Bruss Lima

Bruss Lima
Federal University of Rio de Janeiro | UFRJ · Instituto de Biofísica Carlos Chagas Filho (IBCCF)

Professor

About

104
Publications
7,216
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Introduction
I am interested in visual processing and behavior in non-human and human primates. I employ multi-electrode electrophysiological recordings to study the dynamic mechanisms integrating distributed neuronal populations. I am particularly interested in the attentional and anticipatory processes that underlie and coordinate perception.
Skills and Expertise

Publications

Publications (104)
Article
Full-text available
Circuits of excitatory and inhibitory neurons generate gamma-rhythmic activity (30–80 Hz). Gamma-cycles show spontaneous variability in amplitude and duration. To investigate the mechanisms underlying this variability, we recorded local-field-potentials (LFPs) and spikes from awake macaque V1. We developed a noise-robust method to detect gamma-cycl...
Article
Full-text available
A general assumption in visual neuroscience is that basic receptive field properties such as orientation and direction selectivity are constructed within intrinsic neuronal circuits and feedforward projections. In addition, it is assumed that general neuronal excitability and responsiveness in early visual areas is to a great extent independent of...
Article
Full-text available
A general assumption in visual neuroscience is that basic receptive field properties such as orientation and direction selectivity are constructed within intrinsic neuronal circuits and feedforward projections. Additionally, it is assumed that general neuronal excitability and responsiveness in early visual areas is to a great extent independent of...
Article
Monkeys with selective bilateral lesions of area MT were trained on tasks designed to examine visuomotor function. They were required to: 1- retrieve a small food pellet from a narrow slot; 2- locate and retrieve a loose peanut mounted on a background of fixed peanuts; and 3- retrieve an erratically moving food pellet from a spinning bowl. After th...
Article
Full-text available
We studied the multiunit responses to moving and static stimuli from 585 cell clusters in area MT using multi-electrode arrays. Our aim was to explore if MT columns exhibit any larger-scale tangential organization or clustering based on their response properties. Neurons showing both motion and orientation selectivity were classified into four cate...
Article
Full-text available
Cortical computation depends on interactions between excitatory and inhibitory neurons. The contributions of distinct neuron types to sensory processing and network synchronization in primate visual cortex remain largely undetermined. We show that in awake monkey V1, there exists a distinct cell type (››30% of neurons) that has narrow-waveform (NW)...
Preprint
Full-text available
Communication among visual cortical areas depends on gamma oscillations. Respective gamma cycles vary substantially in amplitude and duration, yet it is unclear how those fundamental parameters relate to each other and to spiking activity. We recorded local-field-potentials (LFPs) and spiking activity from awake macaque area V1 and detected amplitu...
Article
In the present study, we investigated motor cortex (M1) and a small portion of premotor and parietal cortex using intracortical microstimulation in anesthetized capuchin monkeys. Capuchins are the only New World monkeys that have evolved an opposable thumb and use tools in the wild. Like most Old World monkeys and humans, capuchin monkeys have high...
Article
Full-text available
Hemodynamic recordings from visual cortex contain powerful endogenous task-related responses that may reflect task-related arousal, or “task engagement” distinct from attention. We tested this hypothesis with hemodynamic measurements (intrinsic-signal optical imaging) from monkey primary visual cortex (V1) while the animals’ engagement in a periodi...
Data
Increase in temporal precision with reward size is not sensitive to the choice of template used to estimate response time and amplitude. (a-d) Same example data set as in Figs 2 and 3. (a) Orange indicates the alternate template defined as the mean hemodynamic response across correct trials, aligned to a time point one-quarter cycle ahead of trial...
Data
High reward does not correlate with tighter eye movements. (a1) Mean radial eye movement per intertrial interval in an early recording session. Each dot represents a single trial (mean eye movement during 7-second intertrial intervals per 9-second trial). Horizontal lines indicate median eye movement per block of high or low reward (blocks with var...
