scholarly journals Reduced spiking in entorhinal cortex during the delay period of a cued spatial response task

2012 ◽  
Vol 19 (6) ◽  
pp. 219-230 ◽  
Author(s):  
K. Gupta ◽  
L. A. Keller ◽  
M. E. Hasselmo
Keyword(s):  
Entorhinal Cortex ◽  
Delay Period ◽  
Spatial Response ◽  
Response Task

Temporally Irregular Mnemonic Persistent Activity in Prefrontal Neurons of Monkeys During a Delayed Response Task

2003 ◽  
Vol 90 (5) ◽  
pp. 3441-3454 ◽  
Author(s):  
Albert Compte, ◽  
Christos Constantinidis ◽  
Jesper Tegnér ◽  
Sridhar Raghavachari ◽  
Matthew V. Chafee ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Power Spectrum ◽  
Spike Train ◽  
Temporal Structure ◽  
Spike Trains ◽  
Delay Period ◽  
Delayed Response ◽  
Persistent Activity ◽  
Response Task ◽  
Delayed Response Task

An important question in neuroscience is whether and how temporal patterns and fluctuations in neuronal spike trains contribute to information processing in the cortex. We have addressed this issue in the memory-related circuits of the prefrontal cortex by analyzing spike trains from a database of 229 neurons recorded in the dorsolateral prefrontal cortex of 4 macaque monkeys during the performance of an oculomotor delayed-response task. For each task epoch, we have estimated their power spectrum together with interspike interval histograms and autocorrelograms. We find that 1) the properties of most (about 60%) neurons approximated the characteristics of a Poisson process. For about 25% of cells, with characteristics typical of interneurons, the power spectrum showed a trough at low frequencies (<20 Hz) and the autocorrelogram a dip near zero time lag. About 15% of neurons had a peak at <20 Hz in the power spectrum, associated with the burstiness of the spike train; 2) a small but significant task dependency of spike-train temporal structure: delay responses to preferred locations were characterized not only by elevated firing, but also by suppressed power at low (<20 Hz) frequencies; and 3) the variability of interspike intervals is typically higher during the mnemonic delay period than during the fixation period, regardless of the remembered cue. The high irregularity of neural persistent activity during the delay period is likely to be a characteristic signature of recurrent prefrontal network dynamics underlying working memory.

Activity of hippocampal formation neurons in the monkey related to a conditional spatial response task

1989 ◽  
Vol 61 (3) ◽  
pp. 669-678 ◽  
Author(s):  
Y. Miyashita ◽  
E. T. Rolls ◽  
P. M. Cahusac ◽  
H. Niki ◽  
J. D. Feigenbaum
Keyword(s):  
Visual Stimulus ◽  
Rhesus Monkeys ◽  
Hippocampal Neurons ◽  
Hippocampal Formation ◽  
Visual Stimuli ◽  
Video Monitor ◽  
Stimulus Response ◽  
Spatial Response ◽  
The Mean ◽  
Response Task

To analyze neurophysiologically the functions of the primate hippocampus, the activity of 905 single hippocampal formation neurons was analyzed in two rhesus monkeys performing a conditional spatial response task known to be impaired in monkeys and in man by damage to the hippocampus or fornix. In the task, the monkey learned to make one spatial response, touching a screen three times when he saw one visual stimulus on the video monitor, and a different spatial response, of withdrawing his hand from the screen, when a different visual stimulus was shown. Fourteen percent of the neurons fired differentially to one or the other of the stimulus-spatial response associations. The mean latency of these differential responses was 154 +/- 44 (SD) ms. The firing of these neurons was shown to reflect a combination of the particular stimulus and the particular response associated by learning in the stimulus-response association task and could not be accounted for by the motor requirements of the task, nor wholly the stimulus aspects of the task, as demonstrated by testing their firing in related visual discrimination tasks. Responsive neurons were found throughout the hippocampal formation, but were particularly concentrated in the subicular complex and the CA3 subfield. These results show that single hippocampal neurons respond to combinations of the visual stimuli and the spatial responses with which they must become associated in conditional spatial response tasks and are consistent with the suggestion that part of the mechanism of this learning involves associations between visual stimuli and spatial responses learned by single hippocampal neurons.

