Abstract
The precision of projections from dorsal thalamus to neocortex are key toward understanding overall cortical organization and function. To identify the significance of layer 4 cells in receiving the bulk of thalamic projections in somatosensory cortex, we disrupted layer 4 genesis and studied the effect on thalamic terminations in ferrets. Second, we ascertained the result of layer 4 disruption on functional responses and topographic organization. Methylazoxy methanol (MAM) was injected into pregnant ferrets on embryonic day 33 (E33), when most layer 4 neurons of somatosensory cortex are generated. This treatment resulted in dramatic reduction in the thickness of targeted layer 4. E38 MAM treatment was used as a control, when layer 2-3 neurons are generated. The projections of ventrobasal thalamus into somatosensory cortex were studied using Dil injections. We found only subtle differences between groups (normal, E33, or E38 MAM-treated) in the thalamic afferent pattern on postnatal day 1 (P1) and P7. On P14, thalamic terminations distribute almost equally throughout the remaining cortical layers in the E33 MAM-treated group compared with normal and E38 MAM-treated animals, in which the ventrobasal thalamus projects primarily to central layers. Electrophysiological recordings conducted on mature ferrets treated with MAM on E33 demonstrated that somatotopic organization and receptive field size are normal. These findings emphasize the importance of layer 4 in determining the normal laminar pattern of thalamic termination and suggest that, although its absence is likely to impact on complex neocortical functional responses, topographic organization does not arise from the influence of layer 4.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 3184-3195 |
| Number of pages | 12 |
| Journal | Journal of Neuroscience |
| Volume | 21 |
| Issue number | 9 |
| State | Published - May 1 2001 |
| Externally published | Yes |
Fingerprint
Keywords
- BrdU
- Cerebral cortex
- Development
- MAM
- Migration disorder
- Ventrobasal thalamus
ASJC Scopus subject areas
- Neuroscience(all)
Cite this
Disruption of layers 3 and 4 during development results in altered thalamocortical projections in ferret somatosensory cortex. / Noctor, Stephen C; Palmer, Sidney L.; McLaughlin, Debra F.; Juliano, Sharon L.
In: Journal of Neuroscience, Vol. 21, No. 9, 01.05.2001, p. 3184-3195.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Disruption of layers 3 and 4 during development results in altered thalamocortical projections in ferret somatosensory cortex
AU - Noctor, Stephen C
AU - Palmer, Sidney L.
AU - McLaughlin, Debra F.
AU - Juliano, Sharon L.
PY - 2001/5/1
Y1 - 2001/5/1
N2 - The precision of projections from dorsal thalamus to neocortex are key toward understanding overall cortical organization and function. To identify the significance of layer 4 cells in receiving the bulk of thalamic projections in somatosensory cortex, we disrupted layer 4 genesis and studied the effect on thalamic terminations in ferrets. Second, we ascertained the result of layer 4 disruption on functional responses and topographic organization. Methylazoxy methanol (MAM) was injected into pregnant ferrets on embryonic day 33 (E33), when most layer 4 neurons of somatosensory cortex are generated. This treatment resulted in dramatic reduction in the thickness of targeted layer 4. E38 MAM treatment was used as a control, when layer 2-3 neurons are generated. The projections of ventrobasal thalamus into somatosensory cortex were studied using Dil injections. We found only subtle differences between groups (normal, E33, or E38 MAM-treated) in the thalamic afferent pattern on postnatal day 1 (P1) and P7. On P14, thalamic terminations distribute almost equally throughout the remaining cortical layers in the E33 MAM-treated group compared with normal and E38 MAM-treated animals, in which the ventrobasal thalamus projects primarily to central layers. Electrophysiological recordings conducted on mature ferrets treated with MAM on E33 demonstrated that somatotopic organization and receptive field size are normal. These findings emphasize the importance of layer 4 in determining the normal laminar pattern of thalamic termination and suggest that, although its absence is likely to impact on complex neocortical functional responses, topographic organization does not arise from the influence of layer 4.
AB - The precision of projections from dorsal thalamus to neocortex are key toward understanding overall cortical organization and function. To identify the significance of layer 4 cells in receiving the bulk of thalamic projections in somatosensory cortex, we disrupted layer 4 genesis and studied the effect on thalamic terminations in ferrets. Second, we ascertained the result of layer 4 disruption on functional responses and topographic organization. Methylazoxy methanol (MAM) was injected into pregnant ferrets on embryonic day 33 (E33), when most layer 4 neurons of somatosensory cortex are generated. This treatment resulted in dramatic reduction in the thickness of targeted layer 4. E38 MAM treatment was used as a control, when layer 2-3 neurons are generated. The projections of ventrobasal thalamus into somatosensory cortex were studied using Dil injections. We found only subtle differences between groups (normal, E33, or E38 MAM-treated) in the thalamic afferent pattern on postnatal day 1 (P1) and P7. On P14, thalamic terminations distribute almost equally throughout the remaining cortical layers in the E33 MAM-treated group compared with normal and E38 MAM-treated animals, in which the ventrobasal thalamus projects primarily to central layers. Electrophysiological recordings conducted on mature ferrets treated with MAM on E33 demonstrated that somatotopic organization and receptive field size are normal. These findings emphasize the importance of layer 4 in determining the normal laminar pattern of thalamic termination and suggest that, although its absence is likely to impact on complex neocortical functional responses, topographic organization does not arise from the influence of layer 4.
KW - BrdU
KW - Cerebral cortex
KW - Development
KW - MAM
KW - Migration disorder
KW - Ventrobasal thalamus
UR - http://www.scopus.com/inward/record.url?scp=0035341364&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0035341364&partnerID=8YFLogxK
M3 - Article
C2 - 11312303
AN - SCOPUS:0035341364
VL - 21
SP - 3184
EP - 3195
JO - Journal of Neuroscience
JF - Journal of Neuroscience
SN - 0270-6474
IS - 9
ER -