Data
Data for “Hi–Lo” reward pupil dilation histograms in Fig 1B. (XLSX)
Data
Local spiking, although appearing to predict mean hemodynamic responses in individual recording conditions, is a poor and unreliable predictor of task-related responses overall. (a,b) Mean measured responses and optimal predictions for low-reward and high-reward trials, respectively, of a data set recorded in the dark-room task. In each case, the l...
Data
Response timing does not correlate with fixation onset. (a) Simulation of the null hypothesis. The task-related response has a stereotyped time course following the onset of fixation. Response times would then have a constant delay following fix onset, leading to a linear relation between the two with unity slope (the delay was taken to be 10 secon...
Data
Comparing regression lines through alternating blocks of high and low reward, before (top panel) and after (bottom panel) removing error trials. Color coding for high (red) and low reward (cyan) is the same as in the main text. Error trials are indicated in lighter colors and are grouped with the reward block corresponding to the immediately preced...
Data
Data for “Eye Pos” traces in Fig 1B. (XLSX)
Data
Estimating task-related response and its template match in the presence of visual stimulation (one example data set). (a-c) Estimating optimal fitted parameters (see Methods, Eqs 4–6). (a) The mean hemodynamic response per stimulus contrast (see key), averaged across trials. The response is modeled as the sum of the stimulus-evoked component (b) an...
Data
Ramp-like drifts in local blood volume are not accounted for by slow changes in local spiking. (a, c) Hemodynamics and spiking, respectively, showing correct trials from alternating blocks of high and low reward. Lines show regression fits per block (same data set as Figs 2 and 3). (b, d) Histograms with slopes of regression fits from (a), (c). (e)...
Data
Deconvolution fit of the same data segment as in Fig 8A but with no intercept term in the design matrix. The full prediction here matches the measured response reasonably well except for a few locations with large mismatches (black arrowheads; compare with the same locations in Fig 8A). The overall goodness of fit R2 = 0.76, averaged over this rest...
Preprint
Full-text available
Hemodynamic recordings from visual cortex contain powerful endogenous task-related responses that may reflect task-engagement distinct from attention. We tested this hypothesis with hemodynamic measurements (intrinsic-signal optical imaging) from monkey V1, while the animals’ engagement in a periodic fixation task over several hours was varied thou...
Article
Cytochrome oxidase histochemistry reveals large‐scale cortical modules in area V2 of primates known as thick, thin and interstripes. Anatomical, electrophysiological and tracing studies suggest that V2 cytochrome oxidase stripes participate in functionally distinct streams of visual information processing. However, there is controversy whether the...
Article
Full-text available
We studied the tangential distribution of cytochrome oxidase (CytOx)‐rich patches (blobs) in the striate cortex (V1) of normally sighted Homo sapiens. We analyzed the spatial density and cross‐sectional area of patches in CytOx‐reacted tangential sections of flat‐mounted preparations of V1 and surrounding areas. CytOx‐rich patches were most clearly...
Article
We propose a partitioning of the primate intraparietal sulcus (IPS) using immunoarchitectural and connectivity criteria. We studied the immunoarchitecture of the IPS areas in the capuchin monkey using Cat‐301 and SMI‐32 immunohistochemistry. In addition, we investigated the IPS projections to areas V4, TEO, PO and MT using retrograde tracer injecti...
Chapter
Cytochemical and immunocytochemical methods reveal details of the pulvinar architecture that are not apparent from Nissl and myelin staining. The results of these techniques have been interpreted in different ways by different investigators, each adopting different sets of nomenclature for the various pulvinar subdivisions. In this chapter, we disc...
Chapter
The pulvinar receives direct visual information from the retina and indirect visual information from several cortical and subcortical areas. In this chapter, we discuss the visuotopic organization of the primate pulvinar. Electrophysiological techniques have been systematically employed to study pulvinar visuotopy in the owl, capuchin, and macaque...
