Hugo Merchant

Hugo Merchant
Universidad Nacional Autónoma de México | UNAM · Institute of Neurobiology

PhD

About

130
Publications
27,016
Reads
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4,960
Citations
Citations since 2017
51 Research Items
2668 Citations
20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
Additional affiliations
April 2005 - present
Universidad Nacional Autónoma de México
Position
  • Professor (Full)
September 1999 - January 2003
United States Department of Veterans Affairs
Position
  • Research Associate
July 1997 - July 1999
Minneapolis Veterans Affairs Hospital
Position
  • PostDoc Position

Publications

Publications (130)
Preprint
Full-text available
The measurement of time in the subsecond scale is critical for many sophisticated behaviors, yet its neural underpinnings are largely unknown. Recent neurophysiological experiments from our laboratory have shown that the neural activity in the medial premotor areas (MPC) of macaques can represent different aspects of temporal processing. During sin...
Preprint
Full-text available
Beta oscillations are involved in a variety of cognitive functions beyond their traditional sensorimotor role. Based on prior findings of content-specific beta synchronization during working memory and decision making, we hypothesized that beta activity supports the activation and reactivation of cortical representations by mediating neural ensembl...
Preprint
Full-text available
We determined the intersubject association between rhythmic entrainment abilities of human subjects during a synchronization continuation tapping task (SCT) and the macro and microstructural properties of their superficial (SWM) and deep (dWM) white matter. Diffusion-weighted images were obtained from 32 subjects who also performed the SCT with aud...
Preprint
Full-text available
Precise timing is a fundamental requisite for a select group of complex actions, such as music appreciation and performance, where subjects extract the regular beat of a rhythmic sequence to generate an internal pulse representation that allows for predictive responses to the beat. The neural substrate for beat extraction and response entrainment t...
Preprint
Full-text available
Imagine practicing a piece of music, or a speech, solely within the mind, without any sensory input or motor output. Our ability to implement dynamic internal representations is key for successful behavior, yet how the brain achieves this is not fully understood. Here we trained primates to perceive, and internally maintain, rhythms of different te...
Article
Humans perceive and spontaneously move to one or several levels of periodic pulses (a meter, for short) when listening to musical rhythm, even when the sensory input does not provide prominent periodic cues to their temporal location. Here, we review a multi-levelled framework to understanding how external rhythmic inputs are mapped onto internally...
Article
Full-text available
Sharing and pooling large amounts of non-human primate neuroimaging data offer new exciting opportunities to understand the primate brain. The potential of big data in non-human primate neuroimaging could however be tremendously enhanced by combining such neuroimaging data with other types of information. Here we describe metadata that have been id...
Article
Full-text available
Longitudinal non-human primate neuroimaging has the potential to greatly enhance our understanding of primate brain structure and function. Here we describe its specific strengths, compared to both cross-sectional non-human primate neuroimaging and longitudinal human neuroimaging, but also its associated challenges. We elaborate on factors guiding...
Article
The ability to perceive and produce movements in the real world with precise timing is critical for survival in animals, including humans. However, research on sensorimotor timing has rarely considered the tight interrelation between perception, action, and cognition. In this review, we present new evidence from behavioral, computational, and neura...
Preprint
Full-text available
When we intensively train a timing skill, such as learning to play the piano, we do not only produce brain changes associated with task-specific learning, but also improve the performance on other temporal behaviors that depend on these tuned neural resources. Since the neural basis of time learning and generalization are still unknown, we measured...
Article
Full-text available
Accurate extraction of the cortical brain surface is critical for cortical thickness estimation and a key element to perform multimodal imaging analysis, where different metrics are integrated and compared in a common space. While brain surface extraction has become widespread practice in human studies, several challenges unique to neuroimaging of...
Article
Full-text available
Neuroimaging non-human primates (NHPs) is a growing, yet highly specialized field of neuroscience. Resources that were primarily developed for human neuroimaging often need to be significantly adapted for use with NHPs or other animals, which has led to an abundance of custom, in-house solutions. In recent years, the global NHP neuroimaging communi...
Article
The proper response to an ever-changing environment depends on the ability to quantify elapsed time, memorize short intervals and forecast when an upcoming experience may occur. A recent study describes the encoding principles of these three types of time using computational modelling.
