A large body of evidence in humans suggests that recognition memory can be supported by both recollection and familiarity. Recollection-based recognition is characterized by the retrieval of contextual information about the episode in which an item was previously encountered, whereas familiarity-based recognition is characterized instead by knowledge only that the item had been encountered previously in the absence of any context. To date, it is unknown whether monkeys rely on similar mnemonic processes to perform recognition memory tasks. Here, we present evidence from the analysis of receiver operating characteristics, suggesting that visual recognition memory in rhesus monkeys also can be supported by two separate processes and that these processes have features considered to be characteristic of recollection and familiarity. Thus, the present study provides converging evidence across species for a dual process model of recognition memory and opens up the possibility of studying the neural mechanisms of recognition memory in nonhuman primates on tasks that are highly similar to the ones used in humans. I n humans, dual process models of recognition memory, although different in detail, share the core idea that both recollection and familiarity contribute to this mnemonic function (1-5). Recollection is characterized by the retrieval of contextual information about the episode in which an item was encountered, whereas familiarity lacks this context, relying solely on knowledge of prior occurrence. The possibility that nonhuman animals also use separable memory processes to solve recognition memory tasks has begun to be experimentally addressed (6-8), an important shift, inasmuch as an understanding of how the brain gives rise to different memory functions in various species is critical for relating molecular and cellular findings in animals to behavioral and neuroimaging research conducted in humans.Recollection and familiarity are commonly viewed as retrieval processes that support potentially independent routes of cognitive access to stored information. This distinction has been operationalized based on the analysis of receiver operating characteristics (ROCs) (5). ROCs in recognition memory relate the proportion of correctly recognized repeated or old items (hit rate) to the proportion of incorrectly recognized novel distracters (false alarm rate) as a function of response criterion (bias to respond "old"). In a typical recognition memory test aimed at characterizing ROCs, subjects would encounter a list of previously studied items intermixed with new items and be asked to rate how confidently they recognize each item on an arbitrary scale [e.g., ranging from one (sure that it is new) to six (sure that it is old), with two to five reflecting less confident judgments]. These confidence ratings represent different decision criteria, and an ROC curve is produced by plotting the hit rate against the corresponding false alarm rate as a function of decision criterion.Recognition memory ROCs in humans are typicall...

Critical illness and sepsis are commonly associated with subclinical seizures. COVID-19 frequently causes severe critical illness, but the incidence of electrographic seizures in patients with COVID-19 has been reported to be low. This retrospective case series assessed the incidence of and risks for electrographic seizures in patients hospitalized with COVID-19 who underwent continuous video electroencephalography monitoring (cvEEG) between March 1st, 2020 and June 30th, 2020. One hundred and twenty-two patients were initially identified who resulted SARS-CoV-2 nasopharyngeal RT-PCR swab positivity with any electroencephalography order placed in the EMR. Seventy-nine patients met study inclusion criteria: age ≥18 years, >1 h of cvEEG monitoring, and positive SARS-CoV-2 nasopharyngeal swab PCR. Six (8%) of the 79 patients suffered electrographic seizures (ES), three of whom suffered non-convulsive status epilepticus. Acute hyperkinetic movements were the most common reason for cvEEG in patients with ES (84%). None of the patients undergoing cvEEG for persistent coma (29% of all patients) had ES. Focal slowing (67 vs. 10%), sporadic interictal epileptiform discharges (EDs; 33 vs. 6%), and periodic/rhythmic EDs (67 vs. 1%) were proportionally more frequent among patients with electrographic seizures than those without these seizures. While 15% of patients without ES had generalized periodic discharges (GPDs) with triphasic morphology on EEG, none of the patients with ES had this pattern. Further study is required to assess the predictive values of these risk factors on electrographic seizure incidence and subsequent outcomes.

HighlightsThis study was done to evaluate differences in artifacts between the collodion and paste method of EEG administration.Electrode problems are common with both collodion and paste in prolonged AEEG monitoring.For studies less than 24 h, collodion may be a better alternative.