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Spectral and Temporal Acoustic Features Modulate Response Irregularities within Primary Auditory Cortex Columns.

Carrasco A, Brown TA, Lomber SG - PLoS ONE (2014)

Bottom Line: Hence, the purpose of the present investigation was to examine the effects of sensory information features on columnar response properties.Neuronal responses to simple (pure tones), complex (noise burst and frequency modulated sweeps), and ecologically relevant (con-specific vocalizations) acoustic signals were measured.Collectively, the present investigation demonstrates that despite consistencies in neuronal tuning (characteristic frequency), irregularities in discharge activity between neurons of individual A1 columns increase as a function of spectral (signal complexity) and temporal (duration) acoustic variations.

View Article: PubMed Central - PubMed

Affiliation: Cerebral Systems Laboratory, University of Western Ontario, London, Ontario, Canada; Brain and Mind Institute, University of Western Ontario, London, Ontario, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.

ABSTRACT
Assemblies of vertically connected neurons in the cerebral cortex form information processing units (columns) that participate in the distribution and segregation of sensory signals. Despite well-accepted models of columnar architecture, functional mechanisms of inter-laminar communication remain poorly understood. Hence, the purpose of the present investigation was to examine the effects of sensory information features on columnar response properties. Using acute recording techniques, extracellular response activity was collected from the right hemisphere of eight mature cats (felis catus). Recordings were conducted with multichannel electrodes that permitted the simultaneous acquisition of neuronal activity within primary auditory cortex columns. Neuronal responses to simple (pure tones), complex (noise burst and frequency modulated sweeps), and ecologically relevant (con-specific vocalizations) acoustic signals were measured. Collectively, the present investigation demonstrates that despite consistencies in neuronal tuning (characteristic frequency), irregularities in discharge activity between neurons of individual A1 columns increase as a function of spectral (signal complexity) and temporal (duration) acoustic variations.

No MeSH data available.


Related in: MedlinePlus

Neuronal tuning within a primary auditory cortex column.Acoustic receptive fields of neurons within the cortical track highlighted in Fig. 7. Measures of characteristic frequency (CF), defined as the tone frequency that evoked a reliable response at the lowest acoustic intensity level, were conducted by an experienced observer blind to stimulus conditions. Note that CFs remain constant irrespective of cortical depth and as such provide evidence that the electrode trajectory was orthogonal to the cortical tissue.
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pone-0114550-g008: Neuronal tuning within a primary auditory cortex column.Acoustic receptive fields of neurons within the cortical track highlighted in Fig. 7. Measures of characteristic frequency (CF), defined as the tone frequency that evoked a reliable response at the lowest acoustic intensity level, were conducted by an experienced observer blind to stimulus conditions. Note that CFs remain constant irrespective of cortical depth and as such provide evidence that the electrode trajectory was orthogonal to the cortical tissue.

Mentions: Receptive field functions were constructed from neuronal responses to 2,064 frequency-intensity tonal combinations (Fig. 8). Evaluation of tuning properties revealed minor differences in CF measures (mean ± SE. 9.22 kHz±0.17 octaves) and corroborate previous reports of CF consistency within A1 columns [20]–[21], [25]–[26], [29]. Similarity in CF measures across the electrode track served as evidence that the probe was lowered orthogonal to the cortical surface. Despite differences in mean neuronal threshold values (sites 1–4: 6.72 dB SPL; sites 5–8: 11.21 dB SPL; sites 9–12: 19.63 dB SPL), mean receptive field bandwidths did not substantially change as a function of cortical depth (sites 1–4: 1.23 octaves; sites 5–8: 1.19 octaves; sites 9–12: 1.66 octaves, measured at 40 dB SPL, Fig. 8). Examination of PSTH functions generated during tonal stimulation revealed comparable response characteristics across the cortical sheet. In particular, regardless of signal duration (25 or 50 ms) or cortical depth, neuronal responses consisted of a single onset peak (Fig. 9).


