Impairment of visual perception and visual short term memory scanning by transcranial magnetic stimulation of occipital cortex

SummaryTranscranial magnetic stimulation (TMS) of occipital cortex was performed using a magneto-electric stimulator with a maximum output of 2 Tesla in 24 normal volunteers. The identification of trigrams, presented for 14 ms in horizontal or vertical arrays was significantly impaired when the visual stimulus preceded the occipital magnetic shock by 40 to 120 ms. The extent of impairment was related to TMS intensity. The latency of perceptual impairment was shorter for more intense TMS. No perceptual impairment was obtained by “sham” stimulation when TMS shocks were applied to the upper cervical region rather than the occipital region to rule out unspecific startle reactions affecting attention possibly responsible for the observed reduction in performance. Occipital TMS did not evoke systematic eye movements except for blink responses at latencies beyond 40 ms which were too late to interfere with visual input. Depending on the required serial order of readout of the trigram perceptual impairment was more marked for the second and third part of the trigram. This demonstrates that TMS interferes with the internal serial processing of visual input. To elucidate this further, TMS was used in a Sternberg short term visual memory scanning task. TMS caused a marked decrease in memory scanning rates whereas visual stimulus encoding and storage remained unaffected when tested at various TMS delays. TMS appears to be a useful method to study processes of visual perception and short term memory handling in the occipital cortex. Advantages over classical visual masking techniques especially regarding topical localisation are discussed.

[1]  G. Mowbray,et al.  Visual Masking , 1964, Nature.

[2]  V. Hömberg,et al.  Magnetic stimulation of motor cortex and nerve roots in children. Maturation of cortico-motoneuronal projections. , 1991, Electroencephalography and clinical neurophysiology.

[3]  V. Amassian,et al.  Suppression of visual perception by magnetic coil stimulation of human occipital cortex. , 1989, Electroencephalography and clinical neurophysiology.

[4]  Silvanus Phillips Thompson,et al.  A Physiological Effect of an Alternating Magnetic Field , 1910 .

[5]  O. Creutzfeldt,et al.  Reaktionen einzelner Neurone des senso-motorischen Cortex nach elektrischen Reizen , 1956, Archiv für Psychiatrie und Nervenkrankheiten.

[6]  V. Amassian,et al.  Unmasking of visual perception by magnetic coil stimulation of human cerebral cortex , 1990 .

[7]  O. D. Creutzfeldt,et al.  Dark adaptation and receptive field organisation of cells in the cat lateral geniculate nucleus , 1977, Experimental Brain Research.

[8]  M. Turvey.  On peripheral and central processes in vision: inferences from an information-processing analysis of masking with patterned stimuli. , 1973, Psychological review.

[9]  T. Poggio,et al.  Spotlight on attention , 1985, Trends in Neurosciences.

[10]  T. Gualtierotti,et al.  Electrical stimulation of the unexposed cerebral cortex , 1954, The Journal of physiology.

[11]  K. Dunlap.  Visual Sensations from the Alternating Magnetic Field , 1911, Nature.

[12]  M. Manosevitz,et al.  High-Speed Scanning in Human Memory , 2022 .

[13]  K. Rayner,et al.  Handedness, hemispheric specialization and saccadic eye movement latencies , 1980, Neuropsychologia.

[14]  M T Turvey,et al.  Central sources of visual masking: Indexing structures supporting seeing at a single, brief glance , 1979, Psychological research.

[15]  O D Creutzfeldt,et al.  Relations between EEG phenomena and potentials of single cortical cells. I. Evoked responses after thalamic and erpicortical stimulation. , 1966, Electroencephalography and clinical neurophysiology.

[16]  S. Sternberg.  Memory Scanning: New Findings and Current Controversies , 1975 .

[17]  S. Ueno,et al.  Magnetic Stimulation of the Human Brain , 1992, Annals of the New York Academy of Sciences.

[18]  V E Amassian,et al.  An analysis of peripheral motor nerve stimulation in humans using the magnetic coil. , 1988, Electroencephalography and clinical neurophysiology.

[19]  V. Hömberg,et al.  Central motor conduction to hand and leg muscles in Huntington's disease , 1990, Movement disorders : official journal of the Movement Disorder Society.

[20]  O. Braddick.  The masking of apparent motion in random-dot patterns. , 1973, Vision research.

[21]  B. B. Lee,et al.  Neuronal representation of spectral and spatial stimulus aspects in foveal and parafoveal area 17 of the awake monkey , 2004, Experimental Brain Research.

[22]  B. Day,et al.  ABNORMALITIES IN CENTRAL MOTOR PATHWAY CONDUCTION IN MULTIPLE SCLEROSIS , 1984, The Lancet.

[23]  M. Swash,et al.  Central motor conduction is abnormal in motor neuron disease. , 1987, Journal of neurology, neurosurgery, and psychiatry.

[24]  V. Hömberg,et al.  GENERALISED SEIZURES INDUCED BY TRANSCRANIAL MAGNETIC STIMULATION OF MOTOR CORTEX , 1989, The Lancet.

[25]  N. Bornstein,et al.  Computed tomographic findings of brain and skull in myotonic dystrophy. , 1987, Journal of neurology, neurosurgery, and psychiatry.

[26]  J. C. Rothwell,et al.  The interpretation of electromyographic responses to electrical stimulation of the motor cortex in diseases of the upper motor neurone , 1987, Journal of the Neurological Sciences.

[27]  H. Scheffé.  A METHOD FOR JUDGING ALL CONTRASTS IN THE ANALYSIS OF VARIANCE , 1953 .

[28]  H. Morton,et al.  Stimulation of the cerebral cortex in the intact human subject , 1980, Nature.

[29]  B U Meyer,et al.  Magnetic stimuli applied over motor and visual cortex: influence of coil position and field polarity on motor responses, phosphenes, and eye movements. , 1991, Electroencephalography and clinical neurophysiology. Supplement.