Attenuation of Delay-Period Activity of Monkey Prefrontal Neurons by an α2-Adrenergic Antagonist During an Oculomotor Delayed-Response Task

1998 ◽  
Vol 80 (4) ◽  
pp. 2200-2205 ◽  
Author(s):  
T. Sawaguchi
Keyword(s):  
Working Memory ◽  
Target Location ◽  
Spatial Working Memory ◽  
Delay Period ◽  
Delayed Response ◽  
Peripheral Cues ◽  
Adrenergic Antagonist ◽  
Neuronal Processes ◽  
Response Task ◽  
Delayed Response Task

Sawaguchi, T. Attenuation of delay-period activity of monkey prefrontal neurons by an α2-adrenergic antagonist during an oculomotor delayed-response task. J. Neurophysiol. 80: 2200–2205, 1998. To examine the role of norepinephrine receptors in spatial working memory processes mediated by the prefrontal cortex (PFC), noradrenergic antagonists (yohimbine for α2, prazosin for α1, and propranolol for β receptors) were applied iontophoretically to neurons of the dorsolateral PFC in rhesus monkeys that performed an oculomotor delayed-response (ODR) task. The ODR task was initiated when the monkeys fixated on a central spot on a computer monitor and consisted of fixation (1 s), cue (1 of 4 peripheral cues, 0.5 s), delay (fixation cue only, 4 s), and go periods. In the go period, the subject made a memory-guided saccade to the target location that was cued before the delay period. I focused on 49 neurons that showed directional delay-period activity, i.e., a sustained increase in activity during the delay period, the magnitude of which varied significantly with the memorized target location. Iontophoretic (usually 50 nA) application of yohimbine, but not prazosin or propranolol, significantly decreased the activities of most of the neurons with directional delay-period activity ( n = 41/49, 81%). Furthermore, yohimbine attenuated the sharpness of tuning, examined by a tuning index, of delay-period activity and had a greater attenuating effect on delay-period activity than on background activity. These findings suggest that the activation of α2-adrenergic receptors in the dorsolateral PFC plays a modulatory role in neuronal processes for visuospatial working memory.

scholarly journals Parallel processing of working memory and temporal information by distinct types of cortical projection neurons

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jung Won Bae ◽  
Huijeong Jeong ◽  
Young Ju Yoon ◽  
Chan Mee Bae ◽  
Hyeonsu Lee ◽  
...  
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Delay Period ◽  
Temporal Information ◽  
Projection Neurons ◽  
Delayed Response ◽  
Subcortical Structures ◽  
Cortical Projection ◽  
Different Types ◽  
Response Task

AbstractIt is unclear how different types of cortical projection neurons work together to support diverse cortical functions. We examined the discharge characteristics and inactivation effects of intratelencephalic (IT) and pyramidal tract (PT) neurons—two major types of cortical excitatory neurons that project to cortical and subcortical structures, respectively—in the deep layer of the medial prefrontal cortex in mice performing a delayed response task. We found stronger target-dependent firing of IT than PT neurons during the delay period. We also found the inactivation of IT neurons, but not PT neurons, impairs behavioral performance. In contrast, PT neurons carry more temporal information than IT neurons during the delay period. Our results indicate a division of labor between IT and PT projection neurons in the prefrontal cortex for the maintenance of working memory and for tracking the passage of time, respectively.

