequencies <100 Hz for both tone- and noise-carrier stimuli, even with optimal pooling of information across recording sites. Neural envelope synchrony, in contras...
This experiment assessed the effects of Centrophenoxine on counting behavior in rats. Intraperito... more This experiment assessed the effects of Centrophenoxine on counting behavior in rats. Intraperitoneal Centrophenoxine injections were given to rats before training on a 20-fixed-consecutive-number schedule of reinforcement. The primary measure was the number of consecutive lever presses. After Centrophenoxine injections, the number of consecutive lever presses was lower relative to baseline measures. The measures of variability indicated that although the consecutive number of responses was lower this could not be accounted for in terms of run length variability. The behavioral pattern produced by the injections was discussed in terms of possible shortterm physiological effects that affect performance.
Journal of the Association for Research in Otolaryngology, 2015
The acoustical cues and physiological processing mechanisms underlying the perception of the dist... more The acoustical cues and physiological processing mechanisms underlying the perception of the distance of sound sources are not well understood. To understand the relation between physiology and behavior, a first step is to use an animal model to study distance sensitivity. The goal of these experiments was to establish the capacity of the Dutchbelted rabbit to discriminate between sound sources at two distances. Trains of noise bursts were presented from speakers that were located either directly in front of the rabbit or at a 45°angle in azimuth. The reference speaker was positioned at distances of 20, 40, and 60 cm from the subject, and the more distant test speaker was systematically moved to determine the smallest difference in distance that could be reliably discriminated by the subject. Noise stimuli had one of three bandwidths: wideband (0.1-10 kHz), low-pass (0.1-3 kHz), or high-pass (3-10 kHz). The mean stimulus level was 60 dB sound pressure level (SPL) at the location of the rabbit's head, and the level was roved over a 12-dB range from trial to trial to reduce the availability of level cues. An operant oneinterval two-alternative non-forced choice task was used, with a blocked two-down-one-up tracking procedure to determine the distance discriminability. Rabbits were consistently able to discriminate two distances when they were sufficiently separated. Sensitivity was better when the reference distance was 60 cm at either azimuth (distance ratio=1.5) and was worse when the reference distance was 20 cm (distance ratio=2.4 at 0°and 1.75 at 45°).
The Quarterly Journal of Experimental Psychology: Section B, 2003
Experimental studies were performed using a Pavlovian-conditioned eyeblink response to measure de... more Experimental studies were performed using a Pavlovian-conditioned eyeblink response to measure detection of a variable-sound-level tone (T) in a fixed-sound-level masking noise (N) in rabbits. Results showed an increase in the asymptotic probability of conditioned responses (CRs) to the reinforced TN trials and a decrease in the asymptotic rate of eyeblink responses to the nonreinforced N presentations as a function of the sound level of the T. These observations are consistent with expected behaviour in an auditory masked detection task, but they are not consistent with predictions from a traditional application of the Rescorla-Wagner or Pearce models of associative learning. To implement these models, one typically considers only the actual stimuli and reinforcement on each trial. We found that by considering perceptual interactions and concepts from signal detection theory, these models could predict the CS dependence on the sound level of the T. In these alternative implementations, the animal's response probabilities were used as a guide in making assumptions about the "effective stimuli". In recent psychophysical studies (Early et al., 2001; Zheng et al., 2001), we used a Pavlovianconditioned eyeblink in rabbit to study detection of a tone (T) that was presented in compound with a noise masker (N). These experiments used a feature positive procedure, where TN presentations were always accompanied by the unconditioned stimulus (US), and the noise alone, N, was presented frequently and never with the US. These presentation types are designated TN + and N-, respectively. This training resulted in substantial responding to the TN compound and little responding to N.
