Previous studies of visual memory in ventral temporal lobe cortex have been performed by presenting images to monkeys whose gaze is fixed. Preliminary evidence from Ringo's laboratory has shown that over one-third of the units recorded in memory related areas the temporal lobe, (inferotemporal cortex, parahippocampal gyrus and the hippocampal formation) show significant saccadic modulation. This modulation is apparently not a consequence of a shift in visual scene because: (1) cells show saccadic modulation in complete darkness, (2) many cells modulate before the saccades, and (3) non-visual cells can show saccadic modulation. This has led the investigator to suggest that widespread coherent modulation of temporal lobe neurons by saccades may be important in facilitating memory. The experiments described employ single unit recording in behaving monkeys to test the four hypotheses. The first hypothesis is that saccadic modulation is state dependent. That is, it is augmented by general arousal, selective attention to vision and/or purposive command. This will be tested by recording saccades in a broad area of the temporal lobe during auditory and visual tracking and discrimination tasks, and at rest. The second hypothesis, that saccadic modulation has a subcortical route, will be tested by using split brain, cut chiasm monkeys. A subcortical route, will be likely if light delivered to the contralateral eye is capable of modifying the discharge of cells that saccade-modulate in the light in the ipsilateral hemisphere. The third hypothesis is that saccadic modulation has a non-visual role and is therefore found in non-visual cells. To find a population of non- visual cells, studies will be expanded into the upper bank of the superior temporal sulcus, where polymodal cells can be found. The fourth hypothesis is that saccadic modulation functions as a memory modulator and increases single unit memory effects. This will be tested by comparing the amplitude of the decrement with repetition phenomenon in a saccade task and in a fixed gaze task. The prediction here is that decrement in response to a reyeated presentation of a novel stimuli will be greater when the monkey uses saccades to view the new images compared to fixed gaze viewing (the greater the decrement the less novel or the more """"""""remembered"""""""" is the cue).

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS026526-08
Application #
2265971
Study Section
Biopsychology Study Section (BPO)
Project Start
1988-07-01
Project End
1997-06-30
Budget Start
1995-07-01
Budget End
1996-06-30
Support Year
8
Fiscal Year
1995
Total Cost
Indirect Cost
Name
University of Rochester
Department
Physiology
Type
Schools of Dentistry
DUNS #
208469486
City
Rochester
State
NY
Country
United States
Zip Code
14627
Sobotka, S; Nowicka, A; Ringo, J L (1997) Activity linked to externally cued saccades in single units recorded from hippocampal, parahippocampal, and inferotemporal areas of macaques. J Neurophysiol 78:2156-63
Sobotka, S; Ringo, J L (1997) Saccadic eye movements, even in darkness, generate event-related potentials recorded in medial sputum and medial temporal cortex. Brain Res 756:168-73
Ringo, J L (1996) Stimulus specific adaptation in inferior temporal and medial temporal cortex of the monkey. Behav Brain Res 76:191-7
Sobotka, S; Ringo, J L (1996) Mnemonic responses of single units recorded from monkey inferotemporal cortex, accessed via transcommissural versus direct pathways: a dissociation between unit activity and behavior. J Neurosci 16:4222-30
Ringo, J L (1995) Brevity of processing in a mnemonic task. J Neurophysiol 73:1712-5
Ringo, J L; Sobotka, S; Diltz, M D et al. (1994) Eye movements modulate activity in hippocampal, parahippocampal, and inferotemporal neurons. J Neurophysiol 71:1285-8
Sobotka, S; Ringo, J L (1994) Stimulus specific adaptation in excited but not in inhibited cells in inferotemporal cortex of macaque. Brain Res 646:95-9
Ringo, J L; Doty, R W; Demeter, S et al. (1994) Time is of the essence: a conjecture that hemispheric specialization arises from interhemispheric conduction delay. Cereb Cortex 4:331-43
Sobotka, S; Ringo, J L (1993) Investigation of long-term recognition and association memory in unit responses from inferotemporal cortex. Exp Brain Res 96:28-38
Ringo, J L; O'Neill, S G (1993) Indirect inputs to ventral temporal cortex of monkey: the influence of unit activity of alerting auditory input, interhemispheric subcortical visual input, reward, and the behavioral response. J Neurophysiol 70:2215-25

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