Selection and Maintenance of Saccade Goals in the Human Frontal Eye Fields

2006 ◽  
Vol 95 (6) ◽  
pp. 3923-3927 ◽  
Author(s):  
Clayton E. Curtis ◽  
Mark D'Esposito
Keyword(s):  
Working Memory ◽  
Spatial Working Memory ◽  
Response Selection ◽  
Delay Period ◽  
Delayed Response ◽  
Frontal Eye Fields ◽  
Motor Processing ◽  
Visual Encoding ◽  
Prospective Coding ◽  
Response Task

In a delayed-response task, response selection marks an important transition from sensory to motor processing. Using event-related functional magnetic resonance imaging, we imaged the human brain during performance of a novel delayed-saccade task that isolated response selection from visual encoding and motor execution. The frontal eye fields (FEFs) and intraparietal sulcus (IPS) both showed robust contra-lateralized activity time-locked to response selection. Moreover, response selection affected delay-period activity differently in these regions; it persisted throughout the memory delay period following response selection in the FEF but not IPS. Our results indicate that the FEF and IPS both make important but distinct contributions to spatial working memory. The mechanism that the FEF uses to support spatial working memory is tied to the selection and prospective coding of saccade goals, whereas the role of the IPS may be more tied to retrospective coding of sensory representations.

scholarly journals Modification of the responses of hippocampal neurons in the monkey during the learning of a conditional spatial response task

Hippocampus ◽  
1993 ◽  
Vol 3 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Peter M. B. Cahusac ◽  
Edmund T. Rolls ◽  
Yasushi Miyashita ◽  
Hiroaki Niki
Keyword(s):  
Hippocampal Neurons ◽  
Spatial Response ◽  
Response Task

Mnemonic coding of visual space in the monkey's dorsolateral prefrontal cortex

1989 ◽  
Vol 61 (2) ◽  
pp. 331-349 ◽  
Author(s):  
S. Funahashi ◽  
C. J. Bruce ◽  
P. S. Goldman-Rakic
Keyword(s):  
Prefrontal Cortex ◽  
Visual Field ◽  
Visual Cues ◽  
Visual Space ◽  
Delay Period ◽  
Delayed Response ◽  
Oculomotor Behavior ◽  
Dorsolateral Prefrontal ◽  
Excitatory Responses ◽  
Response Task

1. An oculomotor delayed-response task was used to examine the spatial memory functions of neurons in primate prefrontal cortex. Monkeys were trained to fixate a central spot during a brief presentation (0.5 s) of a peripheral cue and throughout a subsequent delay period (1-6 s), and then, upon the extinction of the fixation target, to make a saccadic eye movement to where the cue had been presented. Cues were usually presented in one of eight different locations separated by 45 degrees. This task thus requires monkeys to direct their gaze to the location of a remembered visual cue, controls the retinal coordinates of the visual cues, controls the monkey's oculomotor behavior during the delay period, and also allows precise measurement of the timing and direction of the relevant behavioral responses. 2. Recordings were obtained from 288 neurons in the prefrontal cortex within and surrounding the principal sulcus (PS) while monkeys performed this task. An additional 31 neurons in the frontal eye fields (FEF) region within and near the anterior bank of the arcuate sulcus were also studied. 3. Of the 288 PS neurons, 170 exhibited task-related activity during at least one phase of this task and, of these, 87 showed significant excitation or inhibition of activity during the delay period relative to activity during the intertrial interval. 4. Delay period activity was classified as directional for 79% of these 87 neurons in that significant responses only occurred following cues located over a certain range of visual field directions and were weak or absent for other cue directions. The remaining 21% were omnidirectional, i.e., showed comparable delay period activity for all visual field locations tested. Directional preferences, or lack thereof, were maintained across different delay intervals (1-6 s). 5. For 50 of the 87 PS neurons, activity during the delay period was significantly elevated above the neuron's spontaneous rate for at least one cue location; for the remaining 37 neurons only inhibitory delay period activity was seen. Nearly all (92%) neurons with excitatory delay period activity were directional and few (8%) were omnidirectional. Most (62%) neurons with purely inhibitory delay period activity were directional, but a substantial minority (38%) was omnidirectional. 6. Fifteen of the neurons with excitatory directional delay period activity also had significant inhibitory delay period activity for other cue directions. These inhibitory responses were usually strongest for, or centered about, cue directions roughly opposite those optimal for excitatory responses.(ABSTRACT TRUNCATED AT 400 WORDS)

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