PMID- 1127444
OWN - NLM
STAT- MEDLINE
DCOM- 19750720
LR  - 20171213
IS  - 0022-3077 (Print)
IS  - 0022-3077 (Linking)
VI  - 38
IP  - 2
DP  - 1975 Mar
TI  - Abnormal neuronal responses during evolution of a penicillin epileptic focus in 
      cat visual cortex.
PG  - 250-6
AB  - After defining the receptive fields of single units in cortical area 17 of 
      anesthetized cats, recurrent on-off stimulation with bars of light of optimal 
      configuration win from a second micropipette; Progressively, three distinct 
      alterations of neuronal activity developed. The most longlasting and usually the 
      earliest abnormality was an increase in the number and frequency of spikes 
      comprising a neuron's response to stimuli that were effective prior to 
      iontophoresis. This enhanced physiologic response (EPR) could be elicited from a 
      cell independently of the discharge activity of an induced focus, but only with 
      stimuli appropriate for the cell's receptive field. With additional iontophoresis 
      an entirely new response developed, which was consistent with an extracellular 
      paroxysmal depolarization shift (PDS). This high-frequency burst of spikes 
      appeared only in association with an ECoG interictal potential. It could be 
      triggered, however, by stimuli which were previously effective or ineffective, as 
      well as occur spontaneously. Characteristics which further distinguished the PDS 
      from EPR included a longer and more-variable latency, a longer recovery period, 
      and a different sensitivity to changes of stimulus intensity. A period of 
      response inhibition also accompanied each interictal potential and persisted with 
      a variable duration afterward. It was most noticeable as an interruption in the 
      activity of tonically responding neurons and was often present before the cell 
      began to generate PDSs. It was concluded that the EPR represents a direct effect 
      of penicillin on the cell or its immediate synaptic connections, while the PDS 
      appears dependent on the altered interactions within a population of such 
      affected cells. The inhibitory phenomenon, in addition, seems a result of 
      projected influences from cells more fully involved with the developing focus. A 
      dynamic model of the EPR-PDS relationship is proposed.
FAU - Ebersole, J S
AU  - Ebersole JS
FAU - Levine, R A
AU  - Levine RA
LA  - eng
PT  - Journal Article
PL  - United States
TA  - J Neurophysiol
JT  - Journal of neurophysiology
JID - 0375404
RN  - 0 (Penicillins)
SB  - IM
MH  - Animals
MH  - Brain Mapping
MH  - Cats
MH  - Electroencephalography
MH  - Epilepsy/*chemically induced/physiopathology
MH  - Evoked Potentials
MH  - Iontophoresis
MH  - Models, Biological
MH  - *Penicillins
MH  - Photic Stimulation
MH  - Visual Cortex/*physiopathology
MH  - Visual Fields
EDAT- 1975/03/01 00:00
MHDA- 1975/03/01 00:01
CRDT- 1975/03/01 00:00
PHST- 1975/03/01 00:00 [pubmed]
PHST- 1975/03/01 00:01 [medline]
PHST- 1975/03/01 00:00 [entrez]
AID - 10.1152/jn.1975.38.2.250 [doi]
PST - ppublish
SO  - J Neurophysiol. 1975 Mar;38(2):250-6. doi: 10.1152/jn.1975.38.2.250.