Preprint
Full-text available
Neuroimaging non-human primates (NHPs) is a growing, yet highly specialized field of neuroscience. Resources that were primarily developed for human neuroimaging often need to be significantly adapted for use with NHPs or other animals, which has led to an abundance of custom, in-house solutions. In recent years, the global NHP neuroimaging communi...
Article
Nonhuman primate neuroimaging is on the cusp of a transformation, much in the same way its human counterpart was in 2010, when the Human Connectome Project was launched to accelerate progress. Inspired by an open data-sharing initiative, the global community recently met and, in this article, breaks through obstacles to define its ambitions.
Article
Full-text available
Our motor commands can be exquisitely timed according to the demands of the environment, and the ability to generate rhythms of different tempos is a hallmark of musical cognition. Yet, the neuronal underpinnings behind rhythmic tapping remain elusive. Here, we found that the activity of hundreds of primate medial premotor cortices (MPCs; pre-suppl...
Data
Neural population trajectories during SCT from a subpopulation of cells with task-related activity. The PCA was performed on the time-varying activity of 104 cells that showed at least 15 activation periods on the Poisson-train analysis across the five target durations and six serial order elements of the SCT. The first three PCs explained 32.5% of...
Data
State trajectories during ST and SRTT using simultaneously recorded neurons. A,B. Three-dimensional neural dynamics trajectory of 650-ms single ST (A) and SRTT (B) intervals. Elapsed time is color coded. The previous and the next taps are marked as red and white spheres, respectively. The stimuli are marked as a white pyramid. Underlying data are a...
Data
Effect of timing and firing rate normalization on the amplitude and speed of neural trajectories. We used different combinations of the time and firing rate normalization of the neural data in order to calculate the PCA coefficients and then the neural trajectories. We fitted a sine function on each of the first 10 PCs and measured their amplitude...
Data
Location of the silicon shank for the MPC recordings in Monkey 1 during the ST. MRI cortical surface reconstruction of the macaque brain and the recording position of the Buszaki-64 silicon shank over MPC. The green line corresponds to the anterior-posterior location of the spur of the arcuate sulcus that divides preSMA from SMA. The silicon shank...
Data
State trajectory progress during SCT. A,B. One trajectory loop for the second produced interval of the (A) SC and (B) CC, during 450-ms (dark gray) and a 1,000-ms (light gray) target intervals. Trajectory progression marked as colored spheres is as follows: previous tap (green), first inter-tap quarter (cyan), second inter-tap quarter/half interval...
Preprint
Full-text available
Our motor commands can be exquisitely timed according to the demands of the environment, and the ability to generate rhythms of different tempos is a hallmark of musical cognition. Yet, the neuronal underpinnings behind rhythmic tapping remains elusive. Here we found that the activity of hundreds of primate medial premotor cortices (MPC) neurons sh...
Article
Full-text available
To prepare timely motor actions we constantly predict future events. Regularly repeating events are often perceived as a rhythm to which we can readily synchronize our movements, just as in dancing to music. However, the neuronal mechanisms underlying the capacity to encode and maintain rhythms are not understood. We trained nonhuman primates to ma...
Preprint
Full-text available
To prepare timely motor actions we constantly predict future events. Regularly repeating events are often perceived as a rhythm to which we can readily synchronize our movements, just as in dancing to music. However, the neuronal mechanisms underlying the capacity to encode and maintain rhythms are not understood. We trained nonhuman primates to ma...
Data
Example of a rhythmic pattern used in the isochronous condition. [1_isochronous.wav].
Data
Example of a rhythmic pattern used in the jittered condition. [2_jittered.wav].
Article
Full-text available
Charles Darwin suggested the perception of rhythm to be common to all animals. While only recently experimental research is finding some support for this claim, there are also aspects of rhythm cognition that appear to be species-specific, such as the capability to perceive a regular pulse (or beat) in a varying rhythm. In the current study, using...
Article
Full-text available
Beat entrainment is the ability to entrain one's movements to a perceived periodic stimulus, such as a metronome or a pulse in music. Humans have a capacity to predictively respond to a periodic pulse and to dynamically adjust their movement timing to match the varying music tempos. Previous studies have shown that monkeys share some of the human c...
Chapter
Honing et al. (2015) suggest that the origins of musicality—the capacity that makes it possible for us to perceive, appreciate, and produce music—can be pursued productively by searching for components of musicality in other species. Recent studies have highlighted that the behavioural relevance of stimuli to animals and the relation of experimenta...
