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Joseph R Manns

Publications and source records attributed to Joseph R Manns.

9 recordsLinked to original sources
PubMed2006

Hippocampal CA1 spiking during encoding and retrieval: relation to theta phase.

The hippocampal theta rhythm is a prominent oscillation in the field potential observed throughout the hippocampus as a rat investigates stimuli in the environment. A recent computational model [Hasselmo, M. E., Bodelon, C., & Wyble, B. P. (2002a). A proposed function for hippocampal theta rhythm: separate phases of encoding and retrieval enhance reversal of prior learning. Neural Computation, 14, 793-817. Neuromodulation, theta rhythm and rat spatial navigation. Neural Networks, 15, 689-707] suggested that the theta rhythm allows the hippocampal formation to alternate rapidly between conditions that promote memory encoding (strong synaptic input from entorhinal cortex to areas CA3 and CA1) and conditions that promote memory retrieval (strong synaptic input from CA3 to CA1). That model predicted that the preferred theta phase of CA1 spiking should differ for information being encoded versus information being retrieved. In the present study, the spiking activity of CA1 pyramidal cells was recorded while rats performed either an odor-cued delayed nonmatch-to-sample recognition memory test or an object recognition memory task based on the animal's spontaneous preference for novelty. In the test period of both tasks, the preferred theta phase exhibited by CA1 pyramidal cells differed between moments when the rat inspected repeated (match) and non-repeated (nonmatch) items. Also in the present study, additional modeling work extended the previous model to address the mean phase of CA1 spiking associated with stimuli inducing varying levels of retrieval relative to encoding, ranging from novel nonmatch stimuli with no retrieval to highly familiar repeated stimuli with extensive retrieval. The modeling results obtained here demonstrated that the experimentally observed phase differences are consistent with different levels of CA3 synaptic input to CA1 during recognition of repeated items.

Animals↗
PubMed2006

Evolution of declarative memory.

The present review considers research on the hippocampus and related areas from humans and experimental animals and makes three main points. First, many of the anatomical details of the hippocampus and adjacent cortical areas in the parahippocampal region are conserved across mammals. Second, the functional role of these areas in declarative memory is also conserved across species. Third, an evolutionary approach will be key to understanding exactly how the local circuitry of the hippocampus and parahippocampal region supports declarative memory. To highlight the utility of this approach, a schematic model is described in which separate streams of spatial and nonspatial information converge on the hippocampus. By this view, a fundamental function of the mammalian hippocampus is to combine incoming information about spatial context from the postrhinal (parahippocampal in primates) cortex and medial entorhinal area with incoming information about nonspatial items from the perirhinal cortex and lateral entorhinal area. The underlying neurobiological computations that arise from local circuitry enable item-in-context memory and are proposed to be fundamental to many examples of declarative memory, including episodic memory in humans and spatial memory in experimental animals.

Animals↗
PubMed2005

Acquisition of differential delay eyeblink classical conditioning is independent of awareness.

There has been debate about whether differential delay eyeblink conditioning can be acquired without awareness of the stimulus contingencies. In 4 experiments, the authors reexamined this question. Older participants were tested with a tone and white noise (Experiment 1) or with 2 tones (Experiment 2). In addition, younger participants were tested with 2 tones (Experiment 3) or with 2 tones plus the parameters from an earlier study that had reported a relationship between conditioning and awareness (Experiment 4). Participants who were designated aware of the stimulus contingencies and participants who were designated unaware exhibited equivalent levels of differential eyeblink conditioning. Awareness of stimulus contingencies is not required for differential delay eyeblink conditioning when simple conditioned stimuli are used.

Adult↗
PubMed2005

Time and treason to the trisynaptic teachings: theoretical comment on Kesner et Al. (2005).