Spectral and Temporal Acoustic Features Modulate Response Irregularities within Primary Auditory Cortex Columns.

Carrasco A, Brown TA, Lomber SG - PLoS ONE (2014)

Neuronal tuning within a primary auditory cortex column.Acoustic receptive fields of neurons within the cortical track highlighted in Fig. 7. Measures of characteristic frequency (CF), defined as the tone frequency that evoked a reliable response at the lowest acoustic intensity level, were conducted by an experienced observer blind to stimulus conditions. Note that CFs remain constant irrespective of cortical depth and as such provide evidence that the electrode trajectory was orthogonal to the cortical tissue.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4262427&req=5

pone-0114550-g008: Neuronal tuning within a primary auditory cortex column.Acoustic receptive fields of neurons within the cortical track highlighted in Fig. 7. Measures of characteristic frequency (CF), defined as the tone frequency that evoked a reliable response at the lowest acoustic intensity level, were conducted by an experienced observer blind to stimulus conditions. Note that CFs remain constant irrespective of cortical depth and as such provide evidence that the electrode trajectory was orthogonal to the cortical tissue.
Mentions: Receptive field functions were constructed from neuronal responses to 2,064 frequency-intensity tonal combinations (Fig. 8). Evaluation of tuning properties revealed minor differences in CF measures (mean ± SE. 9.22 kHz±0.17 octaves) and corroborate previous reports of CF consistency within A1 columns [20]–[21], [25]–[26], [29]. Similarity in CF measures across the electrode track served as evidence that the probe was lowered orthogonal to the cortical surface. Despite differences in mean neuronal threshold values (sites 1–4: 6.72 dB SPL; sites 5–8: 11.21 dB SPL; sites 9–12: 19.63 dB SPL), mean receptive field bandwidths did not substantially change as a function of cortical depth (sites 1–4: 1.23 octaves; sites 5–8: 1.19 octaves; sites 9–12: 1.66 octaves, measured at 40 dB SPL, Fig. 8). Examination of PSTH functions generated during tonal stimulation revealed comparable response characteristics across the cortical sheet. In particular, regardless of signal duration (25 or 50 ms) or cortical depth, neuronal responses consisted of a single onset peak (Fig. 9).

Bottom Line: Hence, the purpose of the present investigation was to examine the effects of sensory information features on columnar response properties.Neuronal responses to simple (pure tones), complex (noise burst and frequency modulated sweeps), and ecologically relevant (con-specific vocalizations) acoustic signals were measured.Collectively, the present investigation demonstrates that despite consistencies in neuronal tuning (characteristic frequency), irregularities in discharge activity between neurons of individual A1 columns increase as a function of spectral (signal complexity) and temporal (duration) acoustic variations.

View Article: PubMed Central - PubMed

Affiliation: Cerebral Systems Laboratory, University of Western Ontario, London, Ontario, Canada; Brain and Mind Institute, University of Western Ontario, London, Ontario, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.

ABSTRACT
Assemblies of vertically connected neurons in the cerebral cortex form information processing units (columns) that participate in the distribution and segregation of sensory signals. Despite well-accepted models of columnar architecture, functional mechanisms of inter-laminar communication remain poorly understood. Hence, the purpose of the present investigation was to examine the effects of sensory information features on columnar response properties. Using acute recording techniques, extracellular response activity was collected from the right hemisphere of eight mature cats (felis catus). Recordings were conducted with multichannel electrodes that permitted the simultaneous acquisition of neuronal activity within primary auditory cortex columns. Neuronal responses to simple (pure tones), complex (noise burst and frequency modulated sweeps), and ecologically relevant (con-specific vocalizations) acoustic signals were measured. Collectively, the present investigation demonstrates that despite consistencies in neuronal tuning (characteristic frequency), irregularities in discharge activity between neurons of individual A1 columns increase as a function of spectral (signal complexity) and temporal (duration) acoustic variations.

No MeSH data available.


Related in: MedlinePlus