Chapter
Full-text available
Beat perception is a cognitive ability that allows the detection of a regular pulse (or beat) in music and permits synchronous responding to this pulse during dancing and musical ensemble playing (Honing, 2013; Large & Palmer, 2002). Most people can recognize and reproduce a large number of rhythms, and they can move in synchrony to the beat by rhy...
Article
Extensive research has described two key features of interval timing. The bias property is associated with accuracy and implies that time is overestimated for short intervals and underestimated for long intervals. The scalar property is linked to precision and states that the variability of interval estimates increases as a function of interval dur...
Article
Full-text available
Perceptual categorization depends on the assignment of different stimuli to specific groups based, in principle, on the notion of flexible categorical boundaries. To determine the neural basis of categorical boundaries, we record the activity of pre-SMA neurons of monkeys executing an interval categorization task in which the limit between short an...
Article
Full-text available
The study of non-human primates in complex behaviors such as rhythm perception and entrainment is critical to understand the neurophysiological basis of human cognition. Next to reviewing the role of beta oscillations in human beat perception, here we discuss the role of primate putaminal oscillatory activity in the control of rhythmic movements th...
Article
Inhibitory mechanisms are crucial for the integrated operation of the motor cortical circuit. Local inhibition is exerted by interneurons that are GABAergic, nonpyramidal cells with short, nonprojecting axons. Interneurons can be classified into at least two groups: fast-spiking (FS) neurons and instrinsic bursting (IB) neurons. In the primary moto...
Article
Full-text available
The extraction and encoding of acoustical temporal regularities are fundamental for human cognitive auditory abilities such as speech or beat entrainment. Because the comparison of the neural sensitivity to temporal regularities between human and animals is fundamental to relate non-invasive measures of auditory processing to their neuronal basis,...
Chapter
Inhibitory mechanisms are crucial for the integrated operation of the motor cortical circuit (MCC). Local inhibition is exerted by interneurons that are GABAergic, nonpyramidal cells with short, nonprojecting axons. Interneurons can be classified into at least two groups: fast-spiking (FS) neurons and instrinsic bursting (IB) neurons. In the primar...
Article
Full-text available
Time perception in the milliseconds and seconds ranges is thought to be processed by different neural mechanisms. However, whether there is a sharp boundary between these ranges and whether they are implemented in the same, overlapped or separate brain areas is still not certain. To probe the role of the right dorsolateral prefrontal cortex (dlPFC)...
Book
Full-text available
Optimized interaction of the brain with environment requires the four-dimensional representation of space-time in the neuronal circuits. Information processing is an important part of this interaction, which is critically dependent on time-dimension. Information processing has played an important role in the evolution of mammals, and has reached a...
Article
Full-text available
The neural underpinnings of rhythmic behavior, including music and dance, have been studied using the synchronization-continuation task (SCT), where subjects initially tap in synchrony with an isochronous metronome and then keep tapping at a similar rate via an internal beat mechanism. Here, we provide behavioral and neural evidence that supports a...
Article
Full-text available
An accurate representation of time-dimension in the neuronal circuits is required for a successful interaction of the brain with the four-dimensional physical world. Time-dimension, unlike other three dimensions of our physical universe, is never perceived as a novelty, but only reported as the flow of time. As there are no known neurological or ps...
Article
Full-text available
Timing is a fundamental variable for behavior. However, the mechanisms allowing human and non-human primates to synchronize their actions with periodic events are not yet completely understood. Here we characterize the ability of rhesus monkeys and humans to perceive and maintain rhythms of different paces in the absence of sensory cues or motor ac...
Article
Full-text available
It is becoming more apparent that there are rich contributions to temporal processing across the brain. Temporal dynamics have been found from lower brain structures all the way to cortical regions. Specifically, in vitro cortical preparations have been extremely useful in understanding how local circuits can time. While many of these results depic...
Article
We describe a technique to semi-chronically record the cortical extracellular neural activity in the behaving monkey employing commercial high-density electrodes. After the design and construction of low cost microdrives that allows varying the depth of the recording locations after the implantation surgery, we recorded the extracellular unit activ...
Article
Full-text available
Humans possess an ability to perceive and synchronize movements to the beat in music ('beat perception and synchronization'), and recent neuroscientific data have offered new insights into this beat-finding capacity at multiple neural levels. Here, we review and compare behavioural and neural data on temporal and sequential processing during beat p...