Chapter
Pulvinar connectivity has been studied using a variety of neuroanatomical tracing techniques in both New and Old World monkeys. Connectivity studies have revealed additional maps of the visual field other than those described using electrophysiological techniques, such as P3 in the capuchin monkey and P3/P4 in the macaque monkey. In this chapter, w...
Chapter
In this chapter, we describe the visuotopy of the pulvinar subdivisions P1, P2, and P4. In all primates, P1 colocalizes with the chemoarchitecturally defined PI and a small portion of PL. The peripheral visual field is represented anteriorly in the medial portion of PI, while central vision is represented more posteriorly in the medial portion of P...
Chapter
Full-text available
In this chapter, we compare the pattern of pulvinar immunohistochemical staining for the calcium-binding proteins calbindin and parvalbumin and for the neurofilament protein SMI-32 in macaque, capuchin, and squirrel monkeys. This group of New and Old World primates shares five similar pulvinar subdivisions: PIP, PIM, PIC, PIL, and PILS. In the Old...
Chapter
In this chapter, we discuss the effects of GABA (gamma-aminobutyric acid) inactivation of the pulvinar on the electrophysiological responses to visual stimuli. A direct way to access the pulvinar-cortical interaction is to pharmacologically inactivate the pulvinar and measure the impact on cortical activity. To this aim, we have focused our efforts...
Chapter
In this chapter, we discuss the modulation of pulvinar neuronal activity by arousal. In contrast to electrophysiological recordings in the early visual cortex, neuronal activity in the pulvinar is particularly sensitive to anesthesia. In the absence of sensory stimulation, pulvinar neurons can be characterized by spontaneous low-frequency rhythmic...
Chapter
In this chapter, we discuss the types of visual receptive fields revealed by single-unit electrophysiological recordings in the pulvinar. Nearly all neurons with identifiable receptive fields responded to visual stimulation presented on the contralateral hemifield, within 25° of the fovea. The majority of the visual neurons responded to some form o...
Chapter
In this chapter, we discuss the poor agreement between visuotopic maps described using electrophysiological and connectivity data and the subdivisions of the pulvinar based on chemoarchitecture. We focus on the differences and similarities between New and Old World monkeys to evaluate how this agreement evolved during evolution. There is some agree...
Chapter
In this chapter, we discuss the different ways in which the primate pulvinar has been subdivided, based on cytoarchitectural and myeloarchitectural criteria. One original criterion, based on cytoarchitecture, subdivided the pulvinar into nucleus pulvinaris medialis (PM), nucleus pulvinaris lateralis (PL), and nucleus pulvinaris inferior (PI). Later...
Chapter
This chapter deals with the role of the pulvinar in spatial visual attention. There are at least two aspects in which the pulvinar seems to be instrumental for selective visual processes. The first aspect concerns pulvinar connectivity pattern. The pulvinar is connected with brain regions known to be playing a role in attentional mechanisms, such a...
Book
This book discusses the hypothesis that the primate pulvinar contains an original scaffold which is derived from cytoarchitectural markers and specific protein distributions. Thereafter, along primate evolution, different selective pressures acted in order to shape and fine-tune the connectivity of the pulvinar with specific regions of the neocorte...
Preprint
To investigate the contribution of the feedback circuits from areas MT and V4 and from the pulvinar to the receptive field properties of cells in visual area V2 in anesthetized and paralyzed Cebus apella monkeys. We recorded extracellular single unit activity using tungsten microelectrodes in five monkeys before and after pressure-injection of a 0....
Article
Task-related hemodynamic responses contribute prominently to functional magnetic resonance imaging (fMRI) recordings. They reflect behaviorally important brain states, such as arousal and attention, and can dominate stimulus-evoked responses, yet they remain poorly understood. To help characterize these responses, we present a method for parametric...
Preprint
Full-text available
Sensory cortices represent the world through the activity of diversely tuned cells. How the activity of single cells is coordinated within populations and across sensory hierarchies is largely unknown. Cortical oscillations may coordinate local and distributed neuronal groups. Using datasets from intracortical multi-electrode recordings and from la...
