scholarly journals Rapid, Experience-Induced Enhancement in Odorant Discrimination by Anterior Piriform Cortex Neurons

2003 ◽  
Vol 90 (1) ◽  
pp. 65-72 ◽  
Author(s):  
Donald A. Wilson
Keyword(s):  
Single Unit ◽  
Piriform Cortex ◽  
Receptive Fields ◽  
Odor Discrimination ◽  
Minimum Duration ◽  
Anterior Piriform Cortex ◽  
Single Unit Recordings ◽  
Tufted Cells ◽  
A Site ◽  
Enormous Number

Current views of odorant discrimination by the mammalian olfactory system suggest that the piriform cortex serves as a site of odor object synthesis. Given the enormous number of odorant feature combinations possible in nature, however, it seems unlikely that cortical synthetic receptive fields (RFs) are innate but rather require experience for their formation. The present experiment addressed two issues. First, we made a direct comparison of mitral/tufted cell and anterior piriform cortex (aPCX) neuron abilities to discriminate odorant mixtures from their components to further test whether aPCX neurons can treat collections of features different from the features themselves (synthetic coding). Second, we attempted to determine the minimum duration of experience necessary for formation of cortical synthetic RFs. Single-unit recordings were made from mitral/tufted cells and aPCX layer II/III neurons in urethan-anesthetized rats. Cross-habituation between novel binary mixtures and their novel components was used to determine odor discrimination abilities. The results suggest that after ≥50 s of experience with a binary mixture, aPCX neurons can discriminate the mixture from its components, whereas mitral/tufted cells cannot. However, when limited to 10 s of experience with the mixture, aPCX neurons appear similar to mitral/tufted cells and do not discriminate mixtures from components. These results suggest experience-dependent synthetic processing in aPCX and suggest an important role for perceptual learning in normal odor discrimination.

Comparison of Odor Receptive Field Plasticity in the Rat Olfactory Bulb and Anterior Piriform Cortex

2000 ◽  
Vol 84 (6) ◽  
pp. 3036-3042 ◽  
Author(s):  
Donald A. Wilson
Keyword(s):  
Receptive Field ◽  
Olfactory Bulb ◽  
Piriform Cortex ◽  
Receptive Fields ◽  
Odor Discrimination ◽  
Unit Recording ◽  
Anterior Piriform Cortex ◽  
Carbon Chains ◽  
Rapid Changes ◽  
Tufted Cells

Recent work in the anterior piriform cortex (aPCX) has demonstrated that cortical odor receptive fields are highly dynamic, showing rapid changes of both firing rate and temporal patterning within relatively few inhalations of an odor, despite relatively maintained, patterned input from olfactory bulb mitral/tufted cells. The present experiment examined the precision (odor-specificity) of this receptive field plasticity and compared it with the primary cortical afferent, olfactory bulb mitral/tufted cells. Adult Long-Evans hooded rats, urethan anesthetized and freely breathing, were used for single-unit recording from mitral/tufted and aPCX layer II/III neurons. Partial mapping of receptive fields to alkane odors (pentane, heptane, and nonane) was performed before and immediately after habituation (50-s exposure) to one of the alkanes. The results demonstrated that odor habituation of aPCX responses was odor specific, with minimal cross-habituation between alkanes differing by as few as two carbons. Mitral/tufted cells, however, showed strong cross-habituation within the odor set with the most profound cross effects to carbon chains shorter than the habituating stimulus. The results suggest that although mitral/tufted cells and aPCX neurons have roughly similar odor receptive fields, aPCX neurons have significantly better odor discrimination within their receptive field. The results have important implications for understanding the underlying bases of receptive fields in olfactory system neurons and the mechanisms of odor discrimination and memory.

scholarly journals Binaral Interactions in the Rat Piriform Cortex

1997 ◽  
Vol 78 (1) ◽  
pp. 160-169 ◽  
Author(s):  
Donald A. Wilson
Keyword(s):  
Olfactory Bulb ◽  
Piriform Cortex ◽  
Receptive Fields ◽  
Isoamyl Acetate ◽  
Response Patterns ◽  
Bilateral Stimulation ◽  
Contralateral Stimulation ◽  
Anterior Piriform Cortex ◽  
Single Unit Recordings ◽  
Ipsilateral Stimulation

Wilson, Donald A. Binaral interactions in the rat piriform cortex. J. Neurophysiol. 78: 160–169, 1997. Single-unit recordings were made from layer II/III anterior piriform cortex (aPCX) neurons in adult Wistar rats to examine odor response patterns to unilaterally and bilaterally delivered stimuli. Isoamyl acetate odor stimulation was presented either unilaterally through tubes inserted into the external nares, or bilaterally during unilateral olfactory bulb lidocaine infusions. Olfactory bulb multiunit or slow-wave activity was recorded simultaneously bilaterally to monitor selectivity of unilateral odor stimulation. The results demonstrate that 1) commissural input to aPCX neurons is sufficient to drive odor responses, and 2) aPCX neurons can be classified on the basis of spatial receptive field type. These receptive fields include cells that respond 1) selectively to ipsilateral stimulation, 2) selectively to contralateral stimulation, 3) to either ipsilateral or contralateral stimulation, and 4) selectively to bilateral stimulation. The potential functions of binaral convergence in the piriform cortex are discussed, and may include enhancement of perceived odor intensity and bilateral access to olfactory memory.

