Responses of Human Medial Temporal Lobe Neurons Are Modulated by Stimulus Repetition

Abstract

Here we show how repeated stimulus presentation-photos of celebrities and familiar individuals, landmark buildings, animals, and objects-modulates the firing rate of these cells: a consistent decrease in the neural activity was registered as images were repeatedly shown during experimental sessions. The effect of repeated stimulus presentation was not the same for all medial temporal lobe areas. These findings are consistent with the view that medial temporal lobe neurons link visual percepts to declarative memory.

The functional profile of the human amygdala in affective processing: Insights from intracranial recordings

“…Critically, this selectivity was not linked with the novelty of the event, per se, but to specific stimuli (Pedreira et al, 2010), thus intimating a primacy of intrinsic value (e.g., self-relevance) over novelty alone. While complementary functions such as novelty/familiarity detection, arousal processing and memory should not be discounted, this study suggests that specific amygdala neurons may scan the environment for relevance amongst novel stimuli (Pedreira et al, 2010). While contemporary neuroscience literature supports amygdala relevance processing (Pessoa & Adolphs, 2010;Sander et al, 2003), intracranial data evidence a direct relation between amygdala neuronal activity and relevance processing, both implicitly (Br azdil et al, 2002;Viskontas, Quiroga, & Fried, 2009) and explicitly (Jenison, Rangel, Oya, Kawasaki, & Howard, 2011).…”

“…In further support of this claim, iEEG evidence suggests human amygdala neurons encode events in dissociated segments, organized individually according to category-based or object-based stimulus features (Gelbard-Sagiv et al, 2008;Kreiman et al, 2000a;Paz et al, 2010;Quiroga et al, 2007Quiroga et al, , 2005 and semantic/affective meaning (Naccache et al, 2005;Pedreira et al, 2010;Quian Quiroga et al, 2009). Several single-neuron studies illustrate the amygdala's capacity to selectively encode object categories (Gelbard-Sagiv et al, 2008; Kreiman et al, 2002Kreiman et al, , 2000aMormann et al, 2008;Pourtois, Spinelli, et al, 2010), individual objects (Kreiman et al, 2002;Quiroga et al, 2005, Quian Quiroga et al, 2009, and abstract concepts/images from words (Br azdil et al, 2002;Cameron et al, 2001;Halgren, Babb & Rausch, et al, 1977;Heit et al, 1988;Naccache et al, 2005).…”

“…For instance, relevance may lie in the degree of behavioral or motivational relevance attributed to any given agentic behavior or stimulus, respectively that facilitates the achievement of a personal goal. Importantly, habituation effects discussed above may be due specifically to relevance detection whereby familiar information is filtered for relevance and consolidated while novel information is still treated as potentially relevant until adequate processing confirms or rejects its significance to the individual (Pedreira et al, 2010). In a single-neuron study, Pedreira et al (2010) witnessed high amygdala selectivity to novel events.…”

“…Importantly, habituation effects discussed above may be due specifically to relevance detection whereby familiar information is filtered for relevance and consolidated while novel information is still treated as potentially relevant until adequate processing confirms or rejects its significance to the individual (Pedreira et al, 2010). In a single-neuron study, Pedreira et al (2010) witnessed high amygdala selectivity to novel events. Critically, this selectivity was not linked with the novelty of the event, per se, but to specific stimuli (Pedreira et al, 2010), thus intimating a primacy of intrinsic value (e.g., self-relevance) over novelty alone.…”

“…In a single-neuron study, Pedreira et al (2010) witnessed high amygdala selectivity to novel events. Critically, this selectivity was not linked with the novelty of the event, per se, but to specific stimuli (Pedreira et al, 2010), thus intimating a primacy of intrinsic value (e.g., self-relevance) over novelty alone. While complementary functions such as novelty/familiarity detection, arousal processing and memory should not be discounted, this study suggests that specific amygdala neurons may scan the environment for relevance amongst novel stimuli (Pedreira et al, 2010).…”