Article
Full-text available
Anatomical and electrophysiological studies have provided us with detailed information regarding the extent and topography of the primary (V1) and secondary (V2) visual areas in primates. The consensus about the V1 and V2 maps, however, is in sharp contrast with controversies regarding the organization of the cortical areas lying immediately rostra...
Article
Full-text available
The optic disk is a region of the retina consisting mainly of ganglion cell axons and blood vessels, which generates a visual scotoma known as the blind spot (BS). Information present in the surroundings of the BS can be used to complete the missing information. However, the neuronal mechanisms underlying these perceptual phenomena are poorly under...
Article
The implicit goal of functional magnetic resonance imaging is to infer local neural activity. There is considerable debate, however, as to whether imaging correlates most linearly with local spiking or some local field potential (LFP) measurement. Through simultaneous neuroimaging (intrinsic-signal optical imaging) and electrode recordings from ale...
Article
Full-text available
Neuroimaging (for example, functional magnetic resonance imaging) signals are taken as a uniform proxy for local neural activity. By simultaneously recording electrode and neuroimaging (intrinsic optical imaging) signals in alert, task-engaged macaque visual cortex, we recently observed a large anticipatory trial-related neuroimaging signal that wa...
Article
Full-text available
Even in V1, where neurons have well characterized classical receptive fields (CRFs), it has been difficult to deduce which features of natural scenes stimuli they actually respond to. Forward models based upon CRF stimuli have had limited success in predicting the response of V1 neurons to natural scenes. As natural scenes exhibit complex spatial a...
Data
Varying aperture mask size. The percentage of the PSTH that was statistically different (at 95% confidence levels) between FF and AM movies (upper panel) and the normalized difference in time varying firing rates (lower panel) for different sized apertures. There are (38, 13 38, 38, 38, 19) neurons for the (30, 50, 70, 100, 150, 200 pixel) diameter...
Data
Comparing differences between the PSTHs as a function of eccentricity (2-5 degrees versus 10-14 degrees). A) Percentage of PSTH statistically different, B) normalized difference between PSTHs, C) normalized mean firing rate difference between PSTHs. Distributions are all identical (via KS test) between 2-5 and 10-14 degrees except for the normalize...
Data
Three examples (columns) of aperture mask placement. Top row: movie frame. Second row: CRFs of multiunit activity of recording electrodes. (Example in left column records from both 2-5 degrees eccentricity and 10-14 degrees, i.e. two different electrodes). Third row: aperture masks generated on-line. Bottom row: aperture masks overlaid on CRFs. Not...
Data
Spike waveforms isolated from multiunit activity. Waveforms of the three neurons whose PSTHs are presented in the paper (Figure 1 & Figure S4) are shown in red. Grey shows non-isolated background spikes (MUA). (TIF)
Data
Quantifying spike leakage into the LFP. A) Spike triggered averages from 9 representative neurons. Dark blue: STA of original LFP, Light blue: STA of compound LFP generated using original spike times, Red: STA of compound LFP generated using altered spike times. STAs of the original and first compound LFPs are highly similar indicating that our pro...
Data
Grating stimuli drive strong oscillations that are not observed during natural scenes. A) Z-scored power spectra for LFP and B) MUA during 1.875 Hz grating stimulus (speed 1.5 degree/s and spatial frequency 1.25 cycles per degree) (green) and natural scenes movies (black). C) Frequency dependent coherence between LFP and MUA. Z-scored power spectra...
Data
“Sharp” LFP oscillations cause crosstalk between frequencies. A) sMRA of a 70 Hz sawtooth (black) involves high frequency harmonics (colored curves) to capture its “sharpness”. B) “Preferred” LFP scale phases (at which the GLM predicts the highest probability of spiking) of the 44, 89 and 178 Hz scales compared across all neurons. C) Scatterplot of...