scholarly journals Olfactory Cortical Adaptation Facilitates Detection of Odors Against Background

2006 ◽  
Vol 95 (3) ◽  
pp. 1888-1896 ◽  
Author(s):  
Mikiko Kadohisa ◽  
Donald A. Wilson
Keyword(s):  
Binary Mixture ◽  
Single Unit ◽  
Piriform Cortex ◽  
Anterior Piriform Cortex ◽  
Homosynaptic Depression ◽  
Background Stimulus ◽  
Background Stimulation ◽  
Receptor Neurons ◽  
Tufted Cells ◽  
Rats And Mice

Detection and discrimination of odors generally, if not always, occurs against an odorous background. On any given inhalation, olfactory receptor neurons will be activated by features of both the target odorant and features of background stimuli. To identify a target odorant against a background therefore, the olfactory system must be capable of grouping a subset of features into an odor object distinct from the background. Our previous work has suggested that rapid homosynaptic depression of afferents to the anterior piriform cortex (aPCX) contributes to both cortical odor adaptation to prolonged stimulation and habituation of simple odor-evoked behaviors. We hypothesize here that this process may also contribute to figure-ground separation of a target odorant from background stimulation. Single-unit recordings were made from both mitral/tufted cells and aPCX neurons in urethan-anesthetized rats and mice. Single-unit responses to odorant stimuli and their binary mixtures were determined. One of the odorants was randomly selected as the background and presented for 50 s. Forty seconds after the onset of the background stimulus, the second target odorant was presented, producing a binary mixture. The results suggest that mitral/tufted cells continue to respond to the background odorant and, when the target odorant is presented, had response magnitudes similar to that evoked by the binary mixture. In contrast, aPCX neurons filter out the background stimulus while maintaining responses to the target stimulus. Thus the aPCX acts as a filter driven most strongly by changing stimuli, providing a potential mechanism for olfactory figure-ground separation and selective reading of olfactory bulb output.

Habituation of Odor Responses in the Rat Anterior Piriform Cortex

1998 ◽  
Vol 79 (3) ◽  
pp. 1425-1440 ◽  
Author(s):  
Donald A. Wilson
Keyword(s):  
Olfactory Bulb ◽  
Respiration Rate ◽  
Single Unit ◽  
Piriform Cortex ◽  
Firing Frequency ◽  
Respiratory Cycle ◽  
Intracellular Recordings ◽  
Main Olfactory Bulb ◽  
Anterior Piriform Cortex ◽  
Initial Basis

Wilson, Donald A. Habituation of odor responses in the rat anterior piriform cortex. J. Neurophysiol. 79: 1425–1440, 1998. Simultaneous recordings of main olfactory bulb (MOB) and anterior piriform cortex (aPCX) neuron responses to repeated and prolonged odor pulses were examined in freely breathing, urethan-anesthetized rats. Comparisons of odor responses were made between multi-unit recordings of MOB activity and single-unit extracellular and intracellular recordings of Layer II/III aPCX neurons. Odor stimuli consisted of either 2-s pulses repeated at 30-s intervals or a single, prolonged 50-s stimulus. Respiration rate was monitored throughout. MOB and aPCX neuron responses to odor were quantified both through firing frequency and through the temporal patterning of firing over the respiratory cycle. The results demonstrate that aPCX neurons habituate significantly more (faster) than MOB neurons with both repeated and prolonged stimulation paradigms. This enhanced habituation is expressed as both a decrease in aPCX firing despite maintained odor-evoked MOB input and as a decrease in aPCX respiratory cycle entrainment despite maintained MOB cyclic input. Intracellular aPCX recordings suggest that several mechanisms may be involved in this experience-induced change in aPCX function, including 1) decreased excitatory driveof aPCX neurons, 2) decreased excitability of aPCX neurons,and/or 3) enhancement in odor-evoked inhibition of aPCX neurons. These studies provide the initial basis for understanding the mechanisms of nonassociative plasticity in olfactory cortex.