Early descriptions of the hippocampal formation emphasized the serial nature of its circuitry, a description that suggests even a focal lesion would break a chain of processing and leave the entire region inoperative. Nevertheless, R. P. Kesner, M. R. Hunsaker, and P. E. Gilbert (2005) show that rats with CA1 lesions, but not rats with CA3 lesions, were impaired on a task in which animals were required to make associations between an object and an odor that were separated by a brief (10-s) delay. The present commentary makes 2 points relevant to their findings. First, several lines of evidence suggest that CA1 can operate somewhat independently of CA3 in some instances. Second, it is unclear whether the delay interval acted directly (by requiring a memory for a timeline of events) or indirectly (by outlasting the associative abilities of areas other than CA1) in causing performance to depend on the integrity of CA1.

Animals↗
PubMed2003

Semantic memory and the human hippocampus.

It has been unclear whether the hippocampus is uniquely important for episodic memory (memory for events that are specific to time and place) or whether the hippocampus is also important for learning and remembering facts (semantic memory). In two studies, we assessed the capacity for semantic memory in patients with bilateral damage thought to be restricted primarily to the hippocampal region who developed memory impairment at a known time. Since the onset of their memory impairment, the patients have acquired less factual knowledge than controls. The patients also exhibit temporally limited retrograde amnesia for factual information from the several years preceding the onset of memory impairment. Remote memory for factual knowledge (from 11-30 years before amnesia) is intact. The results show that the hippocampal region supports semantic memory as well as episodic memory and that its role in the acquisition and storage of semantic knowledge is time limited.

Adult↗
PubMed2003

Recognition memory and the human hippocampus.

The capacity for declarative memory depends on the hippocampal region and adjacent cortex within the medial temporal lobe. One of the most widely studied examples of declarative memory is the capacity to recognize recently encountered material as familiar, but uncertainty remains about whether intact recognition memory depends on the hippocampal region itself and, if so, what the nature of the hippocampal contribution might be. Seven patients with bilateral damage thought to be limited primarily to the hippocampal region were impaired on three standard tests of recognition memory. In addition, the patients were impaired to a similar extent at Remembering and Knowing, measures of the two processes thought to support recognition performance: the ability to remember the learning episode (episodic recollection) and the capacity for judging items as familiar (familiarity).

Adult↗
PubMed2002

Standard delay eyeblink classical conditioning is independent of awareness.

P. F. Lovibond and D. R. Shanks (2002) suggested that all forms of classical conditioning depend on awareness of the stimulus contingencies. This article considers the available data for eyeblink classical conditioning, including data from 2 studies (R. E. Clark, J. R. Manns, & L. R. Squire, 2001; J. R. Manns, R. E. Clark, & L. R. Squire, 2001) that were completed too recently to have been considered in their review. In addition, in response to questions raised by P. F. Lovibond and D. R. Shanks, 2 new analyses of data are presented from studies published previously. The available data from humans and experimental animals provide strong evidence that delay eyeblink classical conditioning (but not trace eyeblink classical conditioning) can be acquired and retained independently of the forebrain and independently of awareness. This conclusion applies to standard conditioning paradigms; for example, to single-cue delay conditioning when a tone is used as the conditioned stimulus (CS) and to differential delay conditioning when the positive and negative conditioned stimuli (CS+ and CS-) are a tone and white noise.

Aged↗
PubMedDate not supplied

Impaired visual and odor recognition memory span in patients with hippocampal lesions.

In a recent study, rats with hippocampal lesions performed as well as did unoperated rats on an olfactory memory span task, performing approximately 80% correct even when the span length reached 24 odors. This finding seems potentially at odds with demonstrations that memory-impaired patients typically fail tasks in which large amounts of information must be retained. Accordingly, we have assessed recognition memory span performance for line drawings of objects, designs, and odors in amnesic patients with damage thought to be limited to the hippocampal region. The patients were impaired on all three tasks. We consider possible explanations for the difference between the findings for humans and rats, including the fact that olfactory function is particularly well-developed in rodents.

Adult↗