We have developed a prototype of a multichannel electrode system for recording neural spikes and slow wave activity in acute and chronic vertebrate preparations. From the experience of our initial success with problems in cat visual cortex, we propose modifications that will considerably enhance the system's performance. The modified multichannel electrode will have 22 recording sites and 2 lesion site spanning 2.4 mm and spaced at 100 um intervals along its edge. By the use of integrated circuit technology, the electrode will be built in layers of silicon nitride, platinum, and silicon nitride on a molydenum substrate. The total thickness will only be 20 um and the maximum width at the base of its wedge shape will be 135 um. A modified coonnector will be built that will allow quick replacement of damaged electrodes. It will be small enough for moving preparations, and will contain preamplifiers in a hybrid of IC chips. An amplifier array will also be built to process both unit and slow wave activity. Evaluation of the electrode will be performed by standard electrical tests and by extensive use in vivo. The rat hippocampus is a particularly useful test preparation because of its well studied physiology, distinctive lamination of cellular subpopulations, anatomically separated inputs and outputs, and characteristic slow wave pattern and related unitary activity. Recording performance of the multichannel electrode will be compared with that of a conventional metal microelectrode in 3 measures of neural activity. 1) laminar patterns of field potentials evoked by electrical stimulation of known pathways, 2) laminar amplitude and phase relationships of the theta rhythm, and 3) sensitivity and selectivity for unit activity and fixing patterns in relationship to theta cycle. These evaluations will be carried out in both urethane anesthetized and awake, behaving preparations to examine the generality of the system's usefulness as a new tool for the study of local circuit interactions.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS018744-06
Application #
3398774
Study Section
Surgery and Bioengineering Study Section (SB)
Project Start
1983-01-01
Project End
1989-03-31
Budget Start
1988-01-01
Budget End
1989-03-31
Support Year
6
Fiscal Year
1988
Total Cost
Indirect Cost
Name
Wellesley College
Department
Type
Schools of Arts and Sciences
DUNS #
City
Wellesley
State
MA
Country
United States
Zip Code
02481
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Eichenbaum, H; Mathews, P; Cohen, N J (1989) Further studies of hippocampal representation during odor discrimination learning. Behav Neurosci 103:1207-16
Eichenbaum, H; Wiener, S I; Shapiro, M L et al. (1989) The organization of spatial coding in the hippocampus: a study of neural ensemble activity. J Neurosci 9:2764-75
Eichenbaum, H; Fagan, A; Mathews, P et al. (1988) Hippocampal system dysfunction and odor discrimination learning in rats: impairment or facilitation depending on representational demands. Behav Neurosci 102:331-9
Eichenbaum, H; Kuperstein, M; Fagan, A et al. (1987) Cue-sampling and goal-approach correlates of hippocampal unit activity in rats performing an odor-discrimination task. J Neurosci 7:716-32
Kuperstein, M; Eichenbaum, H; VanDeMark, T (1986) Neural group properties in the rat hippocampus during the theta rhythm. Exp Brain Res 61:438-42
Eichenbaum, H; Fagan, A; Cohen, N J (1986) Normal olfactory discrimination learning set and facilitation of reversal learning after medial-temporal damage in rats: implications for an account of preserved learning abilities in amnesia. J Neurosci 6:1876-84
Kuperstein, M; Eichenbaum, H (1985) Unit activity, evoked potentials and slow waves in the rat hippocampus and olfactory bulb recorded with a 24-channel microelectrode. Neuroscience 15:703-12
Fagan, A; Eichenbaum, H; Cohen, N (1985) Normal learning set and facilitation of reversal learning in rats with combined fornix-amygdala lesions: implications for preserved learning abilities in amnesia. Ann N Y Acad Sci 444:510-2