Whisker Trimming Begun at Birth or on Postnatal Day 12 Affects Excitatory and Inhibitory Receptive Fields of Layer IV Barrel Neurons

2005 ◽  
Vol 94 (6) ◽  
pp. 3987-3995 ◽  
Author(s):  
Michael Shoykhet ◽  
Peter W. Land ◽  
Daniel J. Simons
Keyword(s):  
Single Unit ◽  
Sensory Deprivation ◽  
Receptive Fields ◽  
Sensory Information ◽  
Developmental Period ◽  
Total Effect ◽  
Evoked Responses ◽  
Behavioral Deficits ◽  
Single Unit Recordings

In rats, whisker trimming during development leads to persistent alterations in the function of cortical barrel circuits and to behavioral deficits later in life. Here we examined how whisker trimming begun either at birth (P0) or on postnatal day 12 (P12), around the onset of whisking behavior, affects receptive fields of layer IV barrel neurons. All whiskers on the left face were trimmed for 40–45 days and then allowed to regrow fully. Extracellular single-unit recordings and controlled deflections of principal and adjacent whiskers (PW and AW, respectively), individually or in paired combinations, were used to assess excitatory and suppressive effects of neighboring whiskers on barrel neurons. Results indicate that whisker trimming both from P0 and P12 leads to enlarged excitatory and weakened inhibitory receptive fields in layer IV neurons. PW- and AW-evoked responses are larger in magnitude in trimmed than in control animals; AW-evoked responses are disproportionately affected, decreasing the spatial focus of barrel neurons. Deprivation after P12 accounts for ∼50% of the total effect observed in P0 trimmed animals. Suppressive interactions, evoked by two whiskers deflected in succession, are weaker in trimmed than in control animals. Suppressive caudal/rostral and ventral/dorsal gradients, however, seem unaffected by sensory deprivation. Thus the developmental period during which experience persistently modifies maturing barrel circuitry extends up to and likely beyond the onset of whisking behavior. Sensory deprivation during this time affects development of both excitatory and inhibitory receptive fields of barrel neurons and likely impairs cortical integration of sensory information from multiple whiskers.

Sources of the Scalp-Recorded Amplitude-Modulation Following Response

2002 ◽  
Vol 13 (04) ◽  
pp. 188-204 ◽  
Author(s):  
Shigeyuki Kuwada ◽  
Julia S. Anderson ◽  
Ranjan Batra ◽  
Douglas C. Fitzpatrick ◽  
Natacha Teissier ◽  
...  
Keyword(s):  
Animal Model ◽  
Amplitude Modulation ◽  
Single Unit ◽  
Modulation Frequency ◽  
Multiple Sources ◽  
High Modulation ◽  
Before And After ◽  
Single Unit Recordings ◽  
Composite Response ◽  
The Brain

The scalp-recorded amplitude-modulation following response (AMFR)” is gaining recognition as an objective audiometric tool, but little is known about the neural sources that underlie this potential. We hypothesized, based on our human studies and single-unit recordings in animals, that the scalp-recorded AMFR reflects the interaction of multiple sources. We tested this hypothesis using an animal model, the unanesthetized rabbit. We compared AMFRs recorded from the surface of the brain at different locations and before and after the administration of agents likely to enhance or suppress neural generators. We also recorded AMFRs locally at several stations along the auditory neuraxis. We conclude that the surface-recorded AMFR is indeed a composite response from multiple brain generators. Although the response at any modulation frequency can reflect the activity of more than one generator, the AMFRs to low and high modulation frequencies appear to reflect a strong contribution from cortical and subcortical sources, respectively.

scholarly journals Duplicate Detection of Spike Events: A Relevant Problem in Human Single-Unit Recordings

2021 ◽  
Vol 11 (6) ◽  
pp. 761
Author(s):  
Gert Dehnen ◽  
Marcel S. Kehl ◽  
Alana Darcher ◽  
Tamara T. Müller ◽  
Jakob H. Macke ◽  
...  
Keyword(s):  
Data Quality ◽  
Single Unit ◽  
Human Subjects ◽  
External Noise ◽  
Hospital Environment ◽  
Noise Sources ◽  
Recording Channels ◽  
Waveform Similarity ◽  
Therapeutic Procedures ◽  
Single Unit Recordings

Single-unit recordings in the brain of behaving human subjects provide a unique opportunity to advance our understanding of neural mechanisms of cognition. These recordings are exclusively performed in medical centers during diagnostic or therapeutic procedures. The presence of medical instruments along with other aspects of the hospital environment limit the control of electrical noise compared to animal laboratory environments. Here, we highlight the problem of an increased occurrence of simultaneous spike events on different recording channels in human single-unit recordings. Most of these simultaneous events were detected in clusters previously labeled as artifacts and showed similar waveforms. These events may result from common external noise sources or from different micro-electrodes recording activity from the same neuron. To address the problem of duplicate recorded events, we introduce an open-source algorithm to identify these artificial spike events based on their synchronicity and waveform similarity. Applying our method to a comprehensive dataset of human single-unit recordings, we demonstrate that our algorithm can substantially increase the data quality of these recordings. Given our findings, we argue that future studies of single-unit activity recorded under noisy conditions should employ algorithms of this kind to improve data quality.

A device enabling single unit recordings during head movements in cats

1982 ◽  
Vol 8 (4) ◽  
pp. 443-444 ◽  
Author(s):  
J.S. Schneider ◽  
A.A. Castaldi ◽  
T.I. Lidsky
Keyword(s):  
Single Unit ◽  
Head Movements ◽  
Single Unit Recordings
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