Article
Full-text available
In the introduction to this theme issue, Honing et al. suggest that the origins of musicality-the capacity that makes it possible for us to perceive, appreciate and produce music-can be pursued productively by searching for components of musicality in other species. Recent studies have highlighted that the behavioural relevance of stimuli to animal...
Article
Full-text available
β oscillations in the basal ganglia have been associated with interval timing. We recorded the putaminal local field potentials (LFPs) from monkeys performing a synchronization-continuation task (SCT) and a serial reaction-time task (RTT), where the animals produced regularly and irregularly paced tapping sequences, respectively. We compared the ac...
Article
We determined the response properties of neurons in the primate medial premotor cortex that were classified as sensory or motor during isochronous tapping to a visual or auditory metronome, using different target intervals and three sequential elements in the task. The cell classification was based on a warping transformation, which determined whet...
Article
Full-text available
The gradual audiomotor evolution hypothesis is proposed as an alternative interpretation to the auditory timing mechanisms discussed in Ackermann et al.'s article. This hypothesis accommodates the fact that the performance of nonhuman primates is comparable to humans in single-interval tasks (such as interval reproduction, categorization, and inter...
Article
Time is a fundamental variable that organisms must quantify in order to survive. In humans, for example, the gradual development of the sense of duration and rhythm is an essential skill in many facets of social behavior such as speaking, dancing to-, listening to- or playing music, performing a wide variety of sports, and driving a car (Merchant H...
Article
The precise quantification of time in the subsecond scale is critical for many complex behaviors including music and dance appreciation/execution, speech comprehension/articulation, and the performance of many sports. Nevertheless, its neural underpinnings are largely unknown. Recent neurophysiological experiments from our laboratory have shown tha...
Article
Full-text available
We determined the encoding properties of single cells and the decoding accuracy of cell populations in the medial premotor cortex (MPC) of Rhesus monkeys to represent in a time-varying fashion the duration and serial order of six intervals produced rhythmically during a synchronization-continuation tapping task. We found that MPC represented the te...
Article
Full-text available
Traditionally, the neurophysiological mechanisms of cognitive processing have been investigated at the single cell level. Here we show that the dynamic, millisecond-by-millisecond, interactions between neuronal events measured by local field potentials are modulated in an orderly fashion by key task variables of a space categorization task performe...
Article
Full-text available
It has been argued that perception, decision making, and movement planning are in reality tightly interwoven brain processes. However, how they are implemented in neural circuits is still a matter of debate. We tested human subjects in a temporal categorization task in which intervals had to be categorized as short or long. Subjects communicated th...
Book
How the brain processes temporal information is a fundamental question relevant to systems, cellular, computational, and cognitive neuroscience, as well as to the psychophysics of music and language. During the last and present decades, interval timing has been intensively studied in humans and animals with a variety of methodological approaches. T...
Article
Full-text available
Gamma (γ) and beta (β) oscillations seem to play complementary functions in the cortico-basal ganglia-thalamo-cortical circuit (CBGT) during motor behavior. We investigated the time-varying changes of the putaminal spiking activity and the spectral power of local field potentials (LFPs) during a task where the rhythmic tapping of monkeys was guided...
Article
Full-text available
A critical question in tapping behavior is to understand whether the temporal control is exerted on the duration and trajectory of the downward-upward hand movement or on the pause between hand movements. In the present study we determined the duration of both the movement execution and pauses of monkeys performing a synchronization-continuation ta...
Conference Paper
On the basis of previous work from our and other labs studies we propose the auditory timing dissociation hypothesis that suggests that humans share rhythm perception (or interval-based timing) with other primates, but where rhythmic entrainment (or beat-based timing) is only present in a primitive fashion in macaques and strongly present in humans...
Book
The study of how the brain processes temporal information is becoming one of the most important topics in systems, cellular, computational, and cognitive neuroscience, as well as in the physiological bases of music and language. During the last and current decade, interval timing has been intensively studied in humans and animals using increasingly...
Article
Full-text available
Understanding how sensory and motor processes are temporally integrated to control behavior in the hundredths of milliseconds-to-minutes range is a fascinating problem given that the basic electrophysiological properties of neurons operate on a millisecond timescale. Single-unit recording studies in monkeys have identified localized timing circuits...