Verbal novelty detection within the human hippocampus proper

Abstract

Animal studies and neuropsychological tests of patients with temporal lobe epilepsy have demonstrated the importance of human medial temporal lobes for memory formation. In addition, more recent studies have shown that the human hippocampal region is also involved in novelty detection. However, the exact contribution of the hippocampus proper to these processes is still unknown. To examine further its role we compared event-related potentials recorded within the medial temporal lobes in 29 temporal lobe epilepsy patients with and 21 without hippocampal sclerosis. While in patients with extrahippocampal lesions but without hippocampal sclerosis event-related potentials to first presentations and repetitions of words were reduced on the side of the epileptogenic focus, in patients with hippocampal sclerosis only those to first presentations but not to repetitions were affected. Because sclerosis of the hippocampus proper selectively reduced event-related potentials to new but not old verbal stimuli, it can be concluded that the human hippocampus proper contributes to verbal novelty detection.

Memory encoding and hippocampally-based novelty/familiarity discrimination networks

“…As mentioned earlier, we selected the seed voxels for our analysis in the hippocampus because of considerable evidence in the literature about the involvement of the hippocampus in novelty detection [1,2,[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]47]. It is also generally accepted that novelty detection involves regions beyond the hippocampus [ 1,2,12,17,19,20].…”

“…Novelty/familiarity discrimination (also known as novelty detection, or novelty assessment) is useful for the organism in a variety of situations, can take a number of specific forms, and can serve several functions (see reviews by [1][2][3][4]). The hippocampal system has been found to be critically involved in many tasks involving neural novelty/familiarity (henceforth just 'novelty') discrimination [1,2,[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. In this report, we describe a positron emission tomography (PET) study whose purpose was to explore the idea that novelty discrimination does not depend on the hippocampal system alone but is subserved by large-scale neuronal networks which include but go beyond the hippocampal system.…”

Multiple repetitions reveal functionally and anatomically distinct patterns of hippocampal activity during continuous recognition memory

“…These findings suggest that the relationship between hippocampal (and parahippocampal) activity and continuous psychological dimensions, such as item novelty, cannot be captured by a unitary function. Keywords novelty; familiarity; hippocampus; fMRI; high-resolution Consistent with human and animal lesion data implicating MTL in recognition memory (for reviews, see Brown & Aggleton, 2001;Eichenbaum et al, 2007;Squire et al, 2007), fMRI and intracranial (local field potential and single-neuron) recording studies have demonstrated that hippocampal activity is modulated by the study status of recognition test items (e.g., Grunwald et al, 1998;Heit et al, 1988; for a review of fMRI findings, see Henson, 2005). Among event-related fMRI studies employing separate study and test phases, it has occasionally been reported that correctly-recognized (old) items elicit greater hippocampal activity than correctly-rejected (new) items (e.g., Donaldson et al, 2001;Stark & Squire, 2001).…”

Updating P300: An integrative theory of P3a and P3b

“…stimuli, a frontal/central P300 can be elicited with a relatively short peak latency that habituates rapidly (Courchesne et al, 1975;Knight, 1984). This potential has been called the "novelty P300" and is interpreted as reflecting frontal lobe activity related to the hippocampus (Grunwald et al, 1998;Knight, 1996). It is observed across modalities (Fabiani et al, 1998;Yamaguchi and Knight, 1991) and populations Knight, 1987;Yamaguchi et al, 2000).…”