The Journal of the Acoustical Society of America, 2002
Binaural detection with narrowband and wideband noise maskers was examined by using a Pavlovian-c... more Binaural detection with narrowband and wideband noise maskers was examined by using a Pavlovian-conditioned eyeblink response in rabbits. The target was a tone at 500 Hz, and the maskers were ten individual noise samples having one of two bandwidths, 200 Hz ͑410 Hz to 610 Hz͒ or 2900 Hz ͑100 Hz to 3 kHz͒. The narrowband noise maskers were created by filtering the wideband noise maskers such that the two sets of maskers had identical spectra in the 200-Hz frequency region surrounding the tone. The responses across the set of noise maskers were compared across bandwidths and across interaural configurations ͑N 0 S 0 and N 0 S ͒. Responses across the set of noise waveforms were not strongly correlated across bandwidths; this result is inconsistent with models for binaural detection that depend only upon the narrow band of energy centered at the frequency of the target tone. Responses were correlated across interaural configurations for the wideband masker condition, but not for the narrowband masker. All of these results were consistent with the companion study of human listeners ͓Evilsizer et al., J. Acoust. Soc. Am. 111, 336-345 ͑2002͔͒ and with the results of human studies of binaural detection that used only wideband ͓Gilkey et al.,
The Journal of the Acoustical Society of America, 2011
The use of reproducible noise maskers in studies of detection has proven useful to extend our und... more The use of reproducible noise maskers in studies of detection has proven useful to extend our understanding of coding and processing of complex sounds. In an effort to reveal potential neural mechanisms for the detection of amplitude‐modulation (AM) in the ...
The Journal of the Acoustical Society of America, 2005
The goal of this study was to estimate behavioral detection thresholds in quiet and noise for sub... more The goal of this study was to estimate behavioral detection thresholds in quiet and noise for subsequent physiological studies of responses to near‐threshold stimuli. The difficulty in measuring detection thresholds is maintaining stimulus control of behavior over schedule control. Tracking paradigms are efficient, but the large proportion of trials below threshold weakens stimulus control. The Method of Constant Stimuli controls the proportion of trials below, near, and above the SPL for a given percent correct. Here, percentages of trials at different SPLs and zero intensity catch trials were varied to determine proportions that yielded satisfactory stimulus control by a 500‐Hz tone in quiet. Trials were initiated by nose‐poke observing responses; a nose‐poke reporting response within a 3‐s window after tone onset resulted in food reinforcement. Reporting responses in the absence of tones resulted in timeouts. A metric for stimulus control was the ratio of the number of correct detections to the number ...
The characterization of ability in behavioral sound-localization tasks is an important aspect of ... more The characterization of ability in behavioral sound-localization tasks is an important aspect of understanding how the brain encodes and processes sound location information. In a few species, both physiological and behavioral results related to sound localization are available. In the Mongolian gerbil, physiological sensitivity to interaural time differences in the auditory brainstem is comparable to that reported in other species; however, the gerbil has been reported to have relatively poor behavioral localization performance as compared with several other species. In this study, the behavioral performance of the gerbil for sound localization was reexamined using a task that involved a simpler response map than in previously published studies. In the current task, the animal directly approached the speaker on each trial, thus the response map was simpler than the 90-right vs. 90-left response required in previous studies of localization and source discrimination. Although the general performance across a group of animals was more consistent in the task with the simpler response map, the sound-localization ability replicated that previously reported. These results are consistent with the previous reports that sound-localization performance in gerbil is poor with respect to other species that have comparable neural sensitivity to interaural cues.
A Pavlovian conditioned eyeblink response in rabbits (Oryctolagus cuniculus) was used to study ps... more A Pavlovian conditioned eyeblink response in rabbits (Oryctolagus cuniculus) was used to study psychoacoustical phenomena previously demonstrated in human listeners and other animals. This article contains the results of a tone-in-noise detection study to examine 2 psychoacoustical phenomena in rabbit and in human listeners: (a) the binaural masking level difference (BMLD) and (b) differential performance across reproducible noise masker waveforms. The rabbits demonstrated a BMLD comparable in size to other species. Significant differences in performance across reproducible noise masker waveforms were seen in the rabbits. This performance was compared with the performance of human listeners using the same set of waveforms.
Previous studies have shown increased life span and decreased lipofuscin deposition in brain stru... more Previous studies have shown increased life span and decreased lipofuscin deposition in brain structures when both premature and young adult animals are calorically restricted of an otherwise nutritionally adequate diet. Three-months-old C57BL/6 mice were subjected to 12 months of caloric restriction (2 g/day), and subsequently exposed to a radial maze learning paradigm. Mice in the diet restriction group showed faster learning and higher asymptotic performance on the radial maze task, as well as lower lipofuscin deposition in the neurons of hippocampus and frontal cortex relative to control mice fed ad libitum. The results suggest that dietary restriction has effects on radial maze learning, and this improved behavioral performance was associated with significant reduction in lipofuscin pigment deposition in the neurons of hippocampus and frontal cortex.
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Papers by Fabio Idrobo